NiTi合金表面液相阴极等离子体沉积氧化铝陶瓷涂层的研究

在NiTi合金表面通过液相阴极等离子体技术制备了氧化铝(Al2O3)陶瓷涂层。采用X射线衍射和扫描电镜对涂层的相组成以及表面形貌进行了表征和分析,证实在材料表面形成了由α-Al2O3和γ-Al2O3组成的涂层,发现涂层具有粗糙多孔结构。在模拟体液中对NiTi合金的Ni离子释放情况进行了检测,发现液相阴极等离子体改性后显著降低了Ni离子的释放。为NiTi合金植入体的表面改性提供了一条新途径。     

Structure and properties of TiC/Ti coatings fabricated on NiTi by plasma immersion ion implantation and deposition

A titanium carbide (TiC) nanostructured coating and Ti intermediate layer are fabricated on NiTi by plasma immersion ion implantation and deposition (PIII&D) to improve the surface properties. The chemical composition and structure are determined by X-ray diffraction, Auger electron spectroscopy, scanning electron microscopy, and atomic force microscopy. Nano-indentation is used to evaluate the mechanical properties of the thin film and the biological characteristics are assessed by electrochemical measurement and soaking tests in simulated body fluids. Based on the potentiodynamic polarization and Ni release data after the polarization test, the Ti/TiC nanostructure coating has better corrosion resistance compared to the NiTi substrate and there is significantly less Ni ion release from the NiTi substrate into the simulated body fluids than the uncoated NiTi alloy.     

NiTi superelastic orthodontic archwires with polyamide coating

Twenty orthodontic archwires with 55.2 % Ni and 44.8 % Ti (% weight) were subjected to a dipping treatment to coat the NiTi surface by a polyamide polymer. It has been selected a Polyamide 11 due to its remarkable long lasting performance. The transformation temperatures as well as the transformation stresses of the NiTi alloy were determined in order to know whether the coating process can alter its properties. The adhesive wear tests have been demonstrated that the wear rates as well as the dynamic friction coefficients μ of polymer coated wires are much lower than metallic wires. The corrosion studies have shown that the use of this polymer, as coating, seals the NiTi surface to prevent corrosion and the release of nickel ions. The average decrease of Ni ions release due to this coating is around 85 %.     

不同等离子源形成的DLC涂层对NiTi合金腐蚀行为的影响

采用等离子浸没离子注入和沉积(PIIID)法分别以C2H2和石墨为等离子源在NiTi合金表面形成DLC涂层来提高该合金的耐腐蚀性.利用Raman光谱和扫描电镜分析膜层结构.利用电化学测试和原子吸收光谱测试涂层前后基体的耐腐蚀性和Ni离子析出.结果表明:采用等离子浸没离子注入和沉积法以乙炔和石墨为等离子源在NiTi合金表面形成均匀致密、结合力良好的DLC涂层.两种涂层都明显地提高了NiTi合金的耐腐蚀性能和有效地抑制了Ni离子的溶出.     

NiTi合金生物医用材料表面改性的研究进展

NiTi合金由于其形状记忆效应、超弹性和低模量等优良性能在生物医学领域得到广泛应用。然而,在生理环境中镍离子释放会诱发毒性和炎性反应,因此需要对其进行表面改性。从表面氧化、表面涂层和表面接枝大分子等方面综述了近年来国内外NiTi合金表面改性的研究进展,评述了各种表面改性技术的优势和缺陷,指明了NiTi合金表面改性的未来发展趋势。     

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。     

A comparative study of apatite coating and apatite/collagen composite coating fabricated on NiTi shape memory alloy through electrochemical deposition

To improve bioactivity and long-term biocompatibility of NiTi shape memory alloys (SMAs), apatite and apatite/collagen composite coatings were formed at 37 °C on the metal through electrochemical deposition using double-strength simulated body fluid (2SBF) without and with dissolved collagen, respectively. Surface characteristics, wettability and chemical stability of the coatings were subsequently studied and comparisons were made between the apatite coating and apatite/collagen composite coatings. Surface morphology of the apatite/collagen coating revealed that many collagen fibers were embedded in apatite with flake-like structures. The phase composition and chemical composition analyses showed that calcium-deficient and carbonated hydroxyapatite with low crystallinity was formed in the apatite and apatite/collagen coatings. Moreover, the wettability of uncoated and coated NiTi SMA samples was investigated. Compared to both uncoated and apatite-coated NiTi SMA samples, apatite/collagen-coated samples were more chemically stable and exhibited higher corrosion resistance.     

医用金属表面溶胶-凝胶法和离子束合成TiO2薄膜的结构、性能比较

采用溶胶-凝胶法和离子束增强沉积法在医用NiTi合金表面制备TiO₂薄膜以提高其生物相容性.利用X射线衍射（XRD）、原子力显微镜（AFM）和X光电子能谱（XPS）对薄膜的结构、表面形貌及组成进行了比较研究;电化学腐蚀实验表明,两种方法制备的TiO₂薄膜对金属基体均起到一种保护膜的作用,能够提高医用金属材料在模拟体液中的抗腐蚀性;对薄膜表面固定肝素抗凝血分子进行研究发现,溶胶-凝胶法制备的TiO₂薄膜表面能够获得较好的肝素固定效果.     

Ca/P层对NiTi形状记忆合金生物相容性的影响

用化学法在ＮｉＴｉ形状记忆合金表面修饰了一层Ｃａ／Ｐ层。Ｘ射线分析表明,Ｃａ／Ｐ层的主要成分是Ｃａ５（ＰＯ４）３（ＯＨ）,还有少量的α－Ｃａ２Ｐ２Ｏ７和β－Ｃａ３（ＰＯ４）２。原子吸收光谱的测量表明,Ｃａ／Ｐ层抑制镍离子在人体模拟溶液中的溶出。植入试验的结果表明,Ｃａ／Ｐ层改善了ＮｉＴｉ形状记忆合金的生物相容性。     

Characteristics and in vitro biological assessment of (Ti, O, N)/Ti composite coating formed on NiTi shape memory alloy

In this investigation, plasma immersion ion implantation and deposition (PIIID) was used to fabricate a (Ti, O, N)/Ti coating on NiTi shape memory alloy (SMA) to improve its long-term biocompatibility and wear resistance. The surface morphology, composition and roughness of uncoated and coated NiTi SMA samples were examined. Energy dispersive X-ray elemental mapping of cross-sections of (Ti, O, N)/Ti coated NiTi SMA revealed that Ni was depleted from the surface of coated samples. No Ni was detected by X-ray photoelectron spectroscopy on the surface of coated samples. Furthermore, three-point bending tests showed that the composite coating could undergo large deformation without cracking or delamination. After 1 day cell culture, SaOS-2 cells on coated samples spread better than those on uncoated NiTi SMA samples. The proliferation of SaOS-2 cells on coated samples was significantly higher at day 3 and day 7 of cell culture.     

医用多孔NiTi合金表面微弧氧化改性研究

为解决多孔Ni Ti合金耐蚀性降低和Ni离子释放量增大而引起的使用安全性问题.本文采用微弧氧化技术对医用多孔Ni Ti合金进行表面改性处理,研究结果表明,微弧氧化处理并未改变多孔Ni Ti合金原有的孔隙结构和孔隙率,只在其外表面和孔隙内表面均形成了典型的微弧氧化多孔涂层.该涂层主要由氧化铝相组成,并含有少量的Ti和Ni元素,且外表面涂层的Ti和Ni含量要略低于孔隙内表面涂层.微弧氧化涂层提高了多孔Ni Ti合金的表面接触角,将原有的亲水表面转变成了疏水表面.经微弧处理后,多孔Ni Ti合金的耐蚀性较基体提高了1个数量级以上,Ni离子释放量也较基体降低了1个数量级以上.     

Blood compatibility of zinc–calcium phosphate conversion coating on Mg–1.33Li–0.6Ca alloy

Magnesium alloys as a new class of biomaterials possess biodegradability and biocompatibility in comparison with currently used metal implants. However, their rapid corrosion rates are necessary to be manipulated by appropriate coatings. In this paper, a new attempt was used to develop a zinc-calcium phosphate (Zn-Ca-P) conversion coating on Mg-1.33Li-0.6Ca alloys to increase the biocompatibility and improve the corrosion resistance. In vitro blood biocompatibility of the alloy with and without the Zn-Ca-P coating was investigated to determine its suitability as a degradable medical biomaterial. Blood biocompatibility was assessed from the hemolysis test, the dynamic cruor time test, blood cell count and SEM observation of the platelet adhesion to membrane surface. The results showed that the Zn-Ca-P coating on Mg-1.33Li-0.6Ca alloys had good blood compatibility, which is in accordance with the requirements for medical biomaterials.     

Dissolution effect and cytotoxicity of diamond-like carbon coatings on orthodontic archwires

Nickel–titanium (NiTi) has been used for implants in orthodontics due to the unique properties such as shape memory effect and superelasticity. However, NiTi alloys are eroded in the oral cavity because they are immersed by saliva with enzymolysis. Their reactions lead corrosion and nickel release into the body. The higher concentrations of Ni release may generate harmful reactions. Ni release causes allergenic, toxic and carcinogenic reactions. It is well known that diamond-like carbon (DLC) films have excellent properties, such as extreme hardness, low friction coefficients, high wear resistance. In addition, DLC film has many other superior properties as a protective coating for biomedical applications such as biocompatibility and chemical inertness. Therefore, DLC film has received enormous attention as a biocompatible coating. In this study, DLC film coated NiTi orthodontic archwires to protect Ni release into the oral cavity. Each wire was immersed in physiological saline at the temperature 37 °C for 6 months. The release concentration of Ni ions was detected using microwave induced plasma mass spectrometry (MIP-MS) with the resolution of ppb level. The toxic effect of Ni release was studied the cell growth using squamous carcinoma cells. These cells were seeded in 24 well culture plates and materials were immersed in each well directly. The concentration of Ni ions in the solutions had been reduced one-sixth by DLC films when compared with non-coated wire. This study indicated that DLC films have the protective effect of the diffusion and the non-cytotoxicity in corrosive environment.     

离子束合成TiO2薄膜对医用NiTi合金表面的改性

采用离子束增强沉积法制备TiO2薄膜,对医用NiTi合金进行表面改性处理。系统研究了薄膜的表面组成、结构、形貌及耐蚀性、亲水性等与血液相容性相关的表面性质。NiTi合金表面沉积TiO2薄膜后,抗模拟体液的腐蚀性提高,凝血时间延长。为进一步提高TiO2薄膜的抗凝血性,对TiO2薄膜的进一步表面改性－表面结合肝素分子进行了初步尝试,结果表明,薄膜表面组成发生变化,表面亲水性进一步提高。     

医用金属表面溶胶-凝胶法和离子束合成TiO2薄膜的结构、性能比较

采用溶胶－凝胶法和离子束增强沉积法在医用NiTi合金表面制备TiO2薄膜以提高其生物相容性。利用X射线衍射（XRD）、原子力显微镜（AFM）和X光电子能谱（XPS）对薄膜的结构、表面形貌及组成进行了比较研究；电化学腐蚀实验表明，两种方法制备的TiO2薄膜对金属基体均起到一种保护膜的作用，能够提高医用金属材料在模拟体液中的抗腐蚀性；对薄膜表面固定肝素抗凝血分子进行研究发现，溶胶－凝胶法制备的TiO2薄膜表面能够获得较好的肝素固定效果。     

Electrochemical Corrosion Behavior of the DLC Coated and Uncoated NiTi Alloys

A dense and well-adhered diamond-like carbon （DLC） coating was prepared on the nickel-titanium （NiTi） alloys by plasma immersion ion implantation and deposition （PIIID）. Potentiodynamic polarization tests indicated the corrosion resistance of the NiTi alloys was markedly improved by the DLC coating. The Ni ions release of the NiTi alloys was effectively blocked by the DLC coating.     

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.     

Biocompatibility study of plasma-coated nitinol (NiTi alloy) stents

The authors aimed to assess the surface modification effects of plasma coatings on biocompatibility of nitinol intravascular stent in terms of anticoagulation, haemocytolysis rate, hydrophilicity, cytotoxicity and so on. In order to improve their surface adhesive properties to endothelial cells, NiTi alloy intravascular stents were treated and coated using a low-temperature plasma deposition technique. It was found that plasma coating changed the surface morphology of the stents to a micron-level surface roughness in the range of 1-5 microm. In comparison with the untreated control, the plasma-treated NiTi alloy intravascular stents showed increased surface hydrophilicity and enhanced anticoagulation property. Testing results on plasma-coated NiTi stents indicated that they complied with the standard of national biologic safety evaluation of medical apparatus and instrument (GB/T16886-1997, People's Republic of China) in terms of haemocytolysis rate, cytotoxicity and pyretogen.     

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.     

Electrochemical preparation of protective oxide coatings on titanium surgical alloys

This paper reports a novel electrochemical method for the preparation of protective titanium oxide coatings to improve the corrosion resistance and biocompatibility of the Ti6A14V surgical alloy. Scanning electron microscopy (SEM), electron dispersive spectroscopy (EDS), Auger electron spectroscopy (AES), and the X-ray diffraction technique were used to characterize the structure and the chemical composition of the oxide coatings.In vitro electrochemical corrosion studies were also conducted to assess the effectiveness of the oxide coatings in reducing the metal-ion release from Ti6A14V. The results suggest that the coating process may provide an effective means for improving the corrosion resistance and biocompatibility of titanium surgical alloys under physiological conditions.