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1.
等离子喷涂法制备B4CCu梯度材料   总被引:1,自引:0,他引:1  
以钢为基体,利用大气等离子喷涂技术制备了4种B_4C涂层(纯B_4C涂层和成分分布指数分别为P=0.2,1,2的B_4C/Cu梯度涂层).对这几种涂层的形貌进行了观察;对B_4C/Cu梯度涂层的残余热应力进行了分析:对纯B_4C涂层和B_4C/Cu梯度涂层进行了X射线电子束热冲击测试.结果表明,P=1的B_4C/Cu梯度涂层具有最好的抗热震性.最后对B4C涂层的化学溅射性能进行了测试.  相似文献   

2.
利用半经验MNDO方法,研究了碱金属和卤素离子笼内掺杂对富勒烯C70加成物C70H2立体选择性的影响。研究结果表明,Li^+的掺杂使1,4-异构体C70H2(2/1  相似文献   

3.
对1 ,3 - 二咔唑基丙烷(1 ,3 - DCZP) 在光激发下与电子受体化合物1 , 4 - 二氰基苯(1 ,4 -DNB) 形成三元激基复合物的光物理过程进行了研究. 结果表明, 当1 , 4 - DNB 对高浓度的1 , 3- DCZP荧光猝灭时, 随着猝灭剂浓度的增加, 电子给体和电子受体分子形成了[DDA]* 型(2个1 , 3 - DCZP分子和一个1 , 4 - DNB分子) 的三分子激基复合物; 当1 , 4 - DNB 对低浓度的1 , 3 - DCZP荧光猝灭时形成了[(DD)A] * 型(1 个1 , 3 - DCZP分子具有2 个电子给体基因, 与1 个1 , 4 - DNB分子) 的三元激基复合物.  相似文献   

4.
以掺碳化钨的石墨棒为阳级,以高纯石墨棒为阴极,用直流电弧法合成富勒烯,并对碳化钨对富勒 烯的影响进行了研究。  相似文献   

5.
过渡塑性相工艺制造Ti-B-C复合陶瓷材料   总被引:8,自引:0,他引:8  
给出了以TiH2和B4C为原料通过过渡塑性相工艺(transientplasticphaseprocessing)制备Ti-B-C复合陶瓷材料的方法。同时进行了TiH2-B4C体系和Ti-B4C体系的对比实验,结果表明,TiH2在800℃以下分解获得高性能的Ti粉和B4C发生了如下反应:(3+x)Ti+B4C→2TiB2+(1+x)TiC11+x(0≤x≤1)。在相同条件下以TiH2作为过渡塑性相的TiH2-B4C体系比Ti-B4C体系具有优越的烧结性能,在1600℃时热压烧结4h可以获得高性能的TiB2-TiCx复合陶瓷材料(断裂韧性为7.7GPam1/2,抗弯强度为765MPa)。还利用X衍射和扫描电镜对这种材料的显微结构进行了研究。  相似文献   

6.
用化学掺杂方法合成了Ba1-xSrxTiO3和Ba09Sr01TiO3·yLa2O3(0≤x≤1,0≤y≤03)系列固溶体超细粉末。XRD证实,当x=1,y=0时,为四方晶系BaTiO3纯相,当0<x<1,0<y≤03时,得到一系列完全互溶固溶体,结果符合Vegard定律。SEM观察粒子为球形,大小均匀,粒度02~03μm,制陶实验发现,钛酸钡经化学掺杂后,室温介电常数显著提高,当x=01,y=002时,ε可达30000,比BaTiO3纯相的室温介电常数提高20倍。  相似文献   

7.
以焦磷酸根(P2O7^4-)为配体,二六烷基三甲溴化铵(CTMABr)为鼓泡剂,对Cu(Ⅱ),Pb(Ⅱ),Cd(Ⅱ)等4种金属离子的浮选分离进行了研究。讨论了pH值,氮气流速、P2O7^4-的浓度、CTMABr的浓度、金属离子浓度对浮选率的。到了其最佳分离条件,对Cu(Ⅱ)-Cd(Ⅱ),Pb(Ⅱ)-Cd(Ⅱ),Zn(Ⅱ)-Cd(Ⅱ)等二元组分进行了较好的分离。  相似文献   

8.
本文研究了三元共聚物MBS树脂和PVCNBS共混物的形态、结构及其相关性能。采用间歇加料法得到形态规整的核壳型树脂。改变三元组分比例和玻璃化转变温度(Tg)能大大影响PVC增韧效果,当B=42%时S:M=(34~30):(24~28)为宜。DSC测定结果表明:PVC与MBS的壳层PMMA能很好相容,从二相间的相容结构形态证实,共混物间形成良好的粘合界面层,通过透射电镜(TEM)和扫描电镜(SEM)观察到PVCNBS共混体系由脆性转变为韧性的结构形态和形貌特征,抗冲击值可由纯PVC时的4kJ/m2增到MBS15份时的50kJ/m2以上。  相似文献   

9.
单核和双核Cu(Ⅱ)—Schiff碱配合物的合成,晶体结构?…   总被引:1,自引:1,他引:0  
报导了4个Schiff碱配体的Cu(Ⅱ)配合物[(Cu(Ⅱ)(L1)]ClO4(1),[Cu(Ⅱ)(L2)(H2O)]BF4(2),Cu(Ⅱ)2(L3)2(Cl)2(3)和[Cu(Ⅱ)2(L4)(OH)(H2O)](BF4)2(4)的合成和晶体结构以及它们的电子光谱特性,4个配体由醛与胺综合而得,产物未经分离,直接用于合成配合物,以配合物产率计,综合反应的产率不低于60%。通过比较它们的晶体结构参  相似文献   

10.
选择6头健康、2~3岁、体重300~400kg雄性水牛,研究了睾丸摘除后血液中某些激素水平和免疫功能指标的变化及相关性.结果表明:在水牛睾丸摘除后的15d内,血浆睾酮在摘除2d后呈现极明显下降;皮质醇头7d呈波动性上升趋势,以后下降;T3、T4与摘除前相比无明显差异;WBC呈明显下降趋势;淋巴细胞(%)除第1天显著下降外,其它时间无规律性变化;ANAE阳性淋巴细胞(%)和RBC-CR1花环率分别明显高于和低于摘除前水平;RBC-IC花环率在第5天明显下降,以后又逐渐回升到摘除前水平.相关性分析发现,睾酮分别与WBC和RBC-CR1花环率呈显著正相关,而与ANAE阳性淋巴细胞呈负相关;T4与WBC也呈明显正相关  相似文献   

11.
煤基富勒烯的制备研究   总被引:7,自引:0,他引:7  
以 1 4种国产煤为原料 ,用电弧等离子体蒸发法制备富勒烯 .富勒烯产品的表征采用质谱、紫外光谱、红外光谱及高压液相色谱技术 .考察了煤样的基础性质对富勒烯产率的影响 .结果表明 ,由实验所用煤种均可制得富勒烯 ;原料煤本身的化学结构和组成影响富勒烯的产率和分布 ;由某些煤得到的富勒烯中 ,C70 的含量较之以石墨电极为原料时的含量要高得多 .  相似文献   

12.
评述了近几年来富勒烯的发现过程,论述了纳米洋葱状富勒烯的几种制备方法,并对其生长机理进行了探讨性研究。同时指出了每种方法的优缺点,为富勒烯的宏量制备和应用研究指明了方向。简述了本课题组采用真空热处理方法,石墨在催化剂的作用下转变为洋葱状富勒烯的工作。  相似文献   

13.
Nano-carbon materials were synthesized by the catalytic decomposition of acetylene at 400℃ by using Fe/Al2O3 as catalyst. The product was refluxed in 36% concentrated HCl at 60℃ for 48 h in order to remove the catalyst support. The samples were examined by scanning and high resolution transmission electron microscopy, energy dispersive spectroscopy and X-ray diffraction. The results show that nano onion-like fullerenes encapsulating a Fe3C core were obtained. These had a structure of stacked graphitic fragments, with diameters ranging from 15―50 nm. When the product was further heat- treated at 1100℃ for 2 h, nano onion-like fullerenes with a clear concentric graphitic layer structure were obtained. The growth mechanism of nano onion-like fullerenes encapsulating metal cores is suggested to follow a vapor-solid growth model.  相似文献   

14.
Fullerenes C60 and C70 in flames   总被引:5,自引:0,他引:5  
The fullerenes C60 and C70 were first identified in carbon vapour produced by laser irradiation of graphite, and have recently been produced in macroscopic quantities by vaporization of graphite with resistive heating. It has also been suggested that fullerenes might be formed in sooting flames, and indeed all-carbon ions with mass/charge ratios suggestive of fullerenes have been detected in flames. These species were assumed to have the cage structures of fullerenes, but the mass spectroscopic evidence could not establish this conclusively. We have now collected samples of condensible compounds and soot from hydrocarbon combustion under a range of conditions, and analysed these using conventional techniques in an effort to detect fullerenes. Spectroscopic studies reveal the presence of C60 and C70 in yields and ratios that depend on temperature, pressure, carbon/oxygen ratio and residence time in the flame. Control of these conditions allows optimal yields of 3 g of fullerenes per kilogram of fuel carbon burned, and variation of the C70/C60 ratio over the range 0.26-5.7.  相似文献   

15.
《科学通报(英文版)》1998,43(24):2071-2071
Two fullerene derivatives (compounds 1 and 2) have been synthesized. Their redox properties have been measured by cyclic voltammetry. The photoconductivities of poly(N_vinylcarbazo_le) (PVK) doped with fullerene and with their derivatives have been studied to explore the possible relationship between the reductibility of fullerenes and the photoconductivity of fullerenes_doped PVK. The charge generation efficiencies of PVK doped with fullerene and with its derivatives have changed remarkably: the diversity of charge generation efficiency is obvious in different doping systems. The result indicates that there is charge transfer between fullerenes and PVK.  相似文献   

16.
Two [60]fullerene derivatives (compounds 1 and 2) have been synthesized. Their redox properties have been measured by cyclic voltammetry. The photoconductivities of poly(N-vinylcarbazole) (PVK) doped with [60] fullerene and with their derivatives have been studied to explore the possible relationship between the reductibility of fullerenes and the photoconductivity of fullerenes-doped PVK. The charge generation efficiencies of PVK doped with [60]fullerene and with its derivatives have changed remarkably: the diversity of charge generation efficiency is obvious in different doping systems. The result indicates that there is charge transfer between fullerenes and PVK.  相似文献   

17.
A new process was used for producing FeAl alloy pow de rs with double consumable rotating electrodes and the powders made in this appar atus were analyzed. In this new technology, tungsten rod serves as a cathode ele ctrode, while the alloy rod as an anode electrode. The conventional rotating ele ctrode process must have an anode with pre-melting alloys; however, in this new process, using pure iron as cathode electrode and pure aluminum as anode electr ode can eliminate the step of pre-melting. The e...  相似文献   

18.
Boron-doped diamond has been synthesized from graphite mixed with different ratio of B4C at high pressure high temperature (HPHT) using laser heated diamond anvil cell. The starting composition was transformed to diamond compound at pressure ∼9 GPa, 2300–2400 K as indicated by the in-situ X-ray diffraction pattern with synchrotron radiation source. Raman spectrum of the recovered specimen from HPHT state confirmed that boron has been doped into diamond lattice.  相似文献   

19.
Superconductivity in single crystals of the fullerene C70.   总被引:2,自引:0,他引:2  
The observation of superconductivity in doped C60 has attracted much attention, as these materials represent an entirely new class of superconductors. A maximum transition temperature (Tc) of 40 K has been reported for electron-doped C60 crystals, while a Tc of 52 K has been seen in hole-doped crystals; only the copper oxide superconductors have higher transition temperatures. The results for C60 raise the intriguing questions of whether conventional electron-phonon coupling alone can produce such high transition temperatures, and whether even higher transition temperatures might be observed in other fullerenes. There have, however, been no confirmed reports of superconductivity in other fullerenes, though it has recently been observed in carbon nanotubes. Here we report the observation of superconductivity in single crystals of electric-field-doped C70. The maximum transition temperature of about 7 K is achieved when the sample is doped to approximately four electrons per C70 molecule, which corresponds to a half-filled conduction band. We anticipate superconductivity in smaller fullerenes at temperatures even higher than in C60 if the right charge density can be induced.  相似文献   

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