Research on Optimising Thermal Barrier Coating Removal Processes Based on Plasma Electrolysis Technology

The efficient removal of failed yttria-stabilized zirconia (YSZ) thermal barrier coatings from GH4169 superalloy substrates is crucial for aero-engine maintenance. This study investigates the application of plasma electrolytic technology for YSZ coating removal, systematically examining the effects of key process parameters. Through a three-factor, five-level orthogonal experimental design, the influence of working voltage, solution temperature, and processing time on coating removal effectiveness was analyzed using range analysis. The results demonstrated that solution temperature exerted the most significant effect on coating removal rate, followed by working voltage, with processing time showing the least influence. The optimal parameter combination was determined as 265 V working voltage, 50 °C solution temperature, and 120 s processing time, achieving a maximum coating removal rate of 92.36%. The underlying mechanisms were elucidated through detailed characterization: at 250 V, micro-arc discharge enabled effective coating removal through combined physical bombardment and electrochemical dissolution, while at 300 V, arc discharge caused substrate damage with crater formation. Solution temperature critically affected process stability through its regulation of vapor-gaseous envelope characteristics and current behavior. Verification experiments confirmed that the optimized parameters achieved complete coating removal without substrate damage, preserving surface integrity for subsequent recoating processes. This research provides both theoretical foundation and practical parameters for plasma electrolytic removal of YSZ coatings on hot-section components.