The Surface Morphology, Mechanical Characteristics and Corrosion Resistance of Plasma Sprayed Titanium Dioxide Nanostructured Coatings

Abstract

Nanostructured titanium dioxide plasma sprayed coatings are the focus of attention because of their outstanding combination of properties. Most of the important information on their processing parameters and properties is proprietary and not reported. In this work, important information on mechanical properties, processing parameters and surface morphology combined with the new information arising out of the investigations on surface morphology, powder processing, corrosion and erosion studies is presented. The surface morphology and properties of nanostructured plasma sprayed coatings are high highly dependent upon critical spraying parameters. The surface morphology of nanostructured titanium dioxide coatings dictates their properties. The conventional titanium dioxide coatings showed a distinct layered structure and an uneven surface morphology compared to a more spherical morphology shown by nanostructured coatings. The nanostructured coatings showed a higher resistance to abrasion resistance, crack propagation and erosion resistance. The distribution of splats, intersplat spacing and volume of the fully melted zone and porosity controlled the properties as shown by scanning electronic microscopy and atomic force microscopy. The nanostructured coatings exhibited a high resistance to corrosion in 3.5% NaCl. Powder processing showed a significant effect on corrosion and erosion corrosion. Coatings employing densified powders showed a higher resistance to erosion corrosion than sintered and dried powders. The erosion corrosion resistance of nanostructured titanium dioxide coatings was controlled by surface morphology. Lower spraying temperatures favored increase photocatalytic activity