Jun Gong

Oxidation behaviour of the alloy IC-6 and protective coatings

Abstract In this work, NiCoCrAlY coatings were deposited on a new Ni-base alloy, IC-6. The oxidation kinetic curves of alloy IC-6, K17 and NiCoCrAlY coatings on alloy IC-6 at 900–1100 °C were obtained. The results indicated that the oxide scales consisted of α-Al2O3, NiAl2O4, NiO, as well as a small amount of NiMoO4 and MoO2. These scales occurred after alloy IC-6 exposure at 900 °C for 100 h. The weight loss occurred when alloy IC-6 were exposed at 1050 and 1100 °C due to the formation of volatile MoO3. After the NiCoCrAlY coating was deposited, the scales mainly contained α-Al2O3, when the specimens were oxidized at 900 °C, and α-Al2O3and Cr2O3 at 1050 °C. The formation of α-Al2O3 and Cr2O3 scales on NiCoCrAlY coating was directly responsible for improving oxidation resistance of the alloy IC-6.

Hot Corrosion Behavior of a Cr-Modified Aluminide Coating on a Ni-Based Superalloy

A Cr-modified aluminide coating is prepared on a Ni-based superalloy using arc ion plating and subsequent pack cementation aluminizing. Hot corrosion behavior of the Cr-modified aluminide coating exposed to molten Na2SO4/K2SO4 (3:1) or Na2SO4/NaCl (3:1) salts at 900xa0°C in static air are evaluated as well as the aluminide coating. The results indicate that compared with the aluminide coating, the anti-corrosion properties of the Cr-modified aluminide coating in the both salts are improved, which should be attributed to the beneficial effect of the Cr in the coating. The corrosion mechanism of the Cr-modified aluminide coating, especially the role of Cr in the mixture salt corrosion, is discussed.