Fang Geng
材料科学技术（英文）
Three-dimensional honeycomb-structured magnesium (Mg) scaffolds with interconnected pores of accurately
controlled pore size and porosity were fabricated by laser perforation technique. Biodegradable and bioactive β-
tricalcium phosphate (β-TCP) coatings were prepared on the porous Mg to further improve its biocompatibility,
and the biodegradation mechanism was simply evaluated in vitro. It was found that the mechanical properties
of this type of porous Mg significantly depended on its porosity. Elastic modulus and compressive strength
similar to human bones could be obtained for the porous Mg with porosity of 42.6%-51%. It was observed
that the human osteosarcoma cells (UMR106) were well adhered and proliferated on the surface of the β-
TCP coated porous Mg, which indicates that the β-TCP coated porous Mg is promising to be a bone tissue
engineering scaffold material.
关键词:
Magnesium
,
Bone tissue engineering
,
β-TCP coating
,
Biocompatibility
材料科学技术（英文）
Three-dimensional honeycomb-structured magnesium (Mg) scaffolds with interconnected pores of accurately controlled pore size and porosity were fabricated by laser perforation technique. Biodegradable and bioactive beta-tricalcium phosphate (beta-TCP) coatings were prepared on the porous Mg to further improve its biocompatibility, and the biodegradation mechanism was simply evaluated in vitro. It was found that the mechanical properties of this type of porous Mg significantly depended on its porosity. Elastic modulus and compressive strength similar to human bones could be obtained for the porous Mg with porosity of 42.6%-51%. It was observed that the human osteosarcoma cells (UMR106) were well adhered and proliferated on the surface of the beta-TCP coated porous Mg, which indicates that the beta-TCP coated porous Mg is promising to be a bone tissue engineering scaffold material.
关键词:
Magnesium;Bone tissue engineering;beta-TCP coating;Biocompatibility;simulated body-fluid;mechanical-properties;cancellous bone;foam;scaffolds;magnesium;hydroxyapatite;porosity;bioceramics;fabrication;ph
Journal of Testing and Evaluation
To determine residual stresses in a (flat) plate or bar with a rectangular cross-section by X-ray diffraction after removal of material, we can sectionally approximate the measured stress curve with depth using power series, then consequently evaluate the additional stresses created by removal, and finally obtain the true stress distribution with depth before the layers were removed. Formulas to evaluate corrections for stress have been derived. Two examples demonstrate that power series with few terms can provide us with an approximation good enough for the measured stress curve, and that the influence of the approximation on the corrective result is far less than that of the errors arising from the X-ray stress determination itself.
关键词:
x-ray stress determination;stress correction;approximation;power;series;single-side removal;double-side removal;shot peening
杜龙
,
矫桂琼
,
黄涛
,
赵龙
,
黄峰
复合材料学报
doi:10.3321/j.issn:1000-3851.2007.06.024
通过不同Z-pin角度(15°和25°)和夹芯厚度(8mm和12.7mm)的X状Z-pin增强泡沫夹层材料的剪切性能试验,与相同材料同尺寸的未增强件进行对比,考察X状Z-pin对泡沫夹层结构的增强作用.试验结果表明,X状Z-pin增强使材料的剪切强度和刚度都有较大幅度的提高;同时,Z-pin的加入使该结构具有与传统泡沫夹层材料不同的剪切破坏形式.在此基础上,结合空间网架结构和等效夹杂方法,提出了X状Z-pin增强泡沫夹层结构剪切刚度模型,计算结果与试验值符合良好.结果表明,X状Z-pin增强不仅能大幅度提高泡沫夹层结构的剪切性能,并具有良好的可设计性,可以通过改变Z-pin角度和材料等改变其力学性能.
关键词:
夹层结构
,
Z-pin增强
,
剪切性能
徐祥
,
杨明
,
梁益龙
,
张世伟
,
龚乾江
材料导报
doi:10.11896/j.issn.1005-023X.2016.18.030
在Gleeble-3500热模拟试验机上对211Z.X耐热高强韧铝合金进行了等温热压缩实验,实验的应变温度为350～500℃、应变速率为0.01～10 s-1.研究了不同变形条件下的流变特征,并分析该合金高温变形时流变应力的规律,构建了材料流变应力本构模型;同时基于动态材料模型建立了加工图,确立了该合金在实验条件的最佳工艺参数.结果显示:功率耗散图与失稳图随应变量的增加而变化,功率耗散峰区由3个逐渐减为1个,失稳区域随应变而移动并逐渐增大;在加工图中,随着应变的增大,安全加工区域逐渐减小.综合加工图与微观组织的分析结果,211Z.X铝合金最佳的加工工艺区间为:变形温度485～500℃、应变速率0.03～10 s-1.
关键词:
211Z.X耐热高强韧铝合金
,
热压缩变形
,
加工图
Science
Strengthening materials traditionally involves the controlled creation of internal defects and boundaries so as to obstruct dislocation motion. Such strategies invariably compromise ductility, the ability of the material to deform, stretch, or change shape permanently without breaking. Here, we outline an approach to optimize strength and ductility by identifying three essential structural characteristics for boundaries: coherency with surrounding matrix, thermal and mechanical stability, and smallest feature size finer than 100 nanometers. We assess current understanding of strengthening and propose a methodology for engineering coherent, nanoscale internal boundaries, specifically those involving nanoscale twin boundaries. Additionally, we discuss perspectives on strengthening and preserving ductility, along with potential applications for improving failure tolerance, electrical conductivity, and resistance to electromigration.
关键词:
strain-rate sensitivity;stacking-fault energy;nano-scale twins;cu-al;alloys;nanocrystalline metals;mechanical-properties;activation;volume;copper;deformation;behavior
Applied Physics a-Materials Science & Processing
The Pr(1+x)Ba(2-x)Cu(3)O(7+/-delta) solid solution was investigated by means of X-ray powder diffraction combined with Rietveld analysis. A Pr123 single phase could be synthesized under Pr-rich conditions by sintering at 950 degreesC in air. The solubility range of Pr(1+x)Ba(2-x)Cu(3)O(7+/-delta) solid solution is 0.08 less than or equal to x less than or equal to 0.80. The structure of Pr(1+x)Ba(2-x)Cu(3)O(7+/-delta) for 0.08 less than or equal to x less than or equal to 0.30 is orthorhombic. The structure transforms into tetragonal for 0.30 less than or equal to x less than or equal to 0.80. To form the Pr123 single phase, the Ba sites in the Pr123 structure must have partial Pr ions, and the least amount is x = 0.08. Ba ions cannot occupy the sites of Pr ions. In the Pr123 structure, Ca ions can replace Pr ions; the highest value is x = 0.4 in the PrBa(2-x)Ca(x)Cu(3)O(7+/-delta) system under our experimental conditions. However, Ca ions cannot replace B a ions. The ionic radius plays a more important role than the chemical properties in the substitution between Pr, Ba and Ca ions in the Pr123 structure.
关键词:
cu-o system;approximately 950-degrees-c;superconductivity;diagram;pr;growth;nd;prba2cu3o7-delta;praseodymium;property
