PLASMA SPRAYED Al2O3-13 wt. % TiO2 COATING SEALED WITH ORGANIC-INORGANIC HYBRID AGENT AND ITS CORROSION RESISTANCE IN ACID ENVIRONMENT

A novel organic-inorganic hybrid material of gamma-methacryloxypropyltrime-thoxysilane (KH570)-SiO2 was fabricated by Sol-Gel method. The hybrid material was used as the sealing agent for the plasma sprayed Al2O3-13 wt. % TiO2 coating. Infrared spectrum and grafted mechanism of the hybrid agent (HA) were studied. Moreover, morphology and porosity, as well as characteristics of immersion plus electrochemical corrosion in acid environment of the coating with and without sealing treatment were evaluated, compared with those of the coating sealed with the conventional silicone resin agent (SRA). The results reveal that KH570 was successfully grafted onto the surface of SiO2. The HA film sealed on the surface of the coating presents a little better quality than the SRA film. The porosities of the coatings after the sealing treatment decreased. Furthermore, the sealing treatment can improve efficiently the corrosion resistance of the coating in 5 vol. % HCl solution. The hybrid sealing agent can become a candidate for the plasma sprayed Al2O3-13 wt. % TiO2 coating used in acid environment to overcome some disadvantages of organic agents such as severely environmental pollution.