磷化膜无铬封闭工艺研究

Study on chromium-free sealing process of phosphating film

针对磷化膜重铬酸填充的有毒有害问题,设计开发基于碱溶性聚丙烯酸树脂的无铬封闭液的配方及工艺,以点滴时间为评判指标,通过单因素实验考察了水性树脂种类、碱性助溶剂种类、硅溶胶含量、交联剂种类的影响,确定封闭液的主要组成为聚丙烯酸树脂PAA671、氨水、硅溶胶、锆交联剂;利用正交试验考察了氨水、硅溶胶、锆交联剂的影响,结果显示硅溶胶含量为最重要因子,其次为锆交联剂。浓缩封闭液组成为17.5 wt.%PAA671、14 wt.%中性硅溶胶、14 wt.%氨水、0.14 wt.%有机锆交联剂,余量为离子水,使用时按2∶5用去离子水稀释;封闭工艺为:试样在封闭液中浸泡2 min,然后在70~85℃下烘干15~30 min。

Aiming at the toxic and harmful problem of dichromate filling in phosphating film,the formula and process of chromium-free sealing solution based on the alkali-soluble polyacrylic resin were designed and developed.Taking the dropping time as the evaluation index,the effects of the type of water-soluble resin,the type of alkaline cosolvent,the content of silica sol and the type of cross‐linker were investigated through the single-factor experiment.The main components of the sealing solution were determined to be PAA 671 resin,ammonia,silica sol and zirconium cross-linking agent.The influences of ammonia,silica sol and zirconium cross-linking agents were investigated by orthogonal experiment.The results showed that the content of silica sol was the most important factor,followed by the zirconium cross-linking agent.The concentrated sealing solution group was 17.5 wt.%PAA 671,14 wt.%neutral silica sol,14 wt.%ammonia water,0.14 wt.%organic zirconium cross-linking agent,and the rest was ionic water,which was diluted with deionized water at a ratio of 2∶5.The sealing process was as follows:the sample was soaked in the sealing liquid for 2 min,and then dried at 70‒85℃for 15‒30 min.