递归法研究Pt对Ti合金腐蚀影响

Study of corrosion effect of Pt on Ti alloys by recursion method

采用递归法计算了Ti及Ti合金的电子态密度、环境敏感镶嵌能、费米能级和格位能等电子结构参量.计算发现Pt在晶体中环境敏感镶嵌能和格位能高于表面,从电子层面证实Pt易在Ti合金表面偏聚.偏聚在表面的Pt有序能为正值,故Pt以有序相(Pt与Ti的化合物)形式分布在合金表面.晶体表面Pt与Ti的化合物电极电位较低,它与Ti形成微电池.在腐蚀介质的作用下,Pt与Ti的化合物分解,Pt沉淀到晶体表面造成Pt在合金表面形成凹凸不平的Pt电催化层.Pt电催化层加强Ti钝化作用,从而提高了Ti合金的抗腐蚀能力.

The electronic structure parameters of pure Ti and TiPt alloy, such as density of states, Fermi energy level, environmentsensitive embedding energy and order energy have been calculated by recursion method. The environment-sensitive embedding energy induced by Pt in Ti crystal is greater than that on Ti surface, so Pt is prone to gather on Ti surface. The order energy between Pt atoms is positive, which leads Pt atoms to form intermetallics with bulk Ti atoms. The electric potential of intermetallics is lower than that of Ti atom cluster at Ti alloy surface, so cells will form between intermetallics and Ti atom clusters, then the intermetallic will decompose in corrosive medium. With the deposition of Pt, a rough electrocatalytic Pt layer would form on the surface of Ti alloy. This electrocatalytic Pt layer enhances the passivation of Ti alloy and improves the corrosion resistance of Ti alloy.