The properties of diamond-like carbon coatings used for artificial joints

The paper presents the results of the tribological tests for materials used in elements of hip and knee endoprostheses. The tests were conducted for a Co-Cr-Mo alloy and the same material with a diamond-like coatings (DLC) coating produced by applying the plasma assisted chemical vapor deposition (PACVD) method. The materials to be tested were selected because of their good biocompatibility and high resistance to corrosion and sliding wear. The coating structure was determined by applying scanning electron and atomic force microscopes. The tribological characteristics were obtained with a T-17 tester operating in the pin-on-plate configuration under lubricated friction conditions. The friction pair consisted of a cobalt-based alloy plate, or alternatively, a cobalt-based alloy plate with a diamond-like carbon coating, and an ultra-high molecular weight polyethylene (UHMWPE) pin. The model lubricant used in the tests was Ringer’s solution. The results indicated that the mechanisms of wear of the endoprosthesis elements were dependent mainly on the material used for the working surfaces in the friction joint. The wear resistance and friction coefficient of a cobalt-based alloy disc, or alternatively, a cobalt-based alloy disc with a diamond-like carbon coating, and an alumina ball were also determined by means of a T-01M tester during technically dry friction and lubrication in Ringer’s solution. The comparative analysis confirmed different tribological effectiveness of the cobalt-based alloy and DLC coatings during friction. K e y w o r d s: AFM, biotribology, coatings, diamond, EDS, friction, SEM, wear resistance