Growth and Repair of Rare Earth Oxide Films for Corrosion Protection on the Surface of Stone Cutting Tools

This paper focuses on analyzing the corrosion mechanism of stone cutting tool surfaces. Rare earth oxide films were prepared on the tool surface using the electrophoretic deposition–sintering method, and their corrosion resistance was investigated. Microstructural and compositional analyses of the surface layer of shot-peened tools and rare earth oxide films were conducted using characterization techniques such as SEM, EBSD, and XRD. The corrosion resistance of the rare earth oxide films was evaluated via an electrochemical workstation. The results indicate that the corrosion morphology on the stone cutting tool surface is pitting corrosion, which is significantly influenced by the friction of the tool coolant. Shot-peening treatment refines the grains in the tool surface layer, promoting the growth of rare earth oxide films. The rare earth oxide film is mainly composed of cerium oxide (CeO2), presenting a continuous and dense structure with slight peeling after sintering. The Group 3 (0.1 mol/L, 3000 V/m, 5 min) rare earth oxide film exhibits the optimal electrochemical behavior and excellent corrosion resistance, with a corrosion potential (Ecorr) of −0.49 V and a corrosion current density (icorr) of 1.445 × 10−7 A/cm2.