化学表面处理对NiTi形状记忆合金耐蚀性的影响

通过化学表面处理在医用NiTi形状记忆合金上形成了主要成分为羟基磷灰石的活钙磷层。钙磷层的存在提高了NiTi合金在模拟人体环境中的耐蚀性，抑制了Ni离子在生物体内的溶出，改善了生物相容性。     

NiTi形状记忆合金疲劳行为的研究现状

NiTi形状记忆合金具有比其它同类合金更优良的力学性能、形状记忆效应、超弹性、阻尼特性和生物相容性等特点,广泛应用于工程、民用和医学领域.综述了NiTi形状记忆合金疲劳行为的研究现状;对其疲劳行为及其机制的研究,有助于进一步提高NiTi形状记忆合金的性能并延长它的寿命.     

NiTi合金生物医用材料表面改性的研究进展

NiTi形状记忆合金作为重要的生物医用材料已经获得了广泛的应用,但Ni离子在人体环境中的释放引起了人们的忧虑.系统介绍了近年来表面改性提高NiTi合金生物相容性的主要方法、技术特点和优势.在众多的研究方法中,热氧化和自组装方法因具有工艺简单、成本低等优点而最具工业应用前景.有关NiTi合金表面涂层与细胞和血液的相互作用机理的研究亟待加强,微观方面应重视基因水平的评价,宏观方面应加强活体植入的研究.研究机构应与产业界密切配合,进一步推动相关涂层的产业化进程.     

生物医用多孔金属材料的研究进展

本文综述了生物医用多孔金属材料在制备工艺、力学性能、耐蚀性及生物相容性方面的研究进展。作为一种新型的硬组织修复材料 ,生物医用多孔金属材料以其优良的生物相容性在矫形外科、牙科等医疗领域有广阔的应用前景     

生物医用多孔金属材料的研究进展

本文综述了生物医用多孔金属材料在制备工艺，力学性能，耐蚀性及生物相容性方面的研究进展。作为一种新型的硬组织修复材料，生物医用多孔金属材料以其优良的生物相容性在矫形外科，牙科等医疗领域有广阔的应用前景。     

医用多孔Ni-Ti形状记忆合金的研究与应用进展

总结了医用多孔Ni-Ti形状记忆合金的研究和应用进展情况，多孔Ni-Ti合金由于具有优异的形状记忆性能，良好的力学性能和优良的生物相容性，是最有发展前途的生物医用材料之一，极具开放价值。     

生物医用多孔Ti-Ni形状记忆合金的研究进展

综述了多孔Ｔｉ－Ｎｉ形状记忆合金的发展历史、制备技术、生物相容性、力学性能及其应用等方面的研究进展。一种用于人体硬组织修复和替换的新型生物医用材料－多孔Ｔｉ－Ｎｉ形状记忆合金,由于其多孔结构及独特的形状记忆与伪弹性、优良的生物相容性和力学性能等特点。伴随其制备工艺的改进,已经引起世界各国科学家的极大关注。     

TC4合金表面激光原位合成Ti／TiC生物涂层的组织结构及性能

为了提高医用TC4合金的耐磨性能,在其表面预置石墨粉,激光原位合成了Ti／TiC复合涂层,并分析了涂层的组织结构、显微硬度、耐磨性、耐蚀性及生物相容性。结果表明：涂层无气孔、裂纹等缺陷,组织为树枝晶状,显微硬度和耐磨性能较基材分别提高1倍和4．35倍,且耐蚀性及生物相容性较喷砂处理的医用TC4合金基材明显提高。     

医用多孔Ni-Ti形状记忆合金的制备和性能研究进展

多孔Ni-Ti形状记忆合金作为一种人体硬组织修复和替换的新型生物医用材料,在生物医学方面具有良好的应用前景。综述了多孔Ni-Ti形状记忆合金在制备工艺、孔结构特点、形状记忆效应、超弹性及生物相容性等方面的研究进展,分析并提出了尚待解决的问题,展望了今后的研究方向。     

生物医用镁合金材料的应用及耐蚀性研究进展

镁合金具有良好的力学性能,与人体生物相容性好,尤其是在人体内具有可生物降解的特点,是一种非常有前途的可降解生物医用金属材料.综述了镁和镁合金作为可降解生物医用材料的优越性和存在问题,生物医用镁合金的国内外研究现状,镁和镁合金的腐蚀机理及腐蚀类型,总结了当前用于提高生物医用纯镁和镁合金耐蚀性的方法,并对生物医用镁合金体内体外耐蚀性能进行了比较,展望了可降解生物医用材料的未来发展前景和研究方向.     

Fabrication and biocompatibility of polyethyleneimine/heparin self-assembly coating on NiTi alloy

NiTi alloy has been used widely as biomaterials. But because of toxic effects possibly caused by excess Ni ions released during the corrosion process in the physiological environment, it is still a controversial material. Fabricating medicine-loaded coating, which is expected to decrease the release of Ni ions and improve the biocompatibility of the materials, is a potential way to solve the problem. In this paper, NiTi alloy is coated by polyethyleneimine/heparin films via layer-by-layer (LBL) self-assembly method. UV-Vis, FT-IR, atomic force microscopy (AFM) and contact angle measurements are used to characterize the microstructure of coatings and select the best fabrication conditions. Potentiodynamic polarization researches in sodium chloride and dynamic clotting time experiment are utilized to study its corrosion resistance capability and biocompatibility of coatings, respectively. The results indicate that PEI/heparin multilayer coating can improve the biocompatibility of NiTi alloy surface.     

溶胶-凝胶法制备TiO2与SiO2-TiO2薄膜对医用NiTi合金的表面改性

采用溶胶－凝胶法制备TiO2与SiO2-TiO2薄膜，对医用NiTi合金进行表面改性处理，利用X射线衍射（XRD）、原子力显微镜（AFM）、划痕试验和电化学腐蚀试验等手段系统研究了薄膜结构、形态及性能。通过动态凝血时间和血小板粘附的测量研究和评价了薄膜的体外血液相容性。结果表明，在一定范围内，较高热处理温度有利于薄膜与基体间的结合强度和耐腐蚀性的提高；NiTi合金表面镀TiO2与SiO2-TiO2薄膜后，其血液相容性明显提高。     

医用镍钛合金表面涂覆技术研究概述

镍钛(NiTi)合金因其优异的形状记忆和超弹性性能,良好的耐腐蚀性和生物相容性,在生物医学领域得到了广泛应用。为了避免直接使用可能出现的生物不相容和细胞毒性,采用表面涂覆技术在合金表面涂覆纳米到微米量级厚度的功能薄膜,使其具有比基体更优良的生物相容性、抗腐蚀性和耐磨性等特殊功能。表面涂覆技术与其它表面改性技术相比,具有约束条件少、技术类型广、材料选择空间大等优势,目前应用最为广泛。对电化学沉积、等离子喷涂、磁控溅射、溶胶凝胶法、浸涂技术制备的涂层微观结构、力学性能和耐腐蚀等性能进行综述,并分析各技术的优缺点。随着涂覆技术的发展及制备涂层性能的进一步提高,NiTi合金在牙齿矫正丝、人工关节骨茎、血管成形环等多种医疗领域中的应用将更加广泛和深入。     

Characterization of Sol-gel-derived TiO2 and TiO2-SiO2 Films for Biomedical Applications

In order to improve the corrosion resistance and biocompatibility of NiTi surgical alloy, TiO2 and TiO2-SiO2 thin films were prepared by sol-gel method. The surface characteristics of the film, which include surface composition, microstructure and surface morphology, were studied by X-ray diffraction (XRD), atomic force microscopy (AFM) and X-ray photoelectron spectra (XPS), respectively. A scratching test was used to assess the interface adhesive strength between the film and substrate. The corrosion resistance of NiTi alloy coated with oxide films were studied by anodic polarization curves measurement in biological solution. Additionally, a preliminary study of the in vitro bioactivity of the films was conducted. The results indicated that TiO2 and TiO2-SiO2 (Ti/Si=4:1) films have higher electrochemical corrosion resistance and can be used as protective layers on NiTi alloy. In addition, TiO2-SiO2 composite films have better bioactivity than TiO2 film.     

Characterization of TiO2/Ta2O5 Films Synthesized by Ion Beam on NiTi Alloy for Biomedical Applications

The biocompatibility of implants is determined by their corrosion resistance and surface characteristics. In this study, the surface composition, morphology and microstructure of TiO2/Ta2O5 films synthesized by ion beam enhanced deposition on NiTi alloy were studied. The scratch test results indicate that the interface adhesive strength of TiO2/Ta2O5 film increases with the increasing Ta content. The electrochemical corrosion measurement shows that the TiO2-36%Ta2O5 film is optimal for improving corrosion resistance of NiTi alloy.     

Influence of the microstructure on electrochemical corrosion and nickel release in NiTi orthodontic archwires

The aim of this work was to determine the influence of the present phases and the chemical composition on the corrosion behavior and the nickel ion release of the NiTi orthodontic archwires. Eight Ni–Ti archwires from six commercial brands, in the as-received condition, were studied. The chemical composition, roughness, microstructure and the proportion of the phases as well as the corrosion behavior were analyzed for each archwire. The nickel ion release was characterized in artificial saliva immersion settings ranging up to 4 weeks. The results show that the presence of the martensitic phase improves corrosion resistance and significantly decreases Ni release into exterior medium in comparison with the austenitic specimens. In spite of the partial loss of superelasticity produced in the martensitic phase, it could be of great interest for biomedical applications, as it could minimize sensitization and allergies and improve biocompatibility and corrosion resistance of NiTi shape memory alloys.     

Biocompatibility and corrosion behavior of the shape memory NiTi alloy in the physiological environments simulated with body fluids for medical applications

Due to unique properties of NiTi shape memory alloys such as high corrosion resistance, biocompatibility, super elasticity and shape memory behavior, NiTi shape memory alloys are suitable materials for medical applications. Although TiO₂ passive layer in these alloys can prevent releasing of nickel to the environment, high nickel content and stability of passive layer in these alloys are very debatable subjects. In this study a NiTi shape memory alloy with nominal composition of 50.7 atom% Ni was investigated by corrosion tests. Electrochemical tests were performed in two physiological environments of Ringer solution and NaCl 0.9% solution. Results indicate that the breakdown potential of the NiTi alloy in NaCl 0.9% solution is higher than that in Ringer solution. The results of Scanning Electron Microscope (SEM) reveal that low pitting corrosion occurred in Ringer solution compared with NaCl solution at potentiostatic tests. The pH value of the solutions increases after the electrochemical tests. The existence of hydride products in the X-ray diffraction analysis confirms the decrease of the concentration of hydrogen ion in solutions. Topographical evaluations show that corrosion products are nearly same in all samples. The biocompatibility tests were performed by reaction of mouse fibroblast cells (L929). The growth and development of cells for different times were measured by numbering the cells or statistics investigations. The figures of cells for different times showed natural growth of cells. The different of the cell numbers between the test specimen and control specimen was negligible; therefore it may be concluded that the NiTi shape memory alloy is not toxic in the physiological environments simulated with body fluids.     

On the electropolishing of NiTi braided stents – challenges and solutions

Nickel Titanium (NiTi) alloys possess special mechanical properties and good biocompatibility hence used as base material for the production of vascular stents. Normally, vascular stents are machined from NiTi tubes, using laser cutting processes. Braiding is a promising alternative for the machining of certain NiTi stents. However, a surface finish treatment, such as electropolishing of the braided stents, is still required in order to achieve a medical‐grade surface finish. The thermally‐grown oxide resulting from the shape‐setting heat treatment, following the braiding must be removed. Moreover, electropolishing is required to achieve optimum corrosion resistance. Therefore, the aim of this study is to find suitable parameters for the effective electropolishing of NiTi textile stents. Electropolishing of a device with such a complex geometry is challenging, hence a custom‐designed electrolytic cell was constructed and used in this study. We examined the stent surfaces before and after electropolishing, using scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). Potentiodynamic tests were performed in NaCl 0.9% solution for as‐received and electropolished samples. The results from the present study indicate an improvement in surface quality of the braided stents after electropolishing. Potentiodynamic tests revealed that electropolishing improves the corrosion resistance of the NiTi stents.     

Electropolishing of NiTi for Improving Biocompatibility

A modified electrolyte （CH3COOH-HClO4-A-B） for electropolishing （EP） of NiTi was presented for improving the corrosion resistance and biocompatibility of the alloy. Using the proposed parameters, a homogeneous and uniform surface was obtained. Atomic force microscopy （AFM） revealed that the surface roughness （Ra） for EP sample （23.21 nm） was close to mechanical polishing （MP） sample （19.36 nm）. Analysis by X-ray photoelectron spectroscopy （XPS） showed that Ti/Ni ratio increased from 3.1 for MP sample to 27.6 for EP sample. Measurements using potentiodynamic polarization in Hanks＇ solution showed that no pitting occurred for EP sample even though the applied potential increased up to 1500 mV （vs SCE）, while the MP sample was broken down at 650 mV. The present study indicates that electropolishing NiTi with this modified electrolyte contributes to the improved biocompatibility of NiTi.