钛(Ⅳ)离子改性低铬钝化膜的研究

Study on Low-Chromate Film Modified with Fourvalent Titanium Compound

应用SEM、EDX、XRD和腐蚀测试手段研究了Ti(Ⅳ )化合物改性低铬钝化膜的组成、结构和耐蚀性能。实践和理论表明 :所形成的钝化膜 ,实际上是铬酸钝化反应和Ti(Ⅳ )化合物水解 -沉淀反应产物的有机结合 ,是一种由CrOOH ,ZnCrO4 ,TiO2 ,Cr2 O3 和TiOSO4 等物质组成的复合型钝化膜。这种钝化膜的耐蚀性是低铬钝化膜的 3～ 4倍 ,其主要原因是因为钝化膜内Ti(Ⅳ )离子的掺杂效应和Ti(Ⅳ )化合物水解 -封闭作用 ,能有效地阻止H2 O、O2

The composition, structure and corrosion resistance of Ti(Ⅳ) compound modified passivating film formed from low concentration chromate containing solution are studied by means of SEM,?EDX? XRD and corrosion measurements. Practice and theory show that the passivating film is kind of composite film consisting of CrOOH, ZnCrO 4, TiO 2,Cr 2O 3 and TiOSO 4 because it is formed bv chromatizins and hydrolysis depositione reaction. Corrosion resistance of this kind of passivating film is 3～4 times higher than that of low chromate film, and is caused by hydrolysis sealing effect Ti(Ⅳ) ions in the film, to effectively control H 2O and Cl - attack.