Influence of silicon addition on the oxidation resistance of CrN coatings

Thin CrN and CrSiN films were deposited on steel substrates by DC reactive magnetron sputtering. In this paper, the structure and the oxidation resistance of CrN and CrSiN coatings were studied. Whatever the silicon content, CrN was the sole phase evidenced by X-ray diffraction. Silicon introduction into CrN-based coatings did not modify their preferred orientation. On the other hand, a strong effect of the silicon addition on the film oxidation resistance was noticed. Even for silicon concentration as low as 3 at.%, the films thermal stability, the formation of Cr2N phase and the carbon accumulation at the film-substrate interface were strongly limited. Finally, this value of silicon concentration was sufficient to increase the film oxidation resistance by nearly 150 °C.