Preparation and Thermal Conductivity of 7YSZ Thermal Barrier Coatings Prepared by Plasma Spray-physical Vapor Deposition

Abstract

The 7YSZ thermal barrier coating was prepared with three different process parameters by plasma spraying-physical vapor deposition(PS-PVD). The phase structure and microstructure of the coating were analyzed using XRD and SEM methods, and the thermal conductivity of coating was measured under different temperatures using laser pulse method. The results show that PS-PVD technology can prepare YSZ thermal barrier coating with different structures of columnar section,dense lamellar and column-particle mixed structure with surface "cauliflower" shape or undulating peaks by adjusting the process parameters, such as the current and plasma gas composition.Phase structure of 7YSZ coating is transformed from m-ZrO2 powder to t-ZrO2 coating in the process of preparation and stays in room temperature. The thermal conductivity of 7YSZ coating increases with the rising of temperature between 700-1100℃, the columnar crystal coating with higher porosity can effectively reduce the thermal conductivity of coating and the thermal conductivity is 1.0-1.2W·m-1·K-1; while layered crystal coating is dense with relatively higher thermal conductivity.

Keywords

• plasma spray-physical vapor deposition
• 7YSZ
• thermal barrier coating
• thermal conductivity