Adhesion of plasma sprayed Al2O3–TiO2 layer at high temperatures

Abstract

Three kinds of alumina–titania powder mixtures were produced by various manufacturing methods. The powderswere plasma sprayed on to grit blasted coppersubstrates. The plasma sprayed layers were investigated by thermal cycling from 1073 K to room temperature. Adhesion was evaluated by peeling tests in highfrequency vibration. Thepowders and sprayed layers were examined using scanning electron microscopy and optical microscopy to evaluate adhesion between the sprayed layers and substrates. The highest adhesion was obtained from the layers sprayed with clad alumina powder surrounded by titania on to a copper substrate which had been blasted with mixed grits 0·3–2·5 mm in size. These layers are less than 20 11mthick and contain several microcracks at about 10 11mintervals.