Q345钢在不同pH值人工海水中的电偶腐蚀行为研究

目的 研究不同pH值的人工海水环境中电偶腐蚀对金属的影响。方法 利用自行设计的可拆卸电极，采用浸泡法和电化学方法，结合宏观和微观腐蚀形貌，对Q345钢在不同pH人工海水中的电偶腐蚀行为进行分析。结果 在浸泡初期，不同pH值海水环境中电连接电极间的电位差相差较小，不易发生电偶腐蚀；浸泡至14 d，电极间的电位差相差较大，这表明不同电连接电极之间发生明显的电偶腐蚀。与自腐蚀相比，pH为7.50和8.40的电偶腐蚀的腐蚀电位较大，腐蚀电流密度较小，腐蚀产物膜电阻Rp较大，说明在pH值为7.50和8.40时，电连接电极间的腐蚀以自腐蚀为主。在pH值为7.80和8.70时，电连接电极间发生明显的电偶腐蚀。自腐蚀电极表面的腐蚀产物较少，锈层结构疏松。电偶腐蚀中，在pH为7.50和8.40的电极表面的腐蚀产物较少，锈层结构致密；pH为7.80和8.70的电极表面的腐蚀产物较多，锈层结构比较疏松。结论 通过研究2种腐蚀行为的差异，分析pH值的不同对电偶腐蚀的影响，为海洋环境金属材料的腐蚀防护提供数据支持。

Galvanic Corrosion Behavior of Q345 Steel in Artificial Seawater with Different pH Values

The work aims to study the effect of galvanic corrosion on metals in artificial seawater environment with different pH values. Combined with macroscopic and microscopic corrosion morphology observation, the self-designed detachable electrode was used to analyze the galvanic corrosion behavior of Q345 steel in artificial seawater with different pH values by immersion method and electrochemical method. In the initial stage of immersion, the difference of potential difference between electrically connected electrodes in seawater with different pH values was small and galvanic corrosion was not easy to occur. After soaking for 14 days, the potential difference between the electrodes was quite different, indicating that obvious galvanic corrosion occurred between the different electrically connected electrodes. Compared with self-corrosion, the galvanic corrosion at pH 7.50 and 8.40 had higher corrosion potential, lower corrosion current density and higher corrosion film resistance (Rp), indicating that the corrosion between the electrically connected electrodes was mainly self-corrosion at pH 7.50 and 8.40, and obvious galvanic corrosion occurred between the electrically connected electrodes at pH 7.80 and 8.70. The corrosion products on the surface of the self-corrosion electrode were less, and the rust layer structure was loose. In galvanic corrosion, there were less corrosion products on the electrode surface at pH 7.50 and 8.40, and the rust layer structure was compact. The corrosion products on the electrode surface at pH 7.80 and 8.70 were more, and the rust layer structure was loose. By studying the difference between the two corrosion behaviors, the effect of different pH values on galvanic corrosion is analyzed, which provides data support for corrosion prevention of metallic materials in marine environment.