Dependence of microstructure and thermal conductivity of EB-PVD thermal barrier coatings on the substrate rotation speed

EB-PVD TBCs were deposited at nearly the same process parameters but substrate rotation speed to investigate the effect of rotation adjustment on microstructure and thermal conductivity. The microstructure was checked by scanning electron microscopy (SEM) and the thermal conductivity was calculated on the basis of determination of thermal diffusivity by laser flash method. The results showed the stationary deposition formed most dense coating and increasing rotation speed resulted in wider columnar grains and enlarged shadowing effect which meant much more volume of pores. The density and thermal conductivity at room temperature both decreased with increasing rotation speed. The lowest experimental value, 1.37 W/mK, was obtained for a 171 μm thick free-standing coating, when the rotation speed was 20 rpm in this study.