Q235钢分步法中温锌钙系黑膜磷化

Two-step black phosphating of Q235 steel in the medium temperature Zn-Ca series

通过先常温发黑后中温磷化的方法研制出了1种有效的黑膜磷化工艺.重点讨论了黑化液和磷化液的主要成分以及后处理工艺对Q235钢黑膜磷化的影响.实验结果表明:发黑剂A对钢铁的发黑起着关键性的作用,三氯化铁、钼酸铵、酒石酸对黑化膜的形成也各有不同的作用,最佳发黑时间为3.5～5min;在磷化液中磷酸二氢锌浓度不宜超过9.09%,硝酸钙、促进剂、络合剂和硼酸与黑色磷化膜的质量也有一定的关系;经皂化、油封等后处理后,黑色磷化膜的耐硫酸铜点滴时间可高达35min以上.

In this paper,an effective process of black phosphating was studied by blackening at room temperature first and then phosphating at medium temperature.The roles of main components of blackening and phosphating solutions as well as the influence of post-treatments on the surface of Q235 steel were investigated emphatically.It has been showed that blackening agent A plays a key role for the blackness of the steel surface,FeCl3,（NH4）6Mo7O24 and C4H6O6 also have different roles,the optimum blackening time is 3.5～5 min;The concentration of Zn（H2PO4）2 should not exceed 9.09% in phosphating solution,there is a certain relationship between Ca（NO3）2,accelerating agent,complexing agent,H3PO3 and the quality of black phosphating coating;In addition,by saponification,oil seals and other post treatments,the corrosion time of the black phosphating coating in copper sulfate spot test can be as high as 35min.