Fretting and wear resistant boride coating on titanium alloys


Ti6Al4V alloy is widely used for un-cemented stems of hip joints and tibia components of knee joints, but due to low fretting and wear resistance it is not used for hip joint’s heads, femoral components of knee joints and cemented hip stems. As an alternative, cobalt–chromium–molybdenum (CoCrMo) alloys are widely used, because of higher hardness and wear resistance, but high concentration of stress and direct friction against CoCrMo surfaces leads to release of toxic metal ions into the human body with potential danger for the patients . By focusing on the most biocompatible material, the goal is a surface modification of Ti6Al4V alloy in order to improve its bio-tribological characteristics. The aim is a material combining the good properties of titanium alloys with high hardness, good wettability and lubricant behaviour of ceramics. The obtained coating is composed by an upper compact layer of titanium boride and diboride and a lower layer of whiskers of titanium boride. Size of the whiskers, thickness and hardness of the coating depend on composition of the salt mixture, temperature and time of the heat treatment: penetration depth of boron diffusion is about 10µm and surface hardness is about 45±10GPa. Protein adsorption tests and zeta potential analysis after protein adsorption show that the coated alloy behaves similarly to alumina that is the gold standard considering lubrication behaviour and wear resistance in arthroprosthetic joints.


Recent reference(s)

V. Peretti et al, Boride coating on Ti6Al4V for application in arthroprosthetic joints, ESB 2017


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