骨组织工程用镁基泡沫生物材料的制备与其体外降解行为（英文）

采用熔体发泡法制备了一种镁基泡沫生物材料,其中以镁钙合金为基体材料,羟基磷灰石(HA)为增粘剂,碳酸镁(Mg CO3)为发泡剂。对结构均匀的镁基泡沫生物材料进行测试,研究其生物可降解行为。用腐蚀前后的孔结构、浸泡试验和电化学测试对镁基泡沫材料的生物可降解性进行表征。结果表明,在固定时间内随着试样孔隙率的增加,失重率不断增加;相比于添加了HA的样品,不含HA颗粒的样品呈现出更高的质量损失率。同时,Mg基泡沫生物材料的总孔隙率和HA含量均对Mg基泡沫材料的开孔率有重要的影响。在相同时间内,开孔率随试样总孔隙率的增加而增加。在模拟体液(SBF)介质中,含有HA的Mg基泡沫生物材料比不添加HA的试样具有更高的耐腐蚀性。     

医用镁基HA复合涂层的研究及发展现状

镁及镁合金由于其良好的生物相容性和可降解性能,在生物医用材料领域具有巨大的应用潜力。然而,过快的降解速率限制了其临床应用。羟基磷灰石(HA)涂层具有良好的骨诱导性和骨传导性,可以有效地延缓镁及镁合金的腐蚀速率。但是,单一的羟基磷灰石涂层不能满足镁基植入物的使用寿命要求,因此需对其进一步的改性。本文从生物相容性、可降解性以及力学性能等方面综述镁合金表面以羟基磷灰石为基础,以高分子材料、无机材料以及离子掺杂而成的可降解镁基HA复合涂层的发展和研究现状。     

生物玻璃增强多孔羟基磷灰石生物陶瓷的制备及其性能

研究多孔羟基磷灰石(HA)生物陶瓷的制备方法及性能.采用颗粒尺寸为500～600um的炭粉,以体系为SiO2-Na2O-CaO-MgO-Al2O3的生物玻璃为高温粘结剂,通过一定的混料、压制和烧结工艺,可制得孔隙率为30%～48%,抗弯强度达11.65MPa,大孔孔径约500～600 um、d小孔孔径1～20um并孔隙相互连通的多孔陶瓷.采用扫描电镜(SEM)、X射线衍射仪(XRD)、电子万能实验机对样品的微观结构和抗弯强度进行分析,还通过分析天平,采用阿基米德原理对样品孔隙率进行测量.结果表明:随着烧结温度的升高,气孔率逐渐减小,抗弯强度逐渐增加.通过控制炭粉的含量,可以有效的控制多孔烧结体的孔隙率、大孔的分布及孔径.生物玻璃的加入可以促进材料的液相烧结,使多孔羟基磷灰石生物陶瓷敛密化,改善其力学性能,同时随着生物玻璃含量的增加孔隙率减少.     

镁牺牲阳极法制备羟基磷灰石涂层的电化学性能

羟基磷灰石(HA)作为一种最重要的生物材料被成功采用镁牺牲阳极法在Ti6Al4V合金表面合成,以提高该复合材料的电化学抗腐蚀性能。使用电子能谱(EDX)、电子探针(EPMA)、傅里叶红外变换图谱(FTIR)和X射线衍射(XRD)对HA涂层进行分析。结果表明,涂层主要由针状羟基磷灰石晶体组成,Ca/P比为1.4063。浸泡30 d后,HA涂层在汉克氏溶液中晶体变大,在林格氏溶液和台氏溶液中针状晶体分别转变为片状和柱状。通过测试在3 种模拟体液和人血中的开路电位、极化曲线和交流阻抗图谱表明,有HA涂层的Ti6Al4V合金比未涂层的Ti6Al4V合金具有更好的电化学性能     

粉末冶金法制备多孔Ti-HA生物复合材料的研究

以碳酸氢铵粉末为造孔剂,羟基磷灰石(HA)和Ti-6Al-4V粉末为原料,采用粉末冶金法制备多孔Ti-HA生物复合材料,并测定了其微观结构和力学性能。通过分析碳酸氢铵含量和成型压力对材料力学性能和孔隙率的影响,得到材料的抗压强度和孔隙率随成型压力的增加而分别增加和减少,随碳酸氢铵含量的增加则分别减少和增加。当碳酸氢铵含量为20wt%和30wt%时,材料的孔隙率分布在30%～50%,抗压强度高于20 MPa,孔径分布在100～500μm。     

生物涂层制备技术的研究现状及进展

羟基磷灰石(HA)由于具有良好的生物相容性和骨组织诱导性,被认为是替代人体硬组织的一种很好的生物医用材料,但其溶解度较高,降低植入体的长效性,而将氟渗入HA晶格中能提高HA结构稳定性并降低其溶解性,将硅掺入HA晶格中能有效地提高HA的生物活性,因此含氟羟基磷灰石(FHA)和含硅羟基磷灰石(Si-HA)成为了新兴的改性材料。介绍了羟基磷灰石(HA)、含氟羟基磷灰石(FHA)以及含硅羟基磷灰石(Si-HA)的性能特点以及涂层的制备技术,重点阐述了采用激光熔覆技术制备生物涂层的研究现状以及本课题组的研究进展,指出了目前研究中存在的不足,并展望了生物涂层今后的研究和发展趋势。     

CaCl2作为造孔剂制备泡沫青铜的结构和力学性能

以青铜粉为原料、CaCl_2为造孔剂,采用粉末烧结溶解法制备开孔泡沫青铜。通过改变造孔剂体积分数和粒径成功制备出孔隙率为70%~90%,孔径1~3mm的泡沫青铜试样。研究了孔隙率和造孔剂的关系以及孔隙率、孔径对泡沫试样力学性能的影响,并对其孔结构,相组成和微观形貌进行观察和分析。结果表明:泡沫青铜试样的塑性屈服平台应力随孔隙率增加而减小,当孔隙率为77%~89%时,对应塑性屈服平台应力为12.6~2.6MPa。当应变量为50%时,孔隙率为77%~89%的泡沫青铜单位体积能量吸收值(W)范围为6.21~0.91MJ/m~3。试样的理想吸能效率(I)都接近0.82,说明泡沫青铜可以作为一种理想的吸能材料。     

泡沫镁宏微观结构表征及压缩性能研究

针对熔体发泡法制备泡沫镁存在的困难,使用包覆发泡剂及改进工艺成功制得泡孔均匀的泡沫镁试样。利用OM、SEM、EDS及XRD等分析手段对试样进行宏微观结构表征,结果表明：泡沫镁试样宏观孔以典型的闭孔结构为主,但也存在一些连通孔及少量大孔,它们多是宏观裂纹的产生及扩展位置。泡孔内壁存在一些褶皱缺陷,且弥散分布着许多反应产生的MgO和CaO颗粒,压缩变形过程中,这些部位易产生应力集中,促进微裂纹的形成与扩展。孔壁上主要分布着碳化硅颗粒及生成的Mg2Ca相。测试分析了孔隙率和孔径对泡沫镁压缩力学性能和能量吸收性能的影响,并深入研究其压缩破坏机理,研究发现：随着孔隙率的降低,泡沫镁弹性变形增大,屈服强度升高;随着孔径的增大,泡沫镁屈服强度及平台应力明显减小,表现出显著的孔径效应。随着孔隙率的升高或孔径的增大,泡沫镁的能量吸收性能显著降低。泡沫镁的破坏为解理脆性断裂,这与孔壁组织及镁基体性质有很大的关系。     

纳米羟基磷灰石对钛基生物医用材料性能的影响

采用粉末冶金法制备了纳米羟基磷灰石(nHA)钛基生物医用复合材料,借助XRD、EDS、SEM、压缩弹性模量试验以及生物矿化过程和细胞活性分析,研究了10%的nHA对钛基生物医用材料结构及性能的影响。结果表明,钛基生物医用复合材料的主晶相仍为Ti,同时也有少量的Ti2O、Ti5P3和CaTiO3化合物,这些化合物分布于Ti晶粒的周围;添加nHA改变了钛生物材料的高温烧结性能,材料晶粒间孔隙明显增多;添加nHA后的钛基复合材料,压缩弹性模量仅为纯Ti试样的一半左右,接近人体皮质骨的压缩弹性模量;添加nHA后的钛基复合材料具有更好的生物活性。     

尿素作为造孔剂制备泡沫钛的结构和力学性能

采用针状尿素作为造孔剂,在造孔剂含量介于60%~80%的情况下进行了泡沫钛的制备。通过造孔剂技术成功地制备出孔隙率介于50.2%~71.4%的泡沫钛。扫描电镜结果表明,孔的连通程度随着造孔剂含量的增加而增加,当造孔剂含量超过70%时形成开孔泡沫钛。力学性能测试结果表明,力学性能随着孔隙率的增加而减小,试样的屈服强度、抗压强度和杨氏模量分别介于34.4~146.8 MPa、40.6~193.2 MPa和0.5~3.3 GPa。孔隙率为50.2%和71.4%的泡沫钛的杨氏模量分别匹配于皮质骨和松质骨的模量,理论上可作为潜在的骨替代材料。     

SiCP增强泡沫铝基复合材料的制备工艺研究

将SiC颗粒增强铝基复合材料的制备技术与泡沫铝熔体发泡技术相结合,探索了制备SiC颗粒增强泡沫铝基复合材料的工艺方法。讨论了SiC颗粒与铝基体之间存在的润湿性,界面反应以及SiC颗粒在熔体中沉降等问题,通过选择合适的合金成分,对SiC颗粒进行预处理,采用特定的搅拌和发泡等一系列工艺方案成功地予以解决。在熔体发泡过程中,通过严格控制发泡温度、搅拌速度和搅拌时间等工艺参数,制得了孔隙率基本可调,SiC颗粒和孔洞分布均匀的泡沫铝样品。     

Preparation and properties of open-cell zinc foams as human bone substitute material

Foamed zinc was prepared by infiltration casting process. The mechanical properties and corrosion resistance of the samples were studied, and the feasibility of the foamed zinc as a bone implant material was discussed. All the compression stress-strain curves of open-cell zinc foams with various cell size(1-4 mm) and porosity(55%-67%) show three stages: elastic stage, plastic stage, and densification stage. The compression strength increases with decreasing density. The smooth stress-strain response indicates a progressively deformation of open-cell zinc foam. In addition, the cell wall or edge bending and fracture are the dominated mechanisms for failure of open cell zinc foam. The immersion test for determining the corrosion rate of open cell zinc foam was conducted in simulated body fluid. It was found that zinc foam with a small cell size and high porosity showed a higher corrosion rate. In addition, open-cell zinc foams can effectively induce Ca-P deposition in immersion tests, showing good bioactivity. Therefore, the open cell zinc foam prepared in this experiment has a good potential application as a human bone substitute material.     

泡沫铝制备工艺的改进及关键问题探讨

对熔体发泡法制备闭孔泡沫铝的工艺进行了改进，并研究了发泡过程中TiH2加入量和粒度对泡沫铝孔隙率的影响。改进后的泡沫铝生产工艺在工业化生产方面具有很好地推广价值，主要体现在连续性生产和能源综合利用方面。试验证实：随着TiH2加入量增加，泡沫铝孔隙率不断增加；随着TiH2粒度的加大，孔隙率先逐渐减小后增加。     

粉末冶金法制备SiC_p/2024Al泡沫复合材料的表征(英文)

为了丰富泡沫材料制备工艺、推动其快速发展与广泛应用,以CaCO3为发泡剂采用粉末冶金法制备SiCp/2024Al泡沫复合材料。采用SEM和Magiscan-2A图像分析仪研究了CaCO3发泡剂和SiC颗粒的含量对发泡行为的影响,并且通过Gleeble 1500热模拟机分析了SiC颗粒的含量对压缩性能的影响。结果表明:随着发泡剂的增多,孔隙率和孔径先增加后减小。随着增强体含量的增加,孔隙率和孔径都减小。压缩曲线揭示加入增强体可以改善压缩屈服强度和吸能能力。SiCp/2024Al泡沫复合材料显示为脆性泡沫材料。     

Preparation of Biodegradable Mg/β-TCP Biofunctional Gradient Materials by Friction Stir Processing and Pulse Reverse Current Electrodeposition

Mg alloys, as a new generation of biodegradable bone implant materials, are facing two tremendous challenges of enhancing strength and reducing degradation rate in physiological environment to meet clinical needs. In this study, tricalcium phosphate(β-TCP) particles were dispersed in Mg–2 Zn–0.46 Y–0.5 Nd alloy by friction stir processing(FSP) to produce Mg-based functional gradient materials(Mg/β-TCP FGM). On the surface of Mg/β-TCP FGM, the hydroxyapatite(HA) coating was prepared by electrodeposition. The effects of FSP and electrochemical parameter on the microstructure, microhardness, bonding strength and corrosion performance of the Mg/β-TCP FGM were investigated. After four passes of FSP, a uniform and fine-grained structure was formed in Mg/β-TCP and the microhardness increased from 47.9 to 76.3 HV. Compared to the samples without β-TCP, the bonding strength of the Mg/β-TCP FGM increased from 23.1 ± 0.462 to 26.3 ± 0.526 MPa and the addition of degradable β-TCP contributed to the in situ growth of HA coating. The thickness of HA coating could be dominated by controlling the parameters of electrodeposition. According to the results of immersion tests and electrochemical tests in simulated body fluid, it indicated that the degradation rate of the Mg/β-TCP FGM could be adjusted.     

Preparation and characterization of SiCp/2024Al composite foams by powder metallurgy

SiC_p/2024Al composite foams were manufactured by powder metallurgical methods using foaming agent CaCO₃ in order to enrich the foam fabrication process and promote its development and extensive application. The effects of CaCO₃ and SiC volume fractions on the foaming behaviours were investigated by means of SEM and Magiscan-2A image analysis technique. The influence of SiC content on the compressive behaviour was analyzed using Gleeble 1500 thermal simulation testing machine. The experimental results show that with increasing the foaming agent, the porosity and pore dimension increase first and decrease later. With increasing the reinforcement content, the porosity and pore dimension decrease. The compressive curves reveal that the introduction of SiC particles can improve compressive yield strength and energy absorption capacity. Meanwhile, it is found that SiC_p/2024Al composite foams are the brittle foam materials.     

泡沫铝夹芯板粉末冶金发泡机理的SR-CT研究

利用同步辐射装置的SR-CT,通过图像的断层扫描及3D重建,对轧制复合-粉末冶金发泡工艺制备的泡沫铝夹芯板(AFS)进行了泡孔结构演化的研究,分析了发泡过程中孔隙率的变化及大尺寸连通孔的形成原因。研究结果表明:具有微米级空间分辨率的SR-CT可清晰地观测到泡孔萌生及生长各阶段的泡沫结构。泡孔在发泡15~30 s阶段生成,形状为垂直于轧制方向的类裂纹孔。发泡45 s时,泡孔开始发生明显合并,继续延长发泡时间易导致形成大尺寸连通孔。芯层泡沫铝的孔隙率在泡孔的萌生阶段及合并阶段增长幅度较大,减少混料时发泡剂的"团聚"及提高芯层粉末致密度可获得良好的芯层泡沫结构。     

Study on the Galvanic Current of Corrosion Behavior for AH32 Long-Scale Specimen in Simulated Tidal ZoneEI北大核心CSCD

The environment of the tidal zone is very complex. The interactions of dry-wet alternation and sea erosion lead to serious corrosion of steel structures, which makes it difficult to adopt protective methods. Therefore, it is of great significance to study the corrosion and protection methods of steel in tidal zone. For long-scale steel through the tidal zone and immersion zone, there is a big difference in corrosion behavior with complete immersion condition, the potential of the steel surface changes due to the influence of oxygen concentration difference and tidal fluctuations or other factors. In this study, the galvanic current and open circuit potential of the long-scale AH32 steel were monitored in simulated tidal zone. The results shows that the potential at different tide levels and different immersion depths for a long-scale AH32 specimen is not unified, with the macro cell was formed by the difference of oxygen supply, which caused internal galvanic current. The essence of the galvanic current is the net current that was generated by the sum of anode and cathode current. Galvanic current at different positions on the long-scale AH32 specimen varies with the tidal movement periodically in tidal zone. When tide is at the highest level, the galvanic current of all parts accesses a maximum value, and among these maximum values, the largest one is at the middle part of specimen, which causes the biggest anodic dissolution current density. According to the variation of the galvanic current, the time distributions of the drying, wetting and immersion states were calculated, and the results showed that the corrosion scale of the long-scale AH32 specimen at different positions depends on the time all location of wetting and immersion in tidal zone. The macro cell caused the galvanic current when all parts of the specimen were immersed. At wetting state, the solution resistance of the thin liquid film is very large, which leads to the change of the driving potential of the macro cell into the potential drop. Thus, macro cell is ineffective in the wetting state and cannot produce the galvanic current. According to the relation between wetting time and quantity of electricity at wetting state, the maximum wetting time of the long-scale AH32 specimen is shown above average mean tide level in tidal zone, which indicates that the corrosion loss of this part is maximum due to wetting state. In addition to weight loss measurements, maximum of it for long-scale AH32 specimen was obtained at the average mean tide level caused by immersion state. It can be indicated the maximum weight loss of the long-scale AH32 specimen should appear upper the average mean tide level part in tidal zone. These results were consistent with measurements of corrosion rates.     

纳米羟基磷灰石对血管内支架用可降解Mg-Zn-Zr 合金性能的影响

作为可降解血管内支架材料的探索,制备了Mg-3Zn-0.8Zr合金(质量分数,%,下同)及Mg-3Zn-0.8Zr-1HA复合材料,研究了纳米羟基磷灰石(n-HA)对合金力学性能和生物腐蚀降解性能的影响。n-HA均匀分布于镁合金基体中,使晶粒细化,抗拉强度和延伸率均高于未添加n-HA合金。模拟体液(SBF)浸泡实验表明：随着浸泡时间延长,两种材料表面形貌差异明显。浸泡20 d后,含n-HA的复合材料表面完整,有Ca、P沉积层形成,电化学测试计算的电流密度为0.701×10-5A·cm-2;而不含HA的合金表面严重脱落形成凹坑,对应腐蚀电流密度为1.034×10-5A·cm-2,显示n-HA显著增加了镁合金的耐腐蚀能力     

Corrosion of twin belt and twin roll cast AlMg3Mn alloys

Corrosion of twin belt and twin roll cast AlMg3Mn sheet samples was investigated. The AlMg3Mn sheet samples submitted to immersion tests undergo alkaline pitting around Al–Fe and α_c-Al(Fe,Mn)Si intermetallic particles in the twin roll and twin belt cast samples respectively. The weight loss is higher in the latter and increases with increasing homogenisation temperature for both groups. The twin roll cast AlMg3Mn samples reveal very few and small alkaline corrosion pits and hence much less weight loss in the immersion tests. The pitting activity is governed in the immersion tests by the microgalvanic corrosion activities between the intermetallic particles and the matrix while the anodic particles were inactive.