Highly Dense Ceramic Coatings Produced with Axial Suspension Plasma Spraying

Suspension plasma spraying is a relatively new technique to produce coatings with a variety of unique microstructures and is gaining greater interest in emerging applications. Dense ceramic coatings are required for emerging applications such as solid oxide fuel cells, plasma erosion resistant coatings, and new thermal barrier coatings. These applications present challenges for traditional plasma spraying, while suspension plasma spraying presents significant advantages. Suspension plasma spraying using submicron or even nano powders produces denser coatings with finer lamellae splats when compared to traditionally sized thermal spray powders. This paper presents the approach to enable dense coatings by using axial plasma and an automatic liquid feed system. A robust suspension coating process is demonstrated by the production of dense Al2O3 and Y2O3 coatings primarily for plasma erosion resistance applications.