Microstructure and tribological properties of nanostructured and conventional plasma sprayed alumina-titania coatings

The nanostructured and two conventional alumina-titania coatings were deposited by atmospheric plasma spray. The presented studies show that nanoparticles are the predominant component of nanostructured Al2O3-13TiO(2) powder grains. The microstructure of coating consisted of two distinct regions: fully melted and unmelted or partially melted nanostructured areas, which were comprised of components of a starting powder. Microhardness and modulus of these coatings were significantly lower than the values obtained for nanostructured coating. It was found that the plasma-sprayed nanostructured Al2O3-13TiO(2) coating possessed better tribological properties than those of conventional alumina-titania coatings. The lower coefficient of friction and wear of the nanostructured Al2O3-13TiO(2) coating is attributed to the bimodal microstructure and the enhanced mechanical properties in comparison to conventional alumina-titania coatings. (C) 2014 Elsevier B.V. All rights reserved.