Effect of electro-codeposition parameters on particle incorporation in Ni-CrAlY(Ta) coatings

Abstract

ABSTRACT Electrolytic codeposition is a promising alternative low-cost process for fabricating MCrAlY coatings. In this process, CrAlY particles are codeposited with the (Ni,Co) to form an (Ni,Co)-CrAlY composite coating, which is subsequently heat treated at elevated temperatures to be transformed to the MCrAlY coating containing phases of β-NiAl, γ-(Ni,Co), etc. A permeable rotating barrel was utilized in the present electro-codeposition process, which offered the benefit to apply uniform coatings on the entire sample surface. Such codeposition configuration allowed exchange of electrolyte between the barrel and the plating tank while keeping the specimen and powder inside the barrel. Two types of CrAlY-based particles (made by ball milling and gas atomization) were employed. The effects of several key processing parameters, such as current density, particle loading, and barrel rotational speed, on the CrAlY(Ta) particle incorporation in the electrodeposited Ni-CrAlY(Ta) coatings were studied. The influence of particle geometry/shape was also investigated. Higher CrAlY particle incorporation was observed for the spherical gas-atomized particles than the ball-milled particles with irregular shapes.