Plasma-sprayed nanostructured Al2O3/TiO2 powders and coatings

Air plasma spray has been used to produce metastable oxide-ceramic powders and coatings, starting with commercially available Al2O3/13TiO(2) powder fe ed. The feed material undergoes rapid melting and homogenization in the hig h-temperature zone of the plasma jet. A metastable x-Al2O3. TiO2 phase is f ormed when the molten droplets are quenched on a chilled substrate. The met astable phase has a defect spinel structure and a nanocrystalline grain siz e. When heated, it decomposes into an equilibrium two-phase structure, cons isting of alpha -Al2O3 and beta -Al2O3. TiO2. Both types of ceramic materia ls have potential as hard, wear-resistant coatings.