Ion Selective Permeability of the Rust Layer on Fe-Co and Fe-Ni Low Alloy Steel

Corrosion resistance of designed different low alloy steel was evaluated for the purpose of the development of low alloy steel to use in the ocean beach part by the ion selective permeability of the rust that it is formed on the steel. The rust layer was formed on the two kinds of low alloy steel (Fe-Co, Fe-Ni alloy) by the corrosion cyclic examination which imitated the atmospheric corrosion environment. The form of a rust film was maintained and put so that both sides of a rust film might be next to the diffrerent KCl bath of the concentration, and the measurement of membrane potential between both rust surface side was done. The ion selective permeability of rust on low alloy steels was investigated by measurement of membrane potential. The rust layer on the carbon steel was anion selective. It was shown that changed cation selective permeability as a result of determining the membrane potential of the rust on Fe-1 mass%Co and Fe-3 mass%Co low alloy steel. The addition of a few %Co was sufficient to decrease the corrosion rate because the rust layer being cation selective was obstructed the invation of chloride. Anion permeability was shown from the fructification of the membrane potential measurement of the rust that it was formed on the Fe-3 mass%Ni, however, the corrosion rate of the Fe-Ni low alloy steel was decreased. The material characterization technique with the form of the rust maintained was established through this measurement, and it was effective in the characterization of the rust.