The load bearing capacity of hydrogen-free Cr-DLC coatings on deep-case oxygen hardened Ti6Al4V

Titanium alloys are characterised by poor tribological properties, and a soft substrate such as Ti6Al4V alloy might not be able to provide adequate support for a hard carbon coating. A boost diffusion oxidation (BDO) process had been used to acquire a deep hardened case in Ti6Al4V. A novel duplex surface treatment combining the BDO treatment with carbon based hard coatings (BDO/Cr-DLC) can significantly improve the tribological properties of the Ti6Al4V titanium alloy and increase its load bearing capacity on the basis of scratch and pin-on-disc testing.