Microstructure and properties of TiAlCrN ceramic coatings deposited by hybrid HiPIMS/DC magnetron co-sputtering

Abstract TiAlCrN ceramic coatings were prepared utilizing a hybrid deposition technique consisting of High Power Impulse Magnetron Sputtering (HiPIMS) and Direct Current Magnetron Sputtering (DCMS). The chemical composition, phase structure, morphologies, mechanical and tribological properties of such coatings were systematically investigated. Results indicated that the content of Ti element increased monotonically from 0 at.% to 22 at.% with increasing of Ti target power. The TiAlCrN ceramic coatings presented a competitive growth tendency between (111) and (200) crystal plane through the energetic ion bombardment. Higher Ti target power resulted in stronger compressive intrinsic stress, which significantly suppressed the precipitation of hcp-AlN phase. With enhancing ion bombardment, diffusion energy and nucleation rate of adatoms on the growing surface increased, which caused a denser structure and ultra-smooth surface. The hardness and toughness also varied as a function of Ti target power, with the maximum hardness of 28.3 GPa under a Ti target power of 5 kW. Positive correlation between the adhesion strength (i.e., the critical load of the scratch test) and H3/E2 ratio was discovered indicating a strong dependence of adhesion properties on toughness for the TiAlCrN ceramic coatings in this study, which agreed well with the literatures. As for the tribological behavior, the lowest wear rate of 8.9 × 10-17 m3N-1m-1 was obtained for the TiAlCrN ceramic coating deposited at a Ti target power of 5 kW.