Effect Of Powder Characteristics-On Phase Transformation In Plasma Sprayed Alumina-13 Wt.% Titania Coatings

Commercially available alumina and titania powders were, spray dried to obtain three different powders (A, B and C) with the composition Al2O3/13 wt.% TiO2 but with different size distributions of coarse and fine particles. These powders were plasma sprayed under similar conditions to obtain powders with a two-phase structure. comprising of alpha-alumina: and a metastable chi-Al2O3.TiO2 phase. The ratio of alpha-alumina phase to metastable chi-Al2O3.TiO2 phase was higher for the powders with larger alumina particles. The relative ratios of these phases could be maintained if these powders are coated using a lower enthalpy I thermal spray process. This may result in coatings. that hay-e sufficient wear resistance (obtained form the hard alpha-alumina, phase)and sufficient strength (obtained from the metastable chi-Al2O3.TiO2 phase).