HOMOGENEITY STUDIES OF POWDERS AND PLASMA-SPRAYED DEPOSITS

For production of plasma sprayed protective deposits and self-standing ceramic parts many different feedstock powders are used. The powders are very often of a composite type prepared by various technologies and mostly chemically very inhomogeneous. A method has been developed for evaluation of chemical homogeneity of both, the feedstock powders and the sprayed materials. The backscattered electron images along with the element mapping of dopant have been used as the basic measurement. The homogeneity coefficients were determined by quantitative point analysis with ZAF corrections. The results show that under all spraying parameters there is always a certain redistribution of all species leading to a better homogeneity. But generally, the more homogeneous the feedstock powder, the better the homogeneity of the deposits on both micro and macro scale.