用于制备镁合金蚀刻版的化学整平工艺

Chemical polishing process for preparation of magnesium alloy photoengraving plate

采用单纯机械砂光加工的国产镁合金蚀刻版与美国蚀刻版相比,表面残留清晰加工纹理,感光胶附着力差,影响推广使用。为改善国产镁合金蚀刻版质量,根据镁合金化学抛光理论及控制腐蚀尺寸的酸洗经验,开发了可去除表面砂光条纹,提高涂层附着力与耐蚀性能的化学整平工艺。该化学整平工艺与常规的镁合金酸洗工艺相比,单纯采用低含量的硫酸,且使用了缓蚀剂。附着力测试、腐蚀量测量、工艺稳定性试验等各种应用效果评价实验的结果,证明了该工艺简单,稳定,环保,腐蚀尺寸小,表面形成了均匀且具有一定防锈能力的蜂窝状微观组织,提高了与感光胶的附着力,不影响电泳、粉末喷涂、滚涂等后续处理的外观质量,使国产镁合金蚀刻版质量可与国外产品媲美,并可替代磷化作为镁合金前处理工艺。

Compared with American magnesium alloy photoengraving plate, the photoengraving plate made in China left sanding stripes on the surface and has poor adhesion with photosensitive adhesive due to the fact that it is simply pretreated by mechanical sanding. According to the theory of chemical polishing for magnesium alloy and pickling experience for corrosion control, a chemical polishing process was developed aiming to improve the quality of magnesium photoengraving plate. Unlike the traditional pickling solution for magnesium alloy, the chemical polishing solution contains a low concentration of sulfuric acid and corrosion inhibitor. The results of adhesion strength test, dimensional changes measurement after corrosion, and stability test showed that the process is simple, stable, and environmentally friendly, and has no effect on the appearance quality of further treatments such as electrophoresis, powder spraying, and roll painting. The Mg alloy plate polished by the process slightly change in dimensions and have uniform surfaces with a honeycomb- like microstructure not only having anti-rust performance but also increasing the adhesion of photosensitive adhesive. The quality of Mg alloy photoengraving plates obtained by using the process are comparable with that of their American counterparts. The chemical polishing process can replace phosphating process as a pretreatment of Mg alloys.