TiO_2/316L不锈钢薄膜电极在NaCl溶液中的耐腐蚀性能

Corrosion Resistance for TiO_2 Thin Films Coated 316L Stainless Steel in the NaCl Solution

应用sol-gel法和提拉技术于316L不锈钢表面构筑纳米TiO2薄膜,再经水热后处理以消除膜中的细小龟裂.SEM和XRD技术表征膜的形貌和厚度,线性极化法分别考察膜厚度、pH、和Cl浓度对纳米膜电极耐腐蚀性能影响.电化学交流阻抗检测纳米TiO2膜在0.5mol/L NaCl溶液中的阻抗随浸泡时间的变化,光电子能谱技术测定了经浸泡1008 h后的纳米膜中各元素相对百分含量和价态.结果表明:在中性或碱性条件下,厚度为375～464 nm的纳米膜其耐腐蚀性随浸泡时间的延长呈现初期增加而后稳定,浸泡48 h后腐蚀电流较之浸泡初期降低2个数量级,耐腐蚀电阻增加2个数量级,在浸泡1 008 h内没有发现腐蚀的产物,Fe是以原子态扩散到膜中.

The nano-TiO_2 thin films have been deposited on the 316L stainless steel by sol-gel and the dip- coating methods. Hydrothermal post-treatment leads to crack-free coatings. Meanwhile, the surface structure and properties are optimized. Surface morphology, structure and properties are characterized by XRD, and SEM technologies. The results have shown that the surface of coatings is porous, uniform and orderly, the particle diameters are in the range of 15~18nm and the pores are about 4~8nm and TiO_2 is anatase. The results of electrochemical measurements show that in the NaCl solution with pH ≥ 2 and concentration below 1mol/L, the nano-TiO_2 coatings with thinkness 375~464nm have most excellent anticorrosion properties. Compareing with bare 316L stainless steel, the corrosion current for coating electrodes in 0.5 mol/L NaCl solution has cut down 2 magnitude and the corrosion resistance R_(p) has also decreased nearly 2 magnitude.