Research of Anti-Corrosion of Armour Steel in Surface Chromate Conversion Coating

摘要

This article by orthogonal experimental method to determine the composition of chromate conversion and use of electrochemical method of electrochemical corrosion of the film discussed the substrate in different components, content, time and pH of chromate conversion coating of corrosion resistance. Orthogonal to determine the best experimental chromate conversion solution by adding the rare earth element cerium and lanthanum salt, and discuss the effects of rare earth elements cerium and lanthanum chromate conversion film on the anti-corrosion. The results show that in CrO_3 5.4 g/L, NaF 0.5 g/L, K_3Fe(CN)_6 0.5 g/L, pH 1, conversion time is three minutes, there is a better corrosion resistance. The rare earth elements in a chromate conversion solution, La_2(CO_3)_3 to 0.2 g/L chromate conversion coating of the anti-corrosion better. The corrosion of armous steels is a significant problem, which can result in the service life and severe results in war. It is noted that chromate conversion coatings on armous steels are very effective in protecting against corrosion and improving the capability of anti-corrosion. It is due to the effect of Cr~(6+) component in CCC processing chemistry. However, the high toxicity effect of Cr~(6+) has resulted in increasingly strict regulations because of its usage and waste disposal. The trend was to develop environmentally friendly, alternative coating, but few have been able to better the properties of CCCS. So people thought the additives of rare earth elements in chromate may be a good choice. The studies on the additives of rare earth elements in chromate conversion coatings have been began from 1980's and it has a rapid development until now. Recently, YU etc. thought the rare earth conversion coating have a better anti-corrosion property in LY12Al alloy. Wang etc. showed a well results about the Zinc coating when the additives of rare earth elements in solution. Fang etc. have also gained achieved the yellow rare earth conversion coating using additive of Ce element and improved the surface anti-corrosion properties of the experimental steel. In practice, the applications of the additives of rare earth elements in CCCS have some advantages than others, such as a lower temperatures, lower electric consumption, lower cost, lower contamination and higher quality, higher stabilization, higher efficiency. It was a new processing which can result in great economic and social benefits. However, many phenomena have not yet to be clarified. The present paper was to focus on the influences of the additive of rare earth elements in chromate, such as Ce and La, on the anti-corrosion properties of armous steels. The main motivation was to improve the anti-corrosion and service life of ramous steels.