Influence of HVAF process parameters on in-flight NiCoCrAlY particle oxidation and corresponding splat characteristics

The deposition of MCrAlX coatings (where M is Ni, Co, Fe, or a combination of these, and X is Y, Si, Ta, Hf or a combination of these) via thermal spraying has acquired significant importance in industries such as aerospace, power plants, oil and gas, etc. Among various thermal spray deposition techniques, high-velocity air-fuel (HVAF) has shown a growing potential for the deposition of metallic powders which are sensitive to high-temperature oxidation during spraying. Thus, it is essential to understand the in-flight behavior of these metallic particles in the high-velocity, low-temperature HVAF flame. In this work, a NiCoCrAlY powder was sprayed using different HVAF deposition parameters onto stainless steel substrates. In-flight particle diagnostic tools such as AccuraSpray and DPV were employed to understand the behavior of these spray particles. The deposited splats were studied to evaluate the splat behavior and particle oxidation. The deposited splats were also examined to understand the process-microstructure-splat characteristics correlation. This provided an understanding of the significance of deposition parameters on the in-flight particle oxidation behavior and splat deformation characteristics.