Isothermal oxidation resistance comparison between air plasma sprayed, vacuum plasma sprayed and high velocity oxygen fuel sprayed CoNiCrAlY bond coats

Commercial CoNiCrAlY powders with the same chemical composition were sprayed by vacuum plasma spraying (VPS), air plasma spraying (APS) and high velocity oxygen fuel (HVOF) onto Hastelloy X superalloy substrates obtaining coatings of comparable thickness. After coating, samples were maintained at 1273 K in air for different periods up to 3000 h. Morphological, microstructural and compositional analyses were performed in order to assess the high temperature oxidation resistance provided by the different spraying systems. HVOF technique provided bond coats with higher oxidation resistance compared to APS and VPS.