Low temperature quaternary hard coatings with Cr- to Ti-based transition composition

Abstract

A new quaternary hard coating based on Cr/CrN adhesion layers and a TiCrAlN main coating layer was developed for low-temperature applications. It was deposited in a closed-field unbalanced magnetron sputtering equipment. The nanohardness, adhesion and thickness of the coating were characterized by Anton Paar’s nano-indenter tester, scratch tester and calotester. The chemical composition and surface morphology were investigated by a Hitachi SU 500 scanning electron microscope equipped with an energy dispersion analyzer. The coating showed a low coefficient of friction and a good adhesion strength between the substrate and the Cr/CrN transition layer, as well as between the transition layer and the TiCrAlN layer. The nanohardness achieved was 33 GPa. The research results showed that the quaternary Cr/CrN/TiCrAlN hard coating deposited at 200 °C has mechanical properties comparable to coatings with a similar composition deposited at standard deposition temperatures.