Are coatings produced by ion-beam-assisted deposition superior? A comparison of chemical and mechanical properties of steel coated using different deposition techniques

The aim of this study was a comparison of chemical and mechanical properties of titanium nitride films prepared with arc evaporation (ARC), magnetron sputtering (MAG), activated reactive ion plating (ARIP) and ion-beam-assisted deposition (IBAD) in order to evaluate the advantages and disadvantages of the IBAD process on an objective basis. Hardened ball bearing steel was coated to thicknesses between 3 and 10 μm at low process temperatures. Ball-on-disc wear measurements showed that the friction coefficients vs. steel were around 0.48 for all techniques, with IBAD values slightly lower. Electrochemical measurements showed large differences in corrosion behaviour. ARC TiN turned out to be less effective because of microporosity connected with droplet formation. MAG TiN yielded an average corrosion protection. ARIP and IBAD showed best reduction of corrosion. IBAD values were the lowest in the initial phase of corrosion, but ARIP showed better long-term stability. Taking into account the present state of development, IBAD can compete with other deposition techniques. It is not superior in many cases, but there is still a high optimization potential for low temperature preparation of films with special features. (orig.)