Investigate the corrosion properties of stellite coated on AZ91D alloy by plasma spray technique

Abstract

Stellite alloys are primarily preferred in various component manufacturing industries due to its magnificent mechanical and electrochemical properties. The stellite powder is deposited over the materials by various thermal spray methods in industries. This research proposed investigating the microstructure and corrosion properties of stellite powder that is deposited on an AZ91D magnesium alloy substrate by atmospheric plasma spraying process. The SEM, optical microscopy, and atomic force microscopy are typical of the coatings. Immersion experiments in sodium chloride conditions are conducted at varying pH levels, chloride ion concentration, and exposure time. In addition, XRD examined the phase change properties of the powder and sprayed condition of coatings along with corrosion testing. The corrosion experiments were conducted to establish several regression models based on the central composite design and the response sur-face process. The accuracy of the regression models was sufficient to allow correlations between input parameters and responses through variance analysis. It was found that the pH value significantly influences the corrosion behaviour of stellite coatings followed by other parameters such as chloride ion concentration and exposure time, even in corrosion tests, plasma-sprayed coatings performed better.