带缝隙工件铵盐镀锌后返酸问题的研究

Study of corrosion caused by the acid solution retained in the aperture of workpiece after ammonium chloride zinc plating

螺栓与平板配合件在整体进行铵盐镀锌后,残留在螺栓与平板之间缝隙内的酸性液体常常导致缝隙附近发生腐蚀。这种现象俗称"返酸"。实验表明,电镀后采用超声波清洗、高压水冲洗和高压空气吹干有利于减少返酸率,而烘烤干燥可使返酸缺陷在短时间内显现。缝隙宽度对是否返酸起决定性作用,缝隙越大,返酸可能性越小,缝隙达到一定宽度时不再出现返酸。对于较小的缝隙,镀锌后用清漆进行封闭处理能大幅减少产品的返酸率。

： After ammonium chloride zinc plating of the plate with bolt, the acid solution retained in the gap between plate and bolt often causes corrosion around the gap. This phenomenon is usually called ＂acid return＂. The experimental results showed that ＂acid return＂ is reduced by ultrasonic cleaning, high-pressure flushing, and high- pressure air drying after zinc plating, while occurs in a short time by baking. Whether the ＂acid return＂ will occur or not is mainly determined by the gap width. The larger the gap is, the less the possibility of ＂acid return＂ is. ＂Acid return＂ will not occur when the gap is wide enough. For a narrow gap, varnish sealing as a post-treatment can greatly reduce the ＂acid return＂ rate of products.