对比研究了硬质阳极氧化和微弧氧化铝合金在3.5%NaCl溶液中的空泡腐蚀行为. 结果表明:两种氧化铝合金的空泡腐蚀失重在第1 h内都随着空化作用时间明显增大,此后则缓慢增大. 超过4 h之后, 随着时间又迅速地增大.当硬质阳极氧化和微弧氧化两种膜的厚度相当时,氧化工艺对氧化铝合金的耐空泡腐蚀性能影响并不明显. 在空泡腐蚀过程中,两种氧化处理铝合金的电化学过程都是受阴阳极混合过程控制.硬质阳极氧化铝合金的电化学阻抗谱为一变形的容抗弧, 并且低频出现收缩,呈现多孔电极的阻抗谱特征.微弧氧化铝合金电极的电化学阻抗谱在高频区为一容抗弧,接着又为一容抗弧, 低频区出现扩散阻抗谱特征.
Cavitation corrosion behaviors of aluminum alloys, which were pre-oxidized by anodization and micro arc oxidation respectively, in 3.5% NaCl solution were studied. It was found that the cumulative mass loss rates of anodized and micro arc oxidized Al alloys initially increased with time within the first hour, and then increased slowly until the fourth hour, and subsequently increased rapidly with time. There were no marked effects of oxidation processes on the cavitation corrosion resistance of the oxidized Al alloys if the thicknesses of oxidized films are the same. During cavitation corrosion, the electrochemical corrosion processes of the two oxidized Al alloys in 3.5% NaCl solution were controlled by mixed cathodic and anodic processes. During cavitation corrosion the EIS of the anodized Al alloy was a deformed semicircle with contraction at low frequencies like porous electrodes, however, the EIS of the micro arc oxidized Al alloy was composed of a semicircle at high frequencies and another semicircle and Warburg line at low frequencies.