An investigation of fretting wear behaviour of a ternary (Zr,Hf)N coating

In this study, the wear behaviors of ZrN and (Zr, 21wt.% Hf)N coatings, deposited on hardened AISI D2 cold work tool steel by a arc-physical vapor deposition (PVD) technique were examined by a fretting wear tester, Wear tests were conducted by rubbing Al₂O₃ and steel balls on the surfaces of the coatings under dry sliding condition. Characterization tests showed that, the hardness and the surface roughness of the examined coatings were almost the same. However, addition of 21wt.% Hf to ZrN improved the adhesion between the coating and the substrate. Fretting wear tests conducted by rubbing both Al₂O₃ and steels balls revealed that, addition of 21wt.% Hf achieved an increment in the wear resistance of the ZrN coating. Steel ball encouraged oxidative wear, while wear of the coatings by Al₂O₃ ball progressed by coating removal.