VISVESVARAYA TECHNOLOGICAL UNIVERSITY

“Jnana Sangama”, Belagavi – 590 018, Karnataka

SYNOPSIS

ON

“DEVELOPMENT AND MECHANICAL-WEAR CHARACTERIZATION OF

AL2024 NANO B4C COMPOSITES FOR AEROSPACE APPLICATIONS”

Submitted in partial fulfilment of the requirement for the award of

BACHELOR OF ENGINEERING

in

MECHANICAL ENGINEERING

Submitted by

PRAVEEN P KADUR 1AM16ME441

SALMAN KHAN A 1AM16ME455

MANJUNATHA 1AM16ME425

ADANAGOUDA 1AM16ME403

under the guidance of

Mr. SHIVANAND B.K

Assistant Professor

Department of Mechanical Engineering

AMC ENGINEERING COLLEGE

Department of Mechanical Engineering

18 km, Bannerghatta Road, Bengaluru – 560 083

2018 - 2019

ABSTRACT

Composites are becoming increasingly important in the aerospace industry. At least 30-40

percent of modern airframes are now made of composites, and this percentage is increasing

rapidly due to the technological advances in the composite materials, Metal Matrix

Composites are a broad family of materials aimed at achieving an enhanced combination of

properties. While the matrix can be of any metal or alloy, most interest has been shown in the

lighter structural metal cases. Improvement in the mechanical properties has been the primary

objective. Much of the progress in the field of MMCs is closely linked to developments in

reinforcements for incorporation in MMCs. Composite materials are fast gaining ground as

preferred materials for construction of aircrafts and space crafts. At present composites

material are becoming important in Aerospace engineering due to its increased strength at

lower weight, stiffness and corrosion resistance.

Keywords— AL2024, Mechanical Properties, nanoB4C, C2Cl6

CHAPTER 1

INTRODUCTION

The combination of two are more different materials artificially created structural

materials are composite materials. Which will be having different chemical properties and

physical properties. Matrix, interface and reinforcements are the important constitutes of

composite. The matrix can be ceramic, polymer and metal. The reinforcement is in the form

of whiskers, particulate and fiber. To get the required characteristics reinforcing phase is used

in the matrix. The constituents of composite material should be insoluble in each other and

differ in chemical composition. The size of constituent may vary from nano, micro, macro

based on the application and desired property. Composite materials are the combinations of

two are more constituents that are different, the base will be the matrix and the constituents

are the reinforcements. The best to describe the composites are the natural materials like

wood, mineral rock, skeleton system surrounded by the tissue and some organic materials.

These composites are developed to meet the application as per industrial requirements for a

particular design and other environmental conditions. These composites form a

heterogeneous structure with desired properties. Now a day’s modern composite materials are

being investigated with their own specific requirements like particulate flake, and laminar or

filled composites. Particulate and fiber reinforced are the examples of modern composites

and are more suitable for the structural applications. To perform specific functions and

specific character several distinct layers of materials are added in laminated composites. The

reinforcements are used to increase the load carrying capacity and other required properties

as desired. The main purpose of matrix in matrix based structural composites is to bind the

reinforcement phase and to distribute the generated stresses among the filler materials.

Particulate and fiber reinforced are the examples of modern composites and are more suitable

for the structural applications. To perform specific functions and specific character several

distinct layers of materials are added in laminated composites. The reinforcements are used to

increase the load carrying capacity and other required properties as desired. The main

purpose of matrix in matrix based structural composites is to bind the reinforcement phase

and to distribute the generated stresses among the filler materials.

CHAPTER 2

OBJECTIVES

1. Synthesis of Al2024-nano B4C metal matrix composites by stir casting method

varying the weight percentage of Nano B4C in steps of 0, 2, 4, and 6 wt. %.

2. Characterization of the above-prepared composites by Scanning Electron Microscopy

to know the uniform distribution of Nano particles in the matrix.

3. Analysis of the above-prepared specimens by EDS (Energy Dispersive Spectroscopy)

to know the presence of Nano B4C particulates in the Al2024 matrix alloy.

4. Determination of theoretical and experimental densities of composites for varying wt.

% of Nano B4C particulates.

5. Preparation of test specimens for mechanical properties of both unreinforced and

reinforced Al2024 alloy.

6. Evaluation of mechanical properties like hardness, ultimate tensile strength, yield

strength, and compression properties for both un reinforced Al2024 alloy and Al2024-

nano B4C particle size composites.

CHAPTER 3

METHADOLOGY

Al2024 Base Alloy

Al2024 is one of the 2xxx series alloys, in which contains Copper as their major alloying

element, and it is combined with copper and magnesium. Aluminium 2xxx series alloys have

the highest strength compared to other aluminium alloys.

Nano Boron Carbide as Reinforcement

The chemical formula of Boron Carbide is B4C. Boron carbide and boron nitride are the

hardest metals after diamond and as a ranking at third number.

Stir Casting Method

To carry out the current work for preparing the moulds we have used the stir casting process.

Step by step, stir casting process for the preparation of Al2024 nano B4C composition,

A required weight of Al2024 alloy is weighed and kept in crucible.

For melting, the crucible with Al alloys is placed in furnace at 7300C temperature.

Once the metal in crucible is melted, the degassing process is carried with the help of

solid hexachloroethane as a degassing agent. This tablet is helpful to remove the

entrapped air to prevent the defective castings (blowholes and porosity).

Stirrer with the motor of 1HP is used to mix the molten metal and the arrangement

of stirrer with respect to furnace.

Stirrer is made up of stainless steel with zirconia coating.

To protect the motor from furnace intense heat it is covered with asbestos shield

Prior to the molten metal stirring the slag is removed from the molten metal. To

form the clear vertex of the melt the stirrer will be introduced and rotated at

300rpm.

Nano boron carbide weighed 0%, 2%, 4% & 6% are mixed together, the

reinforcements are pre heated to eliminate the moisture and gasses.

The reinforcement mixture will be introduced slowly into the vortex of molten metal

rotating at 300-rpm form 15 min slowly for better mix-up.

During the addition of the reinforcement (Nano B4C) the temperature of the molten

metal will be maintained at 7300C.

The mixture of molten metal with the reinforcements is poured quickly in the

coated, dried permanent mould allows to solidify, the surfaces are coated to get the

good surface finish.

Once solidification completes the dies were opened to take the composite

specimens.

Degassing process

Degassing process involves reducing the porosity and blowholes in the casting, solid

hexachloroethane (C2Cl6) is used as a degassing agent. By putting 3 to 4 grams of solid

hexachloroethane followed by 5 to 6 min and stirring degassing process will be carried.

Characterization of the Prepared Composites

Microstructure Study: -

To study the microstructure of a material metallographic is used. Analysis of material

microstructure is very important because it aids in determining whether the material is

synthesized properly or is there any defects in the material, with the microstructural study

it is easy to determine the reliability of material and helps to study the dislocations and

why the material fails.

EXPERIMENTAL STUDY

TENSILE TEST:

To investigate the mechanical properties of the composite the tensile test is carried out using

the computerized uni-axial tensile testing machine. The specimen is made as per the ASTM

E8 standards.

COMPRESSION TEST:

The compression test consists of subjecting a test specimen to a continually increasing

compression strain, generally to fracture, for the purpose of determining one or more of the

following compression properties; compression Strength, Declination, Percentage

Declination in Length, etc.

MICROSTRUCTURE STUDY USING SCANNING ELECTRON

MICROSCOPE (Characterization Technique): -

Scanning Electron Microscope is used to evaluate the Nano particles distribution. The

reinforcement pattern and the structure of the composite is examined using Scanning Electron

Microscope.

BRINELL’S HARDNESS NUMBER (BHN) TEST:-

The Brinell’s Hardness test is an indentation hardness test in which a hard metal ball is forced

into the surface of a test piece and the mean diameter of the indentation left in the surface

after removal of the test force, is measured.

DENSITY MEASUREMENTS: -

Density of the specimen was calculated to know the porosity in the composite specimens. By

rule of mixture for base alloy and composites for different wt. % of reinforcements the

theoretical density is calculated. Archimedean will calculate method of weighing the

specimens in water the experimental density of the prepared specimens.

Chapter 4

RESULTS AND CONCLUSIONS

Tensile strength: -

SL NO Composition Ultimate Strength (Mpa)

1 Al2024Alloy 217.5

2 Al2024-2% nano B4C 244.4

3 Al2024-4% nano B4C 281.2

4 Al2024-6% nano B4C 305.8

Yield strength: -

SL NO Composition Yield Strength

1 Al2024All0y 180.7

2 Al2024-2%nano B4C 201.4

3 Al2024-4%nano B4C 235.5

4 Al2024-6%nan0 B4C 264.1

Compression Strength:-

Sl No Material Compression (N/mm2)

1 Al2024 Alloy 554.7

2 Al2024-2% B4C 593.5

3 Al2024-4% B4C 670.8

4 Al2024-6% B4C 703.5

Characterization of SEM

Microstructure of 0% Al2024

Microstructure of 6% Nano B4C Al2024

Density Measurement: -

Hardness: -

Density (gm/Cm3)

Composition Theoretical Experimental

Al2024 Alloy 2.80 2.721

Al2024 + 6% nano B4C 2.781 2.617

SL

NO

Material Hardness (BHN)

1 Al2024Alloy 51.53

2 Al2024-2% B4C 59

3 Al2024-4% B4C 64.61

4 Al2024-6% B4C 68.17

CONCLUSIONS

The present studies and characterization of Al2024-nano B4C composites by stir casting

process are concluded as follows,

The Al2024 with 0%, 2%, 4%, & 6% of nano B4C composites are successfully

fabricated by stir casting method.

The scanning electron microscope revealed the uniform distribution of reinforcement

particles in the Al2024 matrix.

The EDS analysis was done to evaluate the presence of nano B4C in Al2024.

Ultimate tensile and Yield strength of prepared composite is higher compared to

Al2024 alloy. Further, Ultimate tensile and Yield strength changes with the different

reinforcement.

Though nano B4C one of the hardest materials on the globe, the Al2024–nano B4C

composite has higher, Ultimate tensile strength and Yield Strength compared to the

Al2024 - micro B4C. Since the nano particle will have better bonding compared to

that of the micro particles.

Compression strength and hardness of prepared composite is higher compared to

Al2024 alloy. Further, Compression strength and hardness changes with the different

reinforcement

Chapter 5

SCOPE FOR FUTURE WORK

Metal matrix composites (MMCs) are finding more importance where weight reduction is

critical, in aero and automobile sector because of their low weight, high specific stiffness and

high strength. When compared to the monolithic lightweight conventional materials MMC’s

possess superior strength and better structural properties. However, the applications of micro

and Nano B4C particle reinforced aluminium alloy matrix composites in the automotive and

aircraft industries is gradually increasing for pistons, cylinder heads, connecting rods etc.

where the tribological properties of the materials are very important.