Thermal Stablility and Oxidation Resistance of CrAlSiN Nano-Structured Coatings Deposited by Lateral Rotating Cathode Arc

Abstract

In this paper, CrAlSiN coatings are deposited by a lateral rotating cathode arc technique. The high temperature oxidation behaviors of these coatings are studied in ambient atmosphere at temperatures ranging from 800°C-1000°C for an hour. The ternary TiAlN coating is used as the benchmark in this study. The surface morphology and chemical composition of the coating samples before and after oxidation at different temperatures are analyzed by scanning electron microscopy (SEM) equipped by energy dispersive X-ray spectrometer (EDX), glow discharge optical spectrometry (GDOS) and X-ray diffraction (XRD). The CrAlSiN coatings show much better oxidation resistance than the TiAlN coatings. TiAlN starts to oxidize from 800oC and forms a complete surface oxide layer after oxidation at 1000oC for an hour. However, CrAlSiN shows a relatively good oxidation resistance below 1000oC and only is oxidized to form a thin oxide scale with a thickness of 0.3 µm at 1000oC for one hour. It is found that the oxidation of both coatings is triggered from the surface metallic droplets generated by the arc deposition process.