A Multi RIG Screening Test for Thin Ceramic Coatings in Bio - Tribological Applications

A method is presented for the comparative testing of wear resistance of ceramic coatings made from materials potentially feasible in tribo - medical applications, mainly orthopaedic implants made from ceramics coated metals for low cost, long life and low wear particle emission into the body. The method was devised as the main tool for use in research and is comprised of flat on flat and ball on flat surface (sliding) tests. Seven ceramic coatings were chosen as potentially feasible for the application area known to perform well in low viscosity fluid lubrication condition. The materials used in coatings were diamond like carbon (DLC), diamond like carbon with tungsten additive (DLC-W), titanium nitride (TiN), titanium carbide (TiC), silicon carbide (SiC), chromium nitride (CrN), carbon nitride (CNx). The coatings tested were deposited in vacuum to a stainless steel substrate with the use of several methods, each suited to the coating material; The methods were the following: cathode arc evaporation (ARC), magnetron sputtering (MAG), plasma assisted chemical vapour deposition (PACVD), impulse reactive magnetron sputtering (IRMS) and a combined method ARC-MAG-RF-PACVD (radio frequency assisted - RF); A multiple role PT-3 tribometer was used for flat on flat surface tests (ring shaped surface) and a reciprocating linear motion TPZ-1 tribometer for ball on flat surface tests and a CSEM REVETEST® Scratch Tester to perform standard scratch test in air on coatings. A set of results was obtained illustrating the limiting load for each coating (the load inflicting rapid destruction of the coating) and the endurance under light loading conditions. As lubricating agents distilled water and saline water solution were used. Test results examples are presented and discussed as an illustration of the method's usability for the target application area.