Wear and corrosion resistance of Cr2O3%-40%TiO2 coating on gray cast-iron by plasma spray technique

Abstract

In this study, lamellar graphite cast iron was coated with atmospheric plasma spraying (APS) technique. Cr2O3-40%TiO2 ceramic composite powder was used as a coating powder. The microstructure and mechanical properties of cast iron and coating were assessed. The new coating surfaces were analyzed by optical microscope (LM), scanning electron microscope (SEM) and energy dispersive x-ray spectroscopy (EDS). Micro-hardness tests were carried out with 200 g load (Wolpert micro hardness device). Wear tests were performed with a reciprocating wear test device under normal atmospheric conditions (room temperature and 30% humidity) while corrosion tests were performed in a glass cell according to ASTM standards (G1-03, G5-94) in three electrode techniques at room temperature in 3.5% NaCl solution. The results show that the coating microstructure is porous, micro-cracked and contains some non-homogenous structures such as oxide. Based on the EDS analysis, the presence of the existing phases revealed that the coating process was successful. In addition, the presence of hard particles in the coated surface layer increased the hardness of the composite coating compared to that of cast iron. Accordingly, the wear resistance was also high. The Cr2O3-40%TiO2 coating showed an improved corrosion resistance compared to the uncoated cast iron sample.