用XPS研究钢筋钝化膜和C1^-对钝化膜的影响

A XPS STUDY OF REBAR PASSIVE FILM AND EFFECT OF CHLORIDE IONS ON IT

采用光电子能谱(XPS)研究钢筋钝化膜的组成与结构,以及氯离子对钝化膜的影响。结果表明,在本实验条件下钢筋钝化膜为双层结构,外层以γ-FeOOH为主,内层主要为FeO;氯离子对胶的破坏过程可能是先在钝化膜表面吸附,然后穿透到膜中,在铁/氧化物界面即膜的内层形成FeCl_2,而使钝化膜局部溶解;复合缓蚀剂的加入使钢筋钝化膜表面γ-FeOOH的含量增大,膜中夹杂一定深度的有机铵盐,硅酸盐只在表面沉积。

The composition and structure of rebar passive film as well as the effect of composite inhibitors and chloride ions on the film were studied by X-ray photoelectron spectroscopy. It was found that γ- FeOOH was the major oxide in the outer layer and the inner layer only contained FeO. The machanism of pitting corrosion induced by Cl- might be as follows. First, chloride ions adsorbed on rebar passive film, then they penetrated into the film through defects and accumulated in the inner layer of the film. Cl- and Fe2+ might form into FeCl2, so the passive film dissolved from its inner layer locally. After adding composite inhibitors, γ-FeOOH content in the outer layer increased and organic ammonium incorporated in the film to certain depth, and silicate only deposited on the surface of the film.