Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016, People's Republic of China.
Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016, People's Republic of China.
Acta Biomater. 2014 Jun;10(6):2866-75. doi: 10.1016/j.actbio.2014.02.032. Epub 2014 Feb 26.
The use of nanostructuring to improve the stability of passive thin films on biomaterials can enhance their effectiveness in corrosion resistance and reduce the release of ions. The thickness of the ultrathin films that cover Ti and Ti alloys (only several nanometers) has prevented researchers from establishing systematic methods for their characterization. This study employed a multifunctional biomedical titanium alloy Ti-24Nb-4Zr-8Sn (wt.%) as a model material. Coarse-grained (CG) and nanostructured (NS) alloys were analyzed in 0.9% NaCl solution at 37°C. To reveal the details of the passive film, a method of sample preparation producing a passive layer suitable for transmission electron microscope analysis was developed. Electrochemical corrosion behavior was evaluated by potentiodynamic polarization tests and Mott-Schottky measurements. Surface depth chemical profile and morphology evolution were performed by X-ray photoelectron spectroscopy and in situ atomic force microscopy, respectively. A mechanism was proposed on the basis of the point defect model to compare the corrosion resistance of the passive film on NS and CG alloys. Results showed that the protective amorphous film on NS alloy is thicker, denser and more homogeneous with fewer defects than that on CG alloy. The film on NS alloy contains more oxygen and corrosion-resistant elements (Ti and Nb), as well as their suboxides, compared with the film on CG alloy. These characteristics can be attributed to the rapid, uniform growth of the passive film facilitated by nanostructuring.
利用纳米结构化来提高生物材料上无源薄膜的稳定性，可以提高其抗腐蚀的有效性，并减少离子的释放。覆盖钛和钛合金（只有几纳米厚）的超薄薄膜厚度，使得研究人员无法为其建立系统的表征方法。本研究采用多功能生物医学钛合金 Ti-24Nb-4Zr-8Sn（重量%）作为模型材料。在 37°C 的 0.9%NaCl 溶液中分析了粗晶（CG）和纳米结构（NS）合金。为了揭示钝化膜的细节，开发了一种制备适用于透射电子显微镜分析的钝化层的样品制备方法。通过动电位极化测试和 Mott-Schottky 测量评估电化学腐蚀行为。通过 X 射线光电子能谱和原位原子力显微镜分别进行表面深度化学剖面和形貌演化。基于点缺陷模型提出了一种机制，以比较 NS 和 CG 合金上钝化膜的耐腐蚀性。结果表明，与 CG 合金相比，NS 合金上的保护非晶薄膜更厚、更致密、更均匀，缺陷更少。与 CG 合金上的薄膜相比，NS 合金上的薄膜含有更多的氧和耐腐蚀元素（Ti 和 Nb）及其亚氧化物。这些特性可归因于纳米结构化促进的钝化膜的快速、均匀生长。
