Influence of N2 partial pressure on the microstructure, hardness, and thermal stability of CrZrSiN nanocomposite coatings

Abstract

The effects of N₂ partial pressure in the unbalanced magnetron sputtering process on the microstructure, hardness, and thermal stability of the CrZrSiN nanocomposite coating were investigated. A typical nanocomposite structure, composed of a crystalline phase and an amorphous phase was obtained and the distribution of these phases changed with increasing N₂ partial pressure. The N_1s spectra revealed the presence of two-peak characteristic of nitrogen in the CrZrN and SiN_x phases, and the ratio of the peak’s SiN_x to CrZrN intensity increased with increasing N₂ partial pressure, indicating an increase in the amorphous phase in the nanocomposite microstructure. As N₂ partial pressure increased, the CrZrSiN coating hardness decreased from 38 to 30 GPa due to the increasing amount of the SiN_x amorphous phase. After the thermal stability test, the hardness values of the CrZrSiN coatings were maintained at approximately 30 GPa up to 800°C, but the hardness decreased rapidly to 18 GPa after annealing at 900°C. This drastic change of hardness over 900C was due to the formation of a Cr₂O₃ phase in the CrZrSiN coating.