PS-PVD gadolinium zirconate thermal barrier coatings with columnar microstructure sprayed from sintered powder feedstocks

The characteristics of powder feedstock are very critical in the plasma spray physical vapor deposition (PS-PVD) process to produce columnar structured ceramic coatings. In this study, gadolinium zirconate (GZO) powder feedstocks for PS-PVD process were prepared by solid-state reactions and spray drying. Initially, the GZO coating sprayed from the as-prepared powder revealed a low deposition rate of similar to 4 mu m.min(-1) because the powder couldn't reach to the hottest zone of the plasma plume due to the weak binding between the primary particles. Therefore, heat treatment of the powder was performed at temperatures between 1000 degrees C and 1300 degrees C to enhance the binding strength and the powder after 1 h heat treatment at 1200 degrees C exhibited a moderate improved binding strength. The coating sprayed from the sintered powder showed a typical columnar structure and nearly stoichiometric composition as well as a deposition rate of 24 mu m.min(-1).