Effective parameters on microstructure and properties of EB-PVD NiCrAlY coating

This study has been conducted to evaluate the influence of temperature and substrate roughness on microstructure and properties of electron beam physical vapour deposition NiCrAlY coating. The chemical composition was adjusted by continuous feeding in the molten pool. The results show that the coating roughness generally increased with an increase in the substrate roughness and decrease in its temperature. However, in rough substrates, coating roughness were lower than that of the substrates, and in samples with a lower substrate roughness, coatings had a greater roughness level in comparison with their corresponding substrates. The polished samples with the lowest level of substrate roughness had narrower columns, and by an increase in the roughness of the substrate, the columns became thicker. The optimised conditions in terms of microstructure and adhesion strength were observed in the sample with the roughness level of R-a=0.02 mu m and the homologous temperature of theta=0.44.