Structure and properties of AlCrN coatings deposited using cathodic arc evaporation

Abstract

Al-Cr-N coatings were formed at various nitrogen pressures, substrate bias voltages and substrate temperatures using cathodic arc evaporation. The relationship between technological parameters and properties of the coatings was investigated. The phase and chemical composition of the coatings, roughness, hardness, adhesion and thermal stability were analyzed by X-ray diffraction (XRD), scanning electron microscope (SEM), Energy-dispersive X-ray spectroscopy (EDX), micro-indenter, Rockwell, scratch tester and thermomechanical methods. The corrosion resistance of selected coatings was also investigated. XRD analysis indicates that the coatings crystallize in a cubic structure and show preferential orientation (200) CrN. With the increase of nitrogen pressure, the preferential orientation changes to (111). EDX analysis shows that as nitrogen pressure increases, the Al/(Al + Cr) rate decreases. Microscopic observations indicate that the number of macroparticles reduces as nitrogen pressure increases. As a result, the surface roughness parameter Ra of the coatings decreases. The effects of deposition temperature, nitrogen pressure and substrate bias voltage on the mechanical and tribological properties of the coatings were investigated. It was found that the above parameters influence the mechanical properties in different ways. The hardness and adhesion of coatings formed at higher temperatures was lower. Coatings formed under a higher nitrogen pressure or substrate bias voltage were characterized by higher hardness and better wear resistance.