《表面技术》2008年第6期

钛合金生物活性陶瓷膜的电化学制备和性能研究；微弧氧化工艺及封孔处理对镁合金耐蚀性能的影响；热氧化处理对钛合金表面耐磨性能影响的研究；纳米二氧化钛改性弹药用涂料的研究；SiC颗粒表面化学镀铜的研究。     

钛生物种植体表面微弧氧化膜制备的电解液研究

为了得到具有生物活性的陶瓷膜,通过研究微弧氧化的工艺条件,得到了适宜于制备钛合金生物活性膜的电解液配方,其中含20g/L Ca(CH3COO)2·H2O(乙酸钙)、9.3g/L Na5P3O10(多聚磷酸钠).结果表明:采用该电解液并在适当的微弧氧化工艺条件下,在钛合金表面制备的陶瓷膜具有多微孔结构,并且与基体结合良好,微孔分布均匀,孔径为几个微米;陶瓷膜表面含有一定比例的钙、磷元素,且钙磷比约为1.69,与羟基磷灰石中的钙磷比相当;陶瓷膜主要是由锐钛矿型和金红石型二氧化钛构成,其中以锐钛矿型二氧化钛为主.这种含有适当钙、磷元素且表层多孔的氧化钛陶瓷膜有利于骨细胞的吸附和结合.     

阵列状金红石型TiO_2的制备及晶体生长机理

采用催化氧化的方法以特殊的陶瓷粉体在α-Ti表面制备具有生物活性的阵列状二氧化钛薄膜。借助X射线衍射(XRD)、扫描电镜(SEM)、能谱分析(EDS)等手段对材料的相组成和微观形貌进行表征,探究四硼酸钠对薄膜制备工艺的影响以及阵列二氧化钛的晶体生长机理。结果表明:经四硼酸钠催化氧化后,纯钛表层的二氧化钛呈阵列状生长;该二氧化钛为沿(110)晶面生长的金红石相,同(002)晶面α-Ti均为拓扑生长结构;根据晶格匹配原理,(110)晶面金红石在(002)晶面ɑ-Ti上选择性生长;经此方法制备的二氧化钛薄膜粗糙度和表面积均有所增大,钛合金的生物相容性得到改善。     

钛合金表面高频感应热梯度新方法制备生物活性钙磷涂层探索

探索了一种新的生物活性钙磷陶瓷制备工艺，即将导电基体置于钙磷溶液中，通过高频感应的方式加热钛合金基体，同时通过设计相应的装置使钛合金附近区域形成温度梯度。这一温度梯度由钛合金基体表面向外逐渐降低，使基体表面形成了有利于钙磷沉积的热力学条件，从而使钙磷生物陶瓷能够在基体表面生长并形成涂层。初步研究结果证实，该工艺可在钛合金上制备出生物活性五水磷酸八钙涂层。     

通过化学处理制备梯度功能生物活性钛及钛合金

有一些陶瓷在生物体内其表面会形成一薄层类似骨质的磷灰石，通过它与生物骨产生较强的化学结合．如生物玻璃、烧结羟自磷灰石和品化玻治A－W筹，故又称其为生物活性材料，已被用作有效的骨修复材料．但其断裂韧性低，不能承受大的负荷．而钛合金密度低、断裂韧性高、生物相容住好，广泛用于人工齿根和人工关节的芯杆，但不能与骨结合．因此，近年来通过等离子喷涂和溅射在钛合金表面涂覆一层生物活性阳自，来解决此问题．然而，这种方法不能做到生物活性被覆层与金后牢固地结合起来．日本京都大学的学者发现，MP－Tny（M＝Na，K）系玻…     

碱液处理诱导钛合金基体表面沉积磷灰石层

改变碱液处理条件和基体材料,考察了这些参数对钛合金诱导磷灰石能力的影响。结果表明：经过碱液处理钛合金表面形成了多孔网状,带负电荷的二氧化钛水凝胶层,在过饱和的模拟体液中可沉积出骨状磷灰石层;随碱液浓度、温度和处理时间境加,凝胶层的孔径和厚度增加,诱导形成磷灰石的能力增强;不同基体材料的诱导能力为：Ｔｉ〉ＴＣ４,Ｔｉ７５〉ＴｉＺｒ。太合金碱液处理后可在模拟体液中沉积出磷灰石层,因此碱液处理使钛合金表     

多孔钛表面无裂纹生物活化层的制备及表征

采用碱热处理方法对多孔钛进行了表面活化处理,获得了无裂纹的网状微孔结构的生物活化层。利用扫描电镜(SEM)、X射线衍射仪(XRD)和X射线光电子能谱仪(XPS)等设备对生物活化层进行表征,最后用模拟体液中浸泡的方法检测了该活化层的生物活性。结果表明:当NaOH溶液浓度低于8 mol/L,碱处理时间少于36 h时,多孔钛孔内外壁都可获得无裂纹的生物活化层,该活化层呈现网状微孔结构,是由金红石结构的二氧化钛和钛酸钠组成的混合物质。浸泡SBF后结果显示该活化层在浸泡3 d后就已诱导产生了类骨的碳羟基磷灰石,表现出了很好的生物活性。     

钛合金表面微弧氧化膜的特点及成膜分析

用微弧氧化方法在钛合金上形成二氧化钛薄膜，用扫描电镜、X射线衍射以及透射电镜分析了膜的组织结构和化学成分，用纳米压入仪和划擦仪测量了膜的硬度和弹性模量及划擦抗力。结果表明，钛合金表面形成一层微弧氧化膜，含有纳米晶结构。薄膜由晶体和少量非晶体组成，硬度和弹性模量分别为0．78GPa和35．6GPa，划擦过程中未出现膜从基体表面的剥落，但高载荷下膜本身有破坏和脱落。     

医用近β型钛合金TLM的碱液处理与生物活性

采用模拟体液浸泡法评价碱液处理TLM(Ti-25Nb-3Zr-2Sn-3Mo)合金的生物活性。钛合金TLM经过碱液处理后表面生成了钛(铌)酸钠凝胶层,凝胶层厚度随碱液浓度升高而增加。在模拟体液中浸泡43h后,碱液处理钛表面只有少量磷灰石晶核生成,而碱液处理TLM合金表面有五水磷酸八钙晶粒形成,磷灰石的形核也较多。钛合金TLM在碱液处理时生成的钛(铌)酸钠凝胶层厚于纯钛,而较厚的凝胶层使其生物活性提高。     

钛合金表面织构化与构建生物活性涂层的研究进展

医用钛合金作为临时基质的植入材料对周围新组织的生长具有特殊的诱导作用。针对椎弓根螺钉固定系统对钛合金基材表面机械性能和生物活性的共同需求,表面织构与生物活性涂层对钛合金表面的改性展示出独特的优越性。文中详细介绍了钛合金表面织构化对其摩擦学性能和生物相容性的影响,以及构建生物活性涂层的种类;总结了钛合金表面织构的作用机理,生物活性涂层的改善机制,阐述了表面织构化与构建生物活性涂层各自的局限性,并指出钛合金作为生物医用材料仍需要解决的问题及未来的研究趋势。     

Porous TiO2 film prepared by micro-arc oxidation and its electrochemical behaviors in Hank's solution

Porous titanium oxide film was prepared by micro-arc oxidation (MAO) method on the surface of titanium alloy in electrolyte containing Ca and P. Surface characterizations of the film were carried out using X-ray diffractometer (XRD), scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS) before and after immersion in Hank's solution. Electrochemical behaviors and corrosion resistance were studied by electrochemical techniques. The film was mainly composed of titania, α-tricalcium phosphate (α-TCP) and amorphous Ca-P compounds. α-TCP and amorphous compounds could transformed into hydroxyapatite (HA) when immersed in Hank's solution. MAO film showed higher corrosion potential and lower corrosion current than the titanium alloy and its chemical stability was slightly changed after formation of HA. Fitted electrochemical impedance spectroscopy (EIS) data indicated that after immersion for 2 weeks the MAO film kept good corrosion resistance. Porous TiO₂ film on titanium alloy by MAO method showed good chemical stability in Hank's solution and the transformation of Ca-P compounds into HA indicated that MAO was an effective method for preparing titanium alloys as bioactive artificial bone substitute even when Ca and P in the tissue environment were not abundant.     

低温去合金化脱镍处理镍钛记忆合金的表面特性

采用低温去合金化(Dealloying)处理法对医用NiTi合金进行表面脱镍改性。经SEM、XRD、AES、FTIR、XPS和模拟体液(SBF)仿生沉积等分析研究表明,NiTi合金经低温去合金化处理后,在合金表面选择性地除去了有害元素镍,在距表层约400nm深度内原位制备出完全无镍的具有纳米网架结构的水合氧化钛膜,并在500℃,进行1h热处理,晶化为锐钛矿型二氧化钛。由于经低温去合金化脱镍的NiTi合金表面富含羟基(OH-),在SBF溶液中具有良好的生物活性,从而提高了NiTi合金的生物相容性。     

钛合金表面生物活性陶瓷涂层的设计

将生物活性陶瓷涂覆在钛合金表面可以综合金属和生物活性陶瓷的优点,通过对金属基体上陶瓷涂层的设计可以改善涂层与基体的结合强度.本文对钛合金表面不同类型涂层的设计进行了综合评述,并对如何提高生物活性陶瓷涂层与基体的界面结合强度提出建议.     

溶液钙浓度和水热合成条件对微弧氧化TiO2／羟基磷灰石复合膜层形貌和组成的影响

钛在含钙磷的溶液中微弧氧化，表面形成含有钙磷元素的，均匀多孔的氧化膜层，水热合成后转化为含羟基磷灰石晶体的复合氧化膜。研究表明：钙离子浓度未使膜层的形貌和相组成发生明显变化；仅在较低的浓度下增加溶液Ca^2 的浓度，膜层中Ca，P元素的相对含量和Ca／P比都会增加；在不同的水热温度和溶液钙浓度下，得到的羟基磷灰石具有不同的晶体形貌，相对含量和Ca／P比；缩短恒温时间可以使HA晶粒细化。这为优化生物医用钛表面TiO2／羟基磷灰石复合膜层的成分和形貌提供了依据。     

Hydrothermal Surface Modification of a Low Modulus Ti-Nb Based Alloy

采用尿素溶液对一种低模量近?型钛合金(Ti-25Nb-3Zr-2Sn-3Mo,或TLM合金)进行不同温度的水热处理。采用SEM、XRD、XPS、压入法和接触角测试分析了TLM合金处理后的表面结构、化学成分、附着性和亲水性。在105和120℃水热处理后,合金表面形成了钛酸铵的纳米片薄膜;而150℃水热处理后形成了纳米颗粒薄膜,由锐钛矿TiO2和Nb2O5组成。随后的400℃退火热处理使铵盐分解和二氧化钛结晶。生成的氧化物薄膜具有良好的附着性。复合处理增强了TLM合金的亲水性,这有利于改善其生物相容性。     

Scale composition and oxidation mechanism of the Ti–46Al–8Nb alloy in air at 700 and 800 °C

It is known that the oxide scale formed on TiAl alloys is generally composed of a mixture of alumina (Al₂O₃) and titania (TiO₂). The presence of niobium changes the activities of Ti and Al and influences the kinetics of oxidation and oxide layer composition. In this work, the Ti–46Al–8Nb alloy was subjected to cyclic oxidation in air at 700 °C (for 2 and 24 h) and 800 °C (for 300 h). Scale composition was analyzed by means of different techniques including X-ray photoelectron spectroscopy, X-ray diffraction and secondary ion mass spectroscopy. The scale consisted of several layers. The outer layer was built of alumina (amorphous or with very fine grains), whereas the inner layer – mainly of titania. After a longer exposure at a higher temperature (800 °C), niobium-rich precipitates and aluminum oxide grains were detected near to the alloy/scale interface and titanium nitride was found in the inner parts of the scale. Oxidation mechanism was studied by two-stage oxidation method using oxygen-18 and oxygen-16 isotopes combined with SIMS analyses. The distribution of oxygen isotopes over the alloy/scale interface indicated mixed inward/outward diffusion at the of reacting species. The experiments using Au markers showed that after longer oxidation time the inward diffusion was a predominant transport process.     

Bioactivity and cytocompatibility of plasma-sprayed titania coating treated by sulfuric acid treatment

Titania coatings were fabricated on titanium alloy substrate using atmospheric plasma spraying technology, and treated by sulfuric acid (H₂SO₄) at room temperature for 24 h. The as-sprayed and acid-treated titania coatings were soaked in simulated body fluid (SBF) to investigate the formation of apatite on their surfaces. Human mesenchymal stem cells (MSCs) were used to evaluate the cytocompatibility of titania coatings. The results indicated that bone-like apatite was formed on the surfaces of acid-treated titania coatings after soaked in SBF for a period of time. The concentration of sulfuric acid had an effected on the bioactivities of titania coatings. The bioactivity of titania coating could not be improved by 0.01 M sulfuric acid treatment. The MSCs could attach, grow and proliferate well on the surface of titania coatings. The results showed that plasma-sprayed titania coating after acid treatment exhibited favorable bioactivity and cytocompatibility.     

Microstructure and in vitro bioactivity of laser-cladded bioceramic coating on titanium alloy in a simulated body fluid

In order to obtain bioactivity on the surface of titanium alloy, the bioceramic coating on Ti–6Al–4V was designed and fabricated by laser cladding. The microstructure and bioactivity of laser-cladded bioceramic coating were investigated in vitro via soaking in a simulated body fluid (SBF). The results indicated that the laser-cladded bioceramic coating was metallurgically bonded to the substrate and contained such bioactive phases as hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP). A bone-like apatite layer was spontaneously formed on the surface of laser-cladded coating merely soaked in SBF for 7 days. And the appearance of flake-like and cotton-like morphology, which is the characteristic morphology of apatite, offered an advantageous condition for osseo-connection. The formation ability of apatite was remarkably accelerated on the surface of laser-cladded bioceramic coating compared with the untreated titanium alloy substrate.     

Flame Spray Deposition of Titanium Alloy-Bioactive Glass Composite Coatings

Powders of titanium alloy (Ti-6Al-4V) and bioactive glass (45S5) were deposited by flame spraying to fabricate composite porous coatings for potential use in bone fixation implants. Bioactive glass and titanium alloy powder were blended and deposited in various weight fractions under two sets of spray conditions, which produced different levels of porosity. Coatings were characterized with cross-sectional optical microscopy, x-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR). Immersion testing in simulated body fluid (SBF) was conducted for 0, 1, 7, and 14 days. Hydroxyapatite (HA) was found on the bioactive glass-alloy composite coatings after 7 days of immersion; no HA was observed after 14 days on the pure titanium alloy control coating. The HA formation on the alloy-bioactive glass composite coating suggests that the addition of bioactive glass to the blend may greatly increase the bioactivity of the coating through enhanced surface mineralization.