A Ni-Bi self-lubricating Ti6Al4V alloy for high temperature sliding contacts

Abstract

Components made of titanium alloys such as Ti6Al4V operate often close to their thermomechanical limits in aerospace applications, leading to an increased onset of damage mechanisms such as galling. This can lead to the catastrophic failure of key components in a temperature range in which lubricants such as oils and greases quickly degrade. In an effort to overcome these tribological issues, the incorporation of solid lubricants such as bismuth to the widely used commercial grade Ti6Al4V alloy has been performed by means of laser cladding, leading to the production of Ti-based self-lubricating alloys. It has been found that such coatings can lead to significantly decreased friction and wear in the 400 to 800°C range when tested against Ti-alloys, due to the formation of bismuth-rich tribolayers capable of providing effective lubrication at high temperature. It is expected that the implementation of such self-lubricating titanium alloy can serve to substantially broaden the current narrow applicability range of titanium alloys in sliding contact applications due to their poor tribological behaviour.