对Q235钢片进行中性盐雾(NSS)腐蚀后再采用单宁酸–磷酸复合体系进行转化处理。研究了转化液组成和NSS时间对转化膜耐蚀性的影响，表征了单宁酸–磷酸复合转化膜的耐蚀性、表面形貌和组成，并探讨了转化膜的形成和作用机理。结果表明，单宁酸–磷酸复合转化可显著提高带锈钢材的耐蚀性，最佳的转化液组成为5 g/L单宁酸+15 g/L磷酸。单宁酸–磷酸复合转化膜为蓝灰色，主要由单宁酸铁螯合物和FePO4组成，表面平整、致密。%s: Q235 steel plate was corroded by neutral salt spray (NSS) followed by conversion coating with a tannic–phosphoric acid composite system. The effects of conversion bath composition and NSS corrosion time on the corrosion resistance of conversion coating were studied. The corrosion resistance, surface morphology, and composition of tannic–phosphoric acid composite conversion coating were characterized. The mechanism of formation and action of the composite conversion coating was discussed. The results showed that the tannic–phosphoric acid composite conversion can dramatically improve the corrosion resistance of rusty steel substrate. The optimal conversion bath comprises of 5 g/L tannic acid and 15 g/L phosphoric acid. The tannic–phosphoric acid composite conversion film is blue-gray, smooth, and compact, and mainly composed of ferric tannate chelate and FePO4.
展开▼
