低碳钢在模拟酸雨大气条件下的锈蚀演化

RUSTING EVOLVEMENT OF MILD STEEL UNDER WET/DRY CYCLIC CONDITION WITH pH 4 NaHSO_3 SOLUTION

利用干湿循环加速腐蚀实验和电化学极化曲线法研究了低碳钢在模拟工业酸雨大气条件下的锈蚀演化过程.结果表明:实验初期锈蚀速度随干湿循环次数的增加而增大,随后转为随干湿循环次数的增加而降低;带锈低碳钢的干湿循环下的腐蚀产物促进阴极过程抑制阳极过程;在干湿循环加速腐蚀进程中低碳钢表面铁锈的化学组成、结构变化表现为在锈蚀初期α-FeOOH含量较低,锈层疏松,锈蚀速度随干湿循环次数增加呈上升趋势;后期随α-FeOOH含量的增加和锈层变得更加致密,腐蚀速度转变为随干湿循环次数增加而下降.

Corrosion rate of mild steel under wet/dry alternate conditions with 0. 052mass% NaHSO3 （ pH 4） solution was measured. It increased with increasing wet/dry alternate cycles in the initial stage while decreased in the later stage. The change of corrosion rates of mild steel is related to the evolution of the rust in composition and mierostrncture,which is caused by the occurrence of α-FeOOH and Fe304 in the rust layer. Polarization curves of the rusted mild steel in the solution of 0. 052mass% NaHSO3 （ pH 4） showed that the corrosion products formed in the initial stage could accelerate the cathodic process while suppressed the anodic process. A flow chart was proposed to describe the atmospheric corrosion behavior of mild steel.