花天顺,宋仁国,宗玙,蔡思伟.恒载荷下的微弧氧化后7050铝合金在不同pH值NaCl溶液中的腐蚀行为[J].表面技术,2020,49(5):269-278.
HUA Tian-shun,SONG Ren-guo,ZONG Yu,CAI Si-wei.Corrosion Behavior of 7050 Aluminum Alloy after Micro-arc Oxidation under Constant Load in NaCl Solution with Different pH Values[J].Surface Technology,2020,49(5):269-278 |
| 恒载荷下的微弧氧化后7050铝合金在不同pH值NaCl溶液中的腐蚀行为 |
| Corrosion Behavior of 7050 Aluminum Alloy after Micro-arc Oxidation under Constant Load in NaCl Solution with Different pH Values |
| 投稿时间：2019-05-13 修订日期：2020-05-20 |
| DOI：10.16490/j.cnki.issn.1001-3660.2020.05.032 |
| 中文关键词: AA7050 铝合金 应力腐蚀 微弧氧化 EIS 恒载荷 |
| 英文关键词:AA7050 aluminum alloy stress corrosion MAO EIS constant load |
| 基金项目:国家自然科学基金（51871031） |
| 作者 | 单位 |
| 花天顺 | 常州大学 a.材料科学与工程学院 b.江苏省材料表面科学与技术重点实验室，江苏 常州 213164 |
| 宋仁国 | 常州大学 a.材料科学与工程学院 b.江苏省材料表面科学与技术重点实验室，江苏 常州 213164 |
| 宗玙 | 常州大学 a.材料科学与工程学院 b.江苏省材料表面科学与技术重点实验室，江苏 常州 213164 |
| 蔡思伟 | 常州大学 a.材料科学与工程学院 b.江苏省材料表面科学与技术重点实验室，江苏 常州 213164 |
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| Author | Institution |
| HUA Tian-shun | a.School of Materials Science and Engineering, b.Jiangsu Key Laboratory of Materials Surface Science and Technology, Changzhou University, Changzhou 213164, China |
| SONG Ren-guo | a.School of Materials Science and Engineering, b.Jiangsu Key Laboratory of Materials Surface Science and Technology, Changzhou University, Changzhou 213164, China |
| ZONG Yu | a.School of Materials Science and Engineering, b.Jiangsu Key Laboratory of Materials Surface Science and Technology, Changzhou University, Changzhou 213164, China |
| CAI Si-wei | a.School of Materials Science and Engineering, b.Jiangsu Key Laboratory of Materials Surface Science and Technology, Changzhou University, Changzhou 213164, China |
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| 中文摘要: |
| 目的 研究pH值对恒载荷下微弧氧化后铝合金腐蚀行为和耐蚀性的影响。方法 采用恒载荷应力环，研究微弧氧化后的7050铝合金（AA7050）在不同pH值3.5% NaCl溶液中的腐蚀行为。采用动电位极化曲线和原位电化学阻抗谱（EIS），评价pH值对恒载荷下的微弧氧化后AA7050耐蚀性的影响，以及在不同pH值的3.5% NaCl溶液中膜层的腐蚀过程，并建立相应的等效电路模型。结果 恒载荷试验结束后，在pH=7的溶液中，试样表面的微弧氧化膜基本完整，表面覆盖一层腐蚀产物；在pH=3的溶液中，试样表面膜层部分被腐蚀；在pH=13的溶液中，试样表面膜层已经完全脱落。腐蚀初期，在pH为3、7和13的溶液中，试样的低频阻抗模值分别为35 000、90 000、500 Ω•cm2，其腐蚀电位分别为–1.41、–1.43、–1.46 V，腐蚀电流密度分别为2.85×10–5、9.17×10–6、1.75×10–4 A/cm2。恒载荷实验后，在pH为3、7和13的溶液中，试样的伸长率分别为3.41%、3.98%、1.63%。结论 溶液的pH值对恒载荷下微弧氧化后AA7050的耐蚀性和塑性产生了显著的影响。在pH=7的溶液中，微弧氧化铝合金的耐蚀性和塑性最好，在pH=3的溶液中次之，在pH=13的溶液中最差。根据试样的EIS，整个腐蚀阶段被分为腐蚀初期、中期、后期三个阶段。腐蚀初期，在不同pH的溶液中，微弧氧化试样的耐腐蚀性先降低后提高。腐蚀中期，耐蚀性先下降后稳定，在pH=13的3.5%NaCl溶液中，试样膜层完全剥落。腐蚀后期，在不同pH的溶液中，微弧氧化试样的耐蚀性再次下降。 |
| 英文摘要: |
| The paper aims to study the effect of pH value on corrosion behavior and corrosion resistance of aluminum alloy after micro-arc oxidation under constant load. The stress corrosion behavior of 7050 aluminum alloy (AA7050) after micro-arc oxidation in 3.5wt% NaCl solution with different pH was studied with a constant load stress ring. The potentiodynamic polarization curve and in-situ electrochemical impedance spectroscopy (EIS) were used to evaluate the effect of pH value on corrosion resistance of aluminum alloy after micro-arc oxidation under constant load and the corrosion process of coating in 3.5wt% NaCl solution with different pH. The corresponding equivalent circuit model was established. After the constant load tests, the coating on the surface of the specimen in the solution at pH 7 was almost complete, and it was covered with a layer of corrosion products. The coating on the surface of the specimen in the solution at pH 3 was corroded. The coating on the surface of the specimen in the solution at pH 13 was completely fallen off. At the initial stage of corrosion, the low frequency impedance modes of MAO specimens in solution at pH 3, 7 and 13 were 35 000, 90 000, 500 Ω•cm2, respectively. Their corrosion potential and corrosion current were –1.41, –1.43, –1.46 V and 2.85×10–5, 9.17×10–6, 1.75×10–4 A/cm2, respectively. After constant load test, the elongation of MAO specimens in solution with pH 3, 7 and 13 were 3.41%, 3.98%, 1.63%, respectively. The pH value of solution had a significant effect on the corrosion resistance and plasticity of aluminum alloy after MAO under constant load. The corrosion resistance and plasticity of AA7050 after MAO was the best in solution pH 7, intermediate in solution pH 3 and least in solution pH 13. According the corrosion behavior of EIS, the whole corrosion stage was divided into three stages: initial stage, middle stage and later stage. At the initial stage of corrosion, the corrosion resistance of the MAO specimens decreased at first and then increased. In the middle stage of corrosion, the corrosion resistance decreased at first and then stabilized, while the coating of the MAO specimen in solution at pH 13 was completely exfoliated during the middle stage of corrosion. At the later stage of corrosion, the corrosion resistance of MAO specimens in solution with different pH decreased again. |
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