Assessment on thermally sprayed ceramic coatings with CNT nanoparticles

Abstract

ABSTRACT Thermally sprayed ceramic coatings with carbon nanotubes (CNTs) reinforcement in three different weight percentage proportions (1%, 3%, and 5%) were investigated to evaluate their characteristics. The coatings of alumina-titania (Al2O3-3 wt% TiO2), tungsten carbide-cobalt (WC-12 wt% Co), and yttria-stabilised zirconia (ZrO2-8 wt% Y2O3) were deposited using air plasma spraying (APS). The dispersion of CNTs in the coatings’ microstructure and the quality of the coatings in terms of porosity, bond strength, and corrosion resistance were investigated. The thickness of the coatings was also measured. Characterisation techniques such as optical microscopy, scanning electron microscopy, image analysis, bond strength testing, and corrosion analysis were used to study various characteristics of the coatings. The maximum porosity was found in WC-12 wt% Co and ZrO2-8 wt% Y2O3 coatings. The presence of CNTs in the coatings was confirmed through X-ray diffraction analysis. The bond strength of the WC-12 wt% Co coatings was found to be higher than that of the alumina-titania and yttria-stabilised zirconia coatings. Furthermore, the corrosion analysis revealed that alumina-titania coatings have higher corrosion resistance with a passive film when exposed to NaCl solution and better life as compared to WC-12 wt% Co coatings.