原位磷化有机涂层的耐腐蚀性能

Corrosion resistance of in-situ phosphatizing organic coatings

原位磷化是指基体表面磷化成膜过程和聚合物漆膜的固化过程可以在一道工序中同时完成的工艺。通过正交试验优化,得到了原位磷化剂的配方(以质量分数表示)为:磷酸2%,柠檬酸0.3%,酒石酸0.3%。将此磷化剂均匀分散到聚酰胺–酰亚胺(PAI)涂料中,然后涂覆于碳钢表面,探讨了涂膜的固化工艺,利用电化学测试方法对所得涂膜的耐蚀性能进行了研究。试验发现,当固化工艺为280°C/15min时,得到的原位磷化涂膜的附着力为1级,硬度4H,在3.5%NaCl溶液中的自腐蚀电流密度为5.4×104mA/cm2、自腐蚀电位为489mV,经100h中性盐雾试验后不发生变化,耐腐蚀性能优于传统磷化处理后的有机涂层。该工艺操作简单,可代替传统的磷化处理。

The in-situ phosphatizing coating （ISPC） is a one-step self-phosphating process, in which the deposition of phosphate layer on substrate surface and the curing of polymer paint film take place independently, but simultaneously. The formulation of in-situ phosphatizing reagent （ISPR） was optimized by orthogonal test as follows： H3PO4 2wt%, citric acid 0.3wt%, and tartaric acid 0.3wt%. A coating material was prepared by well dispersing the ISPR to polyamide-imide （PAl） resin, and then coated on carbon steel. The film curing process was discussed. The corrosion resistance of the cured film was studied electrochemically. The 1SPC film obtained by curing at 280 ℃ for 15 min features an adhesion strength of 1 grade, hardness 4H, freecorrosion current density 5.4 × 10^-4 mA/cm^2 and flee-corrosion potential -489 mV in 3.5wt% NaCI solution, and no change after 100 h neutral salt spray test, showing better corrosion resistance than the organic coating prepared after traditional phosphating. The process is easy-to-operate and expected to be an alternative to traditional phosphating treatment.