Blood compatibilities of carbon nitride film deposited on biomedical NiTi alloy

Carbon nitride (CNx) film, diamond-like carbon (DLC) film, and titanium nitride (TiN) film were deposited on biomedical NiTi alloy substrates using direct current magnetron sputtering, respectively. In order to improve the adhesive strength between the deposited hard film and the NiTi alloy, a Ti transition layer was pre-deposited firstly. We emphatically evaluated the blood compatibilities of the NiTi alloy substrate and the deposited hard films by haemolysis test and platelet conglutination test. It was shown that the blood compatibilities of NiTi alloy can be improved effectively by the deposition of hard films. In comparison with TiN and DLC film, CNx film had the best surface modification effects covering the minimum haemolysis ratio and the best anticoagulation property.