25Cr2Ni4WA合金钢高温锰系磷化工艺

Technology for High Temperature Phosphating of 25Cr2Ni4WA Alloy Steel in Manganese Series Phosphating Solution

高温锰系磷化对部分高合金钢处理效果不佳。为此,对25Cr2Ni4WA合金钢黑色锰系磷化工艺进行了研究,通过正交试验,分析了磷化过程中总酸、酸比、Fe2+浓度、表调时间、磷化时间等因素对磷化膜耐蚀性能和膜重的影响。结果表明,适当的总酸、酸比、磷化时间以及降低Fe2+浓度和表调时间有利于提高耐蚀性能;适当的表调时间及增加总酸、酸比、Fe2+浓度和磷化时间有利于增加膜重。结果表明,为提高耐蚀性能,应尽量使磷化膜晶粒细小均匀、致密;获得较佳磷化膜耐蚀性能的工艺参数为:总酸110点,酸比6.0,0.6g/LFe2+,表调时间20s,磷化时间20min;膜重较佳的工艺参数为:总酸130点,酸比7.0,1.8g/LFe2+,表调时间40s,磷化时间20min。

The technology for high temperature phosphating of 25Cr2Ni4WA alloy steel in Mn series phosphating solution was studied. The effects of total acidity,the ratio of total acidity to free acidity,ferrous ion concentration,activation time and phosphating time on the corrosion resistance and weight of the phosphating coatings were analyzed by conducting orthogonal tests. Results indicate that the corrosion resistance of the phosphating coatings can be increased by properly controlling total acidity,ratio of total acidity to free acidity and phosphating time,as well as by decreasing ferrous ion concentration and surface modulation time. It was feasible to increase the weight of the phosphating coatings by properly adjusting surface modulation time and increasing total acidity,ratio of total acidity to free acidity,ferrous ion concentration and phosphating time. It was imperative to ensure that the phosphating coatings were compact and consisted of fine and uniformly distributed grains so as to obtain good corrosion resistance. Besides,the phosphating coating obtained at a total acid of 110 point,total acidity to free acidity ratio of 6.0,ferrous ion concentration of 0.6 g/L,activation time of 20 s and phosphating time of 20 min possessed excellent corrosion resistance,and that prepared at a total acid of 130 point,total acidity to free acidity ratio of 7.0,ferrous ion concentration of 1.8 g/L,activation time of 40 s and phosphating time of 20 min had the maximum weight.