锌钴合金及其耐蚀性的电化学研究

CODEPOSITION OF ZINC-COBALT ALLOY IN WEAKLY ACIDIC NaCl ELECTROLYTE AND ITS CORROSION RESISTANCE

采用线性电位扫描、极化电阻、交流阻抗等实验方法，研究弱酸性氯化钠电解液中锌－钴共沉积及其耐蚀性．实验表明：镀层的钴含量随着镀液的钴含量和电流密度的增加而增加．在电解液含钴２．５ｇ／Ｌ左右，电流密度１．５～２．５Ａ／ｄｍ２，ｐＨ值５．０～５．６，温度范围２０—３０℃的条件下镀层的极化电阻Ｒｐ比较大。镀层的腐蚀电化学行为说明：镀层腐蚀产物的阻挡作用提高了锌钴微合金镀层的耐蚀性．在本实验条件下，在弱酸性氯化钠溶液中，锌—钴共沉积属于异常共沉积．

The codeposition of zinc with cobalt in weakly acidic sodium chloride electrolyte and the corrosion resistance of the deposit with less cobalt content have been investigated. Experiments show that the percentage of cobalt deposited increases with increasing bath composition and current density. According to polarization resistance,the optimum depositing conditions are as follows: current density 1.5～2.5 A/dm2, pH 5～5.6, and temperature 20～30℃. The increase in corrosion resistance may be correlated with the barrier effect of the corrosion products. The deposition of Zn-Co alloy in weakly acidic sodium chloride electrolyte is also of anomalous type under existing experimental conditions.