Influence of Sealing Treatments with Ultrasonic Excitation on Corrosion Resistance of Plasma-sprayed Al₂O₃-13% TiO₂ Coatings

The corrosion resistance of plasma-sprayed Al2O3-13% TiO2(AT13) coating was studied before and after sealing with silicone resin, as sealing agent and using the technigues of conventional impregnating and ultrasonic excitation respectively, at different temperatures. The performance after different sealing treatments were studied by 10% HCl immersion testing and electrochemical testing. Morphology and products were analyzed by scanning electron microscopy (SEM) , optical microscopy (OM) and energy disperse spectroscopy(EDS). The results showed that sealing treatments of silicone resin reduced the porosity of plasma-sprayed AT13 coatings effectively. The porosity of coatings sealed at 60 ℃ with ultrasonic excitation decreased by 70.53% compared to the unsealed coatings. Sealing treatment with ultrasonic excitation was more effective than conventional impregnating sealing. Sealing treatment at 60 ℃ with ultrasonic excitation could prolong the service life and increase the corrosion potential by 30% compared to conventional impregnating sealing of coatings. And sealing treatment at 40 ℃ with ultrasonic excitation made the corrosion current decreased by 75% compared to conventional impregnating sealing of coatings. The sealing treatments with ultrasonic excitation reduced the corrosion rate and enhanced the corrosion resistance of ceramic coatings effectively.