Simulated Brackish Water Copper Corrosion Behavior

Weight loss, electrochemical and surface analysis methods were employed to study the corrosion behavior of copper in the solution of NaCl, NaHCO3, Na2S04 and their interactions. Furthermore, the present paper investigated the influence of the temperature, pH, Cl-, HCO3-, SO42-, Mg2+ and the inhibitor HS-99 on the corrosion behavior of copper in the bitter and brackish solution. The experimental results are as follows:Cl-, HCO3- and S042- were all active invasive anions to copper and induced the pitting corrosion of copper. When the concentration of Cl" surpassed 0.05 mol/L, it was advantageous to inducing the pitting corrosion, but inhibited the extension of the pitting corrosion, with the uniform corrosion being predominant. It tended to induce the pitting corrosion of copper under the low concentration of HC03-; when [HCO3-]> 0.05 mol/L, no pitting corrosion happened to copper that was at the state of passivation, while the invasive effect of HCO3- did not abate. Copper tended to produce pitting corrosion when [SO42-] 0. 02 mol/L. The development of pitting corrosion of copper was inhibi ted with the increase of [SO,2"]. The tendency of copper corrosion increased as the temperature rising. Copper presented uniform corrosion in the weak acid solution, the tendency decreasing with the value of pH downing. Copper was easily induced to pitting corrosion in weak alkaline solution, while in the strong alkaline solution no pitting corrosion happened to copper for it was at the state of passivation.In the bitter and brackish solution, Cl" was the most invasive ion prompting the general corrosion of copper; SO42- and HCO3- presented certain prohibiting effect on the corrosion of copper. Although the above three ions all could induce the pitting of copper, Mg2+ was the decisive fact of the development of pitting corrosion in the present studying solution. As a new kind inhibitor, HS-99 had good inhibiting effect on the corrosion of copper in the bitter and brackish solution. The occurrence of pitting of copper was prohibited when the applied potential was lower than 0. 4V. The inhibiting effect of HS-99 on copper was better than that of traditional copper inhibitor BTA and TTA.