程昱琳,张卿和,程英亮.钽在磷酸盐中等离子体电解氧化涂层耐腐蚀性能研究[J].表面技术,2021,50(6):32-40.
CHENG Yu-lin,ZHANG Qing-he,CHENG Ying-liang.Corrosion-resistant Coatings on Tantalum Formed by Plasma Electrolytic Oxidation in Phosphate Electrolyte[J].Surface Technology,2021,50(6):32-40 |
| 钽在磷酸盐中等离子体电解氧化涂层耐腐蚀性能研究 |
| Corrosion-resistant Coatings on Tantalum Formed by Plasma Electrolytic Oxidation in Phosphate Electrolyte |
| 投稿时间：2021-04-23 修订日期：2021-05-27 |
| DOI：10.16490/j.cnki.issn.1001-3660.2021.06.003 |
| 中文关键词: 金属钽 等离子体电解氧化 磷酸盐 陶瓷膜 耐腐蚀性 |
| 英文关键词:tantalum plasma electrolytic oxidation phosphate ceramic coating corrosion resistance |
| 基金项目:国家自然科学基金项目(51671084) |
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| 中文摘要: |
| 目的 探究金属钽在磷酸盐中进行等离子体电解氧化(Plasma electrolytic oxidation, PEO)形成Ta2O5陶瓷涂层后的耐腐蚀性能。方法 在磷酸盐电解液中，采用等离子体电解氧化(PEO)方法，在金属钽表面形成Ta2O5陶瓷涂层。采用XRD、SEM和EDS等方法，表征涂层物相、形貌及元素组成，利用动电位极化曲线和电化学阻抗谱，测试涂层的耐腐蚀性能。结果 在磷酸盐电解液中，金属钽PEO处理形成了晶态Ta2O5陶瓷膜。氧化膜初期形貌为“瘤子状”，后为“沟回状”。在3.5%NaCl溶液中进行动电位极化测试，相比于基体，涂层的腐蚀电流密度降低约4个数量级。PEO处理600 s形成的涂层，相比于基体，自腐蚀电位提高了约1.3 V，腐蚀电流密度为3.7´10–10 A/cm2，保护效率为99.97%;PEO处理1200 s，自腐蚀电位提高了约1.4 V，电流密度为1.46´10–10 A/cm2，保护效率为99.99%。在3.5%NaCl溶液中浸泡160 d发现，在30 d左右，钽基体表面已形成一层极薄的氧化膜，导致阻抗值持续升高，表明对基体有一定的保护作用。然而，PEO处理600 s形成的涂层在浸泡3 d后，低频区域阻抗值大幅下降，且随浸泡时间的延长，阻抗值持续降低。在160 d腐蚀后，电荷转移电阻仍然比未经过处理的金属钽高1个数量级。结论 在磷酸盐电解液中，钽经PEO处理形成的陶瓷膜层具有较强的耐腐蚀性能，PEO处理可大幅度提高钽的耐腐蚀能力。 |
| 英文摘要: |
| This work aims to explore the corrosion resistance of Ta2O5 coatings formed by plasma electrolytic oxidation (PEO) of tantalum in phosphate electrolyte. The phase composition, morphology and elemental composition of the obtained coatings are characterized by XRD, SEM and EDS, respectively. The corrosion resistance is investigated by potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS). The PEO coatings are composed of crystalline Ta2O5. A thin film with nodules is formed at the initial stage of PEO, and later changes to a grooved structure. The potentiodynamic polarization tests are performed in 3.5% NaCl solution, and the results show that the corrosion current density of the coatings is about 4 orders of magnitude lower than that of the substrate. The corrosion potential of the PEO coating formed in 600 s was increased by ~1.3 V compared with the un-treated substrate, and the corrosion current density is 3.7´10–10 A/cm2, showing a protection efficiency of 99.97%; the corrosion potential of the 1200 s PEO coating was increased by ~1.4 V, and the current density is 1.46´10–10 A/cm2, showing a protection efficiency of 99.99%. During 160 days of immersion tests in 3.5% NaCl solution, a thin oxide coating has formed on the surface of bare tantalum and the impedance value increases constantly after immersion for the initial 30 days, which demonstrates a protective effect on substrate to some extent. However, when the coating formed by PEO for 600 s was immersed in the solution, the impedance in the low-frequency region dropped significantly after 3 days. As the immersion time extended, the impedance of the coating continued to decrease. However, the value of the charge transfer impedance is still an order of magnitude higher than that of the un-treated tantalum after 160 days of immersion. It shows that the PEO coating formed on tantalum in the phosphate electrolyte has good corrosion resistance, and PEO can greatly improve the corrosion resistance of tantalum. |
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