Tailoring the Spray Conditions for Suspension Plasma Spraying

In this study, a wide range of suspension plasma spraying conditions are used to produce YSZ coatings for intended use in liquid gas engines. To meet specifications, the coatings must exhibit a homogeneous microstructure with no vertical cracks or columns, low surface roughness, and low thermal conductivity. The properties of the plasma jet (velocity, enthalpy, stability), droplets (trajectory, number, size), and particles (velocity) were measured during spray trials and are correlated with coating microstructure. Suspension plasma spraying conditions necessary for depositing disk-shaped splats and achieving finely structured coatings with no stacking defects are described along with substrate cooling requirements.