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分别采用了动电位极化法、电化学阻抗法研究了不同温度下、不同氯离子浓度下防锈铝在模拟冷却液中的腐蚀行为,采用金相显微镜和扫描电镜对极化后防锈铝的表面特征进行了观察和记录。结果表明,氯离子吸附在防锈铝氧化膜表面,对氧化膜表面造成破坏。在一定温度下(30℃),当氯离子浓度超过0.01 mol/L时,中间产物吸附作用就会增强,阻抗谱中低频区出现感抗弧,点蚀萌生。随着氯离子浓度增高(超过0.01 mol/L),防锈铝的腐蚀加剧,耐腐蚀性能下降。随着温度的升高,阴极和阳极反应阻力变小,阳极金属铝的溶解和阴极氧还原速度增大,腐蚀速度增大。温度升高的同时,溶解氧含量下降,阴极反应受到抑制。与此同时扩散过程在整个腐蚀反应过程中的支配性降低,中间产物在氧化膜表面的吸附作用增强,从而导致低频容抗弧的出现。温度对点蚀形貌的影响主要体现在影响单个点蚀坑的几何大小,促进点蚀坑的生长。
The corrosion behaviors of rust-proof aluminum in simulated coolant under different temperatures and chloride concentrations were investigated by potentiodynamic polarization and electrochemical impedance spectroscopy respectively. The corrosion resistance of the poled aluminum The surface features were observed and recorded. The results show that chloride ions adsorbed on the surface of the rust-proof aluminum oxide film, causing damage to the oxide film surface. At a certain temperature (30 ℃), when the chloride ion concentration exceeds 0.01 mol / L, the adsorption of the intermediate product will be enhanced. The inductive arc will appear in the low-frequency region of the impedance spectrum, and the pitting initiation will occur. With the increase of chloride ion concentration (more than 0.01 mol / L), the corrosion of anti-rust aluminum aggravates and the corrosion resistance decreases. With the increase of temperature, the reaction resistance of cathode and anode becomes smaller, the dissolution of anode aluminum and the reduction rate of cathode oxygen increase, and the corrosion rate increases. At the same time as the temperature rises, the dissolved oxygen content decreases and the cathodic reaction is inhibited. At the same time, the dominance of the diffusion process decreases during the entire corrosion reaction. The adsorption of the intermediate product on the surface of the oxide film is enhanced, resulting in the appearance of a low-frequency capacitive arc. The effect of temperature on pitting morphology is mainly reflected in the influence of the geometry size of a single pitting pit and the growth of pitted pits.