Liu Lin Lin, Xu Jiang, Lu Xiaolin, Munroe Paul, Xie Zong-Han
Department of Material Science and Engineering, Nanjing University of Aeronautics and Astronautics, 29 Yudao Street, Nanjing 210016, P. R. China.
School of Materials Science and Engineering, University of New South Wales, Sydney, New South Wales 2052, Australia.
ACS Biomater Sci Eng. 2016 Apr 11;2(4):579-594. doi: 10.1021/acsbiomaterials.5b00552. Epub 2016 Mar 8.
To explore its potential as a highly corrosion-resistant coating for biomedical titanium alloys, a novel β-Ta nanocrystalline coating, composed of equiaxed β-Ta grains with an average grain size ∼22 nm, was deposited onto Ti-6Al-4V substrate using a double glow discharge plasma technique. The newly developed coating exhibited an extremely dense and homogeneous microstructure, exhibiting a strong (002) preferred orientation. The electrochemical behavior and semiconducting properties, such as donor density, flat-band potential, and diffusivity of point defects (), of the passive film formed on the β-Ta coating were compared to those for both uncoated Ti-6Al-4V and commercially pure Ta in Ringer's physiological solution at 37 °C, using an array of complementary electrochemical techniques. The results showed that the β-Ta coating not only provided Ti-6Al-4V with good corrosion protection but also endowed a higher resistance to corrosive attack than commercially pure Ta in Ringer's physiological solution at 37 °C. Mott-Schottky analysis revealed that the passive film formed on the β-Ta coating had a lower donor density and flat-band potential than commercially pure Ta. The calculated values of for the β-Ta coating (1.45 × 10cm/s) are comparable to that for commercially pure Ta (1.13 × 10 cm/s), both of which are 1 order of magnitude lower than that for uncoated Ti-6Al-4V (2.73 × 10 cm/s). Compared with commercially pure Ta, the higher corrosion resistance of the β-Ta coating results from its nanosized grains and crystallographic orientation, which promotes the rapid formation of a robust passive film with a more compact structure.
为了探索其作为生物医学钛合金高耐腐蚀涂层的潜力，采用双辉光放电等离子体技术在Ti-6Al-4V基体上沉积了一种新型的β-Ta纳米晶涂层，该涂层由平均晶粒尺寸约为22nm的等轴β-Ta晶粒组成。新开发的涂层呈现出极其致密和均匀的微观结构，表现出强烈的(002)择优取向。使用一系列互补的电化学技术，将在β-Ta涂层上形成的钝化膜的电化学行为和半导体性能（如施主密度、平带电位和点缺陷扩散率()）与未涂层的Ti-6Al-4V和商业纯Ta在37℃的林格氏生理溶液中的情况进行了比较。结果表明，β-Ta涂层不仅为Ti-6Al-4V提供了良好的腐蚀防护，而且在37℃的林格氏生理溶液中赋予了比商业纯Ta更高的抗腐蚀能力。莫特-肖特基分析表明，在β-Ta涂层上形成的钝化膜的施主密度和平带电位低于商业纯Ta。β-Ta涂层的计算值(1.45×10cm/s)与商业纯Ta的计算值(1.13×10cm/s)相当，两者均比未涂层的Ti-6Al-4V(2.73×10cm/s)低1个数量级。与商业纯Ta相比，β-Ta涂层更高的耐腐蚀性源于其纳米尺寸的晶粒和晶体取向，这促进了具有更致密结构的坚固钝化膜的快速形成。
