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64 NOVEMBER 2017 MATERIALS PERFORMANCE NACE INTERNATIONAL: VOL. 56, NO. 11 MATERIALS SELECTION & DESIGN A The effects of chloride (Cl – ), sulfate (SO 4 2– ), and carbonate (CO 3 2– ) ions on the crevice corrosion behavior of cop- per were examined. The results indi- cated that chloride and sulfate ions increase crevice corrosion of copper, while the presence of carbonate re- duces crevice corrosion. Sulfate ions promoted crevice corrosion, and high concentrations of chloride ions pro- moted matrix dissolution of the crev- ice exterior. Anions play an important role in local- ized corrosion. The role of water chemistry in localized copper corrosion has been analyzed by many investigators, 1-6 and contradictory results exist regarding the effect of anions on localized corrosion. It was found that chloride (Cl – ) and sulfate (SO 4 2– ) ions may promote pitting corrosion and af fect the pitting susceptibility of copper ; 1-4 however, a negative effect caused by Cl – on the development of pitting corro- sion also was reported. 5 Other research suggested that bicarbonate (HCO 3 – ) or carbonate (CO 3 2– ) ions could cause surface passivation of copper and reduce pitting corrosion, 2,4-5 but pitting corrosion induced by HCO 3 – or CO 3 2– also was described in some literature. 2,6-7 Most studies reported the inf luence of anions on pitting corro- sion. Very little work has been published on the effect of specific anions (e.g., Cl – , SO 4 2– , HCO 3 – , or CO 3 2– ) on the crevice corrosion of copper in groundwater. In the present work, the crevice corro- sion of copper was investigated under aer- ated and high-temperature conditions in solutions containing varying concentra- tions of sodium chloride (NaCl), sodium sulfate (Na 2 SO 4 ), and sodium carbonate (Na 2 CO 3 ). Experimental Procedure The material used in this study was pure copper (>99.9%). Each sample was machined to 20 by 20 by 3 mm. The surface of the sam- ple was mechanically polished using SiC paper, progressively, up to 150 grit. After dry- ing in hot air, the sample was weighed and then stored in a desiccator. The crevice cor- rosion experiments were conducted accord- ing to the procedure described in literature. 8 Specimens were clamped using two poly - tetrafluoroethylene (PTFE) cylinders, and then bundled using a low-sulfur rubber ring. The dimensions of the cylinders were 25-mm long and 13 mm in diameter. The concentrations of Cl – , SO 4 2– , and CO 3 2– in the groundwater were 0.034, 0.012, and 0.0023 mol/L, respectively. The experi- ments were conducted in electrolytes con- taining var ying concentrations of NaCl, Na 2 SO 4 , and Na 2 CO 3 , as listed in Table 1. No attempts to control pH were performed. The corrosion time was one month, and the experiment temperature was 90 ℃. After the immersion tests, the corrosion rate was measured using the weight loss method, and the crevice corrosion depth was analyzed by a surface profiler. Results and Discussion Corrosion Rate The corrosion rates of the specimens exposed to various single-ion concentra- Effects of Anions on Crevice Corrosion of Copper Qiufa Xu, China Academy of Launch Vehicle Technology, Beijing, China, and Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing, China Kewei Gao and Xiaolu Pan G , Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing, China