TiAlN and Ti-Al-O thin films (~3 mm) were deposited on Inconel 617 by an arc-discharge and a RF sputtering method, respectively. The effect of the coatings on the thermal stability and wear properties of the Inconel alloy after heat treatment up to 1000 oC has been studied. The uncoated Inconel 617, heat treated at 1000 oC, showed a poor wear resistance and an inferior thermal stability due to the formation of thick corrosion scales in addition to the distinctive hill-shape crusts, which are both composed of Cr2O3 on the alloy surface. Ti-Al-O coated samples heat treated at 1000 oC also showed a poor wear resistance due to the considerable amount of Cr2O3 scale formation. It has been found that the TiAlN coating layer decomposed at 1000 oC and was oxidized into a TiO2-rich top-layer, followed by an Al2O3-rich layer between the top-layer and the alloy substrate. Since the dense protective oxide layers, which were oxidation products, prevented the formation of thick and brittle Cr2O3 scales (crusts) on the alloy surface, the TiAlN coated Inconel showed an enhanced thermal oxidation resistance and an increased wear resistance.

Keywords: Ceramic coating, TiAlN and Ti-Al-O thin film, Inconel 617, Thermal property, Oxidation.