【摘要】 以化工管道连接使用的Q235钢法兰为研究对象，对其进行磷化处理以提高耐蚀性。采用正交试验法考察了磷酸二氢锌浓度、氟化钠浓度、硝酸镧浓度、磷化液温度和磷化时间对磷化膜耐CuSO₄点蚀时间的影响，并通过极差分析得到最佳磷化工艺条件为：磷酸二氢锌浓度60 g/L、氟化钠浓度2.5 g/L、硝酸镧浓度40 mg/L、磷化液温度70℃、磷化时间15 min。将最佳磷化工艺条件用于法兰磷化处理，结果表明：法兰表面磷化膜呈深灰色，覆盖完整并且致密性较好，其物相组成为Zn₃（PO₄）₂·4H₂O和Zn₂Fe（PO₄）₂·4H₂O，腐蚀电位较Q235钢基体正移了约70 mV，腐蚀电流密度降低了至少一个数量级。该磷化膜能有效阻隔腐蚀介质延缓腐蚀，使磷化处理后法兰的耐蚀性显著提高。更多还原

【Abstract】 The Q235 steel flange for chemical pipe connection was treated by phosphating in order to improve its corrosion resistance,and the influence of zinc dihydrogen phosphate concentration,sodium fluoride concentration,lanthanum nitrate concentration,phosphating solution temperature and phosphating time on CuSO₄ pitting time of phosphating film was investigated by orthogonal experiment. The optimal phosphating process conditions obtained by range analysis were as follows:zinc dihydrogen phosphate 60 g/L,sodium fluoride 2.5 g/L,lanthanum nitrate 40 mg/L,phosphating solution temperature 70 ℃ and phosphating time 15 min,and the optimal phosphating process conditions were applied to the phosphating treatment of flange. The results showed that the phosphating film on the surface of flange was dark gray,completely covered and has good compactness,the phase composition was Zn₃（PO₄）₂·4H₂O and Zn₂Fe（PO₄）₂·4H₂O. The corrosion potential of phosphating film was about 70 mV higher than that of Q235 steel matrix,and the corrosion current density was reduced by at least one order of magnitude. This phosphating film can effectively block the corrosive medium and delay the corrosion,so that the corrosion resistance of the flange after phosphating treatment was significantly improved.更多还原