Effect of atmospheric plasma sprayed TiO2–10% NiAl cermet coating thickness on cavitation erosion, sliding and abrasive wear resistance

Abstract

Atmospheric plasma spray (APS) wear-resistant coatings are popular in mechanical designing for increasing the operation time of machine elements. APS enables the deposition of ceramic, metallic, and cermet coatings to ameliorate the effects of wear that cause most of the failures of machine elements. The aim of the paper was to investigate the influence of the coating thickness of TiO2–10 wt% NiAl on abrasive, sliding, and cavitation erosion resistance. Titania based coatings were deposited by means of APS onto a mild steel substrate using TiO2–10 wt% NiAl feedstock material. The coatings had thicknesses of approximately 50, 100, and 200 µm. The morphology and microstructure of the coatings were examined using a light optical microscope (LOM) and scanning electron microscope (SEM). The as-deposited surface topography and hardness of the coatings were determined. The porosity and thickness were evaluated by using quantities image analysis software. Cavitation erosion tests were performed according to ASTM G32 (vibratory apparatus) and ASTM G134 (cavitating liquid jet). Abrasive and sliding wear tests were conducted using a three body abrasive tester and ball-on-disc apparatus, respectively. Generally the thickest coating presents an increase in resistance to sliding wear and cavitation erosion over the thinnest cermet coating.