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锌铬涂覆技术在国内日趋成熟,已被很多制造企业所应用。根据生产现场的需要,通过试验分析,探究出将镀锌零件改制成合格的锌铬涂层零件的工艺案例,解决了镀锌零件上的锌层对锌铬涂层质量的影响问题。采用由硫酸、氯化钠、OP乳化剂组成的酸洗褪锌工艺,须先以抛丸破坏原有锌镀层的完整性,虽成本低,但存在氢脆的危险,不适用于高强度连接件和弹性类零件。采用由氢氧化钠和亚硝酸钠组成的溶液进行碱煮的工艺,适用于所有铁基材料褪锌后涂覆锌铬涂层。2种工艺处理后的零件均满足耐20%硝酸铵快速腐蚀试验时间>1.5h的要求。
Zinc chrome coating technology matures in China, has been applied by many manufacturing enterprises. According to the needs of the production site, through the analysis of the experiment, we explored the process of transforming galvanized parts into qualified zinc-chromium coating parts and solved the problem that the zinc coating on galvanized parts affected the quality of zinc-chromium coating. Adopting acid pickling and dezincification process which is composed of sulfuric acid, sodium chloride and OP emulsifier, the integrity of the original zinc coating must be destroyed by shot blasting. Although the cost is low, there is the risk of hydrogen embrittlement, which is not suitable for high strength connection Parts and elastic parts. Alkali boiling with a solution consisting of sodium hydroxide and sodium nitrite is suitable for zinc-chromium coatings after all iron-based materials have been zincated. The two kinds of treated parts meet the requirements of 20% ammonium nitrate rapid corrosion test time> 1.5h.