Influence of Substrate and Coating Temperature on Columnar Growth within Plasma Sprayed Zirconia and Alumina Coatings

The temperature within plasma-sprayed oxide coatings depends strongly on the cooling devices used during spraying as well as on coating pass thickness and powder flow rate. Two oxides, alumina and zirconia, were deposited using dc Ar-H₂ plasma jets and the shape, size, and composition of the columnar structures produced were examined and found to correspond with substrate and coating surface temperatures as measured during and after spraying. The relationship between temperature and thermomechanical properties was also investigated and the results are reported in the paper.