Influence of Substrate Bias Voltage on Structure, Morphology and Mechanical Properties of AlCrN Coatings Synthesized Using Cathodic Arc Evaporation

Abstract

AlCrN is one of the most widely studied hard coatings, especially if it is about their thermal resistance and mechanical properties. However, adhesion and wear resistance of AlCrN coatings synthesized from an Al-rich AlCr (80:20) cathode has not been studied yet. The influence of substrate bias voltage on the properties of coatings formed by cathodic arc evaporation was investigated. The morphology, phase and chemical composition, hardness, adhesion as well as wear of the coatings were analyzed by XRD, EDX, SEM, nanoindenter, scratch and ball-on-disc testers. It was found that as the negative substrate bias voltage (UB) increased, the rate of deposition and the macroparticle number on the surface of the coating decreased, mainly due to the resputtering phenomenon. X-ray diffraction showed that the intensity of h-AlN diffraction lines decreases and the intensity of the cubic CrN diffraction lines increases with the increase of the negative substrate bias voltage. The hardness of the coatings increases and critical load Lc2 decreases with negative substrate bias voltage. The lowest wear rate, about 1.1×10-16 m3/Nm, was observed for coating deposited at bias of -100 V.