The influence of Ni concentration on the mechanical properties of Ni doped CrAlSiN coatings

Abstract

Thin film coatings are commonly used in various applications and its performance is of high importance. The mechanical properties such as hardness often evaluated to determine the lifetime of a material. CrAlSiN is hard material and it is the successor of various thin film coatings such as CrN and CrAlN.

CrAlSiN thin film is a hard but brittle material. Previous studies have shown the toughening effect of Ni on the CrAlSiN thin films. However, the performance of CrAlSiNiN at elevated temperature is still unknown. The objective of this experiment is to investigate the mechanical properties of Ni doped CrAlSiN thin film at elevated temperatures.

In this experiment, the Ni content of Ni doped CrAlSiN thin film is increased from 0 to 39.8 at.%. At each concentration of Ni, Ni doped CrAlSiN thin film will be annealed at 500oC, 800oC, 900oC and 1000oC.

The microstructure of Ni doped CrAlSiN thin film is studied using FESEM and it showed that when Ni concentration is increased, the surface morphology become grainier. When annealing temperature of Ni doped CrAlSiN thin film is increased, the surface of the thin film becomes very rough.

The mean hardness of Ni doped CrAlSiN thin film decreases from 39.1±0.8 GPa to 14.9±2.6 GPa when amount of Ni doped increased from 0 to 39.8 at.%. However, hardness of Ni doped CrAlSiN thin film increases when it is annealed at 500oC and 800oC. However, hardness of Ni doped CrAlSiN thin film decreased when annealed at 900oC and 1000oC. The reduction in hardness when annealed at high temperatures could be due to destruction of surface at high temperatures.