XPS和AES研究碳钢表面杂多酸化学转化膜

XPS AND AES STUDIES OF THE POLYHETERO-ACIDS CHEMICAL CONVERSION FILMS FORMED ON STEEL SURFACE

用盐水浸泡、H_2S加速腐蚀试验和硫酸铜点滴试验比较了多种钼钒磷杂多酸对碳钢的防护效果。A_3钢经钼钒磷杂多酸盐溶液处理后,表面形成一层色彩鲜艳的转化膜,不但有良好的耐蚀性,且具有良好的装饰效果。其中以Na_4PMo_(11)VO_(40)所形成的膜最佳。XPS分析结果表明,在该膜层的表面,铁、钼、钒和磷分别以Fe(Ⅲ)、Mo(Ⅵ)、V(Ⅴ)和P(Ⅳ)状态存在;而在膜层的内部有低价的铁、钼和钒存在。从AES深度分布曲线的组成恒定区求得各组成元素的相对原子百分浓度(A·C%)为:Fe1.8%;P 10.0%;Mo 34.4%;V 0.59%;O 50.4%。

The corrosion resistance of chemical conversion films formed in various Mo-V-P polyhetero-acids has been compared by salt water immersion test, H_2S accelerated corrosion test and CuSO_4 spot test. The results show that the film formed by Na_4PMo_(11)VO_(40) has the best protective performance. A coloured conversion film was formed after mild steel had been treated in Na_4PMo_(11)VO_(40) solution, This film possessed both corrosion resistance and decorative function. The results of XPS show that Fe, Mo, V, and P are present as Fe(Ⅱ), Mo(Ⅵ), V(Ⅴ) and P(Ⅴ) respectively in the outer layer of the film, while the elements in the inner layer of the film exist in complex forms such as Fe (Ⅲ), Fe(Ⅲ), Mo(Ⅵ), Mo(Ⅵ) and Mo with lower valency than +4; V(Ⅴ), V(Ⅵ) and V with lower valency than +4 and P(Ⅴ). The atomic percentages (At. %) of the film composition obtained from the element composition constant section of the AES profile curve are Fe 1.8%; P 10. 0%; Mo 34. 4%; V 0. 59%; and O 50. 4%.