日本超高温结构用金属材料的研究现状

简要介绍了日本围绕燃气轮机用关键超高温金属结构材料所展开的研究开发工作,包括Ni基超合金、耐热金属间化合物、Nb基超合金及其复合材料。Ni基超合金仍是当前燃气轮机用超高温结构的主要材料,但其使用温度的上升潜力已经不多,用新的超高温材料替代Ni基超合金是燃气轮机用材的发展趋势,金属材料中耐热金属间化合物和Nb基复合材料是今后关注的焦点。     

Preparation and electrochemical performance of nanosized Co3O4 via hydrothermal method

The hydrotalcite-type cobalt compounds were prepared through oxidation of Co（OH）2 gel using NH4OH as precipitating agent and H2O2 as oxidant. These hydrotalcite-type cobalt compounds were transformed into Co3O4 through hydrothermal decomposition with nanostructural deformation. The precursor and product were characterized by Fourier-transform infrared（FT-IR） spectrum, X-ray diffractometry（XRD） and transmission electron microscopy（TEM）. The electrochemical performances of as-prepared nanosized Co3O4 as anode materials in lithium-ion batteries were tested by charge-discharge test in the voltage range of 0-3.0 V. The influence of morphology of Co3O4 particle on the capacity and cycling performance was studied. The results show that the shape and size of the final product can be controlled by altering cobalt sources. The irregular cubic Co3O4 with the average particle size of about 10 nm shows the best electrochemical performance. After 10 charge-discharge cycles, the specific charge capacity retains 555 mA.h/g.     

用攀枝花钛矿和云南钛矿冶炼钛渣工业试验研究

通过磁性测量和X-射线衍射研究了Gd2(Co，Al)17化合物的结构和磁晶各向异性。当x≤4时，样品具有菱方Th2znl7型结构，x=5时，具有六方CaCu5型结构。随着Al浓度增加，晶格常数和单胞体积单调增大，而居里温度和自发磁化强度近似线性地减小；在x≥l时，观察到Co亚点阵的磁晶各向异性变号，室温易磁化方向由易面转变为易轴，且易轴各向异性场和各向异性常数随Al原子浓度增加出现极大值；基于补偿温度(65K)下自由粉末颗粒的磁化曲线，导出了亚点阵间的分子场系数和Gd-co交换耦合常数，结果表明，Al原子对Gd-Co交换耦合作用的影响较小。根据Al原子在Co亚点阵4种晶位的择优占位，分析了磁晶各向异性的演变。     

含稀土硅化铁热电材料的电学性能初探

采用悬浮真空熔炼和800℃,168h真空退火方法制备了含稀土Sm的FeSi2基金属硅化物,并对其晶体结构、See-beck系数、电阻率进行了初步研究。实验发现,名义组成为Fe0.6Sm0.4Si2的试样的热电功率因子从室温时的0.26×10-4W·m-1K-2随温度上升到500℃时的1.6×10-4W·m-1K-2,比不含Sm或含Sm量很少的对比试样高一个数量级左右。其原因被认为是由于Sm的外层4f电子的贡献。     

室温磁致冷材料成型研究

本文讨论了磁致冷材料在磁致冷机中的使用，针对室温磁致冷材料要与换热流体进行快速、充分的热交换和现阶段开发研究的一些具有巨磁热效应的室温磁致冷材料多为金属间化合物的特点，分析比较了目前已有的一些磁致冷材料成型工艺方法的优缺点，介绍了一种新的成型工艺方法。     

Metallochemical Analysis of the Reaction in a Mixture of Nickel and Aluminum Powders

Phaseformation processes are considered at the level of a mesocell of a mixture with the use of the state diagram for a binary system. Consecutive schemes of metallochemical reactions of formation and decomposition of intermetallide compounds in a mixture of nickel and aluminum powders are suggested. The problem of diffusion annealing of this mixture is numerically solved for two different conditions: at a constant temperature and at a temperature slowly increasing by a linear law.     

Evaluation of oxidative stability of canola oils by headspace analysis

Lipid oxidation is a major factor affecting flavor quality and shelf life of vegetable oils. Oxidative stability is therefore an important criterion by which oils are judged for usefulness in various food applications. In this study a method based on headspace analysis was developed to evaluate relative oxidative stability of canola oils. The method does not require the use of chemicals, involves minimal sample preparation, and can be performed on a relatively small sample size in comparison with traditional wet chemical methods. Canola oils freshly extracted in the laboratory from different seed samples were subjected to accelerated oxidation and analyzed for PV by standard methods and headspace volatiles by solid phase microextraction/GC-MS. Forward stepwise regression analysis of the data revealed a relationship between PV and headspace concentration of the volatile lipid oxidation products hexanal and trans,trans-2,4-heptadienal. The PV calculated using this formula correlated (R ²=0.73) with those measured by conventional methods. Presented in part at the 96th Annual Meeting of the AOCS, 1–4 May 2005, Salt Lake City, UT.     

有机锡化合物引发D,L-丙交酯的开环聚合

D,L-丙交酯在有机锡化合物四苯基锡(Ph4Sn)、三正丁基醋酸锡(Bu3SnOAc)、辛酸亚锡(SnOct2)等催化剂引发下开环聚合,得到高分子量的聚D,L-乳酸,讨论了聚合单体D,L-丙交酯纯度、聚合温度、聚合时间、聚合体系真空度以及引发剂有机锡催化剂与聚合单体D,L-丙交酯的比例对聚D,L-乳酸合成的影响,通过红外光谱和核磁共振光谱对聚D,L-乳酸的结构进行了表征。实验结果表明,D,L-丙交酯开环聚合反应的较佳工艺路线是:D,L-丙交酯重结晶5次,聚合温度140℃,聚合时间24 h,聚合体系真空度13.3~133.3 Pa,引发剂有机锡催化剂与单体D,L-丙交酯比例0.2‰~0.5‰,此时聚D,L-乳酸的粘均分子量最高,分别达到32.46×104,33.43×104和41.36×104。     

表面有机化钛酸材料的制备及吸附染料性能

将K2CO3和TiO2通过高温固相反应制得K2Ti4O9,经酸化处理后得到H2Ti4O9,用正十二胺乙醇溶液与之反应,获得正十二胺柱撑的层状化合物,采用X射线衍射(XRD)、红外光谱(IR)等方法对所得材料进行结构表征,并初步研究了有机胺支撑前后钛酸材料的吸附性能,实验结果表明:在钛酸钾材料的层间引入正十二胺有机基团后,层间距加大,吸附能力大大提高。