甲硫氨酸对铜合金在NaCl溶液中的缓蚀性能研究

发布时间：2019-06-19 18:06

【摘要】：铜镍合金具有良好的耐蚀性,广泛应用于各种海洋工业部门。但长时间在海水的侵蚀下,合金还是会发生严重的腐蚀。向介质中添加缓蚀剂是防止金属腐蚀的一种简单高效的方法。然而大多数传统缓蚀剂都是环境有害的。氨基酸作为一种环境友好型缓蚀剂,曾被用作抑制钢,铝等金属腐蚀。本文选取了含硫原子的一种氨基酸(甲硫氨酸),作为Cu-10 wt.%Ni合金在3.5 wt.%Na Cl溶液的缓蚀剂。采用电化学阻抗谱,动电位极化曲线,循环伏安法研究了所选缓蚀剂的缓蚀行为,通过傅里叶变换红外光谱和扫描电子显微镜分析了试样表面成分及形貌,研究其作用机理。为了提高其缓蚀效率,选择硅酸钠和磷酸钠两种无机缓蚀剂与之复配,探讨协同效果及作用机理。主要的研究成果如下:(1)单独添加甲硫氨酸对Cu-10 wt.%Ni合金在3.5 wt.%Na Cl溶液具有一定的缓蚀效果。在浓度为40 ppm时缓蚀效率达到最大,为60%。属于阴极型缓蚀剂,通过抑制阴极吸氧反应来控制整体的腐蚀过程。对浸泡后的表面膜层进行SEM分析,可以发现,表面形成膜层,但较疏松,只能一定程度上抑制氯离子的侵袭。(2)在3.5 wt.%Na Cl溶液同时添加甲硫氨酸和硅酸钠对Cu-10 wt.%Ni合金的缓蚀具有协同作用。添加20 ppm甲硫氨酸与20 ppm硅酸钠复配,缓蚀效率达到90%。复配缓蚀剂仍属于阴极型缓蚀剂。协同效果是由于两种缓蚀剂分子相互作用,在合金表面生成了平整,致密的膜层,能够有效的抵御氯离子的侵袭。(3)在3.5 wt.%Na Cl溶液中同时添加甲硫氨酸和磷酸钠对Cu-10wt.%Ni合金的缓蚀行为具有良好的协同作用。当添加40 ppm甲硫氨酸与200 ppm磷酸钠复配,缓蚀效率达到最大,为98%,大于两种缓蚀剂单独使用时的缓蚀效率。复配缓蚀剂属于混合型缓蚀剂,既能抑制阳极反应,又能抑制阴极吸氧反应。SEM结果表明,同时添加两种缓蚀剂,能够形成多种遮蔽性化合物,综合两种膜层的优势,使之相互配合,形成了致密又较厚的膜层,从而发挥协同效果。
[Abstract]:Copper-nickel alloy has good corrosion resistance and is widely used in various marine industries. However, under the erosion of seawater for a long time, the alloy will still have serious corrosion. Adding corrosion inhibitor to medium is a simple and efficient method to prevent metal corrosion. However, most traditional corrosion inhibitors are harmful to the environment. Amino acids, as an environmentally friendly corrosion inhibitor, have been used to inhibit corrosion of steel, aluminum and other metals. In this paper, an amino acid containing sulfur atom (methionine) was selected as corrosion inhibitor for Cu-10 wt.%Ni alloy in 3.5 wt.%Na Cl solution. The corrosion inhibition behavior of the selected corrosion inhibitor was studied by electrochemical impedance spectroscopy, potentiodynamic polarization curve and cyclic volt-ampere method. The surface composition and morphology of the sample were analyzed by Fourier transform infrared spectroscopy and scanning electron microscope, and the mechanism of action was studied. In order to improve the corrosion inhibition efficiency, sodium silicate and sodium phosphate were selected to combine them, and the synergistic effect and mechanism were discussed. The main results are as follows: (1) the addition of methionine alone has a certain corrosion inhibition effect on Cu-10 wt.%Ni alloy in 3.5 wt.%Na Cl solution. When the concentration is 40 ppm, the corrosion inhibition efficiency reaches the maximum, which is 60%. It belongs to cathode corrosion inhibitor, which controls the whole corrosion process by inhibiting cathodic oxygen absorption reaction. SEM analysis of the immersed surface film showed that the film was formed on the surface, but it was loose and could only inhibit the invasion of chloride ion to a certain extent. (2) the addition of methionine and sodium silicate at the same time in 3.5 wt.%Na Cl solution had synergistic effect on the corrosion inhibition of Cu-10 wt.%Ni alloy. The corrosion inhibition efficiency was 90% when 20 ppm methionine was added with 20 ppm sodium silicate. The compound corrosion inhibitor still belongs to cathode corrosion inhibitor. The synergistic effect is that a flat and dense film is formed on the surface of the alloy due to the interaction of the two inhibitor molecules, which can effectively resist the invasion of chloride ions. (3) the addition of methionine and sodium phosphate to 3.5 wt.%Na Cl solution has a good synergistic effect on the corrosion inhibition behavior of Cu-10wt.%Ni alloy. When 40 ppm methionine and 200 ppm sodium phosphate were added, the corrosion inhibition efficiency reached the maximum (98%), which was higher than that when the two inhibitors were used alone. The composite corrosion inhibitor is a mixed corrosion inhibitor, which can not only inhibit the anodic reaction, but also inhibit the cathodic oxygen absorption reaction. The SEM results show that the addition of two corrosion inhibitors at the same time can form a variety of concealment compounds, synthesize the advantages of the two films, make them cooperate with each other, and form a dense and thick film, thus giving full play to the synergistic effect.
【学位授予单位】：太原理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG174.42

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