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Journal of Materials Processing Technology 166 (2005) 440–448 Abrasive micro-blasting to improve surface integrity of electrical discharge machined WC–Co composite Jun Qu a,, Albert J. Shih b , Ronald O. Scattergood c , Jie Luo b a Metals and Ceramics Division, Oak Ridge National Laboratory, P.O. Box 2008, MS 6063, Oak Ridge, TN 37831-6063, USA b Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48109, USA c Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695, USA Received 20 November 2002; accepted 15 September 2004 Abstract This study investigates the improvement of surface integrity of wire electrical discharge machined (EDM) WC–Co composite by abrasive micro-blasting. The thermally damaged recast layer generated by EDM has craters, cracks, and bubbles, which deteriorate the surface mechanical properties. The micro-blasting, using 6–12 and 4–20 m size SiC abrasive, enables the removal of the recast layer and is suitable for micro mechanical components. The surface roughness of EDM rough cut WC–Co parts was improved significantly, with the average surface roughness (R a ) dropping down from 1.3 to 0.7 m. Scanning electron microscope (SEM) was used to examine the evolution change of surface texture and subsurface cross-section of EDM WC–Co workpiece. The SEM micrographs showed that the recast layer was removed efficiently. After 5s of micro-blasting, surface textures with ridge and cavity patterns were observed on fine and rough cut EDM surfaces, respectively. These surface textures could be correlated to the surface roughness measurement and crater formation in EDM spark erosion. A series of erosion wear experiment was conducted to quantify the weight reduction, calculate the erosion wear rate, and identify the wear mechanism. © 2004 Elsevier B.V. All rights reserved. Keywords: Micro-blasting; EDM; Surface integrity 1. Introduction Electrical discharge machining (EDM) is a thermoelec- tric process that erodes workpiece material by a series of discrete electrical sparks between the workpiece and elec- trode. Unlike traditional cutting and grinding processes which rely on a much harder tool or abrasive material to remove the softer work-material, the EDM process utilizes electri- cal sparks or thermal energy to erode the unwanted work- material and generate the desired shape. The hardness and strength of the work-materials are no longer the dominating factors that affect the tool wear and hinder the machining effi- ciency. This makes EDM particularly suitable for machining hard, difficult-to-machine materials, such as the metal–matrix Corresponding author. Tel.: +1 865 576 9304. E-mail address: [email protected] (J. Qu). composites (MMC). As shown in Fig. 1, the wire EDM pro- cess uses a traveling wire as the electrode to erode a groove in the workpiece. The close-up view of the gap and electri- cal sparks between the wire and workpiece is illustrated in Fig. 1(b). Mechanical properties of surface layers generated in this process are important to the part performance, partic- ularly the fatigue and wear life. Although EDM can machine precise, complex, and intri- cate MMC components [1–4], the undesired surface recast layer and sub-surface heat-affected zone (HA) are generated [5]. Fig. 2 shows SEM micrographs of the surfaces and sub- surface cross-sections of a WC–Co sample machined under 14 and 2 s pulse on-time and 28 s spark cycle. Pulse on- time is defined as the duration of high voltage in the electrical spark cycle, which is an important EDM process parame- ter that affects the thicknesses of the recast layer and heat- affected zone [2]. Electrical sparks melt the work-material 0924-0136/$ – see front matter © 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.jmatprotec.2004.09.075

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Journal of Materials Processing Technology 166 (2005) 440–448

Abrasive micro-blasting to improve surface integrity of electricaldischarge machined WC–Co composite

Jun Qua,∗, Albert J. Shihb, Ronald O. Scattergoodc, Jie Luob

a Metals and Ceramics Division, Oak Ridge National Laboratory, P.O. Box 2008, MS 6063, Oak Ridge, TN 37831-6063, USAb Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48109, USA

c Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695, USA

Received 20 November 2002; accepted 15 September 2004

Abstract

This study investigates the improvement of surface integrity of wire electrical discharge machined (EDM) WC–Co composite by abrasivemicro-blasting. The thermally damaged recast layer generated by EDM has craters, cracks, and bubbles, which deteriorate the surfacemechanical properties. The micro-blasting, using 6–12 and 4–20�m size SiC abrasive, enables the removal of the recast layer and is suitablefor micro mechanical components. The surface roughness of EDM rough cut WC–Co parts was improved significantly, with the averages changeo as removede surfaces,r park erosion.A fy the wearm©

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urface roughness (Ra) dropping down from 1.3 to 0.7�m. Scanning electron microscope (SEM) was used to examine the evolutionf surface texture and subsurface cross-section of EDM WC–Co workpiece. The SEM micrographs showed that the recast layer wfficiently. After 5 s of micro-blasting, surface textures with ridge and cavity patterns were observed on fine and rough cut EDMespectively. These surface textures could be correlated to the surface roughness measurement and crater formation in EDM s

series of erosion wear experiment was conducted to quantify the weight reduction, calculate the erosion wear rate, and identiechanism.2004 Elsevier B.V. All rights reserved.

eywords:Micro-blasting; EDM; Surface integrity

. Introduction

Electrical discharge machining (EDM) is a thermoelec-ric process that erodes workpiece material by a series ofiscrete electrical sparks between the workpiece and elec-

rode. Unlike traditional cutting and grinding processes whichely on a much harder tool or abrasive material to removehe softer work-material, the EDM process utilizes electri-al sparks or thermal energy to erode the unwanted work-aterial and generate the desired shape. The hardness and

trength of the work-materials are no longer the dominatingactors that affect the tool wear and hinder the machining effi-iency. This makes EDM particularly suitable for machiningard, difficult-to-machine materials, such as the metal–matrix

∗ Corresponding author. Tel.: +1 865 576 9304.E-mail address:[email protected] (J. Qu).

composites (MMC). As shown inFig. 1, the wire EDM process uses a traveling wire as the electrode to erode a gin the workpiece. The close-up view of the gap and elecal sparks between the wire and workpiece is illustrateFig. 1(b). Mechanical properties of surface layers generin this process are important to the part performance, pularly the fatigue and wear life.

Although EDM can machine precise, complex, and incate MMC components[1–4], the undesired surface reclayer and sub-surface heat-affected zone (HA) are gene[5]. Fig. 2shows SEM micrographs of the surfaces andsurface cross-sections of a WC–Co sample machined14 and 2�s pulse on-time and 28�s spark cycle. Pulse otime is defined as the duration of high voltage in the electspark cycle, which is an important EDM process parater that affects the thicknesses of the recast layer andaffected zone[2]. Electrical sparks melt the work-mater

924-0136/$ – see front matter © 2004 Elsevier B.V. All rights reserved.oi:10.1016/j.jmatprotec.2004.09.075

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J. Qu et al. / Journal of Materials Processing Technology 166 (2005) 440–448 441

Fig. 1. Illustration of the wire EDM process and the gap and continuouselectrical sparks.

and generate craters, bubbles, and cracks in the recast layer,marked as RL inFig. 2. A sub-surface heat-affected zone hasessentially no porosity and exists between the recast layer andthe bulk material. As shown inFig. 2(a), the longer (14�s)pulse on-time creates thicker recast layer and heat-affectedzone.

The surface integrity, including the roughness, size ofcraters, and thicknesses of the recast layer and heat-affectedzone, of a wire EDMed WC–Co surface has been investi-gated[2]. Nanoindentation, EDS X-ray, and X-ray diffrac-tion have been applied to study the mechanical properties(hardness and modulus of elasticity) and material composi-tions of the EDM WC–Co surface layers[6]. Nanoindenta-tion and SEM results show the heat-affected zone has morecompact microstructure and higher hardness and modulusof elasticity than that of the bulk material[6]. The recastlayer with craters, cracks, and bubbles deteriorates the sur-face properties and reduced the wear and fatigue life of EDMmechanical parts[2–6]. In this study, the abrasive micro-blasting process was applied to remove the damaged sur-face layers and improve the surface integrity of WC–Coparts machined by wire EDM. Although the erosion prop-erties of WC–Co bulk material have been researched exten-sively[7–15], there is a lack of study on the EDMed WC–Cosurfaces.

F

ig. 2. SEM micrographs of the surface and cross-section of a WC–Co part m achined by wire EDM (CR: crater, RL: recast layer, and HA: heat-affected zone).
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442 J. Qu et al. / Journal of Materials Processing Technology 166 (2005) 440–448

Fig. 3. SiC micro-blasting of a cylindrical wire EDM WC–Co micro shaft and the surface before and after blasting.

Abrasive blasting has been used extensively for sur-face treatment. This process has been applied to increasethe surface roughness for higher coating adhesion strength[16]. With proper process setup, the abrasive blastingcan remove damaged EDM surface layers and introducea new surface layer with desirable compressive residualstresses[11,17–22]. Applications of blasting process to mod-ify EDM surface layers have been investigated by Leeand Zhang[20] for Sylon 501, Deng and Lee[21] forAl2O3/TiC and Si3N4/TiC, and Lee and Deng[22] forAl2O3/TiC/Mo/Ni using 20–40 and 40–60�m size Al2O3abrasive. In this study, SiC abrasive with smaller particle sizewas used.

Micro-blasting using fine abrasive media is particularlysuitable for microfabrication and surface treatment of mi-cro mechanical components[23]. In contrast to conven-tional erosion by large-scale particles, no strength degrada-tion occurs on the micro-blasted surfaces of ceramic ma-terials [24]. The EDM process, which generates small cut-ting force, is ideal to machine micro features[25,26]. Thefine abrasive carried by adequately high air pressure enablesthe micro-blasting process to modify the EDM surface onmicro mechanical components. An example of the applica-tion of SiC micro-blasting of a micro-shaft is illustrated inFig. 3. Fig. 3(a) shows the SEM micrograph of a 100�mdiameter WC–Co micro-shaft machined by the cylindricalw e-u mald byt out1 -

face is modified and exhibits more uniform texture after 5 s ofblasting.

This paper presents a systematic study on micro-blastingof EDMed WC–Co surfaces using fine SiC abrasive. Resultsof the surface roughness, surface texture generated duringblasting, and erosion wear rate are discussed.

2. Sample preparation and experimental setup

The work-material used in this study is the WC–Co com-posite, which consists of 1�m size WC particle in 10 wt% Comatrix. This material has 92 Rc hardness, 3.4 MPa transverserupture stress, and 14.5 specific density. The WC–Co work-material was cut in a Brother HS-5100 wire EDM machine us-ing 0.25 mm diameter brass wire. Two types of EDM WC–Cosurfaces, designated as rough cut and fine cut, were preparedfor blasting experiments.Fig. 2(a and b) shows SEM micro-graphs of the rough cut and fine cut surface, arithmetic aver-age surface roughness (Ra), and subsurface cross-section. Theprocess parameters and material removal rate of the rough andfine cuts are summarized inTable 1. Under the same sparkcycle (28�s), the rough cut has longer pulse on-time (14�s),larger crater, rougher surface, higher material removal rate,and thicker recast layer and heat-affected zone.

ctedo ss &A stingg ed ex-p prob-

ire EDM process[1,2]. The EDM surface and its closp view, which exhibit cracks, bubbles, and other theramages, are shown inFig. 3(b). This surface is blasted

he 6–12�m SiC particle at 0.138 MPa air pressure (ab00 m/s particle speed) for 5 s. As shown inFig. 3(c), the sur

Blasting and erosion wear experiments were condun a Mangum blasting machine, manufactured by Hessociates Inc. The machine used a venturi-type blaun with a 6.35 mm inner diameter Al2O3 nozzle. Since thuration of blasting was short and limited number oferiments was conducted, the nozzle wear was not a

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J. Qu et al. / Journal of Materials Processing Technology 166 (2005) 440–448 443

Fig. 4. Two types of SiC abrasive used in this study.

lem. A time-control device was build to enable the blastingwith a fixed period of time. The SiC abrasive was selecteddue to its high hardness. Two types of SiC abrasive, des-ignated as Abrasives A and B, were used. Abrasive A, asshown inFig. 4(a), was a mixture of particle sizes of 4–8,6–12, and 10–20�m, which corresponded to 1200, 1000,and 800 ANSI mesh, respectively. As shown inFig. 4(b),Abrasive B was only 1000 ANSI mesh with particle sizesin the range 6–12�m. All tests were conducted at 90◦ in-cident angle (normal incidence). The air pressure of 0.138and 0.276 MPa was selected. Using the two-disk method[27], the particle speed for Abrasives A at 0.138 MPa wasabout 100 m/s. Particle speed at 0.276 MPa was expected tobe higher; however, the apparatus used in this study was un-able to accurately measure the high particle speed at thispressure.

Two sets of experiments were performed. One was focusedon measurements and observations of surface integrity androughness. Three blasting tests with a 5 s increment in blast-ing time were conducted. The other set of experiment wasaimed at investigating the weight reduction and erosion wearrate. Three tests with 10 s blasting time increment were car-ried out.Table 2lists process parameters used in the two setsof experiments. In summary, 24 (2× 2× 2× 3) tests werecarried out in the surface integrity experiment and 6 (2× 3)

TM C–Co

P cut

SPAWGM 6b

tests were conducted in the erosion wear rate experiment. Re-sults of these experiments are presented in the following twosections.

3. Results and discussion

3.1. Surface roughness

Fig. 5shows results of arithmetic average surface rough-nessRa for the 24 tests conducted in the surface integrityand roughness experiment. Before the blasting test (0 s), asshown in Figs. 2 and 5, Ra equals 1.34 and 0.83�m onthe rough cut and fine cut surface, respectively. The sur-face finish was improved over time and eventually reacheda stationary level, when the recast layer and heat-affectedzone had been removed. The trend to reach steady-statesurface roughness can be seen inFig. 5. For AbrasivesA and B, theRa is approaching 0.7�m at longer blastingtimes.

The Abrasive A with larger size particles and/or high airpressure (0.276 MPa) removed the recast layer faster and re-duced the surface roughness of rough cut parts more effi-ciently, as shown in roughness charts (Fig. 5) and SEM mi-crographs (Figs. 6–9). The EDM fine cut surface may bed d thes siveA

TP

E test

AEAB

able 1achine setup and process parameters and results of wire EDM of W

rocess parameters Rough cut Fine

park cycle (�s) 28 28ulse on-time (�s) 14 2xial wire speed (mm/s) 18 15ire tension (N) 14.7 17.6ap voltage (V) 45 60aterial removal rate (mm3/min) 5.5a 0.1a Cutting a 6.35 mm thick plate.b Removing a 50�m surface layer.

eteriorated by very short blasting time (5 s) and reachetationary level at longer blasting time (15 s) using Abraand high air pressure, as shown inFig. 6.

able 2rocess parameters used in two blasting experiments

xperiments Surface integrity test Erosion wear rate

brasive A and B ADM surface Rough and fine cut Rough cutir pressure (MPa) 0.138, 0.276 0.138, 0.276lasting time (s) 5, 10, 15 10, 20, 30

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444 J. Qu et al. / Journal of Materials Processing Technology 166 (2005) 440–448

Fig. 5. Surface roughness on EDM WC–Co using SiC micro-blasting.

3.2. Surface layers

The surfaces of the wire EDMed WC–Co parts had thesurface recast layer and sub-surface heat-affected zone, gen-erated by the high local temperature during machining. Therecast layer, also called thermally damaged layer, had cratersand thermal cracks and bubbles, as shown inFig. 2, whichdeteriorates the surface finish and reduced the wear resistanceand fatigue life of the EDMed parts.

SEM was used to examine the surfaces and sub-surfacesof the WC–Co parts to investigate the effect of the micro-blasting. The selected SEM micrographs, shown inFigs. 6–9,indicated that the recast layer was eventually removed af-ter 5 and 10 s for EDM fine cut and rough cut parts, re-

spectively. Longer blasting duration also removed the heat-affected zone and reached a steady-state material removal inthe bulk WC–Co material.

3.3. Surface texture

SEM micrographs of the fine cut surfaces blasted by Abra-sive A at 0.276 MPa pressure are shown inFig. 6. As shownin Fig. 6(a), after blasting by 5 s, ridges that manifest crateredges observed inFig. 2(b) can be seen. During the spark ero-sion, the molten material was splashed and accumulated toform the crater edges. Micro-blasting erodes the damaged re-cast layer and exposes the crater edges as the ridge pattern af-ter the first 5 s of blasting. Evidently, these ridges contributed

F t EDM ree blastingo

ig. 6. SEM micrographs of surfaces and cross-sections of the fine cuf 5 s increment.

WC–Co blasted by Abrasive A at 0.276 MPa air pressure after first th

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J. Qu et al. / Journal of Materials Processing Technology 166 (2005) 440–448 445

Fig. 7. Close-up view of surface of the fine cut EDM WC–CO blasted by Abrasive A at 0.276 MPa air pressure after 10 s blasting time.

to the temporary increase inRa at the beginning of blasting,i.e., the maximum in the curve inFig. 5(a) (open triangles).As shown inFig. 6(b and c), these ridges gradually disap-peared after 10 and 15 s of blasting. The cross-section sur-face showed the recast layer was removed after 5 s of blasting,only a shallow residual of heat-affected zone remained. After10 s of blasting, the heat-affected zone was also removed. Asimilar ridge pattern could be seen on all of the blasted finecut surfaces, though not necessarily as pronounced as thatseen inFig. 6.

Close-up views ofFig. 6(b) are shown inFig. 7. Theboundaries between the 1�m size WC grains are not easilyidentified. Furthermore, there are no distinct cleavage facets

indicative of individual brittle fracture events. Since the ero-dent particles have sizes in the range of 10–20�m for Abra-sive A, one could expect that erosion impact events at the highvelocities used would overlap a large number of WC grains.The erosion mechanism for the blasting conditions used istherefore a composite-like removal of multiple WC grainsper impact facilitated by plastic flow in the surrounding Comatrix. This is in contrast to the case reported by Anand andConrad[13] where small erodent particles at low velocityproduce individual impacts in single WC grain and a clearbrittle-like erosion response.

SEM micrographs of the surface and subsurface cross-section under the same blasting condition as inFigs. 6 and 7,

F ut EDM ree blastio

ig. 8. SEM micrographs of surfaces and cross-sections of the rough cf 5 s increment.

WC–CO blasted by Abrasive A at 0.276 MPa air pressure after first thng

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446 J. Qu et al. / Journal of Materials Processing Technology 166 (2005) 440–448

Fig. 9. Close-up view of surface of the rough cut EDM WC–CO blasted by Abrasive A at 0.276 MPa air pressure after 10 s blasting time.

Fig. 10. Erosion wear rate of SiC micro-blasting on wire EDM WC–Co.

but on the rough cut surfaces, are shown inFigs. 8 and 9.As shown inFig. 8(b and c), a surface texture with manysmall, less than 1�m size cavities that follow the patternof crater edges, as seen inFig. 2(a), can be observed. The2�m tip radius diamond stylus for the profilometer surfaceroughness measurement would not detect these cavities andtheRa results inFig. 5would not be affected.

Fig. 9shows close-up views ofFig. 8(b). From the overallpattern of distribution of these features, it can be assumed thatthe source of the cavities is also related to the crater forma-tion during EDM spark erosion. For the rough cut condition,the energy density in each spark erosion was higher and moremolten material was generated in each spark erosion. Bubblesand cavities on the rough cut surfaces (Fig. 2(a)) are thereforelarger and more prominent than those of the fine cut surfaces(Fig. 2(b)). As shown inFig. 8, these cavities were exposedin the first 5 s of blasting and accentuated in the follow-upblasting at 10 and 15 s. Most cavities disappeared when theprocess reached steady-state after 30 s blasting, as shown inFig. 10. The remaining few cavities on the blasted surface

Fig. 11. SEM micrographs of surfaces of rough cut EDM WC–CO b ).

lasted by Abrasive A at 0.276 MPa air pressure for 30 s (steady-state
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J. Qu et al. / Journal of Materials Processing Technology 166 (2005) 440–448 447

Fig. 12. Close-up views of surface of the rough cut EDM WC–CO blasted by Abrasive A at 0.276 MPa air pressure for 30 s (steady-state).

are possibly due to the porosity in the original WC–Co mate-rial. This can be validated by examining the close-up viewsin Fig. 11. The surface texture, disregarding the cavities andporosity, is similar to that inFig. 7(b). The boundaries be-tween WC grains are not easily identified, and there is nodistinct cleavage facet to indicate the individual brittle frac-ture of WC.

In general, all rough cut EDM surfaces exhibited similarpattern of cavities, as seen inFigs. 8 and 9. All fine cut EDMsurface showed a ridge pattern similar to that inFigs. 6 and 7.These observations manifest the formation of ridges, bubbles,and cavities in EDM recast layers. Further investigations arenecessary to establish the details of the formation mecha-nisms.

3.4. Erosion wear rate

The erosion wear rate experiments were conducted byblasting a 6 mm× 6 mm rough cut EDM WC–Co surfaceusing Abrasive A for 10 s time increments and then mea-suring the weight loss. A blasting time increment of 10 s wasused in order to measure the steady-state erosion wear rate.Due to the limitation of the EDM workpiece sizes, this testsetup was different from the standard erosion tests specifiedin ASTM G76-95[28], in which a larger surface area shouldb

ar-r , and3 t lossw as di-v thee asiveA spec-t

ula-t e A.T osionr d in-c pres-

sure. A higher erosion wear rate was observed in the first 10 sthan the following two blasting durations. This transient canbe attributed to the materials removal associated with ther-mal cracks and bubbles. These defects result in lower erosionwear resistance of the recast layer. At 30 s, when the erosionrates approach steady-state, the 0.0013 and 0.0067 g/g ero-sion wear rates are higher but comparable to that reported byBeste et al.[12] and Anand and Conrad[13].

4. Concluding remarks

The abrasive micro-blasting process was used to improvethe surface integrity of WC–Co samples machined by wireEDM. Two sizes of SiC abrasive, two levels of air pressures,and three time durations were applied to blast EDM rough cutand fine cut WC–Co surfaces to explore effects of blastingparameters on the surface integrity. The recast layer and heat-affected zone can be removed by SiC micro-blasting in veryshort times using easily achieved erosion conditions. Largersize abrasives and higher air pressure produce higher ero-sion wear rate and reduce the EDM surface roughness moreeffectively. The unique surface texture, related to the craterformation of the recast layer, has been revealed on SEM mi-crographs and studied to help understand the influence of them wireE

A

Na-t Ra-j rtiono n theH Laba Pro-g ento

e used.As shown inTable 2, six erosion wear rate tests were c

ied out at 0.138 and 0.276 MPa air pressure with 10, 200 s blasting time. Two parts were blasted and the weighas measured in each test. The average weight loss wided by the weight of SiC abrasive blasted to calculaterosion wear rate. On average, 31 and 46 mg/s of Abrwere blasted at 0.138 and 0.276 MPa air pressure, re

ively, during a 10 s interval.Fig. 12 shows the experimental results of the cum

ive weight reduction and erosion wear rate for Abrasivhe higher air pressure (0.276 MPa) generated higher erates than the lower air pressure (0.138 MPa). A four-folrease in erosion rate was obtained by doubling the air

icro-blasting process on the surface integrity of theDMed WC–Co parts.

cknowledgements

The authors gratefully acknowledge the support byional Science Foundation Grant #9983582 (Dr. K.P.urkar, Program Director) and the assistant by Z. Yu. Pof this research was sponsored by the User program iigh Temperature Material Lab, Oak Ridge Nationalnd the Heavy Vehicle Propulsion Systems Materialsram, Office of Transportation Technologies, US Departmf Energy.

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448 J. Qu et al. / Journal of Materials Processing Technology 166 (2005) 440–448

References

[1] J. Qu, A.J. Shih, R. Scattergood, Development of the cylindrical wireelectrical discharge machining process, Part I: concept, design, andmaterial removal rate, J. Manuf. Sci. Eng. 124 (3) (2002) 702–707.

[2] J. Qu, A.J. Shih, R. Scattergood, Development of the cylindrical wireelectrical discharge machining process, Part II: surface integrity androundness, J. Manuf. Sci. Eng. 124 (3) (2002) 708–714.

[3] L. Llanes, E. Idanez, E. Martinez, B. Casas, J. Esteve, Influenceof electrical discharge machining on the sliding contact response ofcemented carbides, Int. J. Refract. Met. Hard Mater. 19 (1) (2001)35–40.

[4] M. Ramulu, M.G. Jenkins, J.A. Daigneanult, Spark-erosion processeffects on the properties and performance of a TIB2 particulate-reinforced/SiC matrix ceramic composite, Ceram. Eng. Sci. Proc. 18(3) (1997) 227–238.

[5] R.E. Williams, K.P. Rajurkar, Study of wire electrical discharge ma-chined surface characteristics, J. Mech. Process. Technol. 28 (1991)127–138.

[6] J. Qu, L. Riester, A.J. Shih, R. Scattergood, E. Lara-Curzio, T.Watkins, Nanoindentation characterization of surface layers of elec-trical discharge machined WC–Co, Mater. Sci. Eng. A 334 (2003)125–131.

[7] U. Beste, L. Hammerstrom, H. Engqvist, S. Rimlinger, S. Jacobson,Particle erosion of cemented carbides with low Co content, Wear250–251 (2001) 809–817.

[8] V.A. Pugsley, C. Allen, Microstructure/property relationships in thecavitation erosion of tungsten carbide–cobalt, Wear 233–235 (1999)93–103.

[9] K. Anand, C. Morrison, R.O. Scattergood, H. Conrad, J.L. Rout-bort, R. Warren, Erosion of multiphase materials, science of hard

econdInst.986,

[ rials,tional. Ser.4.

[ ma-996sign

pp.

[ son,ear

[13] K. Anand, H. Conrad, Local impact damage and erosion mecha-nisms in WC-6 wt% Co alloys, Mater. Sci. Eng. A 105–106 (1988)411–421.

[14] S.K. Hovis, J.E. Talia, R.O. Scattergood, Erosion in multiphase ma-terials, Wear 108 (1986) 139–155.

[15] H. Engqvist, G.A. Botton, N. Axen, S. Hogmark, Microstructure andabrasive wear of binderless carbides, J. Am. Ceram. Soc. 83 (10)(2000) 2491–2496.

[16] K.D. Bouzakis, N. Michailidis, S. Hadjiyiannis, K. Efstathiou, E.Pavlidou, G. Erkens, S. Rambadt, I. Wirth, Improvement of PVDcoated inserts cutting performance through appropriate mechanicaltreatments of substrate and coating surface, Surf. Coat. Technol.146–147 (2001) 443–450.

[17] J.M. Guilemany, I.N. Llorca, P.J. Szabo, Residual stress character-ization of grit blasted steel surfaces, Surf. Eng. 12 (1) (1996) 77–79.

[18] A. Ben Rhouma, C. Braham, M.E. Fitzpatrick, J. Ledion, H. Sidhom,Effects of surface preparation on pitting resistance, residual stress,and stress corrosion cracking in austenitic stainless steels, J. Mater.Eng. Perform. 10 (5) (2001) 507–514.

[19] M.O. Lai, Y.H. Siew, Fatigue properties of cold worked holes, J.Mater. Process. Technol. 48 (1995) 533–540.

[20] T.C. Lee, J.H. Zhang, Surface treatment of wire electro-dischargemachined engineering ceramics by abrasive blasting, J. Adhes. Sci.Technol. 12 (6) (1998) 585–592.

[21] J. Deng, T.C. Lee, Techniques for improved surface integrity ofelectrodischarge machined ceramic composites, Surf. Eng. 16 (5)(2000) 411–414.

[22] T. Lee, J. Deng, Mechanical surface treatments of electro-dischargemachined (EDMed) ceramic composite for improved strength andreliability, J. Eur. Ceram. Soc. 22 (2002) 545–550.

[ , A.icro-duc-

[ rtiesials,

[ g by

[ l.

[ in

[ Ero-rican

materials, science of hard materials, in: Proceedings of the SInternational Conference on the Science of Hard Materials,Phys. Conf. Ser. No. 75, Rhodes, Greece, Adam Hilger Ltd., 1pp. 949–961.

10] A. Ball, A comparative study of the wear resistance of hard matescience of hard materials, in: Proceedings of the Second InternaConference on the Science of Hard Materials, Inst. Phys. ConfNo. 75, Rhodes, Greece, Adam Hilger Ltd., 1986, pp. 851–86

11] N.P. Hung, L.H. Teong, C.M. Yoong, Review of unconventionalchining of metal matrix composites, in: Proceedings of the 1Third Biennial Joint Conference on Engineering Systems Deand Analysis, vol. 75, no. 3, ASME PD, New York, NY, 1996,47–53.

12] U. Beste, L. Hammerstrom, H. Engqvist, S. Rimlinger, S. JacobParticle erosion of cemented carbides with low Co content, W250 (2001) 809–817.

23] S. Schlautmann, H. Wensink, R. Schasfoort, M. ElwenspoekBerg, Powder-blasting technology as an alternative tool for mfabrication of capillary electrophoresis chips with integrated contivity sensors, J. Micromech. Microeng. 11 (2001) 386–389.

24] M. Wakuda, Y. Yamauchi, S. Kanzaki, Effect of workpiece propeon machinability in abrasive jet machining of ceramic materPrecision Eng. 26 (2002) 193–198.

25] T. Masuzawa, H.K. Tonshoff, Three-dimensional micromachininmachine tools, Annal. CIRP 46 (1997) 621–628.

26] K.P. Rajurkar, Z.Y. Yu, 3D Micro-EDM using CAD/CAM, AnnaCIRP 49 (2000) 127–130.

27] A.W. Ruff, L.K. Ives, Measurement of solid particle velocityerosive wear, Wear 35 (1975) 195–199.

28] ASTM Standard G76-95, Standard Test Method for Conductingsion Tests by Solid Particle Impingement Using Gas Jets, AmeSociety for Testing and Materials, 2000.