Evaluation of dry sliding and slurry erosion behaviour of plasma sprayed nanostructured Cr2O3–3TiO2 coatings

Abstract

Surface treatments and coatings are common practical approaches used to extend the lifetime of components and structures especially if the surface is the most solicited part of the considered engineering component. Plasma spraying is an established technique to produce thick ceramic coatings for protection against heat, corrosion and wear. In the present work, dry sliding and slurry erosion behaviour of plasma sprayed nanostructured Cr2O3–3TiO2 composite powder coatings (NC3T) have been evaluated. In addition to this, additional properties like porosity, hardness and adhesion strength were also evaluated. The results showed that the tribological performance of the coatings produced using the nanostructured Cr2O3/TiO2 powders is greatly improved compared with the coatings produced using the conventional Cr2O3/TiO2 powder (CC3T). The highest dry sliding wear resistance of the coating sprayed with nanostructured Cr2O3/TiO2 powder is ∼25·8% more than that of the coating sprayed with the conventional Cr2O3/TiO2 powder. Cumulative average weight loss was observed for recirculating slurry erosion testing done for 12 h using 30% concentrated SiO2 slurry, having particle size range of 50–75 μm for NC3T and CC3T is 6·4×10−3 and 4·0×10−3 g respectively. Similarly, erosion testing done using ∼50 μm sized SiO2 erosive resulted in the weight loss of the two coatings as 2·0×10−3 and 3·1×10−3 g for NC3T and CC3T respectively. Mechanism of wear and erosion of these coatings has also been evaluated based on their worn surface morphologies as observed using field emission scanning electron microscopy images. The results show that the conventional coating has lamellar stacking characteristics and has some pores. However, the nanostructured coating shows a bimodal microstructure, which is composed of both fully melted regions and partially melted regions.