The erosion–corrosion of aluminum in a 50 °C ethylene glycol aqueous solution (EGAS) was studied. Compared with that in deionized water, the corrosion of aluminum in an EGAS was inhibited to a certain extent. The corrosion potential, corrosion current, and charge transfer impedance of aluminum changed from −1.5776 V, 380.4 nA cm⁻², and 1.924 × 10⁻⁴ Ω cm⁻² in deionized water to −1.3127 V, 285.5 nA cm⁻², and 4.041 × 10⁻⁴ Ω cm⁻² in a 45.3 vt% EGAS, respectively. Ethylene glycol did not ionize in deionized water and the ionic conductivity of the EGAS was low, effectively restraining the corrosion of aluminum. However, a test with aluminum in an EGAS after long-term storage (9 days) showed that ethylene glycol gradually oxidized to glycolic acid, oxalic acid, and other substances, which slowly corroded the aluminum surface. Analysis results showed that the corrosion products on the surface of aluminum were Al(OH)₃ and Al₂O₃. The pitting hole formation mechanism of aluminum occurs via an aluminum–alcohol phase formed on the aluminum surface, which can inhibit the dissolution of the oxide film. Therefore, a suitably concentrated EGAS with a high heat capacity and low ionic conductivity similar to that of deionized water can be used as a coolant in airtight valve cooling systems for high-voltage direct-current transmission.

中文翻译：

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铝在 50°C 乙二醇水溶液中模拟高压直流输电冷却水的侵蚀腐蚀行为

研究了铝在 50 °C 乙二醇水溶液 (EGAS) 中的冲蚀腐蚀。与去离子水相比，EGAS对铝的腐蚀得到一定程度的抑制。铝的腐蚀电位、腐蚀电流和电荷转移阻抗从去离子水中的-1.5776 V、380.4 nA cm ^-2和 1.924 × 10 ^-4  Ω cm ^-2变为 -1.3127 V、285.5 nA cm ^-2和4.041 × 10 ^-4  Ω cm ^-2分别在 45.3 vt% EGAS 中。乙二醇在去离子水中不电离，EGAS的离子电导率低，有效抑制了铝的腐蚀。然而，在长期储存（9天）后的EGAS中用铝进行的测试表明，乙二醇逐渐氧化成乙醇酸、草酸等物质，慢慢腐蚀铝表面。分析结果表明，铝表面腐蚀产物为Al(OH) ₃和Al ₂ O ₃. 铝的点蚀孔形成机制是通过铝表面形成的铝-醇相发生的，它可以抑制氧化膜的溶解。因此，具有类似于去离子水的高热容和低离子电导率的适当浓缩的EGAS可用作高压直流输电的气密阀冷却系统中的冷却剂。