Stripping process of TiAlN/TiSiN coating on WC-Co cemented carbide substrate by using the dry-electropolishing technique

Abstract

Physical Vapor Deposition hard protective coatings are frequently applied to hardmetal cutting tools to extend their lifespan under service-like working conditions. However, these coatings may experience damage during their performance, such as wear. In addition, defective coatings during the production process can occur, requiring reconditioning. In this sense, provided that the coating has not chipped off, removing and recoating the tools is a crucial process for their reuse, ultimately reducing costs. This study investigates the stripping process of an industrial ternary system (TiAlN/TiSiN) coating deposited on WC-Co cemented carbide using the dry-electropolishing technique. X-ray photoelectron spectroscopy was used to analyze the electrochemical surface changes. Chemical analysis reveals that a layer of oxide is created during the stripping process, mainly composed of SiO2, TiO2, and Al2O3, as well as organic compounds (e.g.: pyrrodic group in aromatics C-(NH)-C) and nitrogen oxides (e.g.: pyrinidic O=N-C). The stripping process successfully removed the coating without damaging the WC-Co substrate or leaching metallic Co binder. Additionally, the process follows a linear trend, establishing a correlation between the time of dry-electropolishing applied and the remaining coating thickness.