INFLUENCE OF ULTRASONIC SEALING TREATMENT WITH ALUMINUM PHOSPHATE ON PROPERTIES OF Al2O3–TiO2 PLASMA SPRAYED CERAMIC COATING

Recently, the plasma sprayed ceramic Al₂O₃-TiO₂ coating has been considered as an effective measure for protection against corrosion and abrasion, due to its high hardness, strong wear resistance and excellent durability. However, its inherent porosity might greatly affect the protective performance. This study focused on the effectiveness evaluation of sealing of the as-sprayed Al₂O₃-40TiO₂ ceramic coating by using aluminum phosphate solution under various conditions, with or without the presence of ultra-sonication (20-40 KHz). The effect of various permeability conditions on the microstructure, anti-corrosion and erosion properties of the coating were investigated, using SEM/EDX analysis, potentiodynamic polarization and electrochemical impedance spectroscopy. The obtained experimental data indicated that the optimal permeability condition, under 30 KHz ultra-sonication during 3 hours provided both the best corrosion protection and the highest erosion resistance.