工业纯铝在模拟海水中的电化学腐蚀行为

为研究铝在海水中的腐蚀过程,采用电化学阻抗谱、浸泡试验、扫描电子显微镜研究工业纯铝在模拟海水中的腐蚀行为.结果表明:铝在模拟海水中发生点蚀的区域为富含Fe的晶间化合物处,点蚀半径随时间的增加而扩大.铝在模拟海水中的溶解曲线分为4个区间:活性溶解区、过渡区、过钝化区、钝化区.铝在模拟海水中,极化电位为过钝化区时,转移电阻R t随着电位的升高而变小,铝发生严重的点蚀;而极化电位为钝化区时,铝的转移电阻R t随着电位的升高基本不变,铝的溶解行为受到抑制.工业纯铝在模拟海水中发生点蚀的电位区间是-0.45～-0.65 V,钝化电位区间为-0.75～-0.85 V.

Electrochemical corrosion behavior of industrial pure aluminum in simulated seawater

In order to study the corrosion behavior of aluminum in seawater,corrosion behavior of industry-grade aluminum in simulated seawater is investigated by electrochemical impedance spectroscopy(EIS),immersion test and scanning electron microscopy(SEM).It is found that pitting corrosion of aluminum locates at Fe-rich areas,and the radius of pitting corrosion increases with prolonged reaction period.Dissolution curve of aluminum in simulated seawater can be divided into four parts,including activated dissolution area,transitional area,over-passivation area and passivation area.In over-passivation area,transfer resistance(R t) decreases with increasing polarization potential,where severe pitting corrosion occurs.However,R t almost keeps constant with increasing polarization potential in passivation area,where the dissolution of aluminum can be inhibited.It is determined that pitting corrosion of industry-grade aluminum in simulated seawater happens in the potential range of-0.45 ～-0.65 V,and the passivation potential range locates between-0.75 V and-0.85 V.