Characterization of refractory ceramic-coated Inconel 617 prepared by metallo-organic deposition process

Abstract

TiO2, Al2O3 and TiO2-Al2O3 layers (∼2 μm) were deposited on Inconel 617 by a metallo-organic deposition (MOD) process at 550°C. The effects of coatings on the thermal stability and wear properties of the Inconel alloy after heat-treatment up to 1000°C have been studied. Uncoated Inconel 617 sample heat-treated at 1000°C showed a poor wear resistance and an inferior thermal stability due to the formation of thick corrosion scales in addition to the distinctive hill-like crusts, which are composed of Cr2O3 on the alloy surface. TiO2 coated samples heat-treated at 1000°C also showed a poor thermal properties due to the considerable amount of Cr2O3 formation. It has been noted that the Al2O3 coating layer was diffused into the Inconel alloy, followed by an Al-rich sub-surface layer formation. Since the protective sub-surface layer prevented the formation of thick and brittle Cr2O3 scales (crusts) on the alloy surface, the Al2O3 coated Inconel showed an enhanced thermal oxidation resistance and an increased wear resistance. Meanwhile, the properties of TiO2-Al2O3 coating lay between those of TiO2 and Al2O3 coatings.