The effect of milling and sintering techniques on mechanical properties of Cu–graphite metal matrix composite prepared by powder metallurgy route

Representative FESEM micrograph of Cu–10vol.% graphite MMC sintered at 900°C for 1h. [Display omitted] •Higher density and hardness in spark plasma sintering than conventional sintering.•Less improvement in hardness after graphite addition into Cu–graphite MMCs.•Cu–graphite MMC shows improvement in...

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Bibliographic Details
Published in:	Journal of alloys and compounds Vol. 569; pp. 95 - 101
Main Authors:	Samal, C.P., Parihar, J.S., Chaira, D.
Format:	Journal Article
Language:	English
Published:	Kidlington Elsevier B.V 25-08-2013 Elsevier
Subjects:	Condensed matter: structure, mechanical and thermal properties Contact force Copper Cross-disciplinary physics: materials science; rheology Cu–graphite Density Exact sciences and technology Graphite Hardness Materials science Materials synthesis; materials processing Mechanical and acoustical properties Mechanical and acoustical properties of condensed matter MECHANICAL PROPERTIES Mechanical properties of solids Mechanical property Metal matrix composites Methods of nanofabrication Microstructure MILLING Physical properties of thin films, nonelectronic Physics Powder metallurgy POWDER METALLURGY PROCESSES POWDERS SINTERING Sintering (powder metallurgy) Spark plasma sintering SPARK SINTERING Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties) Tribology and hardness Metal matrix composites Powder metallurgy Microstructure Cu–graphite Mechanical property Vickers hardness Pressure effects Electric contacts Metal matrix composite Cu―graphite Slip Electric sparks Mechanical properties Spark plasma sintering Composite materials Experimental design Sliding contact Wear Graphite Particle shape Copper Nanomaterial synthesis Tribology
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Summary:	Representative FESEM micrograph of Cu–10vol.% graphite MMC sintered at 900°C for 1h. [Display omitted] •Higher density and hardness in spark plasma sintering than conventional sintering.•Less improvement in hardness after graphite addition into Cu–graphite MMCs.•Cu–graphite MMC shows improvement in density, compressive and flexural strength.•Milling results in flake formation up to 20h of milling and after that breakage takes place.•Decrease in density and hardness of the milled samples up to 20h and beyond that improvement takes place. When copper is used as electrical sliding contacts, a large contact force is desirable to maintain effective current transfer, whilst on other hand it is advisable to have as small as contact force as possible in order to reduce the wear of the sliding components. In the present investigation Cu–graphite metal matrix composites (MMCs) were prepared by conventional powder metallurgy route using conventional and spark plasma sintering (SPS) techniques. It has been found that addition of graphite into copper does not result in much improvement on the hardness due to the soft nature of graphite. However, 90% and 97% of relative density have been obtained for conventional sintered and SPS samples respectively. Maximum Vickers hardness of around 100 has been achieved for Cu–1vol.% graphite MMC when it is fabricated by SPS due to the combined effect of pressure and spark plasma effect. However, a hardness value of 65 has been obtained for the same composite when it is fabricated by conventional sintering at 900°C for 1h. It has been found that density and hardness of MMCs decreases up to 20h of milling due to flake formation and increase in size and after that these values increases as particle shape changes to irregular and size reduction takes place.
Bibliography:	ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 ObjectType-Article-1 ObjectType-Feature-2
ISSN:	0925-8388 1873-4669
DOI:	10.1016/j.jallcom.2013.03.122