F

Ca

b

a

ARRA

KLPWMSI

1

dRwRcptablpwtmiftos

0d

Journal of Materials Processing Technology 209 (2009) 5429–5436

Contents lists available at ScienceDirect

Journal of Materials Processing Technology

journa l homepage: www.e lsev ier .com/ locate / jmatprotec

riction and wear behavior of laser-sintered iron–silicon carbide composites

.S. Ramesha,∗, C.K. Srinivasb

Department of Mechanical Engineering, PES Institute of Technology, Bangalore, Karnataka 560 085, IndiaCentral Manufacturing Technology Institute, Tumkur Road, Bangalore 560 022, India

r t i c l e i n f o

rticle history:eceived 19 December 2008eceived in revised form 10 April 2009ccepted 17 April 2009

eywords:aserrototyping

a b s t r a c t

Laser sintering is currently one of the most popular techniques to develop innovative materials for manyof the high tech industrial applications owing to its ability to build complex parts in a short time. As such,material researchers are focusing on developing advanced metal matrix composites through selectivelaser sintering method to develop an intricate component eliminating delay in production time. In thelight of the above, the present work focuses on developing iron–silicon carbide (nickel coated) compositesusing direct metal laser sintering technology. A laser speed of 50, 75, 100 and 125 mm/s were adopted.Metallographic studies, friction and wear test using pin-on-disc have been carried out on both the matrix

earetal matrix composite

ilicon carbideron

metal and its composites. Load was varied from 10 to 80 N while sliding velocity was varied from 0.42to 3.36 m/s for a duration of 30 min. A maximum of 7 wt.% of silicon carbide has been successfully dis-persed in iron matrix by laser sintering. Increased content of SiC in iron matrix has resulted in significantimprovement of both hardness and wear resistance. Lower the sintering speed, higher is the hardness andwear resistance of both the matrix metal and its composites. However, coefficient of friction of compositesincreased with increased SiC under identical test conditions. SEM observations of the worn surfaces have

e to

revealed extensive damag

. Introduction

In this era of global competition, there is a need for customer-riven product development with reduced cost and lead-time.apid prototyping has emerged as a key enabling technologyith its ability to shorten product design and development cycle.apid prototyping (RP) refers to a class of technologies thatan automatically construct physical models directly from com-uter aided design (CAD) data. RP has emerged as a powerfulechnology in reducing product development cycle (Srinivas etl., 2006a,b). RP processes can be divided into three groupsased on the state of material before part formation, namely:

iquid, powder and solid sheets (Kruth, 1991). Powder basedrocess is based on the solidification of fine powder eitherith laser or by the application of binding agent. Among all

he RP processes, direct metal laser sintering (DMLS) is theost popular technique to produce metal prototypes and tool-

ng directly from 3D CAD data using metal powders. Currently

ew materials are developed for producing metal prototypes andooling. Development of materials using laser sintering technol-gy is the most sought-after subject for the researchers. Maragingteel, stainless steel, cobalt chrome and titanium are the lat-

∗ Corresponding author. Tel.: +91 80 2672 1983; fax: +91 80 2672 0886.E-mail address: csr gce@yahoo.co.in (C.S. Ramesh).

924-0136/$ – see front matter © 2009 Elsevier B.V. All rights reserved.oi:10.1016/j.jmatprotec.2009.04.018

the iron pins, when compared with that of the composites.© 2009 Elsevier B.V. All rights reserved.

est materials processed by DMLS process for aerospace, dentaland medical applications as reported by M/s EOS Technologies,Germany (www.eos.com (www.eos.info/en/products/metal-laser-sintering.html)). Cobalt chrome and titanium based materials aresuccessfully processed by using electron beam for producing tool-ing and parts for medical and aerospace applications as reportedby M/s Arcam (www.arcam.com). Development of metal matrixcomposites (MMC’s) by laser sintering is still in infant stage ofits development. Currently, no company or academic institutionis able to process complex near-net shaped MMC’s by rapid pro-totyping techniques to meet the requirements of user industries(Vaucher et al., 2002). The physical and mechanical properties thatcan be obtained with MMC’s, have made them attractive candidatematerials for aerospace, automotive and numerous other appli-cations. Particulate reinforced MMC’s have attracted considerableattention as a result of their low cost and characteristic isotropicproperties. Currently two approaches are adopted for producingMMC’s by RP technology. The first approach is direct sintering ofparts from metal–ceramic powders and the second approach is theproduction of porous ceramic preforms, which are filled by sub-sequent liquid metal infiltration. Few researchers are reported to

have done some work in this area. Vaucher et al. (2002) have per-formed experiments on laser sintering of Al/SiC and Ti/SiC metalmatrix composites using Nd:YAG laser and were able to build fewlayers. Murali et al. (2003) have studied microstructure, microhard-ness and wear of laser-sintered iron–graphite parts. It is reported

5 als Pro

twtaAlcmMtt

litirplWiacpnc

cMoi

2

fwt5pers

pcmwmR0maaeMwsftwtwfa

430 C.S. Ramesh, C.K. Srinivas / Journal of Materi

hat laser sintering of iron and graphite powder produces a material,hich is substantially different from the same produced by conven-

ional sintering. Chong et al. (2001) have studied the microstructurend wear properties of laser surface-cladded Mo-WC MMC’s onA6061 aluminum alloy. It is reported that a crack-free sintered

ayer composite possessed better abrasive wear resistance whenompared with the base metal. Gaard et al. (2006) have studied onicrostructural characterization and wear behavior of Invar 36-TiCMC’s produced by DMLS process. It is reported that the cracks in

he developed MMC’s depend on the TiC content and wear in theested parts was dominated by abrasive process.

Rapid prototyping technology is a boon to tooling industry. Theead-time and cost of tooling can be reduced considerably by adopt-ng RP technology. RP materials available in the market are not ableo meet all the requirements of industry, in particular die and mouldndustry. Dies used in metal forming and die casting applicationsequire high hardness and high wear resistance. Strength and wearroperties of the sintered parts depend on process parameters like

aser speed, laser power, layer thickness and part build orientation.ear and friction play a vital role on the mould life. Wear behav-

or of laser-sintered iron parts have been reported by Ramesh etl. (2007a,b). Silicon carbide being very hard, has been a popularhoice as a reinforcement material to develop metal matrix com-osites. However, from the extensive literature survey, there areo reports as regards the laser processing of iron–silicon carbideomposites although it is very interesting.

In the light of the above facts, this work focuses on the pro-essing of iron–silicon carbide composites by DMLS technique.icrostructure, density, microhardness, friction and wear behavior

f laser-sintered iron–silicon carbide MMC’s have been character-zed.

. Experimental details

Silicon carbide (greenish in color) in powder form was obtainedrom M/s Grindwell Norton, Bangalore. Iron powder produced byater atomization process was procured from M/s Sundaram fas-

eners limited, Hyderabad. The powders were sieved using 20 and0 �m sieves for silicon carbide and iron powders respectively. Thearticle size of the sieved silicon carbide and iron powders wasvaluated using sedigraph and particle size counter equipmentsespectively. The morphology of the powders was evaluated bycanning electron microscope.

Silicon carbide was coated with nickel using electroless platingrocess as described elsewhere (Ramesh et al., 2007a,b). Nickel-oated silicon carbide was mixed with iron powder in a conicalixer. The powders were thoroughly mixed and the mixing timeas optimized to achieve a homogeneous mix. The quality of theix was evaluated by statistical analysis method as described by

ussel and Dotter (1984). A standard deviation in the range of.1–0.2 was achieved for the quality of mix of all the powdersixed. Different powder mixtures were prepared with 1, 2, 3, 5

nd 7 wt.% of nickel-coated silicon carbide with iron powder. Wearnd microstructure specimens were prepared using EOSINT M250xtended sinter-station with CO2 laser as a heat source. EOSINT250 sinter-station and the sintering process is described else-here (Gajendran et al., 2003). The wear specimens were built to a

ize of 12 mm diameter and height of 28 mm while the specimensor microstructure studies were built to a size of 10 mm diame-er and to a height of 5 mm. The build orientation during sintering

as such that the axis of the cylindrical specimens was parallel to

he build direction. Laser power was maintained constant at 180 With laser beam diameter of 0.4 mm. Sintering speed was varied

rom 50 to 125 mm/s in steps of 25, while hatch spacing, hatch widthnd layer thickness were maintained constant at 0.2 mm, 5 mm and

cessing Technology 209 (2009) 5429–5436

50 �m respectively. Nitrogen atmosphere was maintained in thebuild chamber.

Sintered parts were separated from base plate using wire-cutelectrical discharge machine. Wear specimens were machined on alathe to a diameter of 10 and a length of 25 mm. The density of sin-tered parts was evaluated using Archimedes principle of weighingfirst in air and then in water. Sintered specimens for microstruc-ture studies were polished using abrasive papers (silicon carbide)of grit size 120, 220, 320, 400 and 600, 0,1/0, 3/0 and 4/0. Further,they were polished with 8 and 1 �m diamond paste. Microhardnesstests were conducted at different locations along the sintered sur-face with a load of 25 g for a test duration of 9 s. Pin-on-disc typewear tester was used for carrying out the friction and wear studies.The counter disc was an hardened ball bearing steel-EN31 havingnominal composition of carbon 1.0%, manganese 0.37%, chromium1.6% and remaining iron. The dimensions of the counter disc were160 mm diameter and 8 mm thick, with an hardness of Rc 60. Flat-nosed sintered cylindrical specimens of diameter 10 mm and height25 mm, served as pins for wear test. The surface roughness of sin-tered parts and counter disc were maintained at centre line average(CLA) value of 0.8 �m prior to friction and wear tests. Friction andwear tests were carried out under different loads and sliding veloc-ities in ambient atmosphere without lubricant. Loads were variedfrom 10 to 80 N in steps of 10, while the sliding velocities were var-ied from 0.42 to 3.36 m/s in steps of 0.42. Each test was carried outfor a duration of 30 min. Before each test, the specimens and counterdisc were cleaned with acetone. Fresh track on the counter disc wasused for each test. The coefficient of friction was determined usingfrictional force data. Frictional force was measured using a forcetransducer of accuracy 1 N. Wear was measured by weighing thespecimens before and after the test in an electronic digital balancehaving an accuracy of 0.1 mg. Coefficient of friction and wear ratesof sintered samples were evaluated using the following equations:

Coefficient of friction (�) = F

N(1)

where F is the frictional force and N is normal load.

Wear rate = V

N × L(2)

where V is the volumetric loss, L is sliding distance and N is normalload.

Scanning electron micrograph and energy dispersive spec-troscopy studies were carried out on the worn out wear specimens.

3. Results and discussions

3.1. Morphology of iron and silicon carbide powder

Fig. 1a and b shows the morphology of iron and silicon carbidepowders respectively. Iron powder has a spherical shape and sili-con carbide has irregular shape. The composition of iron powder asgiven by the powder supplier contains carbon, sulphur and phos-phorus of 0.14, 0.02 and 0.015% and the rest iron. The grain size ofiron measured by particle size counter equipment varied from 10 to60 �m with an average grain size of 50 �m. The grain size of siliconcarbide varied from 6 to 40 �m with an average grain size of 20 �m.Fig. 2 shows the morphology of silicon carbide particles before andafter electroless nickel plating. It is clearly seen from Fig. 2 b thatthere is a uniform coating of nickel on silicon carbide particles.

3.2. Microstructural studies

Fig. 3a and b shows optical micrographs of iron and 5 wt.% sili-con carbide. Fig. 3b shows a homogeneous dispersion of SiC in ironmatrix is achieved. Fig. 4 shows scanning electron micrographs of

C.S. Ramesh, C.K. Srinivas / Journal of Materials Processing Technology 209 (2009) 5429–5436 5431

Fig. 1. Scanning electron micrograph of iron and silicon carbide.

coate

itb

3

aoft

Fig. 2. Scanning electron micrographs of

ron and iron–silicon carbide composites. It is observed in Fig. 4 bhat the silicon carbide particle is distinct and there exists a goodond between iron matrix and silicon carbide particles.

.3. Density

Fig. 5 shows the variation of density of laser-sintered ironnd iron–silicon carbide composites at different laser speeds. It isbserved that there is a decrease in density with increase in SiC rein-orcement for a given laser speed. Lower the laser speed, higher ishe density of the composites. This can be attributed to the fact that

Fig. 3. Optical micrograph of laser-sintered (a) iron and (b) iron–

d and uncoated silicon carbide powders.

at lower sintering speed, the extent of melting is higher as the heatenergy absorbed by the powder is more. This results in improvedmelting which contributes to the higher density. These observa-tions are in line with other researchers (Simchi et al., 2001; Simchiand Pohl, 2003).

3.4. Microhardness

Fig. 6 shows the variation of hardness of the iron compositewith increased SiC content. It is evident from the figure that hard-ness of the composite increases with increase in silicon carbide

5 wt.%SiC composite sintered at laser speed of 100 mm/s.

5432 C.S. Ramesh, C.K. Srinivas / Journal of Materials Processing Technology 209 (2009) 5429–5436

on–5

cpbmgaSi

Fo

Fp

Fig. 4. Scanning electron micrograph of (a) iron and (b) ir

ontent. A maximum hardness of 740 VHN is achieved for com-osite with 7 wt.% of SiC. The drastic improvement of hardness cane attributed to (a) high hardness of silicon carbide (b) the ther-al mismatch between iron and silicon carbide which leads to the

eneration of high density of dislocation at the interface of ironnd silicon carbide which in turn retards the plastic deformation.imilar results are achieved by other researchers while produc-ng aluminium alloy composite by infiltration process (Sahin and

ig. 5. Variation of density of iron–SiC composites with different weight percentsf SiC.

ig. 6. Variation of microhardness of iron–SiC composites with different weightercents of SiC.

wt.% SiC composites sintered at laser speed of 100 mm/s.

Acilar, 2003). Further, it is observed that hardness of the compos-ite increases with decreased laser speed. At decreased laser speeds,more heat energy is available, there by more melting of powdertakes place leading to increase in density. It is the increased densitythat contributes to the increase in hardness.

3.5. Coefficient of friction

3.5.1. Effect of silicon carbide (SiC)Fig. 7 shows the variation of coefficient of friction with increased

weight percent of silicon carbide in iron matrix. It is observed thatincreased content of SiC a very hard reinforcement in a very softmatrix results in increased coefficient of friction of the compos-ite. Strongly bonded silicon carbide in the composite pins do actas sharp cutting edges resulting in abrading of the hardened steelcounter disc as can be observed in Fig. 8. It is this phenomenon thatis largely responsible for the increased coefficient of friction whencompared to iron. The lower value of coefficient of friction of ironcan be mainly attributed to the material transfer from the softeriron pin on to the hardened counter disc and also to the formationof oxide films, which act as solid lubricant (Ramesh et al., 2007a,b).

3.5.2. Effect of laser speedFig. 9 shows the variation of laser scan speed on coefficient of

friction of iron and its composites. It is observed that the coefficientof friction decreases with increased laser speed for both iron and itscomposites. With increased laser speed, the density of the sinteredparts gets reduced as discussed in the previous section. This factorpromotes lesser extent of asperity interaction leading to the reduc-

Fig. 7. Effect of SiC on coefficient of friction of laser-sintered iron–SiC composites.

C.S. Ramesh, C.K. Srinivas / Journal of Materials Processing Technology 209 (2009) 5429–5436 5433

Fd

tHo

3

iilatosebiiow

3

s

Fc

ig. 8. Optical macrophotograph of worn out wear track of hardened steel counterisc.

ion in the friction during the sliding motion of the contacting parts.owever at all the laser speeds studied, the coefficient of frictionf iron composites is higher when compared with iron matrix.

.5.3. Effect of loadThe variation of coefficient of friction with normal load is shown

n Fig. 10. It is observed that increased load has resulted in decreasen coefficient of friction for both iron and its composite in theoad range of 10–50 N. However for loads beyond 50 N and up tosteady load of 80 N, there is negligible effect on coefficient of fric-

ion. However at all the loads studied, the coefficient of frictionf iron is lower when compared with iron composites. The initialteep decrease in coefficient of friction with increased load can bexplained to the higher probability of shearing of asperity junctionsecause of the increased plastic deformation at higher loads. The

nterlocking phenomena during the sliding motion of the contact-ng pair is not dominant owing to the greater extent of destructionf asperity junctions leading to lowering of coefficient of friction

ith increased load.

.5.4. Effect of sliding velocityThe variation of coefficient of friction with sliding velocity is

hown in Fig. 11. It is observed that at all the sliding velocities stud-

ig. 9. Effect of laser speed on coefficient of friction of iron and iron–5 wt.% SiComposites.

Fig. 10. Variation of coefficient of friction of iron and iron–5 wt.% SiC compositeswith load.

ied, iron–silicon carbide composites exhibit higher coefficient offriction when compared with iron. Increase in sliding velocitiesbeyond 1.26 m/s, results in marginal change in the coefficient offriction of iron and its composites. This can be attributed to thefact that at higher sliding velocities, the material transfer will havereached equilibrium during which a thin and continuous protectivefilm is formed due to which the frictional forces are stable. In case ofiron, initially with increase in sliding velocity up to 1.26 m/s, thereis a gradual increase in coefficient of friction. This can be mainlyattributed to the larger extent of plastic deformation with increasedslid distances which in turn increases the extent of interaction ofasperities leading to higher frictional force during sliding.

3.6. Wear

3.6.1. Effect of reinforcementFig. 12 shows the variation of wear rate of iron and iron–silicon

carbide composites with increase in silicon carbide. It is clearlyobserved that the dispersion of silicon carbide, a hard face in thesoft iron matrix tends to reduce the wear rates of iron compos-ites. Wear rate of iron–silicon carbide composites decreases withincrease in silicon carbide content. It is reported that the incor-

poration of hard particles such as silicon carbide and alumina inwrought and cast aluminium alloys improves the sliding wear resis-tance of these alloys (Saka and Karalekas, 1985; Hoskins et al., 1982;Surappa et al., 1982; Anand and Kishore, 1983; Prasad and Rohatgi,

Fig. 11. Variation of coefficient of friction with sliding velocity of iron andiron–5 wt.% SiC composites.

5434 C.S. Ramesh, C.K. Srinivas / Journal of Materials Processing Technology 209 (2009) 5429–5436

Fc

1a

1

2

3

F

of the iron–silicon carbide composites as shown in Fig. 13. Thetransferred iron layer may get oxidized due to the increased local-ized heating under oxidizing atmosphere, leading to the loweringof material transfer. Similar observations have been reported by

ig. 12. Variation of wear rate of iron and iron–SiC composites with varying SiContent.

987). The drastic reduction in the wear rates of composites can bettributed to the following:

An improved hardness of composites on the incorporation of sili-con carbide which is a hard phase. An increase in hardness resultsin the improvement of wear and seizure resistance of materials(Ramesh et al., 1991).Further, there is an experimental support and practical evidenceto suggest that the onset of adhesive process such as scuffingand seizure are restricted by increase in hardness of materials(Ramesh and Seshadri, 2003).Existence of good bond between the matrix and silicon car-bide particles as evidenced in the scanning electron micrograph

shown in Fig. 4b. Interfacial bond between the matrix and thesilicon carbide particle plays a significant role in wear process.It is reported that the wear resistance of Cu–Al2O3 compositesdecreases with increased alumina content. This deterioration of

ig. 13. Energy dispersive spectroscopy of worn track of iron–SiC composite.

Fig. 14. Variation of wear rate with sliding velocity.

the wear resistance of the composites has been attributed to thepoor interfacial bond between the matrix and the reinforcement(Saka and Karalekas, 1985).

4 Formation of inhomogeneous transfer layer which consists ofiron matrix, fragments of silicon carbide and nickel on the slid-ing surfaces of pins under the steady state of wear as evidencedby energy dispersive spectroscopy pattern of the worn surfaces

Fig. 15. Variation of wear rate with load and laser speed. (a) Variation of wear ratewith load and sintering speed for iron. (b) Variation of wear rate with load and laserspeed for iron composites.

C.S. Ramesh, C.K. Srinivas / Journal of Materials Processing Technology 209 (2009) 5429–5436 5435

20 N.

3

ivwibiampihd

viiibmhoef

3

IrlltsA

Fig. 16. SEM of worn surfaces at sliding velocity of 1.26 m/s and load of

Alphas and Zhang (1994). Further, once the transferred layer areestablished on the composite samples, the steel counter face canbe considered to be mainly in contact with the mixture of ironand its oxide. The iron oxides are known to have low coefficientof friction and these layers are expected to provide in situ lubri-cating effect (Rabinowicz, 1996; Bowden and Tabor, 1953). Thislubricating effect provides the materials with higher incorpora-tion of reinforcement with higher wear resistance. The existenceof such transfer layer in case of aluminum based composites hasbeen reported by several researchers (Alphas and Zhang, 1994;Biswas and Pramila Bai, 1981; Murali et al., 1982).

.6.2. Effect of sliding velocityThe variation of wear rate of iron and its composites with

ncrease in sliding velocity is shown in Fig. 14. At all the slidingelocities studied, iron–silicon carbide composite possesses lowerear rate when compared with iron. A steep decrease in wear rate

s observed with increase in sliding velocity at a sliding velocityeyond 0.84 mm/s and remains steady with further increase in slid-

ng velocity for iron. The steep decrease in wear rate of iron can bettributed to the fact that the higher sliding velocities result in pro-oting slightly higher temperature at the interfaces of the mating

art which may come out as the formation of oxide films on the mat-ng surfaces. These oxide films in between the mating surfaces willave a beneficial effect in retarding the material transfer processuring sliding of the mating parts.

Once a stable film is formed any further increase in slidingelocity will not affect the adhesion process, there by unaffect-ng the material removal rate from the sliding surfaces resultingn steady wear rate. However, in case of Fe–SiC composites theres a steady increase in wear rate with increase in sliding velocityeyond 0.84 m/s. This increase in wear rate of composite can beainly attributed to the fact that silicon carbide which is a very

ard phase present in the composite tends to disturb the formationf protective lubricating film of iron and its oxides. It is important tonsure that the lubricating film is continuous and not fragmentedor lower wear rate.

.6.3. Effect of loadThe variation of wear rate with contact load is shown in Fig. 15.

t is observed that initially for up to a load of 60 N, there is a drasticeduction in wear rate. Beyond 60 N the wear rate is steady for the

oad up to 80 N. However at all loads studied composites exhibitower wear rate when compared with iron. Further it is observedhat the laser speeds during the processing of composites have aignificant effect on the wear rates of the developed composites.

decrease in laser speed results in better wear resistance of the

(a) Iron-sintered at 100 mm/s. (b) Iron–3 wt.%SiC sintered at 100 mm/s.

developed composites. Further for a given laser scan speed, theworn surfaces of iron matrix have undergone severe plastic defor-mation with severe cracking when compared with the iron–siliconcarbide composites as shown in Fig. 16.

4. Conclusions

Iron–silicon carbide composites have been successfully devel-oped by laser sintering. Lower laser speeds have resulted in higherdensity, higher microhardness and higher wear resistance of thedeveloped composites The developed composites have exhibitedhigher microhardness, coefficient of friction and lower wear rateswhen compared with iron. For all the loads and the sliding veloci-ties studied, the developed composites have exhibited higher wearresistance and higher coefficient of friction when compared withiron. An extensive damage has been observed for iron pins whencompared with that of the developed composites.

Acknowledgement

The authors are thankful to Shri B.R.Satyan, Director, CentralManufacturing Technology Institute, Bangalore, India and Princi-pal and Management, PES Institute of Technology, Bangalore forextending support and encouragement through out the course ofthis work.

References

Alphas, A.T., Zhang, T., 1994. Effect of microstructure (particulate, size and volumefraction) and counter phase materials on sliding wear resistance of particulatereinforced aluminium metal matrix composites. Mater. Trans. 25A, 969–983.

Anand, K., Kishore, 1983. On the wear of aluminium corundum composites. Wear85, 163–169.

Biswas, S.K., Pramila Bai, B.N., 1981. Dry wear of Al–graphite particle composites.Wear 68, 347–359.

Bowden, F.P., Tabor, D., 1953. The influence of surface finish on the friction anddeformation of surfaces in properties of metallic surfaces. Inst. Metals, London,197–212.

Chong, P.H., Man, H.C., Yue, T.M., 2001. Microstructure and wear properties of lasersurface-cladded Mo-WC MMC on AA6061 aluminum alloy. Surf. Coat. Technol.145 (1–3), 51–59.

Gaard, P., Karkhmalev, A., Bergstrom, J., 2006. Microstructural characterization andwear behavior of (Fe,Ni)–TiC MMC prepared by DMLS. J. Alloys Compds. 421,166–171.

Gajendran, C., Srinivasa, C.K., Gurumurthy, T., Murthy, J.R.K., 2003. Application ofdirect metal laser sintering (DMLS) RP technology for injection moulding andinvestment cast tooling. In: Mondal, B., Basu, J., Mukherjee, N.P., Sinha, G.P. (Eds.),

Proceedings of National Conference on Investment Casting. Durgapur, India, pp.137–142.

Hoskins, F., Folgar, P.F., Wunderlin, R., Mehrabian, R., 1982. Composites of aluminiumalloys: fabrication and wear behaviour. J. Mater. Sci. 17 (2), 477–498.

Kruth, J.P., 1991. Material increases manufacturing by rapid prototyping techniques.CIRP Ann. 40 (2), 603–614.

5 als Pro

M

M

P

R

R

R

R

R

436 C.S. Ramesh, C.K. Srinivas / Journal of Materi

urali, T.P., Prasad, S.V., Surappa, M.K., Rohatgi, T.K., Gopinath, K., 1982. Friction andwear behaviour of Al-alloy coconut shell char particulate composites. Wear 80,149–158.

urali, K., Chatterjee, A.N., Saha, P., Palai, P., Kumar, S., Roy, S.K., Mishra, P.K., RoyChoudhury, A., 2003. Direct selective laser sintering of iron–graphite powdermixture. J. Mater. Process. Technol. 136, 179–185.

rasad, S.V., Rohatgi, R.K., 1987. Tribological properties of aluminium alloy compos-ites. J. Mater. 39 (11), 22–26.

abinowicz, E., 1996. In: Ling, F.F., Witley, R.L., Ku, P.M., Peterson, M.B. (Eds.), Compat-ibility Criteria for Sliding Metals in Friction and Lubrication in Metal Processing.ASME, New York, pp. 90–102.

amesh, C.S., Seshadri, S.K., Iyer, K.J.L., 1991. A survey on aspects of wear of metals.Indian J. Technol. 29, 179–185.

amesh, C.S., Seshadri, S.K., 2003. Tribological characteristics of nickel compositecoating. Wear 255, 893–902.

amesh, C.S., Srinivasa, C.K., Srinivas, K., 2007a. Friction and wear behaviour of rapidprototype parts by direct metal laser sintering. Trib. -Mater. Surf. Interfaces 1

(2), 73–79.

amesh, C.S., Srinivasa, C.K., Avadani, S.S., Channabasappa, B.H., 2007b. Elec-troless nickel plating on silicon carbide particles for MMC applications.In: Kori, S.A., Claude, E., Mahadevappa, G. (Eds.), Proceedings of Interna-tional Symposium on Advanced Materials and Processing. Bagalkot, India,pp. 150–154.

cessing Technology 209 (2009) 5429–5436

Russel, T., Dotter, 1984. Blending and premixing of metal powders. In: Metals HandBook, vol. 7, 9th ed, pp. 186–187.

Sahin, Y., Acilar, M., 2003. Production and properties of SiCp-reinforced aluminiumalloy composites. Composites Part A 34, 709–718.

Saka, N., Karalekas, D.P., 1985. Friction and wear of particle reinforced metal ceramiccomposition. In: Ludema, K.C. (Ed.), Proc. Conf. Wear of Materials. ASME, NewYork, pp. 784–793.

Simchi, A., Petzoldt, F., Pohl, H., 2001. Direct metal laser sintering: material con-siderations and mechanisms of particle bonding. Int. J. Powder Metall. 37 (2),49–61.

Simchi, A., Pohl, H., 2003. Effect of laser sintering processing parameters on themicrostructure and densification of iron powder. Mater. Eng. A359, 119–128.

Srinivas, C.K., Ramesh, C.S., Somashekar, B.S., 2006a. Sintering processes in pro-duction of industrial components. In: Proceedings of the National Conferenceon Emerging Trends in Mechanical Engineering, BMS College of Engineering,Bangalore, pp. 23–25.

Srinivas, C.K., Ramesh, C.S., Prasad, S.V., 2006b. An overview of rapid prototyping

processes. Manuf. Technol. Today 5 (6), 26–29.

Surappa, M.K., Prasad, S.V., Rohatgi, P.K., 1982. Wear and abrasion of cast Al–aluminaparticle composites. Wear 77, 295–302.

Vaucher, S., Paraschivescu, D., Andre, C., Beffort, O., 2002. Selective laser sinteringof aluminium–silicon carbide metal matrix composites. Materials Week 2002,30.09.-02.10 2002, ICM-Munich. (ISBN3-88355-314-X).