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 Na 2 SO 4 /K 2 SO 4 (3:1) or Na 2 SO 4 /NaCl (3:1) salts at 900 °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.