Improving the protective properties of an artificial joint friction couple by using TiN and DLC films

Artificial joint replacement represents the most effective approach for addressing joint pathologies. However, friction and wear, the production of debris and the release of metal ions reduce the durability of artificial joints and negatively impact human health. This study focuses on a CoCrMo alloy joint femoral head and an ultra-high molecular-weight polyethylene cup, which are commonly used as standard artificial joint friction couples. Two different types of films have been deposited on the surface of the joint femoral head. Multilayer TiN/(Ti/DLC) x 3 films were deposited on the surface of the alloy ball via pulsed cathode-arc discharge, and a friction experiment was carried out by a hip friction simulation tester. As an alternative film for use in medicine, TiN films were deposited by direct current arc evaporation of the titanium cathode in a nitrogen atmosphere at a partial pressure of 1.2 x 10-1 Pa. Prior to conducting the wear test, the film structure was studied through Raman and XPS spectroscopy. The surface morphology and adhesion of the films to the joint femoral head were studied.A change in the mass of the prosthesis has been seen when comparing the presence and absence of deposited films. Inductively coupled plasma mass spectroscopy has shown the effectiveness of protecting the surface of the prosthesis with the deposited TiN/(Ti/DLC) x 3 film. This method successfully reduces the concentration of Co and Cr released during friction. The findings indicate that the TiN/(Ti/DLC) x 3 film deposited on the joint femoral head reduces the wear of the UHMWPE cup and did not degrade over five million cycles, thus signifi-cantly exceeding the operating life of the TiN film. The results show that TiN/(Ti/DLC) x 3 film demonstrates a 55 % reduction in the generation of abrasive debris in the UHMUPE cup. Furthermore, it effectively prevents the release of metal ions from the alloy femoral head.

Automated summary

This study investigates the durability issue of commonly used friction materials in artificial joint replacement and examines the impact of deposited films on this issue. The findings indicate that depositing TiN/(Ti/DLC) x 3 film on the surface of the joint femoral head can effectively reduce wear and debris generated from friction, as well as prevent the release of metal ions.