Cu-Ti合金在模拟S2-污染海水中的腐蚀行为研究

Corrosion behavior of Cu-Ti alloy in simulated S2- contaminated seawater

摘要:

通过浸泡实验与电化学测试,研究了固溶态Cu-4wt.%Ti合金在模拟污染海水(含S2-的3.5wt.% NaCl溶液)的腐蚀行为。借助扫描电子显微镜(SEM)、X射线衍射(XRD)以及X射线光电子能谱仪(XPS)对铜钛合金表面腐蚀产物进行测试分析。结果表明：含Cl-溶液中铜钛合金的腐蚀形式为点蚀,点蚀坑尺寸较小,分布均匀。添加S2-后点蚀更容易被诱发,点蚀坑尺寸较大。当NaCl溶液中的S2-浓度达到60ppm时,点蚀坑在合金表面相互连接,呈现出均匀腐蚀的形态；S2-<和Cl-对铜钛合金的腐蚀存在竞争吸附,S2-吸附性强对铜钛合金的腐蚀剧烈；在含S2-的NaCl溶液中腐蚀产物主要为CuS、Cu2S、Cu2O以及Cu2(OH)3Cl。S2-浓度较大时会导致溶液中OH-浓度增加,使腐蚀产物膜层厚度与致密度增加,因此当S2-浓度达到100ppm时铜钛合金能够发生钝化从而减缓腐蚀。

Abstract:

The corrosion behavior of Cu-4wt.%Ti alloy in solid solution in simulated polluted seawater (3.5wt.% NaCl solution containing S2-) was studied by immersion test and electrochemical test.Scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were used to test and analyze the corrosion products on the surface of copper titanium alloy.The results show that the Cl- causes pitting corrosion of Cu-Ti alloy in solution, and the pitting pits with uniform distribution are smaller in size. When the concentration of S2- in NaCl solution is 60ppm, the pitting pits are connected with each other on the surface of the alloy, showing uniform corrosion morphology.There is competitive adsorption between S2- and Cl- on the corrosion of Cu-Ti alloy, and S2- Corrosion of copper-titanium alloy is severe due to its strong adsorption.In NaCl solution containing S2-, the corrosion products are mainly CuS, Cu2S, Cu2O and Cu2(OH)3Cl.When S2- concentration is high, the concentration of OH- in the solution will increase, which will increase the thickness and density of the corrosion product film. Therefore, when S2- concentration reaches 100ppm, passivation can occur to the Cu-Ti alloy to slow down the corrosion. Key words: Cu-Ti alloy; S2- pollution; Simulated sea water; Corrosion; Competitive adsorption