Phase Formation and Properties of 60/40 Alumina-YSZ Nano-Composite Coating Deposited by Suspension Plasma Spray Process

Suspension Plasma Spray (SPS) process is used for deposition of eutectic composition of Alumina-Yittria Stabilized Zirconia composite as a potential thermal barrier coating. Variables including feed, process and substrate related parameters were altered to find the key spray parameters on phase formation in each component of the composite coating including Alumina and Stabilized Zirconia. The most significant variable was recognized to be the plasma auxiliary gas. This variable rules the formation of the crystalline/non-crystalline phases by affecting the resulting in-flight particle state, especially the particle velocity. In this work also the mechanical properties were revealed to be a function of particle velocity. Thermal changes of the composite coating were studied based on differential thermal analyses as well as heat treatment results.