Synthesis and Cyclic Oxidation Resistance of Hf-Modified Aluminide Coatings on Ni- and Co-Base Superalloys

 With small additions of Reactive Elements (RE), such as Hf, to aluminide coatings used for turboengines or energy generation systems, the adherence of the protective oxide scale to the coatings and the oxidation resistance of the coatings at high temperature can be improved. Previous researches with Hf-containing alloy samples indicate that for the purpose of obtaining optimum oxidation resistance, low Hf content is desired. Due to the complexity of coating processes, successful development of low content Hf aluminide diffusion coatings has not been reported.  A R&D project to develop commercial Hf-modified aluminide coatings for aircraft engine components is ongoing at SIFCO Minneapolis. In this talk, partial R&D results regarding the successful process development and oxidation performance testing of industrial Hf-modified aluminide coatings will be presented.