Tribological Behaviours of Titanium Nitride and Chromium Nitride Based PVD Coating Systems

This study investigates the effects of the deposition process and coating composition on microstructural and tribological properties of TiN and CrN based coating systems. Coatings were produced using various PVD based processes — electron beam (EB), cathodic arc (CA) and plasma enhanced magnetron sputtering (PEMS). All coated samples were evaluated for their composition, microstructure and surface morphology. Coating mechanical properties such as hardness, Young’s modulus and coefficient of friction were also studied and related to their microstructures, wear and erosion resistances. It was found that hardness (H), Young’s modulus (E) and coefficient of friction had impact on both wear and erosion rates. In particular, the H³/E² ratio was inversely proportional to the specific wear rate. For erosion behaviour, higher H³/E² ratios relate to lower erosion rates at low impingement angles; whereas higher H³/E² ratios relate to higher erosion rates at high impingement angles.