Wear and corrosion properties of diamond like carbon (DLC) coating on stainless steel, CoCrMo and Ti6Al4V substrates

Stainless steel, CoCrMo alloy and titanium alloy are the most commonly used metal materials for artificial joint. But the generation of wear debris and metal ions limits the use of the metal, especially for the metal-on-metal type artificial joint. Diamond like carbon (DLC) coating can reduce the wear and corrosion of these metal alloys. But the service behavior of the DLC coating on different metal substrates may be different. This paper studied the difference of the structure, adhesion, wear and corrosion properties of the DLC coating on different substrates (stainless steel, CoCrMo or titanium alloy). The results show that the structure of the DLC coating on these substrates is similar. The DLC coating on titanium alloy shows the best adhesion than that on stainless steel and CoCrMo alloy, because the chemical bond energy holding Ti atom (of titanium alloy surface) and C atom (of DLC) together is the strongest. The failure mode of DLC coatings on 316L stainless steel and CoCrMo alloy in the friction test is coating delamination. The DLC coating on Ti6Al4V alloy shows the best wear resistance due to its good adhesion. Immersion and electrochemical tests show that the DLC coating on Ti6Al4V substrate has better stability than that on 316L stainless steel and CoCrMo alloy because the Ti6Al4V substrate can prevent the corrosion more efficiently than 316L stainless steel and CoCrMo alloy. In the case of no interlayer, Ti6Al4V alloy is the most feasible metal joint material for DLC modification with good adhesion, wear and corrosion resistance compared with 316L stainless steel and CoCrMo alloy.