Modification of working surface of titanium components of friction units

The paper addresses the possibility of using titanium in friction units of artificial joints. Tribotechnical characteristics of titanium-hirulen friction couple is studied. The authors put forward a technology of surface cold plastic deformation (SCPD) of spherical components and thermodiffusion nitriding of spherical pure titanium heads for human hip implants. SCPD is shown to provide a higher level of surface hardening, which makes the curves of microhardness distribution in the cross-section of hardened surface layers shift towards higher hardness values. The surface microhardness (at a depth of about 5 mu m) of the nitrided layer of SCPD-worked specimens significantly exceeds (by up to 30%) that of non-worked specimens.