Low-Cost Corrosion and Oxidation Resistant Coatings for Improved Reliability of Turbine Engine Components
In order to improve high-temperature oxidation and corrosion resistance of critical superalloy components in turbine engines, innovative processing methods must be devised to improve coating and materials properties at higher reliability and lower costs. Electrolytic codeposition is a promising low-cost non-line-of-sight technique for manufacturing MCrAlY coatings (where M = Ni, Co, or Ni + Co). The process involves codeposition of CrAlY-based particles and a metal matrix of Ni, Co, or (Ni,Co), followed by a diffusion treatment to convert the composite coating to the desired MCrAlY microstructure. Recent coating development progress from a collaborative research effort between Tennessee Tech University and Faraday Technology Inc. is presented. Two Ni-based alloys with different chromium levels (Inconel 718 and Nimonic 105) were coated. The coated specimens were evaluated in oxidation testing at 800°C and in hot corrosion tests at 760°C with mixed Na2SO4-MgSO4 salt solution on the specimen surface.