不同元素掺杂对氯离子在TiO_2膜扩散的影响研究

通过过渡态计算软件CINEB模拟了不同元素掺杂到金红石型TiO_2膜后,氯离子在TiO_2膜的扩散路径和对扩散势垒的影响。结果表明,TiO_2膜中扩散路径A具有更大的孔洞,钛和氯离子吸附性较弱,使氯离子扩散势垒较小,因此氯离子在路径A中更容易扩散。Al元素掺杂后铝原子失去电子转移到邻近的氧,氯离子和氧离子间存在较强的排斥作用,导致晶体结构畸变,有效阻碍氯离子扩散,提高耐腐蚀性能。Mo元素掺杂后,Mo的3d轨道与Cl的2p轨道有较强的杂化作用,Mo和Cl之间有较强吸附作用,使得氯离子很难脱离,因此提高材料的耐蚀性。Al、Zr、Mo、Nb的扩散势垒较高,对提高钛合金的耐腐蚀性能有显著作用。通过实验验证了Ti-5.5Al-3.0Zr-2.0Sn-0.8Mo-1.5Nb合金的自腐蚀电流最小,耐腐蚀性能最好,与计算结果一致。

Influence of Different Elements Doping on the Diffusion of Chloride Ion in TiO_2 Film

The transition state calculation software CINEB was used to simulate the diffusion path and diffusion barrier of chlorine ion, after doping with different elements in rutile type TiO_2 film. The results show that the diffusion path A has larger holes and the adsorption of titanium and chlorine ions is weak, which makes the diffusion barrier of chlorine ions smaller, leading to the diffusion of chloride ion easier in path A. After Al element doping, aluminum atoms lose electrons and transfer to adjacent oxygen. Strong repulsion exists between chlorine ion and oxygen ion, result in the distortion of crystal structure and the slowly diffusion of chloride ion to improve corrosion resistance. After Mo doping, the 3 d orbital of Mo has a strong hybridization effect with the 2 P orbital of Cl, and there is a strong adsorption effect between Mo and Cl, making it difficult for chlorine ion to get out, so the corrosion resistance of material improved. The diffusion barrier of Al, Zr, Mo and Nb are high, which has a significant effect on the corrosion of titanium alloy. It is verified by experiments that Ti-5.5 Al-3.0 Zr-2.0 Sn-0.8 Mo-1.5 Nb has the minimum corrosion current and the best corrosion resistance, which is consistent with the calculated results.