Earth Inhibitor Anti-corrosion Of Carbon Steel Research

Recently, people are getting concerned with the the loss and danger caused by the corrosion of the metal, especially by that of the carbon steel.As an effective way to inhibit the corrosion of the metal, inhibitor has been widely used in the industry The inhibitors that have been widely used fall under the categories of chromate, mercurate, nitrite and alkynol, however, they can impose direct danger on the people and the environment.The research and the development of the environment-friendly rare earth inhibitor, which has no danger to the human body, has become an important specialized filed of the inhibitor over the recent years.Some relative researches on the rare earth inhibitor has made some achievements, nevertheless, most of which are confided with the application to the aluminium alloy and the magnesium alloy, and the research on the carbon steel corrosion is not enough; As the pure rare earth, when used as the inhibitor, requires a large amount and the effect is not that stable, therefore, this paper tries to adopt light rare earth salt and compound other inhibitor so as to optimize the rare earth inhibitor used for the research on the carbon steel corrosion. The paper has made some achievements in this field.This paper has adopted three kinds of light rare earth salt that have sequential atomic number, they are lanthanum nitrate, cerium nitrate, and praseodymium nitrate, then, this paper compound them respectively with the environment-friendly inhibitor-sodium molybdate and get the system of three kinds of rare earth inhibitor. By weight loss method and by the combination of the macro-morphology observation and the electrochemical test, this paper has made the research on the corrosion inhibition performance of the different kinds of the rare earth inhibitoras and has evaluated and analyzed the corrosion inhibition efficiency, and has found that the sequential order of the efficiency of the three inhibitor is as followed:Ce> La>Pr, among which, the inhibition efficiency of the inhibitor compounded by the cerium nitrate and sodium molybdate to the carbon steel can reach 98.21%. This paper discovered that after added the rare earth inhibitor, the precipitation film forming on the surface of the samples exert an important influence on the inhibition efficiency of the rare earth inhibitor, and the precipitation film of the three rare earth have shown certain regularity from the appearance to the material formation. This paper conducted the SEM observation on the corrosion inhibition product forming on the surface of the samples and found that this film layer is not only uneven but with some spherical particles;when analyzing the ingredients of the film by XRD, this paper uncovered that the ingredients are mostly the oxide of the rare earth and the hydroxide, as well as some amorphous substance; When conducting the comparative analysis of the film elements by EDS and XPS, this paper also found that there exists the difference of the element distribution and content of the even part of the film and the particles on the film. Finally, this paper also explored the mechanism of the rare earth inhibitor, discovering that the electronic configuration of the rare earth element exerted, to a certain extent, an important influence on the effect of the inhibition efficiency.