investigation of the wear characteristics of helical …hamid et al., 2017 382 table 2 wear debris...

Proceedings of Mechanical Engineering Research Day 2017, pp. 381-382, May 2017

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© Centre for Advanced Research on Energy

Investigation of the wear characteristics of helical gear using wear debris analysis

A.H.A. Hamid1,2,*, R.M. Dan1,2, N.I. Zulkafli1,2, A. Putra1,2, R.K. Mazlan1,2

1) Faculty of Mechanical Engineering, Universiti Teknikal Malaysia Melaka,

Hang Tuah Jaya, 76100 Durian Tunggal, Melaka, Malaysia. 2) Centre for Advanced Research on Energy, Universiti Teknikal Malaysia Melaka,

Hang Tuah Jaya, 76100 Durian Tunggal, Melaka, Malaysia.

*Corresponding e-mail: [email protected]

Keywords: Wear characteristic; wear debris analysis; helical gear

ABSTRACT – The focus of this research is to quantify

the wear characteristics of carbon steel helical gear

operating under controlled condition. Helical gears were

tested on a power recirculating gear test rig with loads of

up to 40 Nm and speed of 1000 rpm. Approximately 30

ml of samples were taken at 1 hour intervals. The samples

were analysed using wear debris analysis and oil

analysis. It is discovered that wear can be characterised

accurately using wear debris.

1. INTRODUCTION

Gears are the mechanism to transmit power by two

surfaces that are in contact with each other which are

common in most machines that utilizes mechanical

transmission. Even the most properly designed, well

fabricated, well fabricated and installed gears will

generally experience failure to fatigue of the meshing

surfaces [1]. Wears are vital to be identified and analysed

to estimate the life of the gear. Numerous past research

has focused on the study of wear of the gear utilizing

condition monitoring tools [2-5]. Helical gears are

chosen for the study due to its high load carrying

capacity, high speed transmission and low noise

operation.

The objective of this study is to investigate the

possibility of wear debris analysis to characterise the

wear of the gear.

2. METHODOLOGY

2.1 Helical gear and lubricant specification

The tested helical gears are in a meshing

configuration and the test is conducted at ambient

condition.

Table 1 Helical gear and lubricant specification.

Specification Value

Gear material AISI 4140, Carburize

No. of teeth 35

Helix angle 17.750

Pitch diameter 110.25 mm

Lubricant Dexron III ATF

2.2 Power recirculating gear test rig

The test rig as shown in Figure 1 is constructed to

deliver approximately 40 Nm of load and rotational speed

of 1000 rpm. Torque transducer is installed to ensure the

loading is accurate as possible.

Figure 1 Gear test rig schematics.

Oil sampling were conducted every hour for 80

hours and test were conducted using wear debris analysis

and IR spectroscopy which follows ASTM D7416 and

ASTM D7889 respectively.

3. RESULTS AND DISCUSSION

The result for the wear debris analysis is highlighted

on ferrous content and at significant point in time for the

gear wear as shown in Table 2 to 6 and the type of wear

from the particle shape are generalized [6-8].

From Table 2, platelets of ferrous composition

started to be observed suggesting that rubbing wear

which is an abrasive wear started to occur. Rubbing wear

is expected during the initial surface contact. A smoother

gear is expected and the rubbing wear reaches optimum

condition per time.

From Table 3, needles ferrous particles is observed

which suggests a surface fatigue of fretting occurring.

Fretting wear occurs due to the meshing surface of the

helical gear experiencing cycling load or vibration.

Hamid et al., 2017

382

Table 2 Wear debris analysis at 1st hour.

Conc. Avg. size Shape Comp Severity

Moderate Med 13-40µ Platelets Ferrous Low

Moderate - Platelets Ferrous Low

Moderate - Platelets Ferrous Low

Table 3 Wear debris analysis at 20th hour.


Moderate Small 6-14µ Platelets Ferrous Low

Few Small 6-14µ Needles Ferrous Low

From Table 4, ribbons ferrous particles suggest that

cutting wear which is an abrasive have started to occur

caused by the gear surface cutting. The presence of

chunks ferrous particles suggests that multiple wear

modes which indicates that a high load or excessive

rotational gear speed. This also indicates that the machine

cycle has entered a steady wear rate.




Few Small 6-14µ Chunks Ferrous Low

Moderate Fine<6µ Ribbons Ferrous Low

Few Small 6-14µ Needles Ferrous Low

From Table 5, at this stage, chunks particle

concentration has entered a high severity due to

progressive wear caused by the chunks as it becomes

involved in the contact fatigue of the helical gear.



Few Med 14-40µ Platelets Ferrous Low

Moderate Fine<6µ Ribbons Ferrous Low

Moderate Med 14-40µ Chunks Ferrous High

From Table 6, signs of progressive wear are not

significant due to the machine cycle entering wear

optimum condition. It is noted that the helical gear has no

significant surface wear visible except for minor scuffing

and minor pitting. It is also noted that the cutting wear

and rubbing has decreased or stopped.




Many Med 14-40µ Chunks Ferrous Low

4. CONCLUSION

The investigative study leads to various results

where it is found that the wear debris analysis can

accurately predict the condition of the machine wear rate

by identifying the particles shape, size, concentration,

composition as well as the severity of the profile. Particle

shape can be utilized to identify the wear mode occurred

to the gear and at the same time could predict the wear

rate profile of the gear. It is observed from the condition

of the experimented gear that it have reached an optimum

wear rate. Thus, the wear of the helical is successfully

characterize through wear debris analysis.

REFERENCES

[1] P.J.L. Fernandes and C. McDuling, “Surface contact

fatigue failure in gears,” Engineering Failure

Analysis, vol. 4, pp. 99-107, 1997.

[2] S. Feng, B. Fan, J. Mao and Y. Xie, “Prediction on

wear of a spur gearbox by on-line wear debris

concentration monitoring,” Wear, vol. 336-337, pp.

1-8, 2015.

[3] V. Fontanari, M. Benedetti, C. Girardi and L.

Giordanino, “Investigation of the lubricated wear

behavior of ductile cast iron and quenched and

tempered alloy steel for possible use in worm

gearing,” Wear, vol. 350-351, pp. 68-73, 2016.

[4] Z. Peng, N.J. Kessissoglou and M. Cox, “A study of

the effect of contaminant particles in lubricants

using wear debris analysis and vibration condition

monitoring techniques,” Wear, vol. 258, no. 11-12,

pp. 1651-1662, 2005.

[5] M. Amarnath and I.R.P. Krishna, “Detection and

diagnosis of surface wear failure in a spur geared

system using EEMD based vibration signal

analysis,” Tribology International, vol. 61, pp. 224-

234, 2013.

[6] D.P. Anderson, “Wear particle atlas,” Naval Air

Engineering Centre, 1982.

[7] B.J. Roylance and M.T. Hunt, “Wear debris

analysis: machine and systems condition

monitoring series,” Coxmoor publishing company,

1999.

[8] B.J. Roylance and S. Raadnui, “The morphological

attributes of wear particles – their role in identifying

wear mechanism,” Wear, vol. 175, pp. 115-121,

1994.


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Electrical conductivity and mechanical properties of graphite/carbon black/carbon nanotube/polypropylene nanocomposites

A. Bairan1,2, M.Z. Selamat1,2,*, S.N. Sahadan1,2, S.D. Malingam1,2, N. Mohamad3


Hang Tuah Jaya, 76100 Durian Tunggal, Melaka, Malaysia. 2) Centre for Advanced Research on Energy, Universiti Teknikal Malaysia Melaka,

Hang Tuah Jaya, 76100 Durian Tunggal, Melaka, Malaysia.

3) Faculty of Manufacturing Engineering, Universiti Teknikal Malaysia Melaka,

Hang Tuah Jaya, 76100 Durian Tunggal, Melaka, Malaysia


Keywords: Carbon nanotube; conductive polymer composites; electrical conductivity

ABSTRACT – The properties of conductive polymer

composites (CPCs) can be improved by the addition of

carbon nanotube (CNTs). This research focuses on vary

of composite composition based on polymer matrix and

carbonaceous fillers including Graphite (G), Carbon

Black (CB) and CNTs in order to improve electrical and

mechanical properties of composites according to the

requirement for bipolar plate material stated by the

United State Department of Energy (U.S DOE). It is

found that the effect of small additions of CNTs (5 wt%)

has been increasing electrical conductivity up to 518.9

S/cm while flexural strengths increase from 41.35 MPa

to 61.43 MPa.

1. INTRODUCTION

The use of carbonaceous fillers in the production

of polymer composites to enhance their electrical

properties has attracted considerable industrial attention

because of the high conductivity, low weight, and ease

of processing of these materials, among other

properties[1–3]. Therefore, researches have selected

different reinforcements including carbon fiber (CF),

carbon black (CB), and carbon nanotube (CNTs) to

prepare reinforced composite bipolar plates to meet the

optimum composition for composite bipolar plates [4].

Among these reinforcements, CNTs exhibit the suitable

nanomaterials to fabricate high performance

nanocomposite bipolar plates due to their extraordinary

intrinsic properties [4,5] and relatively low quantity of

loading for the same reinforcing effect [7]. On the other

hand, CB and G have been considered the more

versatile and low-cost fillers for preparing of CPCs

compared to CNTs.

CNTs have the potential to improve the properties

of such highly filled compounds when used in

combination with other filler materials [6]. CNTs

generally form large agglomerates and the biggest

challenge is to disentangle and to disperse the CNTs

agglomerates during the process of melt-compounding

[8]. To incorporate the CNT homogenously distributed

into a polymeric matrix is necessary to achieve high

conductivities of such materials even at low CNTs

content.

The present work is an extension of the work

reported earlier by Selamat et al. [5] with emphases on

effect of CNTs on properties of G/CB/PP

nanocomposites.

2. METHODOLOGY

2.1 Materials

Polypropylene (PP) grade Titan 600 which was

purchased from Polypropylene (PP) Malaysia Sdn. Bhd

used as matrix material. Graphite powder and Carbon

Black powder purchased from Asbury Carbon, New

Jersey was selected as primary and secondary

conductive filler respectively. The third conductive filler

used in this study is Multiwall carbon nanotubes

(CNTs), with grade name: NC7000 (average diameter of

9.5nm, average length of 1.5µm, 90% carbon purity)

from Nanocyl, Belgium.

2.2 Sample preparation

G, CB and CNTs were mixed in a ball mill to get a

homogenous mixture. Then, Rheomix mixer Haake-

Polylab TM with roller type rotors is used and the

material from the previous stage is mixed and the

composition as shown in Table 1. The nanocomposite

obtained by melt compounding was crushed and

pulverized into powders in order to improve

homogeneity of the specimen for next forming process.

A hot press machine was used to shape the samples for

properties measurements. The mixture of all material

was then preheated for 20 min in a mould placed in the

hot pressing machine before it pressed at a temperature

of 185 ºC and a pressure of 85 kg/cm2 for 15 min.


From the Figure 1, it shown that the electrical

conductivity of G/CB/CNTs/PP composites increases

initially with increment CNTs content went from 0 wt%

up to 5.0 wt%. But, the electrical conductivity drops

after further addition of CNTs due to agglomeration [4].

The flexural strength increases with the increment

of CNTs content and a maximum flexural strength of

61.43 MPa was obtained at 5 wt.% CNTs as shown in

Figure 2. This phenomena occurs due to the high

Bairan et al., 2017

384

mechanical strength possessed by the CNTs, which

leads to an increase in the flexural strength of the

composite [2]. But, the flexural strength also drops after

further addition of CNTs due to agglomeration [4].

Table 1 The composition of composite G/CB/CNTs/PP

(based on weight %).

Filler Binder

G % CB% CNTs% PP%

55.0 25 0 20

54.0 25 1.0 20

53.0 25 2.0 20

52.0 25 3.0 20

51.0 25 4.0 20

50.0 25 5.0 20

49.0 25 6.0 20

48.0 25 7.0 20

47.0 25 8.0 20

Figure 1 Electrical conductivity of various CNTs

content.

Figure 2 Flexural strength of various CNTs content.

Shore hardness and density results are shown in

Figure 3, where the maximum density occurs at 5 wt.%

CNTs. The addition of CNTs decrease the hardness from

65.1 at 1 wt% to 51.2 at 8 wt.% CNTs. With a greater

addition of CNTs, the hardness drops due to

agglomeration, which leads to a poor hardness [5].

4. CONCLUSION

In summary, the findings provide insights that the

G/CB/CNTs/PP composite with 5wt.% CNTs has

synergistic effect in the electrical conductivity, flexural

strength, bulk density and hardness of the composite

which are exceeded of U.S. DOE requirements.

Figure 3 Shore hardness and density of various CNTs

content.

ACKNOWLEDGEMENT

Grant no.: PJP/2013/FKM(6A)/S01181

REFERENCES

[1] M. Wen, X. Sun, L. Su, J. Shen, J. Li and S. Guo,

“The electrical conductivity of carbon

nanotube/carbon black/polypropylene composites

prepared through multistage stretching extrusion,”

Polymer (Guildf)., vol. 53, no. 7, pp. 1602–1610,

Mar. 2012.

[2] H. Suherman, J. Sahari, A.B. Sulong and N.

Royan, “Electrical Conductivity and Flexural

Strength of Graphite/Carbon Nanotubes/Epoxy

Nanocomposites,” Key Eng. Mater., vol. 447–448,

no. October 2015, pp. 643–647, 2010.

[3] M.Z. Selamat, J. Sahari, N. Muhamad and A.

Muchtar, “The effects of thickness reduction and

particle sizes on the properties graphite -

Polypropylene composite,” Int. J. Mech. Mater.

Eng., vol. 6, no. 2, pp. 194–200, 2011.

[4] A. Bairan, M. Selamat, S. Sahadan and S.

Malingam, “Effect of Carbon Nanotubes Loading

in Multifiller Polymer Composite as Bipolar Plate

for PEM Fuel Cell,” Procedia, vol. 19, pp. 91–97,

2016.

[5] M.Z. Selamat, M.S. Ahmad, M.A. Mohd Daud and

N. Ahmad, “Effect of Carbon Nanotubes on

Properties of Graphite/Carbon

Black/Polypropylene Nanocomposites,” Adv.

Mater. Res., vol. 795, pp. 29–34, Sep. 2013.

[6] M.C.L. de Oliveira, G. Ett and R.A. Antunes,

“Materials selection for bipolar plates for polymer

electrolyte membrane fuel cells using the Ashby

approach,” J. Power Sources, vol. 206, pp. 3–13,

May 2012.

[7] M.C. Hsiao, S.H. Liao, M.Y. Yen, A. Su, I.T. Wu,

M.H. Hsiao, S.J. Lee, C.C. Teng and C.C.M. Ma,

“Effect of graphite sizes and carbon nanotubes

content on flowability of bulk-molding compound

and formability of the composite bipolar plate for

fuel cell,” J. Power Sources, vol. 195, no. 17, pp.

5645–5650, Sep. 2010.

[8] M. Grundler, T. Derieth, P. Beckhaus, A. Heinzel

and F. Cell, “CarbonNanoTubes ( CNT ) in Bipolar

Plates for PEM Fuel Cell Applications

CarbonNanoTubes ( CNT ) in Bipolar Plates for

PEM Fuel Cell Applications,” vol. 78, 2010.

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Investigation on properties of woven kenaf fiber reinforced polypropylene composite

N.F.M. Zalani1, D. Sivakumar1,2,*, M.Z. Selamat1,2


Hang Tuah Jaya, 76100 Durian Tunggal, Melaka, Malaysia 2) Centre for Advanced Research on Energy, Universiti Teknikal Malaysia Melaka,



Keywords: Tensile; woven kenaf; natural fiber composite

ABSTRACT – In this study, natural fiber reinforced

thermoplastics composites were fabricated using hot

compression method. The composites were fabricated

with different stacking angle orientation of three layers

of woven kenaf fiber with polypropylene matrix

producing a composite panel with a nominal thickness

of 2 mm. The tensile test was conducted according to

ASTM D3039 using Universal Testing Machine, Instron

model 5969. The results show fiber stacking influences

the tensile strength and strain of the composites.

Hardness and density measurement test also were

conducted to identify physical properties of the

composite samples.

1. INTRODUCTION

Composite materials have been used in aerospace

industries since a long time ago [1]. Composites can be

bonded with metallic alloy to improve the performance

of the materials. The presence of fibres in that laminate

structure can enhance the fatigue life of the structures

[2]. Numerous advantages of natural fiber over synthetic

fiber have caught the attention of most researchers in

the materials field applications, especially in automotive

and aerospace. The high performance of the composite

structure is tremendously being explored due to their

superior mechanical properties which are light weight

and high specific stiffness. There are many other

advantages of using natural fiber instead of synthetic

fiber such as the availability, low cost, light weight, high

specific strength and the most important is

biodegradable [3].

Recently, the thermoplastic-based composites have

become a focus due to the ability of rapid

manufacturing and recyclability advantages compared

to thermoset [4]. The use of natural fiber composites has

increased rapidly due to both economical and

environmentally benefits. Among all the natural fibers

that have been employed in combination with plastics,

kenaf is chosen since they are widely used in this new

century. Also, kenaf is one of the biggest crops that have

high potential to replace tobacco in Malaysia [5]. Kenaf

(Hibiscus Cannabinus) is an annual growth plant which

is in Malvaceae family group. Kenaf plant can grow up

to 12 feet and a type of fast growing plant dependent on

the cultivation, time of planting, harvesting process,

water retting treatments and the processing to get the

fiber [3].

Studies of woven kenaf natural fiber have been

relatively scanty and there are limited studies focusing

on woven kenaf fiber and thermoplastic polypropylene

resin. This present study investigates the tensile

behaviour of the laminated woven kenaf fiber reinforced

polypropylene (kenaf/PP) composite. The effect of three

layers of woven kenaf/PP composite with different

stacking angle orientation of 0°, 45° and various

combinations of the laminate systems were tested and

the failure was analysed.

2. METHODOLOGY

The woven kenaf/PP composite panel consists of

three layers of woven kenaf fiber with different stacking

orientations which are 0°, 45° and combination of both

0°and 45° angle in polypropylene matrix. Table 1 shows

the sample coding and the stacking sequence of the

composite panel produced. The fabrication process

started with the production of PP sheet. Then the orderly

layered woven kenaf fiber was sandwiched in between

PP sheets and placed into a stainless steel picture frame

mould 200×200×2 mm (length×width×thickness). The

laminated structure was compressed using hot press

machine at a temperature of 180℃ and pressure of 50

kg/cm2 for 10 minutes.

Tensile test for kenaf/PP composite was performed

according to ASTM D3039 using Universal Testing

Machine (UTM) Instron model 5969 with a load cell of

50 kN at a speed rate of 2 mm/min. Hardness test was

conducted using shore-D hardness device in accordance

to ASTM D2240 while density test was performed

according to ASTM D792 using densimeter. Three

samples were tested for each orientation to get the

average.

Table 1 Stacking orientation of composite.

Sample Orientation (°)

Polypropylene -

Composite A 0-0-0

Composite B 0-45-0

Composite C 45-0-45

Composite D 45-45-45

Zalani et al., 2017

386


Tensile strength is an essential test for a specimen

to test how the material reacts to the applied tension

load and to predict the material engineering

performance. The result shows that for all types of

composite, the tensile strength is better compared to

virgin polypropylene. Figure 1 shows the trend graph of

stress versus strain for woven kenaf/PP composite. It

can be seen that the stress is directly proportional to the

extension until fracture. The graph shows Composite B

has the highest tensile stress with 29.97 MPa. This

might be due to Composite B consist of a combination

of two layers 0⁰ and one layer of 45⁰ fiber angle that

make the composite the strongest among all.

The highest strain indicated by Composite D

which can extend up to 0.053. This might happen due to

angle orientation of fiber which contains all woven

kenaf fiber with 45⁰. Fiber that aligned with 45⁰ angle

experiences trellis effect and is less stiff compare to 0⁰. The phenomena can be seen by referring to the graph

which shows Composite A with all 0⁰ has the lowest

strain value followed by Composite B, Composite C and

Composite D that contain one, two and three layers of

woven kenaf of 45⁰ angle respectively.

Figure 1 Stress-strain graph.

Figure 2 Hardness and density for composite.

Hardness and density results for the tested sample

were analysed and illustrated in Figure 2. Closer

examination of fracture surfaces revealed the fiber

elongates more than PP before fracture which greatly

affect the tensile properties of composite material

compared to virgin PP [6]. Besides, composites give

greater hardness than polypropylene. Composite C is the

hardest among all sample with 19.33 shore-D while PP

has the lowest reading value of hardness with 15.387

shore-D. Furthermore, density measurement test shows

that composites with 45° angle orientation is denser

than 0°. Composite D is the densest with 8.613 g/cm3

since it contains all 45° angle of kenaf fiber while PP

shows the lowest density of only 6.380 g/cm3. Kenaf

woven fiber with 45° angle orientation has higher

mass thus resulted in higher density for fabricated

composite.

4. CONCLUSIONS

The stacking orientation indeed has an effect on

the tensile results. All composite fabricated has a higher

yield and tensile stress, hardness, and density compared

to virgin polypropylene. The overall analysis shows that

Composite D has the highest tensile strain and highest

density among all the composites fabricated while the

highest tensile stress was shown by Composite B and

the hardest composite was demonstrated by Composite

C. The significant of this analysis confirm that the

stacking angle orientation affected the tensile properties

of the composite.

ACKNOWLEDGEMENT

Authors would like to thank Universiti Teknikal

Malaysia Melaka and Ministry of Higher Education for

supporting this research under

ERGS/2013/FKM/TK01/02/07/E00018. Deepest

gratitude to Lembaga Kenaf dan Tembakau Negara for

sponsoring kenaf fiber for this research.

REFERENCES

[1] S. DharMalingam, P. Compston and S.

Kalyanasundaram, “Process variables optimisation

of polypropylene based fibre–metal laminates

forming using finite element analysis,” Key Eng.

Mater., vol. 410-411, pp. 263-269, 2009.

[2] S. DharMalingam, “An investigation into the

forming behavior of metal composite hybrids,”

Ph.D. Thesis, The Australian National University,

Canberra, 2011.

[3] M.A.C. Mahzan. S. DharMalingam, M.H.R.

Hashim, M.R. Said, A. Rivai, M.A. Daud and

Sivaraos, “Effect of Reprocessing Palm Fiber

Composite on the Mechanical Properties,” Appl.

Mech. Mater., vol. 699, pp. 146–150, 2014.

[4] A.N. Kasim, M.Z. Selamat, M.A.M. Daud, M.Y.

Yaakob, A. Putra and D. Sivakumar, “Mechanical

properties of polypropylene composites reinforced

with alkaline treated pineapple leaf fibre from

Josapine cultivar,” Int. J. Automot. Mech. Eng.,

vol. 1, no. 1, pp. 3157–3167, 2016.

[5] M.F.M. Noor, “buletin lktn.pdf,” Lembaga Kenaf

dan Tembakau Negara, p. 7, 2015.

[6] R. Yahaya, S. Sapuan, M. Jawaid, Z. Leman, and

E. Zainudin, “Mechanical performance of woven

kenaf-Kevlar hybrid composites,” J. Reinf. Plast.

Compos., vol. 33, no. 24, pp. 2242–2254, 2014.

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Fabrication and evaluation of nylon 6 electrospun nanofibre water filtration media for removing suspended solid

N.S.A. Roslan1, A.H. Nurfaizey1,2,*, M.I. Mohamed Hafiz1,2, M.R. Mansor1,2, N.A. Munajat1, Z. Mustafa3



Hang Tuah Jaya, 76100 Durian Tunggal, Melaka, Malaysia 3) Faculty of Manufacturing Engineering, Universiti Teknikal Malaysia Melaka,



Keywords: Electrospinning; electrospun nanofibre; filtration; suspended solid

ABSTRACT – Turbidity of river waters due to the

presence of solid suspensions is a real challenge for

many developing countries. This study is about

fabrication and evaluation of nanofibres incorporated

water filters for removing suspended solids. Nylon 6

nanofibres were electrospun onto standard glass fibre

filters. Evaluations were conducted based on BS EN

872 method and a spectrophotometer. The morphology

of the fibres was studied using a scanning electron

microscope and ImageJ software. From the results,

nanofibres incorporated filters exhibited superior

performances compared to standard filters. Findings

from this study are useful for developing new type of

efficient water filters.

1. INTRODUCTION

As in many developing countries, control of water

pollution in Malaysia faces a serious challenge due to

rapid development. Furthermore, residues or wastes

disposed into the river streams from industries could be

incompletely degraded or removed during wastewater

treatment. For example, the increase of solid particles

which remain in suspension in water also known as

suspended solids would be harmful to aquatic life. As a

result, there will be less amount of dissolved oxygen in

water thus fewer living organisms could inhabit the

polluted water [1]. Filter manufacturers are

continuously looking for ways to improve their filtration

technologies including the use of new class of materials.

Submicron-sized fibres could be a potential candidate to

replace fibrous materials used in conventional filtration

medias [2].

Electrospinning is a process for producing

polymeric fibres with submicron-range in diameter

using electric charge [3]. Electrospun nanofibers can be

formed into highly porous mesh with high specific

surface area, good interconnectivity of pores and the

potential to incorporate active materials [4]. These

unique characteristics of electrospun nanofibres make it

desirable for filtration applications. Bjorge et al. [5]

showed that polyamide nanofibre membrane managed

to capture 99.71% of total suspended solid (TSS).

Asmatulu et al. [6] demonstrated that drinkable level of

water could be achieved using nanofibre membranes.

In this study, Nylon 6 electrospun nanofiber

incorporated filters were fabricated and the performance

of the filters was evaluated based on standard TSS

evaluation methods. The knowledge gained from this

study is important for developing new generation of

efficient filtration media.

2. METHODOLOGY

Electrospinning process was carried out using a

laboratory scale electrospinning machine (Model ES1a,

Electrospinz, NZ). Polymer solution was prepared by

dissolving Nylon 6 pellets (Sigma-Aldrich 181110) in

formic acid (Merck 1002642500) to a final

concentration of 20 wt.%. A constant applied voltage of

14 kV was used throughout the electrospinning process

and the electrospinning distance was set at 10 cm.

Standard glass fibre filters with pore size of 1.5 µm and

diameter of 47 mm (Hach Co., USA) were used as the

substrate materials. Incorporation of nanofibres were

done by directly electrospinning nylon 6 fibres onto the

filters. Electrospinning was performed at different

deposition times of 0 (control sample), 2, 4, and 6

minutes. Triplicate samples were prepared for each case

and labelled as sample A, B, C, and D respectively. Two

experiments were conducted using two different

methods i.e. (i) BS EN 872 “Determination of

Suspended Solids” (ii) using a portable

spectrophotometer (Model DR900, Hach Co., USA).

Filters were weighed using four figure balance Model

AG204 (Mettler Toleddo, Switzerland). Wastewater

sample was taken from a water treatment plant at UTeM

Main Campus. Scanning electron microscope (SEM)

Model JSM-5010PLUS/LV (JEOL Ltd., Japan) was

used to examine the morphology of the fibres and

ImageJ software v1.50 (National Institutes of Health,

USA) was used to analyze the SEM micrographs.


For BS EN 872 method, the value of total

suspended solid (TSS) retentions were calculated from

the dry weight of the filters before and after filtration

(Table 1). The difference between the values divided by

the amount of water sample for each test gave the

Roslan et al., 2017

388

amount of suspended solids trapped by the filter. TSS

value of the water when using the standard filter

(Sample A – control sample) was 15 mg/L. However, a

steep increase of TSS values were found (TSS 22.4 to

23.9) when using Sample B, C, and D filters (Figure 1).

The results suggest that the addition of nylon 6

electrospun nanofibres significantly improved the

capability of the filters. In addition, a steady increase of

TSS values of Sample B, C, D suggests that there was a

positive trend between filter capability and the amount

of applied nanofibres.

Table 1 Total suspended solid (TSS) retentions using BS

EN 872 method.

Sample A B C D

Electrospinning time (min) 0 2 4 6

Filter weight (before)(mg) 99.6 100.6 100.9 101.1

Filter weight (after)(mg) 101.1 101.9 102.7 102.8

TSS (mg/L) 15.0 22.4 23.0 23.9

Figure 1 TSS retentions of sample A, B, C, and D.

TSS values of the water samples before and after

filtration process using a spectrophotometer are shown

in Table 2. The TSS value was reduced from 18 mg/L to

5 mg/L when using Sample A. The TSS values were

significantly reduced when using Sample B, C, and D

(Figure 2). However, due to the limitation of the device

the actual TSS values were only recorded as ‘Not

Detected’ (ND). The results from both methods suggest

that nanofibers incorporated filters exhibited superior

performances compared to the standard filter.

Table 2 Total suspended solid (TSS) values before and

after filtration using spectrophotometer.

Sample A B C D

Electrospinning time (min) 0 2 4 6

TSS (before)(mg/L) 18 18 20 23

TSS (after)(mg/L) 5 ND ND ND

Figure 2 TSS values after filtration using a

spectrophotometer.

The trapped suspended solids after filtration

process are shown in Figure 3. The average fibre

diameter of the nylon 6 nanofibres was 127.9 nm whilst

the average fibre diameter of the substrate fibres was

744 nm. Further works on characterizing and evaluating

the performance of proposed filters are ongoing and the

results will be reported later.

Figure 3 SEM micrograph (x2000) showing the trapped

suspended solids.

4. SUMMARY

In the first experiment, the addition of nanofibres

onto the filters significantly increased the amount of

trapped suspended solids. In the second experiment,

nanofibres incorporated filters were able to remove

suspended solids from the water samples. The results

suggest that nanofibres incorporated filters have

superior capability compared to a standard filter in

terms of capturing suspended solids. The findings of this

study are important as it could open up new

opportunities for engineering the next generation of

efficient filtration media.

ACKNOWLEDGEMENT

Grant no.: PJP/2015/FKM (2A)/S01397.

REFERENCES

[1] M.A. Gosomji and A.D. Okooboh, “Determination

of the concentration of dissolved oxygen in water

samples from pankshin town to monitor water

pollution,” vol. 3, no. 3, pp. 13–17, 2013.

[2] A.H. Nurfaizey, N. Tucker and M.P. Staiger,

“Functional nanofibers in clothing for protection

against chemical and biological hazards,“ in

Functional Nanofibers and their Applications,

Woodhead Publishing Limited, 2012, pp. 236-261.

[3] N. Hamid, J. Stanger, N. Tucker, N. Buunk, A.

Wood and M. Staiger, “Control of spatial

deposition of electrospun fiber using electric field

manipulation,” J. Eng. Fiber. Fabr., vol. 9, no. 1,

pp. 155–164, 2014.

[4] S. Ramakrishna, K. Fujihara, W.E. Teo, T. Yong, Z.

Ma and R. Ramaseshan, “Electrospun nanofibers:

solving global issues,” Mater. Today, vol. 9, no. 3,

pp. 40–50, 2006.

[5] D. Bjorge, N. Daels, S. De Vrieze, P. Dejans, T.

Van Camp, W. Audenaert, J. Hogie, P. Westbroek,

K. De Clerck and S.W. Van Hulle, “Performance

assessment of electrospun nanofibers for filter

applications,” Desalination, vol. 249, no. 3, pp.

942–948, 2009.

[6] R. Asmatulu, H. Muppalla, Z. Veisi, W.S. Khan, A.

Asaduzzaman and N. Nuraje, “Study of

hydrophilic electrospun nanofiber membranes for

filtration of micro and nanosize suspended

particles,” Membranes (Basel)., vol. 3, no. 4, pp.

375–388, 2013.

14

19

24

A B C D

TS

S (

mg/L

)

Samples

0

2

4

6

A B C D

TS

S (

mg/L

)

Samples

Nylon 6

nanofibre Microfibre of

the substrate

material

Trapped

suspended

solids


__________


Design and development of a food tray table for commercial aircraft using hybrid composites

A.F.M. Nor1,2,*, M.T.H. Sultan1,2, A. Hamdan1,2

1) Department of Aerospace Engineering, Faculty of Engineering, Universiti Putra Malaysia,

43400 Serdang, Selangor, Malaysia 2) Aerospace Manufacturing Research Centre, Faculty of Engineering, Universiti Putra Malaysia,

43400 Serdang, Selangor, Malaysia


Keywords: Hybrid composites; flexural; low velocity impact

ABSTRACT – This research attempted to propose a

newly-developed material, which has natural fiber in

hybrid composites with less sustainability issues. Kenaf

(K) and jute (J) are employed to hybrid with fiberglass

(FB). This research aims to analyze the damage

characteristic from flexural and impact testing at

different layer configuration. Hybrid composites with

four different configurations SP1 (FG-K-J-K-FG), SP2

(FG-K-K-K-FG), SP3 (FG-J-J-J-FG) and SP4 (FG-J-K-

J-FG) are fabricated in the first stage for flexural testing.

In the second stage, two best configurations are

subjected to low-velocity impact at energy levels range

10J to 40J. The results show that SP3 and SP4

configurations possess 90% better mechanical

properties while SP3 shows the best configuration for

impact test.

1. INTRODUCTION

The utilization of composite materials has become

the new alternative as compared to the traditional metals

for some aircraft machine parts mostly due to their

quality increment, durability, resistance from corrosion

and fatigue, and also tolerance towards any kind of

damages. Recently, composites materials are applied

massively in advanced structures [1-4]. In addition,

sustainability and environmental issues had been arising

significantly in the matter of time in order toward less

pollution and greener Earth. Therefore, more extensive

researches had been conducted to promote the efficient

and advanced biodegradable composite materials to

replace existing non-biodegradable synthetic composites

materials at a lower rate and lower cost [1-3,5].

Furthermore, the current researches show that it is

possible for natural fiber as reinforcement materials in

composite due to its good performance and resulting in

an arisen the new era of biocomposites. Their properties

gave competiveness to the other synthetic material in

term of production [6], cheaper, renewable, totally or

partially recyclable and biodegradable [7]. Furthermore,

natural fiber is rapid renewability, long-term

availability, low density and price as well as pleasing

mechanical properties.

Composite materials are applied in many parts in

aircraft. One of the parts is a foldable tray table. The

main problem is the common materials in the

manufacturing of the food tray table are using synthetic

fiber and have a sustainability issues. Therefore, this

project proposes a newly develop hybrid composite in

production of the food tray table and is predicted to

have a less maintainability issues as compared to the

existing one.

2. METHODOLOGY

The experiment is first conducted by fabricating

the specimens with four different configurations of

hybrid composites consisted of fiberglass (FG), jute

fiber (J) and kenaf fiber (K) in the form of woven fiber.

The specimens are fabricated using hand lay-up

technique. Each specimen is consisted of five layers of

each fabricated material by following configuration

respectively as shown in the Table 1.

Table 1 Configuration of 5 layers.

Name Configurations Thickness

SP1 FG – K – J – K – FG 3.15mm

SP2 FG – K – K – K – FG 4.00mm

SP3 FG – J – J – J – FG 1.60mm

SP4 FG – J – K – J – FG 2.10mm

All four configurations of the specimens were cut

using vertical saw machine following ASTM D-790

standard, which is 250mm x 20mm for the flexural test.

The testing had been performed on a flexural testing

machine using the 3-point bending by Instron 3382 with

a capacity of 100kN, with the speed of 1mm/min. Then

the results are compared and analyzed. After that, the

best two configurations are choosing to observe and

compared the damage progression via low velocity

impact test. The new specimens with same best two out

of four configurations are fabricated with different

numbers of layer in order to achieve the thickness

required for the testing.

Then, the fabricated specimen is tested with low

impact velocity for impact test by using Imatek, IM10

Drop Weight Impact Tester, where the impactor will

drop freely from some height. The specimens for impact

test were cut according to Boeing Standard

Specifications, BSS 7260, which is 150mm x 100mm. A

preliminary test is conducted as the pilot test to measure

the highest energy level that material can withstand the

impact energy before full penetration from occur. The

Nor et al., 2017

390

results from the preliminary test show that the highest

energy for both configurations is 40 Joules (J). Then,

increment of 10J from 10J until 40J is chosen in order to

fulfill the observation of damage progression.


Figure 1 reports that SP3 shows the highest value

in flexural modulus followed by SP4 composite. The

thickness of the specimen is believed to increase the

strength to withstand bending forces before breaking

point. The detailed result of flexural test is shown in

Table 2.

Figure 1 Flexural stress against flexural strain curve.

Table 2 Data from flexural test.

Specimen Maximum

Load

Flexural

Stress

Flexural

Modulus

SP1 319.77N 120.85MPa 9.16Gpa

SP2 481.61N 144.48MPa 9.92Gpa

SP3 157.56N 230.80MPa 2.50Gpa

SP4 141.03N 163.10MPa 2.05Gpa

High value of flexural modulus indicates that the

material has a high level of stiffness. The SP3 and SP4

composites need higher loads to be elastically deformed

as compared to SP1 and SP2 composites. SP3 and SP4

are selected for low velocity impact test.

Figure 2 Peak impact force-impact energy curve

Figure 2 shows that the average peak impact force

is found to follow the same increasing trend with

respect to impact energy. For comparison, the impact

forces generated for impacts onto SP4 are significantly

larger than SP3 due to its high stiffness. This shows that

SP4 is stiffer than SP3. It can be stated that the greater

the peak impact forces, the stiffer the projectile-to-target

interactions.

4. CONCLUSIONS

The study verified that different configuration with

same number of layers give different mechanical

properties. The results from the flexural test shows it

can be claimed that the best two configurations out of

four are third (SP3) and fourth (SP4) configuration. The

material properties will affect the stiffness of the

structure and the contact stiffness will have a significant

effect on the dynamic response of the structure. In

impact test, the fourth configuration (SP4) has higher

peak load, good impact resistance and a small damage

area. Therefore, the fourth configuration (SP4) has high

strength, slower damage progression and less severe

failure mode compared to the third configuration (SP3).

ACKNOWLEDGEMENT

This work is supported by UPM under GP-IPM

grant, 9415402.

REFERENCES

[1] M.T.H. Sultan, K. Worden, S.G. Pierce, D. Hickey,

W.J. Staszewski, J.M. Dulieu-Barton and A.

Hodzic. “On impact damage detection and

quantification for CFRP laminates using structural

response data only,” Mechanical Systems and

Signal Processing, vol. 25, no. 8, pp. 3135-3152,

2011.

[2] A. Hamdan, F. Mustapha, A.K. Ahmad, A.S.M.

Rafie, M.R. Ishak and A.E. Ismail. “The effect of

customized woven and stacked layer orientation on

tensile and flexural properties of woven kenaf fibre

reinforced epoxy composites,” International

Journal of Polymer Science, vol. 2016, pp. 1-11,

2016.

[3] N. Razali, M.T.H. Sultan, F. Mustapha, N. Yidris

and M.R. Ishak. “Impact damage on composite

structures - A review,” The International Journal

of Engineering and Science, vol. 3, no. 7, pp. 8-20,

2014.

[4] D. Chandramohan and K. Marimuthu. “A review

on natural fibers,” International Journal of

Research and Reviews in Applied Sciences, vol. 8,

no. 2, pp. 194-206, 2011.

[5] A. Chauhan and P. Chauhan. "Natural fibers and

biopolymer," Journal of Chemical Engineering &

Process Technology, vol. S6, pp. 1-4, 2013.

[6] J. Holbery and D. Houston. “Natural-fiber-

reinforced polymer composites in automotive

applications,” JOM Journal of the Minerals,

Metals and Materials Society, vol. 58, no. 11, pp.

80-86, 2006.

[7] A. Bernava, M. Maris and S. Guntis. "Study of

Mechanical Properties of Natural and Hybrid

Yarns Reinforcements," In Advanced Materials

Research, vol. 1117, pp. 231-234. Trans Tech

Publications, 2015.

0

50

100

150

200

250

0 2 4 6

Fle

xura

l st

ress

(M

Pa)

Tensile strain (%)

SP1SP2SP3SP4

0

1

2

3

4

5

6

0 20 40 60

Pe

ak f

orc

e (

kN)

Impact energy (J)

SP3

SP4

Proceedings of Mechanical Engineering Research Day 2017, pp. 391-392, May2017

__________


Behaviour of hybrid fibers in oil palm shell and palm oil fuel ash reinforced concrete beam

S.M. Syed Mohsin*, M.S. Zainal, G.A. Jokhio, K. Muthusamy

Faculty of Civil Engineering and Earth Resources, Universiti Malaysia Pahang,

26600 Pekan, Pahang Darul Makmur, Malaysia


Keywords: Hybrid fibers; lightweight concrete; green structures

ABSTRACT – This paper presents the investigation of

structural behavior of hybrid fibers in oil palm shell

(OPS) and palm oil fuel ash (POFA) reinforced concrete

beam. Four-point bending test was conducted on five

beams with various fiber volume fraction ranging from

0 % to 2.0 %. Based on the results obtained, it was

observed that fibers have the capability to increase the

load carrying capacity, shear strength and ductility of the

beam. Moreover, the crack propagation is lower when the

amount of fiber is increased.

1. INTRODUCTION

Palm oil industries is one of the biggest industry in

Malaysia. Being one of the largest palm oil producers in

the world, the industry continuing generates high solid

waste, for example OPS and POFA. The wastes produced

needs to manage and dispose in appropriate manner that

may contribute to some environmental problems. Thus,

in order to cater these issues, some researcher attempted

to reuse the waste to produce green material, and one of

the way is to replace some of the material in concrete [1-

4]. For instance, the OPS have been used to replace the

aggregate whereas the POFA is used as partial cement

replacement [1-2,4], thus producing a lightweight

aggregate concrete. However, lightweight concrete is a

brittle material. Therefore, in order to add ductility to the

concrete, fibres are added into the concrete mixture. This

is because fibres have the capability to improve the

strength and ductility of the reinforced concrete

structures [3,5].

2. METHODOLOGY

In order to study the structural behavior of hybrid

fibers in OPS and POFA reinforced concrete beam, two

types of fibers, namely kenaf fiber and steel fiber are

mixed into the concrete. The type of steel fiber used is

hooked end with aspect ratio of 120. Whereas, for kenaf

fiber the specification is 30 mm length and diameter in

range 0.5 – 1.5 mm.

The ratio of the fiber is half. Five volume fractions

are considered; 0%, 0.5%, 1.0%, 1.5% and 2.0%

represented in Mix1, Mix2, Mix3, Mix4 and Mix5,

respectively, as shown in Table 1. The coarse aggregate

of the beam is fully replaced with OPS, whereas 20% of

POFA is used to replace the cement. The OPS is sieved

to get the size of 15 mm. Water cement ratio considered

for this study is 0.5. To maintain water cement ratio,

superplasticizer is added as addition of fibers onto the

mixture will reduce its workability.

Table 1 Concrete mix design.

Properties Mix

1

Mix

2

Mix

3

Mix

4

Mix

5

Vf (%) 0 0.50 1.00 1.50 2.00

Water(kg) 18.00 18.00 18.00 18.00 18.00

OPS (kg) 26.00 26.00 26.00 26.00 26.00

POFA(kg) 7.14 7.14 7.14 7.14 7.14

OPC(kg) 29.00 29.00 29.00 29.00 29.00

Sand(kg) 62.00 62.00 62.00 62.00 62.00

SP (kg) 0.60 0.60 0.60 0.60 0.60

Kenaf fiber

(kg) 0 0.25 0.50 0.83 1.08

Steel fiber

(kg) 0 1.52 2.95 4.47 5.99

A square beam of 150 x 150 mm is constructed with

total length of 1500 mm. 3T10 and 2T10 are used for its

tensile and compressive longitudinal reinforcement,

while R6 is used for its shear reinforcement. The loading

arrangement, shear links spacing and dimension of the

beam are given in Figure 1. All the beam is tested on 28th

day.

Figure 1 Loading arrangement and beam dimension.


Figure 2 shows the load versus deflection curves of

the tested beams. It can be seen that, as the amount of

fibers increases, the stiffness and the load carrying

capacity of the beam increased as well. The key data

extracted from the load-deflection curves such as Yield

Load (Py) and its deflection (δy), Maximum Load

Carrying Capacity (Pmax) and its deflection (δmax) and

Ultimate Load (Pu) before failure and ultimate deflection

(δu), are summarized in Table 2.

Syed Mohsin et al., 2017

392

Figure 2 Load vs deflection curves.

From the table, it can be seen that the as the fiber

content increases, the strength (Py and Pmax) of the beam

also increase. This is due to the fact that fibers reduce the

rate of crack propagation, and higher forces is required in

order to produce larger crack width. Indirectly, the load

carrying capacity of the beam will also increase. In term

of ductility, μ is ductility ratio obtained by dividing δu by

δy as shown in Table 2. It can be seen that the ductility

ratio of the beam continuing to increase up to 1.5% of

fiber content. This is the limit of the fibers amount of the

beam. After this amount, the ductility ratio is reduced due

to the effect of multiple cracking.

Table 2 Key results from the load-deflection curves.

Properties Mix

1

Mix

2

Mix

3

Mix

4

Mix

5

Vf (%) 0 0.5 1.0 1.5 2.0

Py (kN) 58.40 64.20 70.60 76.10 78.30

δy

(mm) 5.01 5.20 5.23 5.30 5.40

Pmax

(kN) 80.66 83.50 88.70 89.80 94.00

δmax

(mm) 7.20 7.28 73.30 7.38 7.40

Pu

(kN) 78.90 80.50 86.80 88.00 92.00

δu

(mm) 21.60 23.30 25.50 24.00 23.30

μ 4.31 4.48 4.88 4.53 4.32

The load at first crack and cracking pattern of the

beam at failure is shown in Figure 3. Similarly, the values

of the load at first crack is also in upward sequence as the

amount of fibers are increased. For the 1st beam with 0%

fiber, the beam failed in shear-bending mode. Adding

hybrid fibers change the failure mode to a more ductile

one, as the beam now show bending mode of failure.

However, as explained earlier, as the optimum amount of

fibers is observed at 1.5%, the mode of failure now

become bending-shear.

4. CONCLUSION

Hybrid fiber consistently enhances the load

carrying capacity and the ductility of the beam.

Furthermore, the fibers help in slowing the crack

propagation, thus improves the strength of the reinforced

concrete beam. However, sufficient amount of

superplasticizer is needed in order to improve the

workability of the mixture while maintaining the water

cement ratio.

Figure 3 Beam failure mode and cracking pattern.

REFERENCES

[1] P. Shafigh, M.Z. Jumaat and H. Mahmud, “Mix

design and mechanical properties of oil palm shell

lightweight aggregate concrete: A review,”

International Journal of Physical Sciences, vol. 5,

no. 14, pp. 2127-2134, 2010.

[2] K. Muthusamy, Z. Nur Azzimah, N. Ghazali, S.M.

Syed Mohsin and K. Andri, “Compressive strength

and density of oil palm shell lightweight aggregate

concrete containing palm oil fuel ash under

different curing regime,” in Proceeding of

International Conference on Innovations in Civil

and Structural Engineering, pp. 242–247, 2015.

[3] S.M. Syed Mohsin, S.J. Azimi and A. Namdar,

“Behaviour of oil palm shell reinforced concret

beams added with kenaf fibers,” Journal of Applied

Mechanic and Materials, vol. 567, pp 351-355,

2014.

[4] K. Muthusamy and Z. Nur Azzimah, “Exploratory

study of palm oil fuel ash as partial cement

replacement in oil palm shell lightweight aggregate

concrete,” Research Journal of Applied Sciences,

Engineering and Technology, vol. 8, no. 2, pp 150 –

152, 2014.

[5] S.M. Syed Mohsin, M.F. Manaf, N.N. Sarbini and

K. Muthusamy, “Behaviour of reinforced concrete

beams with kenaf and steel hybrid fibre,” ARPN

Journal of Engineering and Applied Sciences, vol.

11, no. 8, pp. 5385 – 5390, 2016.


__________


Effect of repetitive rework on tensile testing of dissimilar austenitic stainless steel pipes using GMAW orbital welding

S. Laily*, N.I.S. Hussein, M.S. Salleh, M.N. Ayof, T.H. Kean

Faculty of Manufacturing Engineering, Universiti Teknikal Malaysia Melaka,



Keywords: Stainless steel pipe; orbital welding; gas metal arc welding; repetitive rework

ABSTRACT – This study investigates the effect of

repeated repairs welds on the tensile testing of dissimilar

austenitic stainless steel using gas metal arc welding

(GMAW) orbital welding. The weld beads are then

ground away and repair welds are fabricated again by

GMAW. All the samples then cut into dog bone shape

with dimension according to ASTM E8M-04. Then

filling was applied to flatten the gripping sections of each

tensile specimen. Yields strength, ultimate tensile

strength and percentage of elongation were investigated

with maximum 100kN.It is evident from the result that

there increasingly trend of tensile strength only up to

second weld repair, then it started to decrease for the next

weld repair. In this article, the effect of repair welding on

tensile testing of dissimilar stainless steel pipes has been

studied.

1. INTRODUCTION

Orbital welding is the most applicable joining

process in industry whenever high quality of welding

results is desired. Since pharmaceutical equipment

always subjected to high temperature and pressure, they

are more susceptible to premature failure after a certain

service period and it becomes more critical when there is

involvement of dissimilar metal weld joints. This is

because dissimilar metal weld joints have higher

tendency encountered to material degradation such as

thermal aging [1]. Austenitic stainless steels have good

performance in corrosive working environment. This

type of stainless steel is applicable in either conducive or

elevated temperature service environment. Besides that,

they have also good mechanical properties particularly

ductility and toughness, so that it shows remarkable

elongation during tensile testing. Indeed, practice of

DMW with formation of dissimilar metal joint allows the

transition in mechanical properties or in service

conditions as required in certain applications [2].

Repair welding is often desired in industry to

prolong the service lives or enhance performance of the

components. Defects on weldment such as porosity, lack

of penetration, slag inclusion and incomplete fusion may

develop in pipeline fabrication [3]. On the basis of the

comprehensive literature review, the study of repair

welding on dissimilar steel material had rarely been

reported. The main objective is to determine the effect of

repair welding on tensile testing using dissimilar stainless

steel using GMAW orbital welding.

2. EXPERIMENTAL

Setting of equipment to carry out repair welding is

illustrated in Figure 1. The input parameter of welding

machine was arc current 133A and 21V of voltage with

using 70% of argon and 30% of carbon dioxide. With

25mm/min of rotating speed, repair welding was done

until four times. Figure 2 shows turning process for grind

weld bead before followed with repair welding.

Figure 1 1G Position of pipe specimen.

Figure 2 Lathe turning process.


Table 1 shows result of tensile testing for base metal

while Table 2 shows result on results for as-welded

specimen and repaired specimens. Every value listed in

the table represented average value of two specimens.

The fractured tensile specimens are shown in the Figure

3.

Laily et al., 2017

394

Table 1 Results of tensile testing for base metals.

Sample

Ultimate

Tensile

Strength

(MPa)

Yield

Strength

(MPa)

Elongati

on (%)

Failure

Location

AISI 304 613.78 310.63 62.00 BM

AISI

316L 612.06 363.13 54.00 BM

By comparison in between two different base

metals, AISI 304 has higher tensile strength than AISI

316L. This is because of its higher carbon content, which

is marked 0.05wt% in extra. Therefore, high carbon

content is responsible to high tensile strength [4].

Table 2 Result for as-welded specimen and repaired

specimen.

Sample

Ultimate

Tensile

Strength

(MPa)

Yield

Strength

(MPa)

Elongation

(%)

Failure

Location

RW0 401.41 240.09 55.00 WM

RW1 470.97 289.82 58.00 WM

RW2 531.91 296.43 63.00 WM

RW3 383.81 260.09 53.50 WM

RW4 330.72 259.30 53.00 HAZ

Figure 3 Fracture tensile specimen after tensile testing.

Figure 3 shows fracture tensile specimen and base

metal after tensile testing. There are two replications for

every repaired samples. While Figure 4 shows graph on

tensile properties versus number of weld repair.

Weld repaired specimens showed an increasing

trend only up to second weld repair, then it is started to

decrease from the next following weld repair. The highest

ultimate tensile strength, yield strength and percent of

elongation for weld repaired samples were observed on

sample RW2 due to the grain growth substantially

affected the tensile strength of weld metal. This is

because coarser grain cannot bear high tensile stress and

crack is usually initiated from coarser grain [5]. After

second repair welding, the grain growth substantially

affected the tensile strength of weld metal. This is

because coarser grain cannot bear high tensile stress and

crack is usually initiated from coarser grain.

Figure 4 Tensile properties vs number of weld repair.

4. CONCLUSION

Tensile testing showed that tensile properties such

as ultimate tensile strength, yield strength and percent of

elongation of weld metal was increased only up to second

repair. This is due to significant grain growth in the

weldment after second repair which facilitated crack

initiation took place. Besides, fracture of tensile

specimens was mostly happened at weldment which had

lowest microhardness. By considering all the factors, it is

suggested that second weld repair is the optimum number

of repair welding.

ACKNOWLEDGEMENT

This research is funded by FRGS Grant numbered

FRGS/1/2015/TK03/FKP/02/F00280.

REFERENCES

[1] A. Aloraier, A. Al-Mazrouee, J.W.H. Price, T.

Shehata, “Weld repair practices without post weld

heat treatment for ferritic alloys and their

consequences on residual stresses: A review,”

International Journal of Pressure Vessels and

Piping, vol. 87, pp. 127-133, 2010.

[2] H. Eisazadeh, J. Bunn, H.E. Coules, A. Achuthan, J.

Goldak, and D.K. Aidun, “A residual stress study in

similar and dissimilar welds,” Welding Research

Journal, vol. 95, pp. 111-119, 2016.

[3] P. Varghese, M.S. Prasad, F. Joseph, M.J. Varkey, K.

Anthony, and A. Sreekanth, “The effect of repeated

repair welding on the corrosion behavior of

austenitic stainless steel and mild steel dissimilar

weldment,” in Proceeding of International

Conference on Advanced in Materials,

Manufacturing and Applications, 2015, pp. 864-

869.

[4] C. Balaji, S.A. Kumar, V.A. Kumar, S.S. Satish,

“Evaluation of mechanical properties of ss 316l

weldments using tungsten inert gas welding”,

International Journal of Engineering Science and

Technology, vol. 4, no. 5, pp. 2053-2057, 2012.

[5] S.G. Wang and X.Q. Wu, “Investigation on the

microstructure and mechanical properties of ti-6al-

4v alloy joints with electron beam welding”,

Materials and Design, vol. 36, pp. 663-670, 2012.

0

100

200

300

400

500

600

700

800

900

1000

RW0 RW1 RW2 RW3 RW4

Str

eng

th [

MP

a]

Number of weld repair

ultimate tensile

strength (MPa)

yield strength

(MPa)

elongation (%)


__________


Effects of ABS/PC blends ratio towards strength performance R.M.R. Mamat*, M.H. Basir, Z.N. Zakaria, W.M.W. Ibrahim

Faculty of Manufacturing Engineering Technology, TATI University College,

Teluk Kalong, 24000 Kemaman, Terengganu, Malaysia


Keywords: ABS; ratio; strength

ABSTRACT – The aim of this study is to analyze the

effect of PC and ABS formulation ratio upon tensile

strength characteristic. A series of three samples

composition of 25, 50 and 75 vol % of ABS product was

prepared by injected together with PC resin and tested

using universal testing machine (UTM). The tensile

strength was measured according to ASTM D-638. The

samples with 25 vol % ABS displayed the highest value

of strength. This is due to proper distribution adhesion

by the ABS and PC. As a conclusion, the higher

composition of PC added to the PC/ABS polymer

resulted in better strength performance.

1. INTRODUCTION

Acrylonitrile-butadiene-styrene (ABS) is a widely

used thermoplastic in polymer industry. In ABS,

acrylonitrile causes an improvement in chemical

resistance and weatherability, while butadiene has the

character of rubber toughness, and styrene offers

glossiness and processability. In PC/ABS blend,

mechanical and thermal properties are improved by PC

while processability, economics and impact resistance

are improved by ABS [1].

In order to upgrade the use and function of ABS,

the simple way is to formulate ABS resin with other

high performance engineering plastics such as

polycarbonate (PC). Mixture of PC and ABS has been

commercially available for a number of years. PC can

contribute towards improvements in strength,

dimensional stability, heat distortion temperature and

impact resistance of the blends. On the other hand, ABS

provides processing advantages, chemical resistance

besides cost reduction with respect to PC.

PC/ABS mixtures have interesting properties that

vary by percent composition of each material. A higher

concentration of PC increases the Young’s Modulus and

results in a higher stress at fracture. Both tensile

strength and Young Modulus increased with increasing

PC content in the ABS/PC [2]. Similar observation was

also reported by Khan et.al (2005) [3], which stated that

tensile strength increased with the increasing PC

contents in ABS/PC blends. Hence, this study is carried

out to determine the optimum formulation ratio of ABS

and PC which contributes to higher strength value of

injected samples.

2. METHODOLOGY

2.1 Material and equipment

The material used in this research work was

summarized as in Table 1.

Table 1 Material Properties from manufacturer.

Polycarbonate, Panlite L-1225Y

Tensile modulus 2400 MPa

Tensile stress 62.0 MPa

Tensile strain 6.00%

Melt Flow Rate 300°C

ABS, TORAY 700-314

Tensile modulus 2700 MPa

Tensile stress 54.0 MPa

Tensile elongation >10%

Melt Flow Rate 220°C

Injection moulding machine: The testing samples

were prepared on TOYO Plastar Injection moulding

machine with technical data shown in Table 2 below.

The shape of specimen sample was prepared according

to ASTM D638 as shown as in Figure 1. Table 3 show

the technical data of UTM was used for testing of

tensile strength properties.

Table 2 Technical data Toyo Plastar Ti-50GX injection

moulding machine.

Name of Machine PLASTAR Ti-50GX

Clamping Force 50 Tonne

Injection Capacity 80cm3

Max Injection Pressure 2500 MPa

Screw diameter 32mm

Table 3 Technical data UTM machine.

Name of

machine

Universal Material Testing

Machine

Brand INSTRON

Max. load 50KN

Max. speed 500 mm/min

Software Series IX

Mamat et al., 2017

396

Table 4 Injection moulding parameter.

Variables Symbol

Actual Value

(coded value)

Low High

Injection Pressure, MPa A 75 (-1) 85 (+1)

Barrel Temperature,°C B 270 (-1) 280 (+1)

Cooling Time, s C 25 (-1) 35 (+1)

Table 5 Blends formulation of materials.

Blends Formulation

PC (wt%) ABS (wt%)

B1 25 75

B2 50 50

B3 75 25

Figure 1 Injected sample according to ASTM D638.


Table 6 shows the tensile strength for overall

samples according to design matrix. The details

comparison of tensile strength values for each sample

was summarized by Figure 2.

Table 6 Design matrix with response.

Std Run Factor Tensile strength (MPa)

A B C B1 B2 B3

4 1 75 280 25 49.343 54.461 55.634

8 2 85 280 25 50.845 55.634 53.522

6 3 85 270 35 47.020 47.891 54.390

7 4 75 270 35 51.103 55.165 55.986

1 5 75 280 35 51.666 53.968 54.367

5 6 85 270 25 47.067 52.889 52.795

2 7 85 280 35 52.440 54.179 55.587

3 8 75 270 25 52.018 55.071 52.748

No. of Experiment

Te

nsile

Str

en

gth

(M

Pa

)

87654321

56

54

52

50

48

46

B1

B2

B3

Formulation Ratio

Tensile Strength versus ABS/PC Blends

Figure 2 Graph tensile strength vs ABS/PC blends.

It was observed that the strength decreased with

increasing ABS weight percentage. This is due to ABS

having the rubbery main chain polybutadiene.

According to Krache et.al (2011) [4], by adding some of

ABS content in sampling, the value of strength should

be increase. The scientific explanation to the increment

of the strength was due to the properties of the ABS

where it able to allocate more strong properties as it

dispersed phase in the polymer.

4. CONCLUSION

As conclusion, the higher PC content the higher

the result obtained for the strength which is believed

due to physical properties of the ABS itself. ABS able to

provide good adhesion and bonding between the ABS

and PC resin which lead to good strength distributions

and absorption which proportionally increased the

strength.

REFERENCES

[1] M.M. Raj, “Studies on mechanical properties of

PC-ABS blends,” Journal of Applied Sciences and

Engineering Research, vol. 3, no. 2, 2014.

[2] A. Hassan, and Wong Y. J, “Mechanical properties

of high impact ABS/PC blend,” Simposium

Polimer Kebangsaan, 2005.

[3] M.M.K. Khan and R.F. Liang, “Rheological and

mechanical properties of ABS/PC blends,” Korea-

Australia Rheology Journal, vol. 17, no. 1, pp. 1-7,

2005.

[4] R. Krache and I. Debbah, “Some mechanical and

thermal properties of PC/ABS blends,” Scientific

Research: Materials Science & Applications, vol.

2, pp. 404-441, 2011.


__________


Study on dimensional accuracy of lattice structure bar using FDM additive manufacturing

M.S. Azmi1, R. Ismail1,2,*, R. Hasan1,2, M.R. Alkahari1,2





Keywords: Fused Deposition Modeling (FDM); polymer lattice structure; dimensional accuracy

ABSTRACT – Fused Deposition Modeling (FDM) is a

simple low cost rapid manufacturing technique that

creates part by fusing successive thermoplastic material

layer by layer. However, the capability of FDM to create

accurate parts has been always discussed in many

researches. This paper discusses the dimensional

accuracy of FDM in printing lattice structure. Lattice

structure made using lightweight material such as

Acrylonitrile butadiene styrene (ABS) thermoplastic

material can be used in industry where manufacturing

cost, parts weight and load-bearing capability are

important such as in transportation industry.

1. INTRODUCTION

Current performance of automated devices that uses

battery for its movement is limited due to heavy

sophisticated sensors and body parts[1]. These problem

has caused the device to consume higher energy during

operation. In order to reduce overall weight of a body part

of the automated device, structural properties,

manufacturing technique and material selection must be

continually improved.

Lattice structure is a low density cellular structure

that exist in wide range of things ranging from natural to

human made creation. Lattice structure are favored due

to its better properties of lower density that will

eventually reduce weight of the structure and high

strength to weight ratio when compared to solid bulk

structure and stochastic foam[2]. Lattice structure can be

made using many techniques from conventional

techniques such as injection moulding to additive

manufacturing such as Selective Laser Sintering (SLS),

Selective Laser Melting (SLM) and Fused Deposition

Modelling (FDM).

FDM is one of solid based additive manufacturing

technique that uses lightweight thermoplastic filament as

material. FDM was first invented in early 1990s and

widely used due to its simple, low cost material and

minimum waste that shows a great potential for

fabricating plastic parts for rapid manufacturing

compared to conventional technique[3]. FDM technique

has been widely used ranging from medical treatment,

mould design, automotive and aeronautics[3]. Thus, the

use of FDM technique can reduce manufacturing cost of

parts. Unfortunately, like other rapid manufacturing

techniques, FDM has drawback as the parts made using

FDM are not accurate to the desired dimensions.

Thus, the aim of this paper is to investigate

dimensional accuracy of lattice structure bar in order to

propose a new lightweight body part for application in

small automated device system to extend its operational

hours. This can be done by using lighter weight material

with lower density structure.

2. METHODOLOGY

2.1 Design of lattice structure

The lattice structure is designed using Solidwork

Computer Aided Design (CAD) software with body-

centered-cubic (BCC) topological design as shown in

Figure 1.

Figure 1 Lattice structure design in Solidwork.

The BCC lattice structure unit cell is designed with

length, L= 5 mm and strut to surface angle, =35.26o

angle. The unit cell of BCC lattice structure is shown in

Figure 2.

Figure 2 BCC unit cell.

The drawing is then saved as Solidwork part

document and later converted into. STL file before

inputted into CubePro software for printing.

Azmi et al., 2017

398

2.2 Fabrication of lattice structure Lattice structure specimens are fabricated with

dimension of 160x20x30 mm3 to match industrial part of

an automated autonomous device. The specimens are

fabricated using ABS thermoplastic using CubePro 3D

printer by 3D System Inc. The specimen printing

specifications are as tabulated in Table 1.

Table 1 Specification of specimens.

Strut

diameter

Print

Strength

Print

Pattern

Layer

Thickness

1.2 mm Solid Cross 200 𝜇𝑚



The smallest strut diameter for this study is

fabricated as 1.2 mm, due to the capability of CubePro

3D printer that shows a successful print of strut with at

least 1.0 mm diameter [4].


The printed specimens’ strut diameter was

measured using profile projector. Profile projector is a

non-contact measurement device that can measure

sample of variety specimen shapes, size and can measure

accuracy up to 1μm dimension. Profile projector is also

known as shadowgraph because of its working principle

that project the shadow of the sample on the

measurement screen.

Figure 3 Profile projected specimen

The measurements are taken from three different

regions for each specimens and the average printed

diameter is calculated. The data measurements taken are

tabulated in Table 2.

From Table 2, it can be seen that the printed

diameter has about 0.16 mm diameter deviation from the

preset diameter in the drawing for all three specimens.

According to Nancharaiah et al. [5], layer thickness

can affect part accuracy greatly. Bakar et al. [6] also

mentioned that the deviation become worse when

fabricating the circular shape part. As all the specimens

are made with same layer thickness and also with circular

shape strut, the dimensional accuracy deviation of all

three specimens are almost the same.

Table 2 Strut diameter measurements.

Strut

diameter Printed diameter

Percentage

different

1.2 mm 1.045 ± 0.031 mm 12.92 %

1.6 mm 1.434 ± 0.072 mm 10.38 %

2.0 mm 1.842 ± 0.059 mm 7.90 %

4. CONCLUSIONS

FDM is a good manufacturing technique for

fabricating plastic parts due to its lower cost, minimum

waste and lightweight printing material for automated

device body parts. By using lattice structure, the body

parts weight can be further reduced because of its low

density but high strength to weight ratio. However, the

capability of FDM in printing accurate dimension of

lattice structure due to its circular shape strut must be

improved by adjusting the FDM process parameter so

that the deviation from the preset dimension is lower to

acceptable deviation.

ACKNOWLEDGEMENT

The research was supported by research grant

FRGS/1/2016/TK03/FKM-CARE/F00316.

REFERENCES

[1] D. Pebrianti, F. Kendoul, S. Azrad, W. Wang and K.

Nonami, "Autonomous Hovering and Landing of a

Quad-rotor Micro Aerial Vehicle by Means of on

Ground Stereo Vision System," Journal of System

Design and Dynamics, vol. 4, pp. 269-284, 2010.

[2] L. Xiao, W. Song, C. Wang, H. Tang, Q. Fan, N. Liu

and J. Wang, "Mechanical properties of open-cell

rhombic dodecahedron titanium alloy lattice

structure manufactured using electron beam melting

under dynamic loading," International Journal of

Impact Engineering, vol. 100, pp. 75-89, 2017.

[3] J. Wang, H. Xie, Z. Weng, T. Senthil and L. Wu, "A

novel approach to improve mechanical properties of

parts fabricated by fused deposition modeling,"

Materials & Design, vol. 105, pp. 152-159, 2016.

[4] R. Hasan, M. Baharudin, M. Nasarud’din and M.

Alkahari, "Fabrication of polymer lattice structure

using additive manufacturing for lightweight

material," in Proceedings of Mechanical

Engineering Research Day, 2016, pp. 129-130.

[5] T. Nancharaiah, D.R. Raju and V.R. Raju, "An

experimental investigation on surface quality and

dimensional accuracy of FDM components,"

International Journal on Emerging Technologies,

vol. 1, pp. 106-111, 2010.

[7] N.S.A. Bakar, M.R. Alkahari and H. Boejang,

"Analysis on fused deposition modelling

performance," Journal of Zhejiang University-

Science A, vol. 11, pp. 972-977, 2010.


__________


A techno-economical study on medium density fiberboard using napier grass fiber as ceiling board

Norrahim A. Bakar1,2,*, M. Edyazuan Azni3, M.T.H. Sultan1,2, A. Hamdan1,2

1) Faculty of Aerospace Engineering, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia

2) Aerospace Manufacturing Research Centre, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia 3) Universiti Kuala Lumpur Malaysian Institute of Chemical & Bioengineering, 78000 Alor Gajah, Melaka, Malaysia


Keywords: Napier grass; medium density fiberboard; insulation

ABSTRACT – This project is about extraction of bast

fiber from Napier grass which is known as Pennisetum

purpereum. The purpose of this research is to produce

Medium Density Fiberboard board with density of

350kg/m³ using natural fiber and to investigate the

optimum properties towards the application as ceiling

board. Napier grass fiber board has values resulted at

Modulus of rupture (MOR) is 2.90GPa and Modulus of

elastic (MOE) is 39.03MPa. Water absorption (WA) at

27.83% and thickness swelling (TS) at 6.67% with

thermal conductivity (λ) value is 0.044W/mK. This

fiberboard can be an insulation which contributes to

save production cost, less hazardous, low environmental

footprint and a new innovation.

1. INTRODUCTION

Recently researchers are now on biodegradable

materials as alternative to synthetic materials due to

increasing of environmental issues. Natural fibers are

promising alternative raw materials to be embedded or

substitute the existing in green composite. The

flexibility of the processing, highly specific stiffness,

low cost, renewability, suitability, no impact on global

warming, biodegradability makes the natural fibers have

significant advantages compared with synthetic fibers

[1]. Pennisetum purpureum fiber, also locally known as

Napier grass (Rumput Gajah), is composed of 46%

cellulose, 34% hemicellulose, and 20% lignin [2]. The

objective is to investigate insulation board produced by

using Napier grass as a ceiling board. This is a new

innovation green biodegradable technology.

2. METHODOLOGY

Napier Grass “Pennisetum purpereum” were

collected from a farm located at Sg.Buloh,Selangor.

Three to six month old of Napier grass was used for this

project. The grass was extracted using water retting

process to obtain the bast fiber. Then the bast fiber were

treated using alkali (sodium hydroxide) NaOH solution

of 10% concentration to treat Pennisetum Purpereum

fibers at room temperature and soaking times 6 hours

[3]. Napier grass bast fibers extracted were mixing with

fiber binder PVA (Polyvinyl acetate) in ratio 36% resin

together with 60% solid content Napier Grass Fiber into

mold. The mixtures were hand-formed into

homogeneous single layer mat and pre-cooling. Then

the mixture consequently pressed in a hot press machine

at 175ºC for 5 minutes with pressure of 160kg/cm². Last

stage was drying process and been coated with Gelcoat.

The sample was prepared in dimension 200mm in

length and 200mm in width with thickness 6mm. The

density of fiberboard is 350kg/m³.

The MDF product was investigate accordingly for

thermal and mechanical properties. The mechanical

properties tested following the tensile strength testing

according to ASTM D368-03. From the experimental,

the values modulus of rupture (MOR) and modulus of

elasticity (MOE) are reported. All properties were

calculated from the equations (1) and (2) respectively. (1)

Where Fmax is the maximum load (N), l₁ is the span

(mm), b is the width of the test sample (mm) and t is the

thickness of the test sample (mm).

(2)

Where F₂-F₁ is the increasing load in the range of linear

line of graph (N) and a₂-a₁ is the increasing bending

distance in the range of linear line of graph (N).

Water absorption and thickness swelling according

to ASTM D570-98 was also tested. The percentage of

water absorption (WA) and thickness swelling (TS) are

measured following the standard. The moisture content

of samples is determined by the following the equation

(3).

(3)

Where m1 is mass of sample before drying (g) and m2 is

mass of sample after drying (g).

Thermal conductivity of all board was tested

accordance with the American Society for Testing

Material [4]. The thermal conductivity of a sample is

determined by following the equation (4)

(4)

Where Qu is the output of the upper heat flux

transducer, Ql is the output of the lower heat flux

transducer, D is the thickness of the sample and ΔT is

the temperature difference between the surfaces of the

sample.

Bakar et al., 2017

400


3.1 Results for MOE and MOR

The alkaline treatment is for sizing. This treatment

improved the adhesion characteristics by increase the

surface tension roughness and the possibility for

mechanical interlocking and chemical bonding between

the matrixes. These fibers are treated with several alkali

concentrations in 5%, 10%, 15% and untreated. The

effect of fiber to the result obtain is because of the

surface modification has been made by treated to the

NaOH solution for 6 hours. Fiber loading at 0%, 10%,

20%, 30% applied for tensile properties.

Figure 1 Modulus of Elasticity for Napier fiber (MOE).

Figure 2 Modulus of Rupture for Napier fiber (MOR).

The result recorded yield good mechanical

properties for modulus of rupture (MOR) is 2.90Gpa

and modulus of elastic (MOE) is 39.03Mpa at 10%

concentration treatment at 20% fiber loading. The

purpose of treatment to remove hemicelluloses, split the

fiber into fibrils and produce a closely pack cellulose

chain owing to the release of internal strain. It is also

improving the bonding between the fiber-matrix

interfaces.

3.2 Result for water absorption (WA) and thickness

swelling (TS)

According to the data in Table 1, water absorption

for the fiberboard is 27.83% which is the mass for this

fiberboard is 97g after drying. After immersed mass is

124g. This is because improper coating Gelcoat on the

fiberboard surface that course small leaks on the surface

which is percentage moisture content can be absorbed.

The thickness swelling for this Napier grass Fiberboard

is 6.67% after being dried. This is because the fiber

have good matrix bonded between the fibers that gives

good physical properties.

Table 1 Physical properties.

Properties Data (%)

WA 27.83

TS 6.67

3.3 Result for thermal conductivity

The thermal conductivity (λ) values recorded for

this sample is 0.044W/mK. Thermal conductivity values

are numerical values that are determined by experiment.

The higher the value, the more heat is rapidly

transferred through that material. Materials with

relatively high thermal conductivities are referred to as

thermal conductors. Typical value for insulation board

thermal conductivity (λ) is 0.038 W/mk – 0.060 W/mK.

The result show Napier fiber is in between the range of

the insulation board. This is because fiber contain high

cellulose that response as thermal insulation.

4. CONCLUSION

The result indicated that the medium density

fiberboard of Napier grass fiber with density of

350kg/m³ with thickness of 6mm, which bonded by

PVA during hot pressing process have a good physical,

mechanical and thermal properties according to the

standard of insulation board and ASTM C 518. It can be

seen that the board of Napier grass fibers has the

thermal conductivity with the range of 0.0438-

0.0606W/mK which is in range of insulation material.

This shows that the Napier grass is a candidate raw

material for an insulator of particle board for ceiling

board, partition board and other building material for

energy saving [5].

5. ACKNOWLEDGEMENT

This work is supported by UPM under GP-IPM

grant, 9415402.

6. REFERENCES

[1] P.A. Fowler, J.M. Hughes and R.M. Elias,

“Biocomposites: technology, environmental

credential and market forces,” J. Sci. Food

Agric, vol. 86, no. 12, pp. 1781–1789, 2006.

[2] K.O. Reddy, C.U. Maheswari, M. Shukla and

A.V. Rajulu, “Chemical composition and

structural characterization of napier grass

fibers,” Mater. Lett., vol. 67, pp. 35 – 38, 2012.

[3] M.S. Abdul Majid, M. Afendi and S.N.

Aqmariah Kanafiah, “Effects of alkaline

concentrations on the tensile properties of

napier grass fiber,” Appl. Mech. Mater. 2014.

[4] American Society of Testing and Materials.

Standard Test Method for Steady-State

Thermal Transmission Properties by Means of

the Heat Flow Meter Apparatus (C 518), West

Conshohocken, PA 19428-2959, United Stated;

p. 152-166, 2010.

[5] R. Bruce Hoadley Understanding wood: A

Craftmann’s guide to wood technology, United

Stated: Taunton Press; 2005.


__________


The formation of thermally aged stress corrosion cracking on copper oxide surface under high temperature

G. Omar1,2,*, S.R. Esa3, N. Tamaldin1, N.A.B. Masripan1,2, S. Jasmee1




3) MIMOS Semiconductor Sdn. Bhd, Technology Park Malaysia, Bukit Jalil, 57000 Kuala Lumpur, Malaysia


Keywords: Corrosion; copper oxide; interface crack

ABSTRACT – The mechanism of stress corrosion

cracking was investigated on copper surface at various

elevated temperature. The thermally aged copper oxide

was mechanically analyzed by micro indentation and

further investigated by Scanning Electron Microscopy

(SEM) and Transmission Electron Microscopy (TEM)

specifically at the cracked interface. The copper oxide

leads to the formation of thin layer brittle surface

resulting to stress corrosion cracking which is due to the

differences in the diffusion kinetics between copper

oxide and copper causing the formation of micro-voids.

1. INTRODUCTION

Corrosion of copper at elevated temperature can

cause serious reliability issues in semiconductor

packaging. The long-term oxidation at an elevated

temperature leads to corrosion of copper. The corrosion

layer may flake off due to corrosion and surface film

growth [1]. Wan et al, has done the oxidation study of

copper at 800˚C and found that the corrosion products

of copper are easily broken into two layers; the inner

and the outer layers. The outer layer is easy to flake off

from the inner layer as the effect of corrosion [2].

The formation of the flakes is a phenomenon of

Stress Corrosion Cracking (SCC). This is the results of

the interaction of corrosion and mechanical stress

produced a failure by cracking. In engineering material,

SCC is used to describe failures that occur by

environmentally induced crack propagation. In SCC, the

cracks initiate and propagate progressively until the

stresses in the remaining metal exceed the fracture

strength. The process of SCC involved three stages:

a. Crack initiation; small crack forms at some

point of high stress concentration

b. Crack propagation; the crack advances

incrementally with each stress cycle

c. Final failure; occurs rapidly once the advancing

crack has reached a critical size

The contribution of the final failure of the SCC is

insignificant since it occurs rapidly. Crack associated

with SCC always initiates on the surface of a

component at some points of stress concentration. Crack

nucleation includes surface scratches, sharp fillet,

thread, dent and the like. Once the stable crack has

nucleated, it then initially propagates slowly. In metals,

cracks normally extend through several grains during

this propagation stage.

Several mechanisms have been proposed to

explain stress-corrosion interactions that occur at the

crack tip. It is likely that more than one process can

cause SCC. The proposed mechanisms can be classified

into two basic categories: anodic mechanisms and

cathodic mechanisms. That is, during corrosion, both

anodic and cathodic reactions must occur, and the

phenomena that result in crack propagation may be

associated with either type.

2. METHODOLOGY

In this study, a commercial cold work copper alloy

leadframe material was used. The oxidation of the

copper alloy leadframe sample was introduced via a

heat treatment process in an oven under oxygen

environment to promote the oxidation process. The

oxidation temperature was varied at 30°C intervals at

the temperature ranging from 60°C up to 240°C for 3

hours. The surface indentations were carried out using

micro hardness tester. The indentation time was set to 5

seconds for each indentation point. The indentation

mark on the sample surface was imaged using FESEM.

The interface voids were analyzed using Focused Ion

Beam (FIB) and Transmission Electron Microscopy

(TEM).

3. RESULTS AND DISCUSSIONS

3.1 Interface cracking

Figure 1 is the result of micro hardness and SEM

surface imaging. Result shows that despite small

variation of the surface hardness value among the

oxidized samples, there are significant transformation of

the surface properties from ductile metal surface to

brittle metal surface as indicated by the crack formation

on the top surface. This is evidently seen in the sample

that experienced heat treatment temperature of 180°C

and above.

The thin, brittle layer of metal oxide was found

cracked and separated from the base material of copper

that follows the geometry and the perimeter of the

indentation imprint. This is a phenomenon of Stress

Corrosion Cracking (SCC) that the corrosion layers

Omar et al., 2017

402

flake off due to corrosion and surface film growth. The

higher rate of copper oxidation at an elevated

temperature promotes the nucleation, grain growth and a

depleted layer of copper oxide resulting in the formation

of a brittle surface with the interaction of corrosion and

mechanical stress produced a failure by cracking.

Figure 1 Micro indentation micrograph acquired by

FESEM.

3.2 Void formation

The interface layer of copper oxide appeared as a

bright contrast in the bright field TEM image due to the

low density formation of copper oxide resulting in the

development of micro-voids along the interface. Figure

2 is the low magnification of bright field TEM

micrograph that shows the evidence of micro-voids

along the interface of copper to copper oxide. No micro-

voids were observed in the sample that was heat treated

at 150˚C and below. Scattered micro-voids were

observed at the interface region of the sample that was

heat treated at 180˚C and 210˚C. At a higher heat

treatment temperature; 240˚C, the micro-voids start to

initiate the separation in between copper oxide and bulk

copper.

Copper oxide has different diffusion kinetics than

the copper itself. Since the diffusion mechanism

involves lattice vacancies, an atom can move into a

vacant lattice site, effectively causing the atom and the

vacancy to switch places. If large-scale diffusion takes

place in a copper to copper oxide interface, there will be

a flux of atoms in one direction and a flux of vacancies

in the other direction which results in volume defects. In

many metals, voids will form in the oxide film when

oxidized, especially at the metal-oxide interface.

These voids formation, a volume defect, causes the

electron beam to easily transmit during the TEM

imaging process resulting in bright contrast as compared

to intact areas. The micro-voids may cause poor

adhesion in between copper oxide and bulk copper.

Severe effects may be experienced at higher

temperatures since complete separation may occur. In

semiconductor packaging, poor adhesion at this

interface region was found to be the root cause of

delamination issue and product failure.

Figure 2 TEM micrograph on copper oxide interface

voids.

P. Gondcharton et al, in his study on TiN-Cu

bonding also observed a void nucleation and growth at

the bonding interface of TiN-Cu, during post bonding

annealing at the temperature beyond 300˚C [3]. This

phenomenon suggested to the vacancy diffusion due to

thermal stress sustained by copper during post bonding

thermal budget

4. CONCLUSIONS

The copper oxide leads to the formation of thin

layer brittle surface resulting to stress corrosion

cracking. This is due to the differences in the diffusion

kinetics between copper oxide and copper causing the

formation of micro-voids along the interface of copper

to copper oxide. Further increasing the temperature

resulting to the complete separation between base

copper to copper oxide.

REFERENCES

[1] A.E. Segneanu, I. Grozescu, I. Balcu, N.

Vlatanescu and P. Sfirloaga, “A comparative study

between different corrosion protection layers,”

INTECH Open Access Publisher, 2012.

[2] Y. Wan, X. Wang, H. Sun, Y. Li, K. Zhang and Y.

Wu, “Corrosion behavior of copper at elevated

temperature,” Int. J. Electrochem. Sci, vol. 7, pp.

7902-7914, 2012.

[3] P. Gondcharton, B. Imbert, L. Benaissa and M.

Verdier, “Copper-copper direct bonding: Impact of

grain size,” in Interconnect Technology Conference

and 2015 IEEE Materials for Advanced

Metallization Conference, 2015, pp. 229-232.

Severe separation

240˚C

180˚C

210˚C

RT

Micro Voids

Extended Voids

No Voids 180˚C

210˚C

240˚C

RT

Hardness: 135 Hv

Hardness: 137 Hv

Hardness: 143 Hv

Hardness: 147 Hv


__________


The effect of aluminum thin film thickness on gold wire bond intermetallic formation

G. Omar1,2,*, S.H.S.M. Fadzullah1,2, N. Tamaldin1,2, S.R. Esa3




3) MIMOS Semiconductor Sdn. Bhd, Technology Park Malaysia, Bukit Jalil, 57000 Kuala Lumpur, Malaysia


Keywords: Intermetallic phases; wire bonding; thin film

ABSTRACT – The rate of intermetallic growth in gold

wire bonding is dependent on the microstructural

properties of the aluminum thin film. The high grain

boundary density of thin film promotes faster

intermetallic growth. All five intermetallic phases (IP)

can be observed in gold aluminum bonding but they

cannot be observed in one particular sample. The

intermetallic phases have different microstructural

properties. The Au2Al has fine and elongated structure,

the Au4Al has fine and equiaxed structure, the Au5Al2

has very fine structure and Au2Al has big structure.

1. INTRODUCTION

Au-Al welding system is the most commonly used

in wire bonding process. However, this bonding system

can easily lead to formation of Au-Al intermetallic

compounds and associated Kirkendall voids [1]. The

formation can be accelerated with the temperature and

time of the operational life. An early study on the

intermetallic compound was performed by Philofsky [2]

that according to him there are five intermetallic

compounds that are all colored: Au5Al2 (tan), Au4Al

(tan), Au2Al (metallic gray), AuAl (white), and AuAl2

(deep purple). Xu [3] has performed similar study but

found another intermetallic phase apart from initial five

intermetallic compounds. The findings on the

intermetallic formation of Au-Al wire bond system is

quite conflicting to each other. Anyone can make a case

for any intermetallic being present and cite his evidence.

This paper studies on the characteristics of and the

microstructural properties of the intermetallic phases

(IP) boned on two different thin film thickness. The

objective is to understand the factors that influenced the

presence of intermetallic phases.

2. METHODOLOGY

In this experiment, the 25 um gold wire were

bonded onto thin film of 2000 nm and 4000 nm. The

samples were thermally aged at 200 ºC. At appropriate

time frame, the samples were taken out and sent for

metallurgical cross sectioning and chemical etched to

investigate the intermetallic phases and microstructural

properties. The elemental composition analysis was

carried out using Energy Dispersive X-ray (EDX)

technique to detect the intermetallic phases.


3.1 Effect of thin film thickness on intermetallic

phases

Figure 1 is the result of intermetallic phases of Au-

Al system on 2000 nm and 4000 nm thin film. The

result shows that the all five intermetallic phases (IP)

was observed but not in every specimen. The number of

IP is dependent on the thin film thickness and aging

temperature. The 2000 nm thin film that was aged for

117 hours has two intermetallic phases that are Au5Al2

and Au4Al while the 4000 nm that was aged for 117

hours has four intermetallic phases that are Au5Al2,

Au4Al, Au2Al and AuAl.

Figure 1 The intermetallic formation of 4N gold wire on

two different film thickness that was aged at 200 °C.

Omar et al., 2017

404

This study indicates that the presence of

intermetallic phases (IP) of any sample is dependent on

the materials and the timeframe the sample being

analyzed. The result shows that purple-phase (AuAl2)

for 2000 nm 4000 nm thin film was observed at 5 hours

and 22 hours of thermal aging but totally disappear after

they reach 22 hours and 117 hours respectively. The

2000 nm thin film has minute appearance of Au2Al as

compared to 4000 nm thin film. This is because the

2000 nm thin film has lower supply of aluminum than

the latter. The growth of Au2Al is considerably slow

and being replaced by the AuAl and the rate constant

even becomes negative after long time due to AuAl

nucleating and growing into AuAl2.

The result shows that white-phase (AuAl) only

appeared at aging time of 22 hours and 117 hours for

2000 nm and 4000 nm thin film respectively. This AuAl

phase appeared to have difficulty nucleating initially

and formed in the slow growing AuAl2 at longer times

by excess gold diffusing into it. The white-plague Au2Al

appeared to nucleate slowly but once started, grew at the

second fastest rate.

The predominant phase in all the intermetallic

phases was Au5Al2. This phase nucleated immediately

and grew at fastest rate. At 1316 hours aging time, the

Au5Al2 IP dominating all other phases. This is observed

on of both 2000 nm and 4000 nm thin film. Voids also

appeared in this phase as shown in Figure 2 that

evidently occurred at the gold side of the phases and

were probably caused by the gold diffusing out faster

than the aluminum could replace it. Obviously, cracks

nucleate and grow along this void line in some

specimens. The propagation of the void along the gold

interface was presumably caused by the stresses

generated by thermal expansion differences between the

phases on cooling to room temperature.

The presence of intermetallic phase of Au4Al is in

minute quantity. The only instance when substantial

quantities of this phase were found was when the supply

of aluminum was limited, as behind the voided region

and the Au5Al2 was transformed into Au4Al by the

diffusing gold.

3.2 The microstructural and mechanical properties

of intermetallic phases

Figure 2 is the result of microstructural analysis on

one of the specific sample that has five different

intermetallic phases. The only not observable

intermetallic is AuAl that is difficult to be observed due

to its minute quantity. This result clearly shows that the

intermetallic phases have different microstructural

characteristics.

The Au2Al has a small grain and a columnar structure

pointing in vertical direction. The Au5Al2 is relatively

small grain than the rest of the intermetallic phases and

is in equiaxed structure. The Au4Al has about the same

grain size as the Au2Al but in equiaxed structure. The

AuAl intermetallic phase is the biggest grain size among

the other three intermetallic phases.

The result also shows that the separation of the

intermetallic phases is clearly visible and very well

separated. In this specimen, the small and equiaxed

microstructure of the Au4Al is seen consistently

presence below the gold interface. This is the

intermetallic phases that the void is initiated and

propagated along the gold and Au4Al interface.

Figure 2 The grain structure of intermetallic phases of

Au-Al wire bonding system.

4. CONCLUSIONS

Five intermetallic phases (IP) can be observed in

gold aluminum welding. However not all the

intermetallic phases can be observed in any of the

samples. The presence of intermetallic phases is

dependent on the availability of the material. The

variation in aluminum thin films manipulates different

type of intermetallic phases. The intermetallic phases

have different microstructural properties. The Au2Al has

fine and elongated structure; the Au4Al has fine and

equiaxed structure; the Au5Al2 has very fine structure;

Au2Al has big structure and in addition, all these

structures is relatively smaller than the gold grain

structure.

REFERENCES

[1] H. Xu, C. Liu, C., V.V. Silberschmidt, S.S.

Pramana, T.J. White, Z. Chen and V.L. Acoff,

“New mechanisms of void growth in Au–Al wire

bonds: volumetric shrinkage and intermetallic

oxidation,” Scripta Materialia, vol. 65, no. 7, pp.

642-645, 2011.

[2] Philofsky E., “Design limits when using gold-

aluminum bonds,” in Proceedings 9th Annual

IEEE Reliability Physics Symposium, pp.177-185,

1970.

[3] H. Xu, C. Liu, V.V. Silberschmidt, S.S. Pramana,

T.J. White, Z. Chen and V.L. Acoff, “Intermetallic

phase transformations in Au–Al wire bonds,”

Intermetallics, vol. 19, no. 12, pp. 1808-1816,

2011.


__________


Weight loss by soil burial degradation of green natural rubber vulcanizates modified by tapioca starch

M. Mazliah1, N. Mohamad1, H.E. Ab Maulod2,*, A.R. Jeefferie1, I.S. Othman1, H. Hanizam2, M.A. Azam1, Q. Ahsan1,

N.M.N. Mohd Safeai2, H. Mohd Mef’at3

1) Carbon Research Technology, Advanced Manufacturing Centre, Faculty of Manufacturing Engineering,

Universiti Teknikal Malaysia Melaka, Hang Tuah Jaya, 76100 Durian Tunggal, Melaka, Malaysia 2) Faculty of Engineering Technology, Universiti Teknikal Malaysia Melaka,

Hang Tuah Jaya, 76100 Durian Tunggal, Melaka, Malaysia 3) Sindutch Cable Manufacturer Sdn. Bhd., Lot 38, Alor Gajah Industrial Estate, 78000 Alor Gajah, Melaka, Malaysia


Keywords: Natural Rubber; tapioca starch; biodegradable

ABSTRACT – The weight loss of soil degraded natural

rubber vulcanizates modified by tapioca starch was

investigated. The samples were prepared by melt

compounding using a Haake internal mixer at different

tapioca starch loading of 0, 5, 10, 20, 40, and 60 phr. The

samples were exposed to soil burial testing for duration

of 7, 14, 21 and 28 days. Then, the weight loss was

measured using the difference in weight before and after

the testing. The mass reduction was observed to be

proportionately increased with the increment of tapioca

starch loadings and prolonged soil burial duration. The

rate of degradations observed was supported with

morphological characteristics of the vulcanizates. This

study is highly significant towards the development of

green natural rubber composites by incorporation of

tapioca starch.

1. INTRODUCTION

To date, there are growing interest in the use of

natural fillers such as starch [1] in rubbers and their

blends. The benefits of these fillers include low cost, easy

availability, sustainable sources and a greener choice to

our environment. Starch is one of the biopolymer

substances most widely found in nature and mostly

consists of amylose and amylopectin. There are several

works of reinforcing elastomers with tapioca starch [2-

3], but only a few addressed the degradation of natural

rubber vulcanizates. Thus, the aim of this study is to

assess the potential utilization of tapioca starch as

biodegradability agent in natural rubber formulations.

This study is part of our research work to produce

biodegradable natural rubber based composites which

proven to have diverse applications from general

household products to engineering components.

2. RESEARCH METHODOLOGY

2.1 Materials

Natural rubber (NR) with commercial trade name of

‘SMR20’ was purchased from Felda Global Ventures

Holdings Bhd (FGV). The NR was masticated using a

two-roll mill for about 10 min at 30 °C prior to

compounding. Carbon black was supplied by Lembaga

Getah Malaysia whereas tapioca starch (TS) was

purchased from Polyscientific Enterprise Sdn Bhd. Other

compounding ingredients such as sulfur, zinc oxide,

stearic acid were purchased from Systerm Classic

Chemical Sdn. Bhd. Tetramethylthiuram disulfide

(Perkacit-TMTD) was purchased from Aldrich

Chemistry, while 6PPD was supplied by Flexys America,

USA. All of the other compounding chemicals were used

as received without further purification steps.

2.2 Sample preparation

The NR was compounded using a Haake internal

mixer working at 60°C and a rotor speed of 60 rpm for 7

minutes according to ASTM D-3192. The TS loading was

varied (Table 1) and the recipe was based on semi-EV

curing [1]. Then, the compounds were subsequently

molded into sheets at 160°C and 150 kgf using a hot press

model GT7014-A from GoTech [4].

Table 1 Formulation recipe used in the preparation of

the composites. Materials Compound (phr)a

Natural rubber 100

Carbon Black 50

Tapioca starch 0 /5 / 10/ 20 / 40 / 60 a Parts per hundred b Tetramethylthiuram disulfide c(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine

2.3 Soil degradation test

Biodegradability of the samples in soils was

measured from percentage weight loss of the samples [5].

In this study, samples prepared in accordance to ASTM

D-412 type C were weighed and buried in natural soil

outdoors, approximately at a depth of 10 cm below the

surface. Five samples were removed every week for

different burial duration of 7 days, 14 days, 21 days and

28 days. After removal, samples were washed in distilled

water and dried at 60°C in a vacuum oven for at least 24

hours. The weight of each specimen was measured before

(W1) and after (W2) degradation. The weight loss (WL)

was calculated using Equation 1.

Mazliah et al., 2017

406

𝑊𝑒𝑖𝑔ℎ𝑡 𝐿𝑜𝑠𝑠 (𝑊𝐿) = 𝑊1− 𝑊2

𝑊1 𝑥 100 (1)


3.1 Weight loss

Figure 1 depicts the degradation rate experienced by

NR vulcanizates for the effects of tapioca starch loading

and soil exposure time. From the results, both factors

played significant roles. The samples exhibited

pronounced lost in their weight once exposed to almost 2

weeks to the soil degradation which shown by drastic

change in the curve. The rate of the degradation started at

very low rate of almost 0 %/day to upto 0.21 %/day for

sample with 60 phr tapioca starch. The rate of

degradation was dramatically increased beyond this point

and in some formulations the curve manifested a constant

change until 28 days. The degradation rate was

accelerated with the amount of tapioca starch present in

the samples. It was noted that weight loss was highly

proportional to the starch content. As the samples

exposed to the moistures, heat and microbes in the soils,

the hydrophilic portions of the starch will be degraded,

consumed and depicted as weight loss. Therefore, the

degradation process of a natural polymer such as tapioca

starch is highly complex which involved both climate and

biology elements. During the soil burial test, the starch

structure is destroyed and the amylopectin and amylase

chains degraded [6].

Figure 1 Percentage of weight loss versus time of NR

vulcanizates modified by tapioca starch for soil burial

degradation test.

3.2 Surface morphology

The degradation experienced by samples were

explained by the morphological characteristics of the

samples exposed to the soil burial testing. Figure 2 shows

the morphologies of three selected samples before and

after the testing at 500X magnifications via optical

microscopy. From the morphology, the white phase is

recognized as dispersed tapioca starch in the natural

rubber matrix which clumped together during the

compounding process. The starch aggregated into larger

particles as the loading of starch increased in the samples.

The starch aggregates appear smeared with larger sizes in

vulcanizates after soil burial testing of 28 days. This was

due to the swollen starch particles from reactions with

microbes, moistures and other factors in soil. Presence of

water promotes the microbe activities which results in

molecular degradation of the vulcanizates. The biological

degradation process form microbe’s enzymes could

occur under aerobic and anaerobic conditions, leading to

complete or partial removal of components to

environment [7].

4. CONCLUSION

As the conclusion, it was found that rate of

degradation of natural rubber vulcanizates is highly

influenced by the loading of tapioca starch into the

matrix. Nevertheless, the degradation curves nearly

achieved their constant rates after almost 2 to 3 weeks of

exposure to soils. This demonstrates the promising

potential for sustainable mechanical properties and

confirms the biodegradability tendency once in contact

with soils. The findings are significant to be exploited for

future green rubber composites based products.

Figure 2 The comparison of morphology for before and

after exposed to soils for 28 days.

ACKNOWLEDGEMENT

The authors acknowledge the UTeM for funding under

the project number of PJP/2016/FKP/HI6/S01484.

REFERENCES

[1] M. Mazliah, N. Mohamad, A.R. Jeefferie and H.E.

Ab Maulod, “cure characteristics and tensile

properties of natural rubber vulcanizates modified

by tapioca starch,” in Proceedings of Mechanical

Engineering Research Day 2016, 2016, pp. 163-

164.

[2] A.W.M. Kahar and H. Ismail, “High-density

polyethylene/natural rubber blends filled with

thermoplastic tapioca starch: Physical and

isothermal crystallization kinetics study,” J Vinyl

and Additive Technology, vol. 22, no. 3, 2016.

[3] S. Attharangsan, H. Ismail, M. Abu Bakar and J.

Ismail, “Carbon black (CB)/rice husk powder

(EHP) hybrid filler-filled natural rubber

composites: Effect of cb/rhp ratio on property of the

composites,” Polym Plast Technol Eng, vol.51,

no.7, pp.655–662, 2012.

Mazliah et al., 2017

407

[4] A.R. Jeefferie, S.H. Ahmad, C.T. Ratnam, M.A.

Mahamood and N. Mohamad, “Effects of PEI

adsorption on graphene nanoplatelets to the

properties of NR/EPDM rubber blend

nanocomposites,” J Mater Sci, vol. 50, pp. 6365 –

6381, 2015.

[5] Y.H. Lum, A. Shaaban, N.M.M. Mitan, M.F. Dimin,

N. Mohamad, N. Hamid and S.M. Se,

“Characterization of urea encapsulated by

biodegradable starch-PVA-glycerol,” Journal of

Polymers and the Environment, vol. 21, no. 4, pp.

1083-1087, 2013.

[6] N.I. Miren, A. Carmen, H. Marianella, G. Jeanette

and P. Jenny, “Characterization of natural

rubber/cassava starch/maleated natural rubber

formulations,” Revista Latinoamericana de

Metalurgia y Materiales, vol. 31, no. 1, pp.71-84,

2011.

[7] K. Leja and G. Lewandowicz G, “Polymer

biodegradaion and biodegradable polymers – A

review,” Polish Journal of Environmental Studies,

vol. 19, no. 2, pp. 255 – 266, 2010.


__________


Synthesis of TiO2 powders with addition of (NH4)2SO4 for cold spray coating

A.R. Toibah1,2,*, M. Yamada1, M. Fukumoto1

1) Faculty of Manufacturing Engineering, Universiti Teknikal Malaysia Melaka,

Hang Tuah Jaya, 76100 Durian Tunggal, Melaka, Malaysia 2) Department of Mechanical Engineering, Toyohashi University of Technology, 1-1, Tempaku-cho,

Toyohashi, Aichi, 441-8580, Japan


Keywords: Titanium dioxide; hydrolysis; cold spray coating

ABSTRACT – In this work, a simple hydrolysis

process has been employed to synthesize anatase TiO2

using titanyl sulphate; TiOSO4 with the addition of

ammonium sulphate; (NH4)2SO4 as starting materials

for cold spray process. SEM images revealed that higher

mol addition of (NH4)2SO4 into the precursor promotes

the formation of agglomerates of primary and secondary

particles of TiO2 powder. However, there are no

significant changes in terms of crystallinity as shown by

XRD patterns. A preliminary study on coating

deposition using cold spray showed that TiO2 powders

can be deposited onto the ceramic tile substrate.

1. INTRODUCTION

Of the several factors contributing to successful

ceramic coating formation during the cold spray

process, feedstock powder, in particular, stands out as

shown by several studies that have been conducted [1-

2]. Plastic deformation, which is required for powder

deposition using cold spray method, can occur in

ceramic material when the feedstock materials are in

nanosized particles [3]. The used of nanoparticle

powder for cold spray can promote ductility in the

powder by having a better capacity for the sliding of

small grains over each other and it is believed to be a

factor that help build up the coating when using ceramic

as feedstock material [4]. For a cold spray process, the

feedstock powder should be in the microsized range as

to avoid the powder clogging inside the feeding system

that transports the particles from the powder feeder to

the nozzle [2]. Moreover, due to a safety and

environmental regulations issue, the handling of fine

particles during spraying requires more safety

precautions than with the handling of coarser particles

[4]. Usually nanosized powders were agglomerated up

to submicron sized by means of a spray drying process.

However, spray-drying process that used to agglomerate

the fine particles into microsized range particles might

contribute to the loss of the nanosized grains especially

after the heat exposure during the sintering process.

Therefore, other alternative methods to prepare powder

feedstock materials for cold spray coating are crucial to

preserve the properties of the original properties of the

feedstock powders. In this paper, anatase TiO2 powders

in agglomerated form were synthesized by hydrolysis

method. The effect of the addition of (NH4)2SO4 during

the synthesis on microstructure and crystallinity of the

obtained powders were investigated. Coating deposition

using the synthesized powders were also conducted.

2. METHODOLOGY

The hydrolysis reaction was performed using 10

wt. % of TiOSO4 as the precursor for TiO2 and distilled

water. During the hydrolysis, 0.1, 0.5 & 1 mol% of

(NH4)2SO4 was added. The solution was stirred on a hot

plate to hold the temperature of the solution at ~80 °C

for 8 h. Upon completion the synthesis, a white

precipitate was formed. The precipitate was washed

with distilled water several times and then dried in an

oven to obtain a powder. As a comparison, a reference

TiO2 powder without the addition of (NH4)2SO4 was

performed with the same procedure.

A CGT Kinetiks 4000 cold-spray system was used

to deposit the coating using as-synthesized TiO2 powder

onto the ceramic tile substrate. The process gas

temperature and pressure used were 500°C and 3 MPa,

respectively. Nitrogen was used as the process gas in

this experiment.

The XRD patterns were obtained using a Rigaku

RINT 2500 with Cu-Kα radiation (λ = 1.5406 A) over

the 2θ range of 20-80°. The morphology of the resulting

powders and the obtained fractured cross sections of the

coating samples were examined using a Field Emission

Scanning Electron Microscope (FESEM: SU8000,

Hitachi).

3. RESULTS & DISCUSSION

Figure 1 shows the SEM image illustrating the

morphology of the TiO2 powders obtained from 0-1

mol% (NH4)2SO4 addition during the synthesis process.

The results show that the simple synthesis method can

produce powders that readily agglomerate the nano-

sized primary particles to micro-sized feedstock

powders for the cold spray process. Moreover, it is

clearly evident from the SEM image that the TiO2

powders that synthesized without the addition of

(NH4)2SO4 seem highly porous, where big pores were

observed and pointed out by arrows in Figure 1 (b). The

results also show that more spherical profile with more

pronounce of small agglomerates (secondary particles,

2°) inside larger agglomerates (tertiary particles, 3°)

with denser particle packing was obtained and more

Toibah et al., 2017

409

visible in the TiO2 powders which synthesized with the

addition of (NH4)2SO4.

Figure 1 SEM images of the TiO2 powders synthesized

with different mol% addition of (NH4)2SO4 at

magnifications of 5000 and 30 000, respectively:

(a & b) 0 mol%, (c & d) 0.1 mol%, (e & f) 0.5 mol%,

and (g & h) 1 mol%.

Figure 2 XRD pattern of as-synthesized TiO2 at

different mol% addition of (NH4)2SO4: (a) 0 mol%, (b)

0.1 mol%, (c) 0.5 mol%, and (d) 1 mol%.

However, no significant difference in crystallinity

can be observed when the TiO2 powders were

synthesized with different mol% addition of (NH4)2SO4

as shown by the XRD patterns in Figure 2. The patterns

show the characteristics of the anatase phase of TiO2

and are in good agreement with PDF card No. 21-1272.

The preliminary study of coating formation

depicted that the powder obtained could be used as the

feedstock powder for cold spray process to make

coating as it can be deposited onto the ceramic tile

substrate as shown in Figure 3. This study showed that

addition of (NH4)2SO4 during powder synthesis

provides denser microstructure of agglomerated TiO2

powders which produce a thicker coating compared to

the powder synthesized without the addition of

(NH4)2SO4 as shown in Figure 3 (b). Addition of

(NH4)2SO4 during the synthesis has produced

agglomerated powders with less porosity and tightly

bonded particles which lead to better particle impact

onto the substrate which help to build up the coating.

Moreover, details observation of the surface and cross-

sectional views of cold sprayed TiO2 coating which

synthesized with 1 mol% addition of (NH4)2SO4 shows

that the coatings composed of small TiO2 particles in the

size of <20 nm as shown on Figure 3 (c) and (d),

respectively.

Figure 3 Cross-sectional view of TiO2 coating deposited

by cold spray process: (a) without addition of

(NH4)2SO4 (b) 1 mol% addition of (NH4)2SO4 (c)

surface of coating and (d) cross-section of coating.

4. CONCLUSION

This study investigated the influence of addition of

different mol % of (NH4)2SO4 to promote agglomeration

of TiO2 that synthesized by simple hydrolysis method

for cold spray process. The study showed that

agglomeration of TiO2 powders can be promoted even at

lower percent of addition of (NH4)2SO4; 0.1 mol%. This

method is capable to produce an organize structure of

microsized agglomerated powders which were desired

for cold spray process.

REFERENCES

[1] N.T. Salim, M. Yamada, H. Nakano, K. Shima, H.

Isago and M. Fukumoto, “The effect of post

treatments on the powder morphology of titanium

dioxide (TiO2) powders synthesized for cold

spray,” Surf. Coatings Technol., 206, pp. 366-371,

2011.

[2] M. Gardon and J.M. Guilemany, “Milestones in

functional titanium dioxide Thermal Spray

coatings: A review,” J. Therm. Spray Technol., vol.

23, pp. 577-595, 2014.

[3] H. Park, J. Kwon, I. Lee and C. Lee, “Shock-

induced plasticity and fragmentation phenomena

during alumina deposition in the vacuum kinetic

spraying process,” Scr. Mater., vol. 100, pp. 44-47,

2015.

[4] L. Pawlowski, “Finely grained nanometric and

submicrometric coatings by thermal spraying: A

review,” Surf. Coatings Technol., vol. 202, pp.

4318-4328, 2008.

10 20 30 40 50 60 70 80

Inte

nsi

ty (

a.u

.)

2 theta (degree)

(101)

(004) (200) (105)(204)

Anatase TiO2

(c)

(b)

(a)

(d)


__________


Epoxy/carbon black/graphite composite bipolar plate prepared by high speed mixing technique

Y. Sudiana1, M.Z. Selamat1,2,*, S.N. Sahadan1,2, S.D. Malingam1,2, N. Mohamad3



Hang Tuah Jaya, 76100 Durian Tunggal, Melaka, Malaysia 3) Faculty of Manufacturing Engineering, Universiti Teknikal Malaysia Melaka,



Keywords: Carbon black, graphite composite, epoxy, bipolar plate

ABSTRACT – Conducting polymer composite (CPC)

has produced used epoxy resin (EP), carbon black (CB)

and graphite (G) as main composition. Various weight

percentage (wt.%) of CB, G and EP has been selected.

The fillers (CB and G) were mixed together with the

matrix (EP) used high speed mixer with no heat

treatment. The mixture was poured into the steel mold

and formed used hot pressed. After that, all sample’s

electrical conductivity and flexural strength had been

measured and the properties of EP/CB/G composite was

analyzed. The result found that the best plate produced

was the 20/25/55 of EP/CB/G weight ratio (wt.%). It has

102 S/cm in-plane electrical conductivity and 12 MPa

flexural strength.

1. INTRODUCTION

The biggest obstacle in the commercialization of

fuel cell vehicle (FCV) is the economic cost and

durability. The current situation of fuel cell system cost

for vehicle application, according to US Department of

Energy (DOE), is still more than twice as expensive as

other conventional and advanced vehicle technologies

[1]. The important component of fuel cell system is the

fuel cell stack. The stack is mainly constituting of bipolar

plate which contribute 80% of the stack weight and

almost 50% of stack cost [2]. Hence, the investigation on

cost/performance materials of bipolar plate has become a

critical research. The graphite-based composites offer

good electrical conductivity and economical processing

[3]. Addition of filler such as carbon black or carbon

nanotube to the graphite matrix has resulted in a bipolar

plate that has electrical conductivity above expected

value, but still its mechanical strength is still below

expectation [4-7]. The aim of this study is to apply the

high speed mixing technique in the fabrication of

graphite-based bipolar plate to meet DOE expectation as

shown in Table 1 below.

Table 1 DOE technical targets for bipolar plate [1]. Property 2015 Status 2025 Targets

Electrical

conductivity

> 100 [Scm-1] > 100 [Scm-1]

Flexural strength > 34 [MPa] > 25 [MPa]

2. MATERIALS AND METHODS

2.1 Materials

The conductive filler materials used in this study

were carbon black (CB) and graphite (G), while the

binder was epoxy (EP). The G powder was supplied by

Asbury Carbon Inc., that has density of 1.7 g/cm3, surface

area of 1.5 m2/g, particle size of 59 µm and 99% of purity.

The CB was also provided by Asbury Carbon Inc., that

has density of 0.096 g/cm3, has surface area of 254 m2/g,

average particle size of 30 nm, and 99% of purity. The

epoxy resin was 105 West System Epoxy Resin/206 Slow

Hardener wich has viscosity of 725 cps.

2.2 High speed mixing

Before the high speed mixing technique is applied,

samples were prepared by following steps. Firstly,

powder mixtures of CB and G were made by different

wt.% using a ball milling. To get a homogenous mixture,

the powder was mixed at rotating speed of 200 rpm for

one hour. Lastly, the powder mixture and epoxy were

mixed in the high speed mixer (Waring) at 1900 rpm

speed for 10 minutes. The liquid epoxy resin and curing

agent used in the mixture was 6:1 ratio, which is an

acceptable ratio recommended by the manufacturer. The

various composition of EP/CB/G shown in Table 2. The

composition mixture then poured into steel mould at

molding temperature 80 0C and 30-ton pressure for

30 minutes.

Table 2 The composition of composite EP/CB/G based

on weight %.

Filler Binder

G % CB% EP%

60 20 20

55 25 20

50 30 20

45 35 20

Sudiana et al., 2017

411

2.3. In-plane electrical conductivity

The in-plane electrical conductivity of the EP/CB/G

composite was measured by a Jandel Multi Height Four

Probe as per ASTM C611.

2.4. Flexural strength

The static Universal Testing Machine (Instron) was used

to measure the sample flexural strength according to

ASTM D70 at room temperature. The dimension of

samples was 100 mm x13 mm x 5 mm, the support span

length of each sample was fixed at 70 mm and the cross

head speed was 2 mm/min.


All of the various composition of EP/CB/G was

successfully fabricated except that the 20/35/45

composition has failed. It was due to the bonding of

graphite and carbon black with EP is weak. Graphite has

poor wettability with the binder resin, while carbon black

has very large specific surface area [8-10]. Therefore,

lack of bonding to the conductive fillers during the

fabrication process of 20/35/45 composition produce the

defect of composite structure.

3.1 In-plane electrical conductivity

Figure 1 shows the effect of addition carbon black

(CB) as the second fillers in the G/epoxy composite. The

in-plane electrical conductivity of the EP/CB/G

composites has double from 20 wt.% to 25 wt.% of CB

content. The highest value of in-plane electrical

conductivity belongs to 20/25/55 composition of

EP/CB/G and the 102 S/cm of value has met the DOE

target. This phenomenon may be attributed to the better

dispersion of carbon black into the G/epoxy composite

during high speed mixing. Carbon black help build better

conductive pathway throughout the plate. Nevertheless,

addition of more than 25 wt.% of CB decreased the in-

plane conductivity because the epoxy resin as a matrix is

not sufficient enough to bind the fillers. Similar trend of

in-plane electrical conductivity also found in other study,

such as Dweiri and Sahari [4], Suherman et.al [6], and

Mathur et.al [8].

Figure 1 Electrical conductivity (Average).

3.2 Flexural strength

Figure 2 shows the trends of flexural strength from

the addition of CB to the G/epoxy composite. Similar to

the in-plan electrical conductivity above, the highest

value of flexural strength belongs to the 20/25/55

composition of EP/CB/G with the value of 12 MPa.

However, the value does not meet the DOE target. These

phenomena also present in other study that use epoxy as

binder such as Suherman et.al [6].

Figure 2 Flexural strengthy (Average).

4. CONCLUSION

The application of the high speed mixing technique

in fabrication of graphite-based bipolar plate has resulted

in a similar in-plane electrical conductivity’s and flexural

strength’s trend with other previous study but simpler in

the procedure.

ACKNOWLEDGEMENT

The authors would like to thank the Malaysia

Ministry of Higher Education, Malaysia and Ministry of

Science, Technology and Innovation for sponsoring this

work under Grant PJP/2013/FKM(6A)/S01181 and

Universiti Teknikal Malaysia Melaka (UTeM) for

financial sponsoring during this research.

REFERENCES

[1] US Department of Energy,

https://energy.gov/eere/fuelcells - accessed 12

December 2016.

[2] I. Bar-On, R. Kirchain and R. Richard, “Technical

cost analysis for PEM fuel cells,” Journal of Power

Sources, vol. 109, pp. 71-75, 2002.

[3] A. Hermann, T. Chaudhuri and P. Spagnol, “Bipolar

plates for PEM fuel cells: A review,” International

Journal of Hydrogen Energy, vol. 30, pp. 1297-

1302, 2005.

[4] R. Dweiri and J. Sahari, “Electrical properties of

carbon-based polypropylene composites for bipolar

plates in polymer electrolyte membrane fuel cell

20

40

60

80

100

120

Elec

tric

al C

on

du

ctiv

ity

(S/c

m)

20/20/60 20/25/55 20/30/50

EP/CB/G Composition

55

102

37

2

4

10

6

14

8

Flex

ural

Str

engt

h (M

pa)

20/20/60 20/25/55 20/30/50

EP/CB/G Composition

12

6

12

5

Sudiana et al., 2017

412

(PEMFC)”, Journal of Power Source, vol. 171, pp.

424-432, 2007.

[5] R. Taherian, M.J. Hadianfard and A.N. Golikand,

“Manufacture of a polymer-based carbon

nanocomposite as bipolar plate of proton exchange

membrane fuel cells,” Materials & Design, vol. 49,

pp. 242-251, 2013.

[6] H. Suherman, J. Sahari, A.B Sulong, S. Astuti, and

E. Septe, “Properties of epoxy/carbon

black/graphite composites bipolar plate in polymer

electrolyte membrane fuel cell,” Advanced Material

Research, vol. 911, pp. 8-12, 2014.

[7] M.Z. Selamat, M.S. Ahmad, M.A.M. Daud and N.

Ahmad. “Effect of carbon nanotube on properties of

graphite/carbon black/polypropylene

nanocomposites,” Advanced Material Research,

vol. 795, pp. 29-34, 2013.

[8] R.B. Mathur, S.R. Dhakate, D.K. Gupta, T.L.

Dhami and R.K. Aggarwal, “Effect of different

carbon fillers on the properties of graphite

composite bipolar plate”, Journal of Material

Processing Technology, vol. 203, pp. 184-192,

2008.

[9] R.A. Atunes, M.C.L. Oliveira, G. Ett and V. Ett,

“Carbon materials in composite bipolar plates for

polymer electrolyte membrane fuel cells: A review

of the main challenges to improve electrical

performance”, Journal of Power Sources, vol. 196,

pp. 2945-2961, 2011.

[10] M.Z. Selamat, J. Sahari, N. Muhamad and A.

Muchtar, “The effects of thickness reduction and

particle sizes on the properties graphite

polypropylene composite”, International Journal of

Mechanical and Materials Engineering, vol. 6, pp.

194-200, 2011.


__________


Low cycle fatigue of hybrid woven kenaf fiber reinforced epoxy composite with 1% addition of silica aerogel

Ellyna Chok Yee Ling, Dayang Laila Abang Abdul Majid*

Department of Aerospace Engineering, Faculty of Engineering, Universiti Putra Malaysia,

43400 Serdang, Selangor Darul Ehsan, Malaysia


Keywords: Natural fibers; biocomposite; fatigue

ABSTRACT - This paper presented the mechanical

and fatigue behavior of woven kenaf fiber reinforced

epoxy composites with the composition of 16.67%

kenaf and 83.33% of epoxy (1:5 weight ratio) with 1%

of silica aerogel. Hand lay-up technique was used to

prepare the specimens. Fatigue test was conducted at

constant stress amplitude, 5 Hz frequency, 0.5 stress

ratios and the maximum stress applied was from 90 %

to 70 % of ultimate tensile strength (UTS) with

decrement of 5%. From the results, tensile properties

and fatigue life improved as silica aerogel is added into

the composite.

1. INTRODUCTION

Biocomposites had been put under the spotlight

for their mechanical properties competitiveness. Kenaf

fiber had been the subject to be implemented into

biocomposite nowadays for their economic and

ecological advantages. Hence, a series of studies were

conducted in order to better understand their properties

[1-3]. Although the potential of the material is

promising, it may not be able to escape the load

demand issue which includes fatigue load. Studies

involving fatigue damage had been widely explored in

these years [4-5]. However, unlike the research works

on synthetic fibers, the works in natural fibers

especially kenaf is very lacking. Other natural fibers

besides kenaf fiber had been tested for fatigue test [6-

7]. Kenaf fibers are not the best choice to be used to

bear loads as they possess lower mechanical properties

than synthetic fibers [8-9]. Hence, silica aerogel had

been chosen as filler for the composite. This study is

then intended to explore and compare the fatigue life of

a single layer woven kenaf fiber reinforced epoxy

composite with and without aerogel in 5 different

levels of stresses.

2. METHODOLOGY

Tensile test was used to investigate the properties

for the specimens before performing fatigue test. The

test is performed using the 10 kN Servo Hydraulic

Instron Machine (Instron 3366). The test was

conducted by setting a standard strain rate of

0.01𝑚𝑖𝑛−1 and head displacement rate of 2𝑚𝑚/𝑚𝑖𝑛

according to ASTM D3039. ASTM D3479 on the other

hand is used to conduct the fatigue test on the

specimens through the tension-tension fatigue loading

mode. Stress ratio used is 0.5 with frequency of 5 Hz.

The stress levels are varied from 90%, 85%, 80%, 75%

and 70% of the ultimate tensile strength (UTS). The

specimens were cycled using 810 Material Test System

(MTS) machine with the number of cycles to failure

recorded by data acquisition system.


3.1 Tensile results

Figure 1, and 2 below exhibit the load-

displacement and stress-strain curves of all categories

of specimens. It is shown that kenaf composite that is

added with 1% of silica aerogel is 27.3% higher in

UTS compared to kenaf/epoxy composite that is

without addition of silica aerogel. However, the

Young’s modulus decreases with the addition of silica

aerogel.

Figure 1 Load displacement curves for all three

materials.

Natural fibers are reported to possess high

strength. However, following the experiment

conducted, the tensile properties of both kenaf/epoxy

and Kenaf/Epoxy/Silica Aerogel composites are lower

than pure epoxy. The incompatibility of fibers and

matrix is the main cause in this behavior. The

incompatibility hence brings inefficiency of stress

transfer in the matrix.

3.2 Fatigue results

Fatigue test was conducted using different stress

levels. The average number of cycles to failure for all

three categories is tabulated in Table 1.

From Figure 3, it can be observed that the fatigue

life of pure epoxy is higher than kenaf/epoxy/silica and

kenaf/epoxy. Kenaf/epoxy composites have the lowest

fatigue life compared to all three specimens. However,

the addition of silica aerogel into the kenaf/epoxy

Ling et al., 2017

414

composites has boosted the properties of the

composites by more than 100% in every stress level. It

can hence be concluded that the fatigue life increases

significantly with the addition of 1% of silica aerogel.

Table 1 Average fatigue life data for the specimens.

Stress

Level

(UTS)

Number of cycles to failure

Pure

Epoxy

Kenaf/epoxy/silica

aerogel Kenaf/epoxy

0.90 1821.3 316.0 7.3

0.85 4593.3 751.3 112.3

0.80 5646.7 4186.0 208.7

0.75 10070.0 5632.7 1085.7

0.70 13620.3 12449.2 5177.3

(a)

(b)

Figure 2 (a) UTS and (b) Young's Modulus for all three

materials.

Figure 3 S-N curve generated for all tested specimens.

The pure epoxy exhibits better fatigue behavior

compared to the kenaf composites. The incompatibility

of fibers and matrix is the main cause in this behavior.

The incompatibility hence brings inefficiency of stress

transfer in the matrix [10].

4. CONCLUSION

The study verified that the addition of silica

aerogel into composites provide better tensile and

fatigue properties. In terms of tensile test, the ultimate

tensile strength increases with the addition of silica

aerogel but the Young’s modulus is decreased. Hence,

it can be said that there is a trade off in implementing

the composite into any sorts of structures. On the other

hand, the composite provides significant increment in

fatigue strength than composites without addition of

silica aerogel. The composite can then be candidates

for applications that are tend to be subjected to fatigue

phenomenon.

REFERENCES

[1] A. Bakar, S. Ahmad and W. Kuntjoro, “The

mechanical properties of treated and untreated

kenaf fibre reinforced epoxy composite,” Journal

of Biobased Materials and Bioenergy, vol. 4, no.

2, pp. 159-163, 2010.

[2] T. Hojo, Z. Xu, Y. Yang and H. Hamada, “Tensile

properties of bamboo, jute and kenaf mat-

reinforced composite,” Energy Procedia, vol. 56,

pp. 72-79, 2014.

[3] N.A.K. Hafizah, M.W. Hussin, M.Y. Jamaludin,

M.A.R. Bhutta, M. Ismail and M. Azman,

“Tensile behaviour of kenaf fiber reinforced

polymer composites,” Jurnal Teknologi, vol. 3, pp.

11-15, 2014.

[4] K.L. Reifsnider and A. Talug, “Analysis of fatigue

damage in composite laminates,” International

Journal of Fatigue, vol. 2, no. 1, 3-11, 1980.

[5] J.W. Holmes, B.F. Sørensen, Fatigue behavior of

continuous fiber-reinforced ceramic matrix

composites, Butterworth-Heinemann; 1995.

[6] S. Liang, P.B. Gning and L. Guillaumat, “A

comparative study of fatigue behaviour of

flax/epoxy and glass/epoxy composites,”

Composites Science and Technology, vol. 72, no.

5, pp. 535-543, 2012.

[7] F. de Andrade Silva, N. Chawla and R.D. de

Toledo Filho, “An experimental investigation of

the fatigue behavior of sisal fibers,” Materials

Science and Engineering: A, vol. 516, no. 1, 90-

95, 2009.

[8] H. Akil, M.F. Omar, A.A.M. Mazuki, S.Z.A.M.

Safiee, Z.M. Ishak and A.A. Bakar, “Kenaf fiber

reinforced composites: A review,” Materials &

Design, vol. 32, no. 8, pp. 4107-4121, 2011.

[9] B.M. Philip, E. Abraham, B. Deepa, L.A. Pothan

and S. Thomas “Plant fiber-based composites,”

Green Composites from Natural Resources, CRC

Press, pp. 95-124, 2014

[10] H.D. Rozman, G.S. Tay, R.N. Kumar, A.

Abusamah, H. Ismail and Z.M. Ishak,

“Polypropylene–oil palm empty fruit bunch–glass

fibre hybrid composites: a preliminary study on

the flexural and tensile properties,” European

Polymer Journal, vol. 37, no. 6, pp. 1283-1291,

2001.


Compressive behaviour of filament wound steel/carbon hybrid composites tube

N.A. Jamaluddin1,*, S.A. Hassan1,2, B. Omar3, U.A. Hanan1, M.A.M. Adam1

1) Faculty of Mechanical Engineering, Universiti Teknologi Malaysia, 81310 Skudai Johor, Malaysia

2) Centre for Composites, Institute for Vehicle and System Engineering, Universiti Teknologi Malaysia,

81310 Skudai Johor, Malaysia

3) Department of Structure and Materials, Faculty of Civil Engineering, Universiti Teknologi Malaysia,

81310 Skudai, Johor, Malaysia


Keywords: Composites; crashworthiness; energy absorption

ABSTRACT – The crushing behaviour of composites

tube were investigating by applied the different layer in

filament winding process which is the CCC and CSC

samples. Compression test on CCC and CSC epoxy

composites hexagonal tubes were conducted. Effect of

height of the tube and comparison between CCC and

CSC samples on the load-displacement behaviour as

well as energy absorption of composites hexagonal

tubes has been investigated. Results obtained shows

that, CCC samples stands higher load and energy

absorption capability than CSC samples. However, the

important parameter for crashworthiness is specific

energy absorption and crush force efficiency which is

for ideal crashworthiness.

1. INTRODUCTION

Composite parts as sandwich structures are

specifically used in applications for automotive,

aerospace and vehicle industries. Approaches reducing

the weights of vehicles using polymers most frequently

involve replacing ferrous and non-ferrous metals with

polymers and increasing the specific strengths and

rigidities of polymers. Researches into polymers for use

in lightweight vehicle are classified into high

performance polymers, polymers for weight reduction,

reinforced polymer composites, polymer sandwich

panels, and polymer/metal hybrid systems. Weight

reduction of vehicle is very important because vehicle

weight directly affects energy consumption [1]. An

important parameter when studying energy absorption is

the energy absorbed per unit mass of crushed material.

This is often called the specific energy absorption

(SEA). Schultz [2], has conduct research on effect of

geometry which is subject of the ability to absorb

impact energy and be survivable for the occupant is

called the ‘‘crashworthiness’’ of the structure.

Crashworthiness is concerned with the absorption of

energy through controlled failure mechanisms and

modes that enable the maintenance of a gradual decay in

the load profile during absorption. Therefore, in this

paper, inclusive experimental work was implemented to

study the response of crushing behaviour on composites

tube by applying different layer in filament winding

process with different length which are 40 mm and 45

mm. The winding angle that was chosen is 45° as in

previous studies done by Misri [3] which indicated that

the value of energy absorption for 45° winding angle is

higher compared to 90°.

2. METHODOLOGY

In this experiment, two types of composites will be

produced: Carbon-Carbon-Carbon (CCC) and Carbon-

Steel-Carbon (CSC) at 45° winding angle using filament

winding process. Then, the composites are cut into two

different heights which is 4.5 cm and 4 cm respectively

as shown in Fig. 1. The upper and lower ends of the

composites are trimmed properly and attached with

strain gauge (FCA-1-11) with a gauge length of 1 mm

and gauge resistance of 120 ± 0.5 Ω. The strain gauge

was attached at an angle of 0° and 90° and the channel

were soldered with wire and will be later attached to

data logger. Compression test provides a standard

method of obtaining data for research and development,

quality control, acceptance or rejection under

specifications and special purposes. From the test as

shows in Fig. 2, the behaviour of the core, maximum

load, compression strength, modulus, extension, strain

and energy absorption of the core had been determined.

Figure 1 Samples for (a) CCC 45mm, (b) CCC 40mm,

(c) CSC 45mm and (d) CSC 40mm.

Jamaluddin et al., 2017

416

Figure 2 Sample under compression test.


Based on the compression that were conducted, the

result shows in form of Load-Displacement curves and

Stress-Strain curves. According to the load displacement

curves in Fig. 3 and Fig. 4, the CCC composites tube

behave linearly first and the axial load is absorbed as an

elastic strain energy in the material and same goes for

CSC tube but however the for CCC, the elastic slope is

greater compared to CSC and this can be seen from

graph for 40 cm specimen and 45 cm specimens as both

shows the same. Elasticity is the ability of an object or

material to resume its normal shape after being

compressed and modulus of elasticity is a measure of

the ability of a material to withstand changes in length.

Figure 3 Load-Displacement curve for CCC and CSC

with samples length of 40 mm.

Figure 4 Load-Displacement curve for CCC and CSC

with samples length of 45 mm.

The value of the Compressive Modulus can be

calculated from the Combined Stress-Strain curves

shown in Fig. 5 and Fig. 6 as it is equivalent to the

value of the gradient and the data calculated were

presented in Table 1.

Figure 5 Stress-Strain Graph for CCC and CSC with

samples length of 40 mm.

From the table it is clearly shows that the

Compressive Modulus for 3 layers of Carbon samples

are greater compare to CSC samples. Although it can

withstand load, but after it reaches to a peak load, the

CCC specimens fail suddenly or catastrophically and it

can be seen from the load-displacement curves for both

40 mm and 45 mm specimens as the load drops down

by compressive shear parallel to fibre.

Table 1 Value of Compression Modulus according to

samples.

Sample Compressive Modulus, MPa

CCC 40 294.77

CSC 40 184.858

CCC 45 511.61

CSC 45 254.43

It occurs when unstable interlaminar or

intralaminar crack growth occurs and also in long thin

walled tubes because of column instability [1] . As a

result of this, the actual magnitude of specific energy

absorbed is much less and the peak load is too high to

prevent injury to the passengers. The crush mode of

CCC 40 and 45 mm are shown in Fig. 7.

Figure 6 Stress-Strain Graph for CCC and CSC with

samples length of 45 mm.

Figure 7 Crush Mode (a) CCC 45 mm, (b) CSC 45 mm,

(c) CCC 40 mm and (d) CSC 40mm.

(a) (b) (c) (d)

Jamaluddin et al., 2017

417

4. CONCLUSION

Overall, the purpose of this study is to analyse the

effect of core height on the crashworthiness parameter

and to study the mechanical behaviour of filament

wound steel/carbon hybrid hexagonal tube composites

under compression load. From the analysis that have

been made to the hexagonal structure, it can be conclude

that the Carbon-Steel-Carbon have a good potential in

energy absorber.

REFERENCES

[1] A. Alias and Y.S. Ismail, “Composite materials,”

Universiti Technologi Malaysia, 2003.

[2] M.R. Schultz, “Energy absorption capacity of

graphite-epoxy composite tubes”, Master of

Science Thesis, Virginia, pp. 110-115, 1998.

[3] S. Misri, M.R. Ishak, S.M. Sapuan and Z. Leman,

“The effect of winding angles on crushing

behavior of filament wound hollow kenaf yarn

fiber reinforced unsaturated polymer composites,”

Fibers and Polymers, vol. 16, no. 10, pp. 2266-

2275, 2015.


__________


Synthesis of oxygen carrier for chemical looping combustion from iron ore N.F. Afandi1,*, Wen Liu2, A. Manap1, D. Naidu1

1) Faculty of Mechanical Engineering, Universiti Tenaga Nasional, Jalan IKRAM-UNITEN, 43000 Kajang, Selangor

2) Cambridge Centre for Advanced Research in Energy Efficiency in Singapore,

Nanyang Technological University, 637459, Singapore


Keywords: CLC; Fe-based; iron ore

ABSTRACT – Chemical looping combustion (CLC) is

a promising technology for fossil fuel combustion that

prevents greenhouse gas (GHGs) release into the

atmosphere. In CLC, oxygen carrier provides oxygen

during combustion process. This research focuses on

using iron ore that was found at iron mining site, Kuantan

Pahang as oxygen carrier. Iron ore was grinded to sub-

micron sized particles to increase performance of CLC.

Then, the phase and morphology of the powder was

characterized to evaluate the Fe2O3 content. Fe2O3 shows

favorable thermodynamics in CLC application. This

research succeeded in producing sub-micron sized iron

ore particles that contain high Fe2O3, which is suitable to

be used as oxygen carriers in CLC application.

1. INTRODUCTION

Chemical looping combustion (CLC) is a carbon-

capturing technology that uses oxygen carriers (OCs) to

provide oxygen during combustion process. Hence, it

reduces the emission of greenhouse gases (GHGs) into

the atmosphere. OCs play an important role in CLC

performance [1]. Suitable oxygen carriers should have

good fluidization properties, high oxygen content and the

capacity to convert fuel to CO2 and H2O, low cost and

environmental friendly [2].

There are 5 metal based OCs that are usually used

in CLC, which include Fe-based, Ni-based, Co-based,

Mn- based and Cu-based [3]. From previous studies, Cu-

based and Ni-based shows good performance as oxygen

carriers. However, Cu-based cannot withstand at high

temperature because it has low melting point temperature

and Ni-based is costly and needed special safety measure

to handle this material due to its hazardousness [4-5].

Mn-based has low reactivity with fuels that can reduce

efficiency of CLC system. Meanwhile the Co-based is

highly cost and toxic to the nature [6]. This research

focuses on Fe-based oxygen carrier since it is more

environmental friendly than other OCs, abundant, and

low cost, thus substantially reducing the operational cost

[4]. In recent years, iron ores have become popular source

for Fe-based OCs due to its high reactivity in CLC,

especially iron ores that contain high amounts of Fe2O3

[7].

This research aims to investigate the suitability of

mineral iron ore found at iron mining site in Kuantan,

Pahang as OCs to be used in CLC. The iron ore was

characterized using X-Ray Diffraction (XRD), Field

emission Microscopy (FESEM) and Energy Dispersive

X-Ray (EDX) to determine the crystalline phase,

morphology and elements of the obtained iron ore.

2. METHDOLOGY

The iron ore samples were collected from iron

mining site at Kuantan, Pahang. The weight of the iron

ore was 200g. Then, iron ore was crushed using mortar

for 15 to 20 minutes. High blender DM-6 was used to

grind the iron ore (raw material). The iron ore was

grinded at 20 000 rpm for 30 minutes into micron size

particles using tungsten carbide blade.

The sub-micron sized iron ore materials were then

characterized. Phase was identified using XRD

(SHIMADZU 6000) that uses CuKα radiation at a scan

speed of 3°/min. The data were collected at scan range of

20° to 80° with voltage and current of 30 kV and 20 mA

respectively. Meanwhile, morphology was observed

using FESEM (HITACHI SU8030) with acceleration

voltage from 1 to 5 kV. The elemental composition of the

powder was analyzed using EDX.


Figure 1 shows XRD result of iron ore after

grinding for 30 minutes. Presence of Fe2O3 can be

observed in Figure 1 corresponding to Fe2O3 structure

(JCPDS card no: 39-1346 and 25-1402). The conversion

of Fe2O3 to Fe3O4 shows favorable thermodynamics in

CLC. Hence, high composition of Fe2O3 is needed in OCs

to increase the performance and efficiency of CLC [4].

Figure 2(a) shows the microstructure of raw iron

ore. They are irregularly shaped with particle size of

more than 300 nm. Figure 2(b) shows microstructure of

iron ore after grinding. Particle size ranging between

150nm-900nm can be achieved using grinding process.

Based on Song et al. [7], OCs with smaller particles are

more stable at high temperature, have superior

mechanical properties and are capable of reducing the

sulphur content that comes from the solid fuel, which is

not favorable in CLC. The sulphur presence can be

deteriorating the oxygen carrier hence decrease the

function of redox reaction. Therefore, it can decrease the

efficiency of CLC [8].

Afandi et al., 2017

419

Figure 1 XRD result of iron ore after had been grinded

about 30 minutes.

Figure 2 Microstructure result of iron ore (a) raw

material (b) after grinding process.

Figure 3(a) shows EDX analysis of raw iron

ores and Figure 3(b) shows iron ores after grinding. EDX

analysis shows no impurities for both samples. The

sample was not contaminated even after the grinding

process. Therefore, this iron ore is fit to be tested in

thermogravimetric analysis (TGA) in order to simulate

its performance in CLC application.

Figure 3 Elemental compositions of iron ore (a) raw

material (b) after grinding process.

4. CONCLUSIONS

Iron ore that was collected from iron mining site at

Kuantan, Pahang can be used as OCs since it contains

high Fe2O3 that can increase performance of CLC.

Moreover, this iron ore is the least expensive metal that

is accessible in nature and give less impact to the

environment. This powder will be tested using TGA for

its performance as oxygen carrier.

ACKNOWLEDGMENT

The authors acknowledge the financial supports by

the Malaysian Ministry of Higher Education (Grant No.

FRGS20160105).

REFERENCES

[1] C.Y. Sim, T. Brown, Q. Chen, V. Sharifi, J.

Swithenbank, J. Dennis and S. Scott., “Particle

characterization in chemical looping combustion,”

Chemical Engineering Science, vol. 69, pp. 211-

214, 2012.

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investigation of the wear characteristics of helical …hamid et al., 2017 382 table 2 wear debris...

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