PS-PVD deposition of thermal barrier coatings

In this study, the influence of the deposition parameters on the coating structure during the ‘quasi-PVD’ process was investigated. This type of coating could be deposited at powder feed rates between 10 and 20 g/min using He/Ar plasma gasses. The microstructure of the ceramic coating obtained using these parameters is unique because the evaporation of the ceramic powder was not complete. The deposition was conducted by the LPPS-Hybrid system produced by Sulzer Metco. Rene 80 nickel superalloy was used as a base material. A Zr-modified aluminide coating deposited by the CVD (Chemical Deposition) method, and a MeCrAlY coating deposited by the APS (Air Plasma Spraying) method were used as bond coats. Metco 6700 yttria-stabilized zirconia powder was used as a coating material. An increase in the coating thickness was triggered by increasing the powder feed rate. The pressure inside the working chamber exercised a strong influence on the structure and thickness of the coatings. In coatings deposited under a pressure of 200 Pa, unevaporated powder particles were observed along with a significantly lower thickness. The same effect was rendered by decreasing the power current of the plasma gun to 1800 A. The PS-PVD method provides an alternative process to APS and EB-PVD (Electron Beam Physical Vapor Deposition) technologies.