铂族及过渡金属对Ti合金钝化影响机理研究

The study of the influence mechanism of platinum group and transition metals on the passivation of Tialloys

采用递归法计算了Ti合金的电子结构,从电子层面证实了Ni,Co,Pt,Ru,Ir在合金表面偏聚.聚集的Ni,Co以团簇的形式分布在合金表面,Pt,Ru,Ir与钛形成有序相.合金元素团簇与不含合金元素的Ti区形成微电池,在腐蚀介质的作用下使Ti优先分解,留下难溶的合金元素的颗粒在合金表面形成富集层.有序相中Ti的活性高于合金元素,Ti溶解,同样留下合金元素的颗粒在合金表面形成富集层.合金元素的富集层通过电催化作用促进Ti合金的钝化,从而提高Ti合金的抗腐蚀能力.同时添加贵金属和过渡元素(Ru和Ni,Ru和Ir,Ru和Mo,Ru和W)与添加单独Pt等贵金属产生同样效果.

The electronic structure of Ti alloys has been calculated by the recursion method. Alloying element s Ni, Co, Pt, Ru and Ir were confirmed to segregate on the surface of Ti alloys. Ni and Co atoms formatomic clusters, while Pt, Ru and Ir atoms form the ordered phase with Ti atoms. The microcells are formed between the area with alloying atomic clusters and the region without alloying elements. Ti is dissolved preferentially in the corrosive media, and the enrichment layer on the surface of Ti alloys is formed by the remaining insoluble grain of the alloying elements. The enrichment layer of alloying atoms serves as the electrocatalytic surface, which facilitates the passivation of Ti alloys and improves the corrosion resistance. The co-added alloy elements, such as Ru-Ni, Ru-Ir, Ru-Mo and Ru-W, have the same effect as adding the noble metals （such as Pt）.