薄钢板锌酸盐连续镀锌工艺研究

Alkaline Zincate Continuous Zinc Plating Process for Steel Sheet

原有的碱性氰化物镀锌工艺存在有毒有害物质排放及对人体的伤害,被国家强制限制.近年来,国内对镀锌薄钢板的需求不断上升.为此,研究了用于薄钢板连续电镀的锌酸盐镀锌工艺,重点研究了镀液成分及工艺条件对电流效率的影响,用Hull槽8点法测试了镀液的均镀能力;用加热骤冷法测试了镀层的结合力,并对薄钢板连续电镀锌的前后处理工艺作了探讨.结果表明,该工艺电流效率高(锌离子含量16～24 g/L时,电流效率可提高约20%),镀液均镀能力好(宽度为1 m的镀锌薄板,中心点厚度与边缘厚度差不大于10%),镀层结合力优良(将试片180°任意弯曲,镀层无起皮、剥落现象;在烘箱中加热至180～200 ℃,保温60 min,冷水中急剧冷却,镀层无突起、鼓泡、剥落现象),所镀得的镀锌薄钢板适合于钝化和彩涂等后处理.研究结果为工业生产提供了参考.

Conventional alkaline cyanide zinc plating process was compulsively restricted for its emission of toxic and hurtful substances and harm to the environment and human being. Therefore, it is imperative to develop cyanide free zinc plating process so as to meet with the increased demand for galvanized steel sheet in our country. Thus the alkaline zincate continuous zinc plating technology for steel sheet was investigated, with the emphasis being placed on the effects of the bath composition and process conditions on the current efficiency. The throwing power of the plating solution was tested using Hull’s cell 8 points thickness method, and the adhesion strength of the coating was examined by heating and shock cooling test. Moreover, the pre treatment and post treatment processes for the steel sheet subject to continuous zinc plating were also discussed. Results showed that the alkaline zincate plating process had many advantages over conventional alkaline cyanide zinc plating process, including high current efficiency, good throwing power, and strong adhesion strength of the coating. The resulting galvanized steel sheet can be readily post treated by passivation and pre coating.