Isothermal Oxidation Behaviors of Packed Aluminide Coatings of Ni-Cr-W Superalloy at 1100 °C

Abstract:

The isothermal oxidation behavior of packed aluminide coatings of Ni-Cr-W superalloy at 1100 oC was investigated. Results from scanning electron microscopy and X-ray diffraction indicate that the oxidation dynamics curve of packed aluminide coatings can be divided into two stages: initial rapidly stage and metaphase slowly stage. Oxides on packed aluminide coatings surface have a transformation process as following: crystal θ-A12O3→equalaxial α-A12O3→α-A12O3→particle α-A12O3→particle unite α-A12O3 during the whole oxidation. During the initial stage of oxidation, carbides can be able to holdback coating degeneration caused by interdiffusion between Ni element and Al element.

Key words:Ni-Cr-W superalloy; packed aluminide coatings; oxidation scale