Abstract
A computer-aided interactive system for coating desing has been developed, which enables to analyze coveniently the reaction diffusion of bonded materials. The object of this study is the overlay coatings of MCrAlY alloy sprayed by a low-pressure-plasma spray (LPPS) process for protection against high-temperature corrosion and oxidation in the field of gas turbine components. However, the reaction diffusion behavior at the interface between the MCrAlY coating and the substrate, which has an important effect on coating degradation, has not been fully clarified. Four kinds of low-pressure-plasma sprayed MCrAlY alloys, namely CoCrAlY, NiCrAlY, CoNiCrAlY and NiCoCrAlY, and single-crystal CMSX-2 were selected for the experiments.
The experimental results showed that the reaction diffusion layers consisted of aluminum compound layer and low aluminum layer. In case of the NiCoCrAlY and CoNiCrAlY coatings, the aluminum compound layer could not be observed clearly. It was also indicated that each diffusion thickness could be expressed by the parabolic time dependence. The order of reaction diffusion rate was NiCrAlY>CoCrAlY>CoNiCrAlY>NiCoCrAlY. It was also clarified by the simulation analysis that the diffusion distance during heating process can not be ignored in comparison with the total diffusion distance, and the estimation of long time diffusion was made.
