Thermal Hydrolysis Synthesis and Characterization of Monoclinic Metahewettite CaV_6O_(16)·3H_2O

Monoclinic metahewettite CaV 6 O 16 ·3H 2 O has been fabricated via thermal hydrolysis of calcium vanadate(Ca 10 V 6 O 25). High purity calcium vanadate precipitate, featuring column structure with surface area of 8.61 m2/g, can be obtained by reacting sodium orthovanadate(Na 3 VO 4) with calcium oxide at 90 ℃ for 2 h. By acidifi cation of calcium vanadate in hot water at pH of 1.0-3.0, the monoclinic metahewettite crystals with uniform particle distribution, layered structure and nonporous structure can be fabricated. With the well crystallized layered structure, CaV 6 O 16 ·3H 2 O may be a potential cathode material for secondary batteries as well as super capacitor materials.     

Direct reduction of carburized pre-reduced pellets by microwave heating简

A new iron-making process using carburized pre-reduced iron ore pellets and microwave heating is investigated. The pre-reduced pellets, with a porous structure, and fine particles are carburized homogeneously at 400-650 ℃ in a CO atmosphere. The carburized carbon not only acts reaction as a reduction agent, but also absorbs microwave in the reduction process. Hence, the carburized pre-reduced pellets can be rapidly reduced by microwave heating. There are three procedures involved in the process, namely, gas-based pre-reduction, low-temperatttre carburization and deep reduction by microwave heating. Carburized pre-reduced iron ore pellets show a rapid temperature rise that is twice as fast as the results for pre-reduced pellets in the laboratory. This not only improves the efficiency of the microwave heating, but also accelerates the reduction of iron oxides. The temperature of the pre-reduced pellets rises to 1050 ℃ in 45 min when the carburization rate is 2.02%, and the metallization rate and compressive strength reach 94.24% and 1725 N/pellet, respectively.     

激光粉末床成形316L不锈钢多孔结构力学性能研究

以激光粉末床熔融(LPBF)技术成形的316L不锈钢体心立方型(BCC)多孔结构为研究对象,利用有限元分析法对不同长径比杆件的体心立方型多孔结构进行了准静态压缩过程模拟,分析了其微观力学响应和应力-应变特性。制备了体心立方型316L不锈钢多孔结构样件,对样件进行了准静态压缩试验,分析了具有不同几何参数的多孔结构的应力-应变特性和变形失效机制,并对比分析了仿真和力学试验的结果。研究结果表明：当成形样件杆件的直径从0.4 mm增加到1.2 mm时,杆件直径的相对误差从15.00%下降到6.08%,直径越大,相对误差越小,等效弹性模量从59.87 MPa增加到3356.21 MPa,压缩屈服强度从1.02 MPa增加到33.88 MPa;有限元分析法与力学试验得到的等效弹性模量和压缩屈服强度的平均相对误差分别为9.11%和7.86%。     

生物医用多孔钛及钛合金激光快速成形研究进展

多孔钛及钛合金具有良好的生物相容性和与人骨更匹配的力学性能,是人体理想的替代材料,因此其制备技术及相关性能研究引起了广泛关注。激光快速成形是一项先进的制造技术,在制备生物多孔金属材料时具有独特的优势。介绍了激光快速成形的工作原理和技术特征,根据成形工艺特点简要回顾了4种代表性激光快速成形技术(选择性激光烧结、选择性激光熔化、激光近净成形和激光立体成形)的国内外发展现状,并重点论述了这几种技术在制备生物医用多孔钛及钛合金方面的最新研究进展,最后指出了今后在该领域的主要研究工作。     

全组分木质活性炭球的制备及其乙烯吸附性能研究

目的 制备全组分木质活性炭球,应用于乙烯吸附,筛选出乙烯吸附效果最好的活性炭球制备工艺。方法 以木材液化物为原料,探究不同的固化时间对制备的全组分木质活性炭球微观形貌的影响,利用场发射扫描电子显微镜观察其微观结构,通过氮气吸附-解析等温线计算样品孔径分布及其比表面积;使用气相色谱仪,结合乙烯吸附标准曲线,分析时间及吸附剂用量对4种活性炭球吸附乙烯性能的影响。结果 随着固化时间的增加,碳球表面趋于光滑、内部结构越来越致密,石墨化程度逐渐提高,比表面积和孔容逐渐减小。当固化时间为0.5 h时,比表面积高达2 073 m²/g,乙烯吸附量高达197.99 mg/g,约3 h达到吸附平衡。结论 全组分木质活性炭球能有效吸附乙烯气体,固化时间太长,活性炭球内部孔隙减少,不利于吸附乙烯气体。活性炭球孔容越大,乙烯吸附效果越好。     

Evaluation of Porous Structure of Cement Pastes Made with Residual Rice Husk Ash

In several countries, the residual RHA （rice husk ash） has been produced in rice processing industries or in thermoelectric plants that use rice husk to generate heat and/or electrical energy, usually without burning process control. This causes a reduction in the amorphous silica content of residual RHA, which distinguishes them from the RHA produced according to controlled burning process, which is totally amorphous and considered a highly reactive pozzolan. In this paper, the hydration products and the porous structure of binders paste were studied by replacing, in weight of 5%, 10% and 20% of Portland cement OPC （ordinary Portland cement）, by residual RHAs named A and B, which have high and low content of amorphous silica, respectively, using microstructure evaluation techniques as XRD （X-ray diffraction）, TG （thermogravimetric） tests and MIP （mercury intrusion porosimetry）. A reducing the size of the pores of the pastes was observed according to the increase of content replacement of RHA A and RHA B.     

一种具有微纳孔隙结构的二氧化钛多孔膜层光催化系统

采用溶胶-凝胶法配合以离子注入的方式,研制了一种具有纳米和亚微米(零点几个微米)孔隙结构的锐钛矿相二氧化钛光催化膜。首先通过常规的溶胶-凝胶法制得密实的二氧化钛膜层,然后采用具有一定动能的Fe离子轰击膜层,从而在膜层中形成大量的微纳孔隙。这些微纳孔隙明显提高了原膜层的比表面积。光催化降解甲基橙溶液的实验结果表明,无论是在紫外光下还是在可见光下,所得多孔膜层的光催化效果均优于未造孔的二氧化钛膜层。     

生物医用多孔Ti-6Mo合金选择性激光烧结的结构特征和力学行为

采用选择性激光烧结金属元素Ti、Mo和粘结剂的混合粉末,制备了多孔Ti-6Mo合金,并研究了其结构特征和力学性能。结果表明,多孔Ti-6Mo合金的孔隙结构与烧结工艺有关,随着烧结温度从1000℃升高到1200℃,孔隙由三维连通孔变为相互孤立孔,孔隙率从58%下降到24%,孔径从112μm减小到43μm;多孔Ti-6Mo合金在室温为片层组织,均由大量α相和少数β相构成,并伴有微量α析出物;压缩应力-应变曲线表现为弹性变形、塑性屈服和断裂区三阶段,随着孔隙率降低,弹性模量和屈服强度分别在2.07~11.9 GPa和31.4~152.8 MPa增大,且相对弹性模量和相对屈服强度和相对密度之间遵循幂律关系。多孔Ti-6Mo合金的孔隙特征和力学性能均可满足自然骨要求,是一种可行的医用材料。     

硫酸胍制备多孔石墨型氮化碳及其光催化降解苯酚

为了增加比表面积和提高催化活性,一种无毒和易得的前驱体硫酸胍被首次用于制备石墨型氮化碳(g-C_3N_4)。用X射线粉末衍射、红外光谱、扫描电镜、透射电镜、N_2吸附-脱附、光电子能谱、紫外-可见光吸收光谱和荧光光谱对所得多孔g-C_3N_4进行表征。与由三聚氰胺为前驱体制备的体相g-C_3N_4相比,硫酸胍为前驱体制备的多孔g-C_3N_4具有更高的比表面积、发达的孔结构和较好的光电性能。以光催化降解苯酚为模型反应考察催化剂性能,结果表明,所得多孔g-C_3N_4的催化活性明显高于体相g-C_3N_4。优异的光催化性能和简单的合成方法使硫酸胍制备的多孔g-C_3N_4可广泛用于环境和能源领域。     

钛合金植入物梯度孔结构设计及其力学性能

植入物多孔结构的设计研究多以规则孔结构为主,而少有针对梯度孔结构设计。本文提出平面center及空间sphere两种梯度圆孔设计方法,实现完成对某一平面center梯度孔的植入物结构设计,采用激光选区熔化技术(Selective Laser Melting, SLM)制备出孔隙率为75%的医用钛合金Ti6Al4V梯度孔与规则孔结构植入物样件,进行微观材料表征和力学性能测试,得到相关力学数据。结果表明：该种梯度孔结构的力学性能优于规则孔,在孔隙率为75%的条件下,梯度孔样件的平均弹性模量较规则孔高36.25%,平均抗压强度提高29.9%。