Development of Ti-TiC composites by powder metallurgy route using recycled machined Ti chips

Abstract

A large amount of waste in the form of chips is generated during production processes like machining, grinding or cutting of Ti/Ti based alloy. From the economic, strategic and environmental point of view, these chips should be reused and recycled. Powder metallurgy provides a very suitable and economical way for the utilization of these chips. Initially, Ti chips were cleaned with acetone, cut into small pieces and then milled in a high energy planetary mill. Milling was carried out using stainless steel ball in a stainless steel jar. Wet milling was conducted where chips and balls were immersed under toluene to prevent oxidation. Milling was carried out for two hours and then Ti powders were characterized by XRD, SEM and TEM. The prepared Ti powder and graphite powder were mixed in different weight percentage (48:12, 100:6) and then milled in planetary mill. The milled powders were compacted at different pressure (400-700 MPa) by using a powder compaction press and then sintered at different temperatures (1000-1200 C) in a tubular furnace under argon gas. It has been found that the weight ratio of Ti and C (graphite) has great influence on the formation of TiC in the produced composite. The phase study and microstructural characterization of Ti-TiC composites were characterized by XRD and SEM. Experimental results show that with the increase in compaction pressure and sintering temperature; the density, micro-hardness and wear resistance of the Ti-TiC composite increases.