Wear Properties of Cu-CNT Nanocomposites

Abstract

Currently, Carbon Nano Tubes (CNTs) are gaining wide spread applications in several high technological areas owing to its remarkable mechanical and electronic properties. Carbon nano tubes were discovered to be the fourth form of carbon by the classic experiments of Ijima in 1991. After that paper there was a flurry of activity worldwide on studies and emphasis on synthesis of CNTs (Ebbesen et al.). Worldwide the major emphasis has been on to develop quality CNTs, several routes of processing CNTs do exist which are Laser Ablation, Electric Arc Discharge and Chemical Vapor Deposition. The properties, both electrical and mechanical of the CNTs have been studied extensively all over the world by several researchers (Tans et al.).It is reported that the CNTs do processes a very high modulus of one Tera Pascal (Harris) and electrical conductivity (1013 A/cm2). Because of these superior properties CNTs are a potential candidate as reinforcement material to produce composites. Copper and its alloys are used commercially because of its high electrical and thermal conductivity coupled with strength. The hard and refractory ceramic reinforcements such as silicon carbide, Alumina, titanium oxide have commonly been used as reinforcements in the ductile copper matrix. Although they posses higher strength, better wear resistance they exhibit lower ductility and thermal conductivity when compared with copper. Further the enhancement in the elasticity modulus of copper based particulate composites is not significant. It is also reported that CNTs can be an ideal reinforcements to develop high-quality composites owing to their low weight and exceptional properties. Kashyap et al., have reported that use of CNT as reinforcements in Aluminum matrix has resulted in drastic improvements in strength which has been attributed to Orowan looping. It is reported that use of CNTs in Ni-matrix has resulted in lowering of Coefficient of friction and wear rates of the composites when compared with nickel matrix. However meager information is available as regards to development and study on tribological behavior of Cu/CNT composites. Dong et al., developed the composites using HIP process and reported. Copper with its low stacking fault energy enables one to observe free dislocations on a Transmission Electron Microscope (TEM) since dynamic recovery will not take place in copper during processing. This aspect has not been studied so far in the literature. In the light of the above, this research focuses on development and characterization of tribological properties of Cu/CNT (MWCNTs and SWCNTs). There is only one paper where Dong et al. studied the sliding wear behavior of