Improved tribological properties and corrosion protection of CrN coating by ultrathin composite oxide interlayer

Abstract The intrinsic columnar structure and pinholes existing in the hard coatings via physical vapor deposition (PVD) could deteriorate their tribological and electrochemical properties. In order to improve the tribological and corrosion protection properties of CrN, TiO2 and HfO2 composite oxides deposited by atomic layer deposition (ALD) were inserted into the sputtered CrN. The influence of TiO2 and HfO2 composite oxides on the micro-structure, mechanical, tribological and electrochemical corrosion properties of coatings was investigated. By contrast with the pure CrN, the ALD-oxide inserted CrN coatings particularly the one added with TiO2-HfO2 nanolaminate significantly decrease the grain size, surface roughness and enhance the mechanical property of CrN. Additionally, the TiO2-HfO2 nanolaminate inserted CrN delivers excellent tribological and anti-corrosion properties. It is attributed to the synergistic effect of TiO2 and HfO2, which not only blocks the defect proliferation and dislocation motion during sliding, but also prevents the diffusion of corrosive media from migrating through the intrinsic pinholes in coatings and delivers outstanding barrier properties.