Influence of 13 wt% TiO2 content in alumina-titania powders on microstructure, sliding wear and cavitation erosion resistance of APS sprayed coatings

Abstract

Abstract This paper discusses the influence of using 13 wt% of TiO2 addition to Al2O3 powder and selection of plasma spray parameters on morphology, microstructure, phase composition, mechanical properties, and, particularly, tribological behaviour and cavitation erosion performance of produced coatings. Two types of powders were used to spray the coatings by means of atmospheric plasma spraying (APS): Al2O3 (AT0) and Al2O3 + 13 wt% TiO2 (AT13). The stand-off distance and torch scan speed were two spray parameters considered in this work. The aim of the study was to investigate how the addition of titania to alumina in agglomerated and sintered nanostructured powders could improve the coating microstructure and functional properties. The results demonstrated that addition of TiO2 in the powder provides denser microstructure of the coating, improves the contact between splats, prevents the coating from severe fragmentation and spallation during wear, and prolongs the cavitation lifetime. In general, AT0 coatings exhibit slightly better wear resistance than AT13 equivalents. On the other hand, it was found that AT13 coatings present superior cavitation erosion resistance when compared with AT0.