Cyclic oxidation behavior of MCrAlX coatings made by electrolytic codeposition

Abstract

MCrAlY coatings made by electron beam physical vapor deposition or thermal spray are often used to provide protection for superalloys against high‐temperature oxidation and corrosion. In addition to Y, other elements such as Ta, Hf, and Si have been reported to be beneficial. In this paper, NiCoCrAlX (where X = Y, Ta, Hf, and/or Si) coatings were fabricated via an electrolytic codeposition process in a sulfate‐based Ni–Co plating solution. As compared to uncoated René 80 substrates, the electro‐codeposited NiCoCrAlX coatings demonstrated superior performance during oxidation testing with a 1‐h cycle frequency at 1000°C and 1100°C. Further improved oxidation resistance was observed for the coatings with Hf and Si additions, but not with the addition of Ta. The levels of S, Y, and O in the electrodeposited NiCoCrAlY coating were measured by high‐resolution glow discharge mass spectrometry and were compared to those in thermal spray coatings.