The protective and adhesion properties of silicone-epoxy hybrid coatings on 2024 Al-alloy with a silane film as pretreatment

The electrochemical and water transport properties of silicone-epoxy coatings on Al-alloy pretreated with silane films are investigated in NaCl solution. The results show the non-continuity of water concentration at the interface of silane film and silicone-epoxy coating. The silane film as pretreatment provides enhanced barrier properties and excellent corrosion protection. Considering water concentration jump on the silane film/silicone-epoxy boundary, diffusion coefficient of the coating obtained by validation model is similar to that obtained from the experimental method. In addition, relative to the other three coating systems, the best adhesion is maintained for the silicone-epoxy/silane film (pH 3.5)/Al-alloy system.