Effect of the Si content on the structure, mechanical and tribological properties of CrN/AlSiN thin films

Abstract

Thin films of CrN/AlSiN were deposited on SKD 11 tool steel and Si wafer substrates using Cr and AlSi alloy (0at.% Si, 12at.% Si, 15at.% Si and 18at.% Si) cathodes in a nitrogen gas flow in a cathodic arc plasma deposition system. The effect of Si addition on the microstructure, mechanical and tribological properties of the films was investigated. The CrN/AlSiN thin films had a multilayered structure by rotating the substrate in which nano-crystalline CrN layers alternated with amorphous AlSiN layers, while CrN/AlN thin film contained nano-crystalline CrN layers alternated with hcp type AlN layers. The CrN/AlN thin film exhibited low hardness and low wear resistance. As the Si content in the amorphous AlSiN layers increased, the hardness and wear resistance of CrN/AlSiN thin films increased. The films deposited using Al0.82Si0.18 alloy cathode showed a maximum hardness of 47GPa and excellent wear resistance, in which a low coefficient of friction of 0.28 and low wear rate of 6.67×10−7mm3/Nm were presented. We also presented the simulation of amorphous AlSiN models with different Si contents. The simulation revealed that the Young's modulus, yield stress and flow stress increased with the increase of Si content in amorphous AlSiN models.