Suspension sprayed YSZ thermal barrier coatings: on the road to industrial application

Thermal barrier coatings (TBCs) are one of the most promising applications for suspension thermal spraying. By using a liquid feedstock, coating morphologies close to the columnar-like structure of Electron-Beam Physical Vapor Deposition (EB-PVD) are possible. Additionally, vertically cracked TBC coatings (VC-TBC) have shown a great potential for industrial applications. In this work, we will analyze the process window for TBCs produced by using suspension spraying. Commercially available alcohol- and water-based YSZ suspensions have been processed using atmospheric plasma spraying (S-APS) and high-velocity oxy-fuel (S-HVOF) to achieve both columnar-like and VC morphologies. The coatings have been analyzed and compared in terms of microstructure, phase composition, bond strength and thermal cycling performance. Additionally, the suitability of S-APS and S-HVOF TBCs for industrial applications will be discussed, as well as which actions are needed to increase its competitiveness.