Thick coatings (>1.5 mm) of CoNiCrAlY sprayed by HVOF

Spherical CoNiCrAlY powders (- 45 + 5 mu m) were sprayed using a Jet Kote II HVOF gun working with propane and oxygen. The coatings sprayed on two base materials : Inconel 625 (Ni base) and MarM 509 (Co base) were between 1,6 and 3 mn thick. The aim of the study was to examine the adherence problems in relation with this thickness and the imposed thermal cycles (thermal diffusion treatment and aluminizing). The studied parameters were the expansion coefficients evolution before and after the different treatments and the residual stresses between coating and substrate measured by incremental hole dilling method.