Microstructure and Wear Behavior of Zircon Reinforced Copper Based Surface Composite Synthesized by Friction Stir Processing Route

Abstract

Although copper has its use in many industrial and functional applications, but its low wear resistance limits its potential application. Hard particulates are generally reinforced in bulk copper to increase its wear resistance but it tend to decrease its toughness. Thus the present research focuses on synthesis of copper based surface composite by friction stir processing. Zircon sand was used as reinforcement in copper as it is hard and fairly inexpensive. To prepare the composites, a groove of defined dimension was machined in the copper plate for compaction of zircon sand (18 vol%) at the centre of the plate. After filling the zircon sand in grooves, friction stir processing technique was employed to reinforce it in copper. For microstructure analysis, XRD, microhardness and wear characterization, specimens were cut from the processed portion of the plate. The micrograph obtained by optical and scanning electron microscope revealed equiaxed and fine grain structure in stir zone with no sign of concentration gradient, aggregation and segregation of particles. XRD pattern revealed no peaks corresponding to intermetallics or interfacial reaction products. The microhardness and wear resistance of fabricated surface composite improved significantly as compared to pure copper. The micrograph of worn surface was also analysed to investigate the predominant wear mechanisms. Adhesion and delamination wear were predominant wear mechanisms in pure copper whereas these wear mechanism was not significant in Cu/Zircon composite.