Acta Phys. -Chim. Sin. ›› 2012, Vol. 28 ›› Issue (05): 1153-1162.doi: 10.3866/PKU.WHXB201203022

• ELECTROCHEMISTRY AND NEW ENERGY • Previous Articles     Next Articles

Effect of Rust Layer on the Corrosion Behavior of Carbon Steel in Reverse Osmosis Product Water

HU Jia-Yuan1, CAO Shun-An1, XIE Jian-Li2   

  1. 1. College of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, P. R. China;
    2. Suzhou Nuclear Power Research Institute, Suzhou 215004, Jiangsu Province, P. R. China
  • Received:2012-01-15 Revised:2012-02-29 Published:2012-04-26
  • Contact: HU Jia-Yuan
  • Supported by:

    The project was supported by the Fundamental Research Funds for the Central Universities, China (20102080101000090).

Abstract: The morphologies and electrochemical characteristics of rust layers generated in seawater and reverse osmosis (RO) product water were investigated by scanning electron microscopy (SEM), infrared spectroscopy (IR), X-ray diffraction (XRD) and electrochemical tests. Experimental results revealed obvious differences in the components, structures and functions of rust layers in two types of solutions, so that the corrosion rates of carbon steel were markedly different. The reduction potential of γ-FeOOH is higher than the corrosion potential of carbon steel in RO product water, such that γ-FeOOH is easily reduced to Fe3O4 and two layers emerge in the rust structures. The outer layer (γ-FeOOH layer) is too thin to inhibit oxygen diffusion, and tends to accelerate the cathodic process via reduction of γ-FeOOH. Because Fe2 + and electrons can pass through the Fe3O4 layer, oxygen can be directly reduced on the surface of the inner layer (Fe3O4 layer). Therefore, the inner rust layer (Fe3O4 layer) can provide a large cathode area on which to promote oxygen reduction. As a result, the corrosion process of carbon steel in RO product water can be accelerated greatly. The corrosion rate of carbon steel is determined by the limiting diffusion rate of oxygen from solution to the inner rust layer. Anti-corrosion measures should inhibit the reduction reaction of γ-FeOOH.

Key words: Rust layer, Seawater, RO product water, Electrochemical behavior, Corrosion mechanism, Anti-corrosion


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