柠檬酸钠在常温磷化中的作用

Action of Sodium Citrate Accelerating Agent in Phosphating at Ambient Temperature

传统的亚硝酸盐磷化促进剂不符合清洁生产的发展需要，为此，通过X射线衍射、极化曲线、扫描电镜方法研究了柠檬酸钠作为促进剂对常温磷化的成膜时间、成膜厚度、磷化膜的表面状态及耐蚀性等的影响。结果表明，柠檬酸钠含量在0．5～2．5g／L时能有效增加磷化膜的厚度，成膜均匀致密，膜层耐腐蚀性能最佳。

Sodium citrate was used as an accelerating agent for phosphating to replace conventional nitrite accelerating agent so as to realize clean production of phosphating.Thus the effects of the sodium citrate accelerating agent on the film-forming time,film thickness,and the morphology and corrosion resistance of the phosphating film were investigated by means of X-ray diffraction analysis,measurement of polarization curve,and scanning electron microscopic observation.As the results,it was feasible to prepare thick,uniform,and compact phosphating film when the concentration of the sodium citrate was kept within 0.5~2.5(g/L),and the resulting phosphating film had good corrosion resistance as well.