Effect of heat treatment on dry sliding wear of titanium-aluminum-vanadium (Ti-6Al-4V) implant alloy

摘要

Titanium and its alloys have very attractive properties that enable them to be used in the fields of aero space, biomedical, marine and also in many corrosive environments. The application of these alloys is more attractive today in the field of biomedical implant materials due to their superior biocompatibility and strength. These alloys have high coefficient of friction and poor abrasive wear resistance which results in the wear of the implant during its fixation in the body. Implant wear is a common phenomenon which results due to high friction between artificial implant materials when in contact with natural bone - this is much higher than healthy and natural joints that can withstand cyclic loads acting on them. The corresponding wear of the implant results in the accumulation of wear debris in the body tissues which results in inflammation, pain and loosening of implant resulting in shorter life period of the implant. Heat treatment of the alloy is one of the important techniques to improve the sliding wear properties of the alloy. The property of poor abrasive resistance can be altered by changing the microstructure of the alloy where the formation martensitic structure (acicular α or retained β) is resulted. The formation of martensitic structure in titanium alloy results in improved hardness value with a subsequent improvement in its sliding wear behavior. In this work, the implant material is subjected to heat treatment above its transformation temperature followed by slow cooling in furnace, air and water. These specimens were further aged and tested for dry sliding wear properties against hardened steel disc using a pin-on-disc apparatus using weight loss method with an optimal load of 50 N and a sliding distance of 500 m. An improvement of wear rate is reported under different heat treatment condition and an analysis of wear track of the specimens is done using scanning electron micrographs (SEM).