表面封闭法对铝阴极耐腐蚀性的影响

目的提高锌电积中铝阴极表面耐腐蚀性能,从而延长其使用寿命,降低生产成本。方法对铝阴极采用不同的表面处理工艺,对耐腐蚀处理后的铝阴极进行了铜加速乙酸盐雾试验、电液腐蚀失重试验和工业扩大化试验研究,考察其耐腐蚀性能。结果在经历120 h盐雾腐蚀后,溶胶-硬脂酸封闭试样仅9.5%的表面被腐蚀,沸水封闭、铈盐封闭试样表面分别有50%与27%左右的面积遭到腐蚀破坏,出现腐蚀孔与腐蚀裂纹,而未经处理的普通铝板表面则已完全被腐蚀破坏。在电解液腐蚀失重试验中腐蚀32 min后,溶胶-硬脂酸封闭试样的单位面积失重达到0.4 mg/cm~2,沸水封闭、铈盐封闭试样的单位面积失重较为相近,均在0.9 mg/cm~2左右,普通铝板的单位面积失重高达1.3 mg/cm~2。工业扩大化试验中,溶胶-硬脂酸封闭后的铝阴极在锌电积生产40 d期间失重约为1.8%且其电流效率保持在91%左右,而普通铝阴极失重则达7.7%。使用90 d后,溶胶-硬脂酸封闭的铝阴极板还能正常使用,而普通铝阴极由于腐蚀破坏需要更换。结论采用沸水封闭、铈盐封闭和溶胶-硬脂酸封闭处理后的铝阴极板耐腐蚀性能均有相应提高,其中以溶胶-硬脂酸封闭工艺最佳。可见表面封闭法对于提高铝阴极耐蚀性延长使用寿命起到了较好作用,同时也保持了较高的电流效率。

Effect of Surface Sealing on Corrosion Resistance of Aluminum Cathode

The work aims to prolong service life of aluminum cathode surface during zinc electrodeposition and reduce producing cost by improving its corrosion resistance. Different surface treatment processes were applied to aluminum cathode, corrosion resistance of the aluminum cathode subject to corrosion resistance treatment was studied by performing copper accelerated acetic acid salt spray test, corrosion electrolyte weight loss test and industrial expanded test. After 120 h salt-spray corrosion, only 9.5% of the sol-strearic acid sealed sample surface was corroded, nearly 50% and 27% of the boiling water-sealed sample and cerium salt-sealed sample were corroded respectively with corrosion holes and cracks. The surface of common aluminum plate was completely corroded and destroyed. After being corroded in zinc electrolyte for 32 min during the corrosion weight loss test, unit area weight loss of the sample sealed by sol-stearic acid was up to 0.4 mg/cm2, that of the samples sealed by boiling water and cerium salt was about 0.9 mg/cm2, and that of common aluminum sheets was 1.3 mg/cm2. In industrial expanded experiments, weight loss of aluminum cathode sealed by sol-stearic acid was about 1.8% after 40 days, and current efficiency of zinc electrodeposition stayed at nearly 91%, while weigh loss of common aluminum cathode plate was 7.7%. Moreover, the aluminum cathode plate sealed by sol-stearic acid for 90 days could be used normally while common aluminum cathode should be replaced due to corrosion damage. The corrosion resistance of aluminum cathode sealed by boiling water, cerium salt and sol-stearic acid increases respectively, the sol-stearic acid sealing works better. Surface sealing method plays a good role in improving the corrosion resistance of aluminum cathode while maintaining high current efficiency.