固溶处理对NbTiZr合金微观组织与力学性能的影响

采用粉末冶金方法制备了50Nb-20Ti-Zr(mass%)合金,并研究了固溶处理对其组织和性能的影响。结果表明:当固溶时间为6 h时,该合金的典型组织是以条幅分解为基础的片层状组织,并且随固溶温度的升高,晶界无析出带现象越明显,合金的弹性模量没有明显的变化,但其断裂强度有所下降;当固溶时间为18 h时,随固溶温度的升高,合金的组织呈现出"片层状-球化-针片状-等轴化"的演化过程,合金的弹性模量与断裂强度均逐渐增加。合金的断口形貌是由塑性韧窝、河流花样和平行分布的准解理小刻面组成,属于韧性断裂和脆性断裂组合的混合型断裂。     

介质黏度对PCC分散体系流变行为的影响

在AR2000ex型流变仪上对沉淀碳酸钙(Precipitated calcium carbonate,PCC)在PEG(聚乙二醇)悬浮体系进行稳态剪切流变实验。通过2种方法来改变分散体系黏度:1)以PEG200(相对分子质量为200)为连续相,分散体系以10℃为间隔从10℃上升至50℃;2)在30℃用相同的聚合物3种不同相对分子质量的PEG(PEG200、PEG400和PEG600)。结果表明随着温度升高,PCC/PEG200分散体系的临界剪切速率越来越大。在剪切增稠区内流动指数N随温度升高而降低,稠度系数K随着温度升高而升高。临界剪切速率以及临界剪切黏度与温度严格满足Arrhenius关系:η=A exp[Ea/(RT)]。研究发现随温度的变化临界剪切应力不变。随着PEG的相对分子质量增加,分散体系的黏度增加,临界剪切增稠速率减小。PCC粉末的分形结构以及聚集体的形貌使得体系的相对黏度远大于硬球体系的相对黏度。     

功能梯度骨质生物材料的研究进展

功能梯度骨质生物材料为根据人体自然骨的特殊结构,结合金属材料和生物陶瓷材料各自的优点而制备的一类既具有仿生孔隙分布,又具有良好力学性能的骨质生物复合材料.简要介绍了功能梯度骨质生物材料的研究背景,评述了Ti基、316L不锈钢基、Co-Cr-Mo基、Ti4Al6V基四大类功能梯度骨质生物材料的研究进展.同时指出,相比其它制备方法,粉末冶金法由于其近净成形的特点在制备功能梯度骨质生物材料时具有更大的优势.     

Bioactive Ca-P scaffolds used for bone reconstruction

1　INTRODUCTIONSkeletalreconstructionorregenerationisre quiredincasesinvolvinglargedefectscreatedbytu morresection ,trauma ,andskeletalabnormalities .Graftsandflapsofautogenoustissuearetwoofthemostsuccessfulmeansofreconstructionbecausetheyallowthetransplantationofbonecontainingbioactivemolecules,livecells ,andfrequently ,avascularsup plythatallowthetransplanttosurviveandremodeleveninhostileradiatedenvironments .However ,onlyaminimalamountoftissuecanbeharvestedforauto grafts,anditisverydiff…     

Syntheses, characteristics and fluorescence properties of complexes of terbium with benzoic acid and its derivatives

The binary complexes of terbium with benzoic acid and its derivatives (phthalic acid, iso-phthalic acid, oaminobenzoic acid, salicylic acid, sulfosalicylic acid) were synthesized and their compositions were identified by elemental analyses. UV, IR of the complexes were investigated. The UV spectra indicate that the complexes‘ ultraviolet absorption is mainly the ligands‘ absorption, but the location of peak drifts. The IR spectra show that the IR spectra of complexes are different from those of free ligands, and the band at 400 - 500 cm^-1 , due to the stretching vibration of Tb--O, is absent for free ligands. The fluorescence properties were investigated by using luminescence spectroscope, the results show that all the six complexes of terbium exhibit excellent luminescence, due to the transition from the lowest excited state ^5D4 to ^7F ground state manifold, the complexes of terbium with sulfosalicylic acid have the strongest fluorescence intensity, and is stronger than o-aminobenzoic acid-terbium, whose fluorescence intensity is regarded as the strongest one in the literature, and even stronger than some phosphor of terbium.     

HA-Ti和HA-BG-Ti复合生物材料的力学性能和微观结构

研究了不同成分HA—Ti和HA-BG—Ti复合生物材料的烧结收缩率、微观结构、物相结构与力学性能之间的关系。结果表明：当钛含量达到45％～65％时，HA-Ti系复合材料的抗压强度达到最低值76MPa左右，呈谷值分布．而HA—BG—Ti系复合材料的抗压强度却达到最大值180MPa左右，呈峰值分布；HA—Ti系复合材料的抗弯强度为58～79MPa，而HA-BG—Ti系复合材料的抗弯强度在钛含量为45％～65％时出现最大值164MPa；HA-BG—Ti系的抗压强度和抗弯强度均高于HA—Ti系的抗压强度和抗弯强度。物相分析和微观结构分析表明：HA-BG—Ti复合陶材料中的HA-Ti相间界面依靠生物玻璃以复杂的强键相结合，是HA—BG—Ti系复合材料的力学性能优于HA-Ti二元系复合材料力学性能的原因。     

纳米二氧化硅粉末的制备

采用微乳液法制备了高比表面积纳米SiO2粉末，考察了微乳液体系的配制、反应物浓度、反应温度、焙烧温度、共沸蒸馏脱水工艺制备的纳米SiO2性能的影响，并通过比表面积（BET）、透射电镜（TEM）、红外光谱分析（IR）、X射线衍射（XRD）对样品进行了表征。结果表明，粉末制备的工艺参数对样品性能影响较大，在较佳工艺条件下制备的纳米SiO2粉末近似呈球形，粒径为15～30nm，比表面积高达580-630m^2／g。共沸蒸馏工艺能充分地脱去凝胶中残余的水分，防止因含水胶体干燥过程引起的粉末硬团聚，从而显著地提高了粉末的性能。     

一步还原包裹粉工艺制备WC-Co超粗硬质合金

以费氏粒度为4.1μm的WC粉末和CoCl_2·6H_2O、(NH_4)_2C_2O_4·H_2O为原料,将钴粉制备过程与粉末混合过程相结合,一步还原制备WC-Co包裹粉,并以包裹粉为原料成功制备了WC-8%Co(质量分数)超粗硬质合金。借助扫描电镜、X射线衍射仪、化学元素分析仪、力学试验机等分别对WC-Co复合粉末及硬质合金的微观形貌、物相组成和性能进行表征与分析。结果表明,一步还原法制备的WC-Co包裹粉末中,Co为fcc和hcp双相结构,Co相呈树枝状包裹在WC粉末表面。由该包裹粉制备的硬质合金组织结构均匀,综合性能优异,合金平均晶粒尺寸为8.9μm,密度14.63g·cm~(-3),硬度87.6HRA,抗弯强度2438 MPa,断裂韧性20.92 MPa·m~(1/2)。一步还原包裹粉工艺克服了传统湿磨工艺混料过程中WC粒度显著减小的问题,晶粒度可控性好,且工艺流程简单,有潜在的工业应用价值。     

Evaluation of PLGA/chitosan/HA conduits for nerve tissue reconstruction

A micro-envioment for nerve cells and tissue growth were designed and constructed via surface modification of poly(L-lactide-co-glycolide)(PLGA) with chitosan and hydroxyapatite(HA). The poly(L-lactide-co-glycolide)/chitosan/hydroxyapatite (PLGA/chitosan/HA) conduits were manufactured by a combined solvent casting and particulate leaching technique. The conduits were highly porous with an interconnected pore structure and 76.5% porosity. Micropores with 50–100 micrometer diameter were formed in the conduits. In vivo application of PLGA/chitosan/HA conduits for reconstruction of 10 mm sciatic nerve defect was assessed by the walking track analysis, the quantifying of the wet weight of tibialis anterior muscle and the histological assessment. The conduits in host rats in vivo can not only be an effective in promoting regenerating of nerves but can also lead to favorable nerve functional recovery. Funded by the National Natural Science Foundation of China(No.50774096)