中性氯化钠溶液中硝酸根和电偶对7075-T651铝合金缝隙腐蚀行为影响研究
Effect of Nitrate and Galvanic Couple on Crevice Corrosion Behavior of 7075-T651 Al-alloy in Neutral NaCl Solution
乔泽 1李清泉 2刘晓航 3李燚周3
作者信息
- 1. 福建福清核电有限公司 福清 350318
- 2. 江苏核电有限公司 连云港 222042
- 3. 中国海洋大学材料科学与工程学院 青岛 266100
- 折叠
摘要
采用电化学测试、共聚焦显微镜、扫描电子显微镜等手段,研究硝酸根和电偶对7075-T651高强铝合金缝隙腐蚀行为影响.结果表明,硝酸根作为氧化剂能促进铝合金表面形成保护性的氧化膜,有效抑制铝合金的腐蚀.然而,当存在缝隙结构时,在没有硝酸根的溶液中,缝隙内没有发生明显腐蚀现象.而在含有硝酸根溶液中,硝酸根还原产生的氨气将富集在缝隙内,并选择性溶解含铜颗粒,诱发缝隙内点蚀形核,促进缝隙腐蚀发展.与304不锈钢偶接后,使缝隙内外电极之间产生较大的电偶腐蚀驱动力,加速缝隙内金属溶解及溶液劣化过程,从而导致更严重的缝隙腐蚀.
Abstract
The effect of the presence of nitrate and galvanic couple on the crevice corrosion behav-ior of 7075-T651 Al-alloy in 3.5％NaCl solution is investigated by the electrochemical tests and surface analysis techniques.The results indicate that the nitrate as an oxidizing agengt could promote the forma-tion of passive film,so that inhibit the corrosion of the Al-alloy.However,when there is a formed crevice on the Al-alloy in a solution without nitrate,inside the crevice corrosion is hard to occur and develop,in the contrast,in a solution with the presence of nitrate,which could be reduced forming NH3,the later agent may accumulate inside the crevice and selectively dissolve the copper particles,thereby induced the nucleation of pitting corrosion,afterwards,further promoted the propagation of crevice corrosion.After coupling with 304 stainless steel,a large Galvano-corrosion driving force is generated between the elec-trodes inside and outside the crevice,which accelerates the metal dissolution and solution deterioration process in the crevice,resulting in much more serious crevice corrosion in the solution with nitrate.
关键词
7075-T651铝合金/304不锈钢/电偶腐蚀/缝隙腐蚀Key words
7075-T651 Al-alloy/304 stainless steel/galvanic corrosion/crevice corrosion引用本文复制引用
出版年
2024
NETL
NSTL
万方数据