免水洗钡盐改性常温复合磷化研究

Room Temperature Washing-Free Composite Phosphating Coating Modified with Barium Salt

钢铁试片在由磷酸、氧化锌、硝酸钙、硝酸钡、钼酸铵等组成的钡盐改性复合磷化液中常温快速磷化后,自然干燥3h以上,即生成免水洗的彩色磷化膜。采用SEM和EDS技术对磷化膜形貌和元素含量进行了分析。结果表明:免水洗的磷化膜由Fe2+、Zn2+、Ca2+、Ni2+、Mn2+、Ba2+的磷酸盐及少量的钼酸盐等组成,膜晶粒尺寸≤2μm,膜连续、致密,膜重约1.5g/m2,耐3%NaCl溶液腐蚀约2h,喷涂铁红环氧底漆后附着力达1级。

Room-temperature fast phosphating of steel was conducted in a barium salt-modified composite phosphating solution consisting of phosphate, zinc oxide, calcium nitrate, barium nitrate and ammonium molybdate to generate color washing-free phosphating coating after drying in air for more than 3 h. The morphology and composition of the composite phosphating coating were analyzed by means of scanning electron microscopy and energy dispersive spectrometry. Results show that the washing-free phosphating coating consists of the phosphates of Fe2+, Zn2+, Ca2+, Ni2+, Mn2+ and Ba2+, and a small amount of molybdates. The phosphating coating was continuous and compact with a crystalline size of less than 2 μm and weight of 1.5 g/m2, and only experienced slight corrosion after being immersed in 3% NaCl solution for 2 h. After being coated with iron red epoxy resin lacquer, the adhesion of the phosphating coating reached first grade.