Effect Of Tio2 On The Microstructure And Phase Composition Of Al2o3 And Al2o3-Tio2 Aps Sprayed Coatings

Plasma sprayed ceramic coatings serve as protective layers and are frequently exposed to aggressive wear, corrosion, or high-temperature environment. Currently, alumina and alumina-titania are some of the most popular protective ceramic composite coatings used in the industry. The present work deals with the investigation of the influence of TiO2 content in the feedstock powder on the resulting microstructure and properties of Al2O3, Al2O3 + 3 wt% TiO2, Al2O3 + 13 wt% TiO2 and Al2O3 + 40 wt% TiO2 coatings developed via atmospheric plasma spraying (APS). Specifically, the phase composition, morphology, and microstructure, as well as the mechanical and tribological performance of the coatings were examined. Results revealed that higher content of TiO2 induced the transformation of phases, leading to the formation of intermediary Al2TiO5 and Al2-xTi1-xO5 phases. Also, the dominant alpha-Al2O3 to gamma-Al2O3 transformation confirmed the formulation of well-melted lamellas within the coating structure. It was also shown that the increase in TiO2 content decreased the micro-hardness of the coatings due to the formation of the intermediary phases as mentioned above and thus, affected their tribological performance. The lowest volumetric wear, equal to 7.2x10(-5) mm(3)/(N . m), was reported for Al2O3 + 13 wt% TiO2 coating.