Porosity and mechanical properties of porous titanium fabricated by gelcasting

Porous Ti compacts with large size and complex shape for biomedical applications were fabricated in the porosity range from 40.5% to 53.8% by controlling gelcasting parameters and sintering conditions. The experimental results show that the total porosity and open porosity of porous titanium compacts gelcast from the Ti slurry with 34 vol.% solid loading and sintered at 1100℃ for 1.5 h are 46.5% and 40.7%, respectively, and the mechanical properties are as follows： compressive strength 158.6 MPa and Young＇s modulus 8.5 GPa, which are similar to those of human cortical bone and appropriate for implanting purpose.     

烧结温度对多孑L钛组织结构与性能的影响

分别在1000、1100、1200、1300和1400℃下真空烧结制备了多孔钛试样,并对多孔钛试样进行孔结构、组织结构和性能检测,研究了烧结温度与多孔钛的结构和性能的关系。结果表明:随着烧结温度的提高,多孔钛中颗粒边缘由尖锐变圆滑,孔型由不规则形向圆形转变,烧结颈由细变粗进而出现颗粒表面熔化,孔隙率下降。硬度随烧结温度的提高,呈现先升后降的变化规律,抗压强度逐步提高。     

Additive manufacturing technologies of porous metal implants

Biomedical metal materials with good corrosion resistance and mechanical properties are widely used in orthopedic surgery and dental implant materials,but they can easily cause stress shielding due to the significant difference in elastic modulus between the implant and human bones.The elastic modulus of porous metals is lower than that of dense metals.Therefore,it is possible to adjust the pore parameters to make the elastic modulus of porous metals match or be comparable with that of the bone tissue.At the same time,the open porous metals with pores connected to each other could provide the structural condition for bone ingrowth,which is helpful in strengthening the biological combination of bone tissue with the implants.Therefore,the preparation technologies of porous metal implants and related research have been drawing more and more attention due to the excellent features of porous metals.Selective laser melting（SLM）and electron beam melting technology（EBM）are important research fields of additive manufacturing.They have the advantages of directly forming arbitrarily complex shaped metal parts which are suitable for the preparation of porous metal implants with complex shape and fine structure.As new manufacturing technologies,the applications of SLM and EBM for porous metal implants have just begun.This paper aims to understand the technology status of SLM and EBM,the research progress of porous metal implants preparation by using SLM and EBM,and the biological compatibility of the materials,individual design and manufacturing requirements.The existing problems and future research directions for porous metal implants prepared by SLM and EBM methods are discussed in the last paragraph.     

钛基植入材料的物理抗菌表面修饰（英文）

钛基植入体的感染是其临床应用的重要挑战,特别是当植入体表面形成了生物膜之后。抗生素、金属纳米颗粒和抗菌肽等抗菌药物已经广泛用于治疗钛植入体的感染。然而,这些化学手段具有潜在的毒性、抗生素抗药性以及长效抗菌效果不足等缺点。因此,钛基植入体的物理抗菌表面正吸引着越来越多的关注。概述了不同的钛基生物材料表面仅依靠植入体本身的物理性质（如纳米拓扑结构）或外源性物理刺激（如光催化）对各种细菌的抗菌效果。影响物理抗菌过程的因素有很多,包括纳米拓扑结构的尺寸、形貌和密度以及细菌生长周期等。此外,对钛基植入材料不同物理抗菌表面的机理进行了总结。     

钛及钛合金的激光表面改性研究现状

硬度低、耐磨性能差是制约钛合金发展的关键问题,而激光表面改性处理是解决这一问题的有效途径。结合近年来激光表面改性处理的研究进展,综述了激光表面处理的影响因素,激光表面处理表层的组织、性能及缺陷控制,并指出了目前存在的问题和今后研究的重点方向。     

钛种植体表面CuO和Nb2O5共掺杂TiO2涂层的制备及抗菌性能和生物相容性

利用等离子体喷涂技术在医用钛合金表面成功制备TiO₂、50% Nb₂O₅-TiO₂和1% CuO-49% Nb₂O₅-TiO₂涂层,并对涂层的微观结构、表面粗糙度、表面亲疏水性、化学稳定性进行表征。利用金黄色葡萄球菌和大肠杆菌来评价涂层的抗菌性能,利用小鼠颅顶前骨细胞亚克隆14细胞来评价涂层的细胞相容性。结果表明：等离子体喷涂TiO₂涂层主要由金红石和少量锐钛矿相组成,而在50% Nb₂O₅-TiO₂和1% CuO-49% Nb₂O₅-TiO₂涂层中均出现了Ti_0.95Nb_0.95O₄固溶体和特殊的棒状交织结构;Nb₂O₅和CuO的掺杂增加了TiO₂涂层的表面粗糙度,改善其亲水性。Nb₂O₅掺杂提高了细胞的增殖能力和成骨分化能力,CuO和Nb₂O₅共掺杂显著提高了TiO₂涂层的抗菌性能,但Cu离子的释放降低了50% Nb₂O₅-TiO₂涂层的细胞相容性。和TiO₂涂层相比,1% CuO-49% Nb₂O₅-TiO₂涂层的细胞相容性并未明显降低,说明Nb₂O₅掺入可一定程度上抑制了Cu离子对细胞的副作用。     

Parametric studies of the mechanical behaviour of porous titanium

This paper investigates the prediction of some common mechanical properties of sintered pure titanium. Tensile strength was determined using the radial crush strength method and the fracture toughness tests were performed using disk-shaped compact tension specimens. Empirical models that predict the mechanical behaviour of sintered titanium are reported in this paper and compared with other models like those of Hashin-Strikman, Fleck and Smith, Griffithset al. and Nielson.     

粉末冶金多孔钛表面生物活化的研究

采用粉末冶金法制备了具有适合人体组织长入孔径的多孔钛,并对其进行生物活化处理.利用EPMA、SEM、XRD等研究了不同预处理方法和浸泡时间对多孔钛表面羟基磷灰石(HA)的形貌及形成速度的影响.结果表明,多孔钛的表面以及孔的内表面上均有纳米晶TiO2生成,预钙化处理能够明显提高多孔钛表面生成羟基磷灰石的速率,促进HA的形核长大,预钙化后磷含量增加明显,验证了Na2HPO4在预处理中对多孔钛的活化是有利的.     

Porous titanium implants fabricated by metal injection molding

Sodium chloride (NaCl) was added as a space holder in synthesis of porous titanium by using metal injection molding(MIM) method. The microstructure and mechanical properties of porous titanium were analyzed by mercury porosimeter, scanning electron microscope(SEM) and compression tester. The results show that the content of NaCl influences the porosity of porous titanium significantly. Porous titanium powders with porosity in the range of 42.4%–71.6% and pore size up to 300 μm were fabricated. The mechanical test shows that with increasing NaCl content, the compressive strength decreases from 316.6 to 17.5 MPa and the elastic modulus decreases from 3.03 to 0.28 GPa.     

Preparation and characterization of porous titanium using space-holder technique

Titanium-based porous materials can be used in structural applications and medical implants because of their excellent mechanical properties at elevated temperatures, good corrosion resistance and wonderful biocompatibility. However, most of the methods used to produce the po-rous metal can only give limited porosity and uncontrollable pore morphologies. In the present study, a newly developed method of powder metallurgy using the space-holder technique was used to fabricate porous titanium with controllable porosity. The morphological features and mechanical properties of the products were fully investigated. The results show that the porosity is in the range of 55%-75%, and the mean pore size, with an average sphericity of～0.72, is 600 μm The plateau stresses vary between 10 MPa and 35 MPa. As predicted by the Gibson-Ashby model, the plateau stress decreases with increasing porosity.     

不同结构的牙种植体骨界面应力的有限元分析(英文)

用Ansys Workbench 10.0有限元软件研究静态加载下种植体结构、低模量层的模量和厚度对骨界面应力分布的影响。用CAD(Pro/E Widefire 2.0)软件建立颌骨和种植体的三维有限元模型,设置整体低弹性模量型(1号)、仿生型(2号)、松质骨区低模量型(3号)和全致密型(4号)。结果表明:种植体的结构影响骨界面应力分布,2号种植体在松质骨和根端区的界面最大应力均低于另外3种结构种植体的;2号种植体的低模量层模量的降低有利于松质骨区界面应力传递致周围骨质,增加低模量层厚度能降低松质骨区界面应力,使界面应力分布更趋均匀。仿生型2号种植体在界面应力传递致周围骨质方面优于其它3种结构种植体。     

多孔钛表面改性对其蛋白质吸附行为的影响

考察了酸碱处理多孔钛、碱热处理多孔钛及未改性多孔钛对牛血清白蛋白的等温吸附行为,探讨了多孔钛表面改性对其蛋白质吸附性能的影响。并通过扫描电子显微镜、X射线衍射仪、台阶仪、接触角测量仪等分别考察了3种样品表面形貌、相组成、粗糙度及润湿性等性质。结果表明,表面改性后多孔钛的表面形貌、相组成、粗糙度及润湿性等性质均发生了明显改变,蛋白质吸附性能得到了显著提高。     

Preparation of titanium dioxide/silver sulfate powder and its antibacterial activity

Antibacterial powders of titanium dioxide/silver sulfate were produced by heat-treatment of the metatitanic acid, as precursor, into which the silver nitrate was added. The influences of heating temperature on the structure and composition of the product were investigated through XRD and SEM. The results show that the powder is spherical in the phase of TiO2-Ag2 SO4. The granularity of the particles increases from 10.7 nm to 28.7 nm with the temperature of heat-treatment increasing from 300 ℃ to 800 ℃. The antibacterial activity of the powder was judged in the way of the minimum inhibitory contents (MiCs). When the content of silver sulfate is less than 2%, the photocatalysis of titanium dioxide and silver ions cooperate to kill bacteria. And the MiCs decrease and keep around 1.0× 10-4- 1.5 × 10-4 constantly with the increase of silver content. Furthermore, the MiCs decrease with the increase of temperature of heat-treatment when the temperature is lower than 500 ℃. But when the temperature is beyond 600 ℃ the MiCs increase quickly, which shows the inferior antibacterial performance.     

纯钛表面微弧氧化多孔陶瓷膜的结构特性

采用微弧氧化处理技术和电解液成分的优化设计,在纯钛表面制备了含钙磷的多孔复合陶瓷膜,并考察了陶瓷膜的表面形貌、截面形貌、化学成分、物相构成、生物活性及其与基体的结合强度等特性。研究结果表明:纯钛表面微弧氧化后形成了凹凸不平的多孔陶瓷膜,整个膜层分为表层疏松层、中间过渡层和内部致密层三个区域,总厚度为25～40μm,膜层与基体的界面呈锯齿状紧密结合。膜层主要由金红石相TiO2和锐钛矿相TiO2构成;膜层中含有Ca,P,O,Ti四种元素,其钙磷比ω(Ca)∶ω(P)为1.528;膜层中的Ti,Ca,P元素呈梯度分布,由表及里Ti含量逐渐增多,Ca和P含量逐渐减少,O元素分布比较均匀。含钙磷多孔复合陶瓷膜具有良好的生物活性,样品经碱液处理后再在快速钙化溶液(FCS)中浸泡4d即有羟基磷灰石(HA)形成;膜层与基体具有高的结合强度,在450V和600Hz时膜层的临界载荷值高达29.5N。     

Nanospike surface-modified bionic porous titanium implant and in vitro osteogenic performance

This work aimed to prepare the nanospike surface-modified bionic porous titanium implants that feature favorable osteointegration performance and anti-bacterial functions. The implant was prepared using freeze casting, and nanospike surface-modification of the implant was performed using thermal oxidation. The pore morphology and size, mechanical properties, and osteogenic performance of the implants were analyzed and discussed. The results showed that when the volume ratio of titanium powder in slurry was set to be 10%, the porosity, pore diameter, compressive strength, and elastic modulus of the porous samples were (58.32±1.08)%, (126.17±18.64) μm, (58.51±20.38) MPa and (1.70±0.52) GPa, respectively. When the porous sample was sintered at a temperature of 1200 °C for 1 h, these values were (58.24±1.50)%, (124.16±13.64) μm, (54.77±27.55) MPa and (1.63±0.30) GPa, respectively. The nanospike surface-modified bionic porous titanium implants had favorable pore morphology and size, mechanical properties and osteointegration performance through technology optimization, and showed significant clinical application prospect.     

Processing and characterization of porous titanium for implants by using NaCl as space holder

Porous samples of commercially pure titanium (CP Ti) were fabricated by using sodium chloride (NaCl) as space-holder with percentages between 40 and 70 vol%. The dissolution of NaCl in distilled water, the structural integrity of samples and the reproducibility of the procedure were studied as a step prior to sintering. All these parameters were evaluated in terms of the compaction pressure, temperature and agitation of water, and dissolution time. The characterization of samples included density, porosity and dynamic Young's modulus. The results indicate that the most efficient lixiviation, according to the desired balance of properties, was by immersion in hot water, without agitation and for prolonged cycles of immersion time.     

不同孔径分布多孔钛的力学性能

从生物学角度出发设计并制备2种不同孔径分布的多孔钛,并研究其力学性能。采用造孔剂烧结方法制备孔隙率为36%~63%的多孔钛,通过室温压缩测试其力学性能。多孔钛的弹性模量和抗压强度分别在2.662~18 GPa和94.05~468.57 MPa范围内,且都随着孔隙率的增加而降低。抗压强度和孔隙率的关系曲线呈现完全的线性特征,表明抗压强度主要受孔隙率的影响,几乎不受孔径的影响。Gibson-Ashby力学关系分析结果显示：常数项C值的差异说明孔径分布对多孔钛的屈服强度有一定的影响;密度指数n值均大于临界值3,表明这2种不同孔径的多孔钛的变形方式相同,为孔壁的屈曲作用。     

医用钛合金激光表面改性抗菌涂层的研究进展

激光作为一种高效、清洁热源,在材料表面改性中占有重要地位。激光表面处理可以调控材料表面组织结构和合金成分,改善材料的耐磨、耐腐蚀和抗菌等性能。钛及钛合金具有优异的力学性能、生物相容性和耐腐蚀性能,是人体硬组织的主要替代产品之一,在生物医用材料领域得到广泛应用。但钛及钛合金不具有抗菌性能,在植入过程中易发生细菌感染而造成植入手术失败,是目前钛合金骨科植入手术中亟待解决的问题。该文针对钛合金抗菌性差的问题,采用激光表面处理工艺,综述了激光表面合金化、激光表面织构和激光熔覆等激光表面改性技术改善钛合金抗菌性能的研究现状,阐明其抗菌机理,并对发展趋势进行展望,为激光技术提高钛合金抗菌性能的深入研究及应用提供理论基础及技术支撑。     

医用钛合金及其表面活化的研究现状

医用Ti合金具有良好的力学性能、耐腐蚀性能和生物相容性,在医学临床上获得广泛应用,但是其耐磨性能和生物活性等方面仍不够理想,耐腐蚀性能也有待于进一步提高.开发具有更佳综合性能的医用钛合金,或对现有成熟医用钛合金进行表面改性是解决上述问题的有效途径.本文综述了医用钛合金的发展及其存在的问题和表面活化研究进展,并对医用Ti合金的表面活化的前景进行了展望.     

外科植入物用钛及钛合金金相试样制作浅谈

对钛及钛合金金相试样制样用的砂纸、抛光织物、抛光试剂和侵蚀剂的合理选择以及制样方法和侵蚀方法作了叙述.