Friction and wear characteristics of various prosthetic materials sliding against smooth diamond-coated titanium alloy

Duplex coating with an external nano-smooth fine-grained diamond (SFGD) layer, a thin titanium carbide interlayer and a carbon diffusion layer have been deposited by PACVD on titanium alloy at 600 °C. These coatings have already shown low wear against various counterfaces in ambient air. They might have potential applications in the field of prostheses because of their high resistance to corrosion and wear. Rotating pin-on-disc friction tests have been carried out here at room temperature in ambient air, Ringer’s solution and synthetic serum to approach the in vivo wear conditions, with a sliding velocity of 0.1 m s−1 and a normal load varying in the 0.5–13 N range. Diamond-coated Ti–6Al–4V samples were used as the discs. The counterface materials were hemispherical pins fabricated from diamond-coated Ti–6Al–4V, Ti–6Al–4V and Co–28Cr–6Mo alloys, 316L steel and UHMWPE. During the sliding tests, the total wear heights were measured and recorded on-line. After the tests, the final mean wear rates of the pins were determined from the diameter of their wear scars. The friction coefficients and wear rates of the different materials allow one to compare their performance and to demonstrate the potential of the nano-smooth diamond coatings for biomechanical applications.