Ni/Cu定向结构涂层在不同浓度H2SO4中的耐蚀性能

为了研究Cu元素对Ni基合金定向结构涂层耐腐蚀性能的影响，向Ni60合金粉末中添加了5%Cu(质量分数，下同)，制备了定向结构Ni60/Cu复合涂层。采用电化学试验和浸泡试验，评估了涂层在不同浓度H₂SO₄溶液中的电化学腐蚀特性和浸泡腐蚀性能，探讨了涂层在不同浓度H₂SO₄溶液中的腐蚀行为。结果表明，涂层在不同浓度H₂SO₄溶液中的腐蚀均表现为活化-钝化-过钝化的过程，电化学阻抗谱在整个时间常数内具有典型的容抗特征，H₂SO₄溶液浓度从5%增至80%时，电荷转移电阻先减小后增大，涂层的耐腐蚀性呈现先降低后升高的趋势。随着H₂SO₄溶液浓度的增加，涂层表面的腐蚀程度先加剧后逐渐减缓，且在H₂SO₄溶液浓度为40%时，腐蚀电位移至最负，腐蚀电流密度增至最大。但在H₂SO₄溶液浓度达到80...

Corrosion Resistance of Ni/Cu Directional Structure Coatings in Different Concentrations of H2SO4 Solution

In order to study the influence of Cu element on the corrosion resistance of directional structure coating of Ni-based alloy, 5%Cu element was added to Ni60 alloy powder, and the directional structure Ni60/Cu composite coating was prepared. The electrochemical corrosion properties and immersion corrosion properties of the coatings in different concentrations of H₂SO₄ solutions were evaluated by electrochemical tests and immersion tests, and the corrosion behavior of the coatings in different concentrations of H₂SO₄ solutions was discussed. The results showed that the corrosion of the coatings in different concentrations of H₂SO₄ solution shows the process of activation -passivation-overpassivation, and the electrochemical impedance spectroscopy has typical capacitive reactance characteristics in the whole time constant. The charge transfer resistance decreased firstly and then increased, and the corrosion resistance of the coating showed a trend of first decreasing and then increasing when the concentration increased from 5% to 80%. With the increase of H₂SO₄ concentration, the corrosion degree of the coating surface first intensified and then gradually slowed down, and the corrosion potential shifted to the most negative and the corrosion current density increased to the maximum when the concentration of H₂SO₄ solution was 40%. However, the surface of the coating is accompanied by the formation of a dense and uniform corrosion reaction passivation film mainly composed of NiO, Cr₂O₃ and Cu₂O when the concentration of H₂SO₄ solution reaches 80%. These reactive passivation films effectively prevent the H₂SO₄ solution on the coating surface, making the coating exhibit good corrosion resistance in high concentrations of acid.