The EIS Study Of Corrosion Behavior Of Epoxy And Zinc-rich Composite Coatings Under A Few Corrosion Environments

The effect of pressure, surface pretreatment, salt pray, oxygenous environment on epoxy and zinc-rich compound coating was studied by EIS. The electrochemistry parameter of coating, coating porosity and the rate of water transmission were got, and then concluded the law of change with the environment. The main concludes showed that:1. The influence of press to the protection performance of inorganic zinc-rich compound coating, epoxy anti-rust coating, solventless epoxy resin coating in 3.5%NaCl was studied. The results showed that: with the higher of the solution pressure, the corrosive production of inorganic zinc-rich compound coating and epoxy anti-rust coating could not leading out successfully, so the small opening was blockaded and the form rate of corrosive production was reduced. The remissive expand pressure lead the decrease of the coating porosity.2. The effect of surface pretreatment on the protection performance of modified epoxy anti-rust coating and glass-flake epoxy coating was researched. When the metal was pretreated to rank Sa2.5, the coating resistance was higher than 10⁸Ω·cm². Then, with the reduce of the rank, the coating resistance decreased to 10⁵Ω·cm² at the rank St2. The coating porosity on rank St2 metal was more than others (higher than 10^-4).3. The corrosive electrochemical behaviors of watercraft inorganic zinc-rich compound coating, imbricate inorganic zinc-rich compound coating, solventless epoxy resin coating in salt spray or immersion environment was studied. The results showed that: in the salt spray environment watercraft inorganic zinc-rich compound coating and imbricate inorganic zinc-rich compound coating had better protection performance, the coating resistance was higher than 10⁸Ω·cm²; in the immersion environment the protection performance decreased rapidly, and the coating resistance was lower than 10⁵Ω·cm².4. The protection performance of epoxy zinc-rich coating and epoxy coating corroded in different oxygenous environment was studied. With the amount of oxygen raised, the protection performance came down. The coating resistance was 10⁸Ω·cm² in the 0.1 MPa natural oxygenous environment, and then decreased to 10⁵Ω·cm² in the 3.0MPa pressured oxygenous environment.