共查询到20条相似文献,搜索用时 109 毫秒
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利用高分辨率的Guinier-Hagg相机和计算机控制的底片扫描及数据处理程序系统,测定了复合添加,组份为(Ca0.5Mg0.5)xSi12-3xAl3xOxN16-x(x=0.3、0.6、1.0和1.4)的α-Soalon的晶胞参数.材料由热压工艺制备而得.研究结果表明,当x≥1.0时,材料的主晶相为α-Sialon和含Mg的AlN多型体.(Ca,Mg)-α-Sialon的晶胞参数明显低于相同组份下的Ca-α-Sialon的晶胞参数·EDAX的结果进一步给出固溶进入α-Sialon的包括名义组份中90%的Ca++和少量的Mg++,而大部分Mg++进入AlN多型体,这一结果为净化α-Sialon陶瓷的晶界提供了新的有效途径. 相似文献
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Ca-α-Sialon的形成特性和显微结构的研究 总被引:4,自引:0,他引:4
由热压工艺制备了组份为CaxSi12-3xAl3xOxN16-x(0.3≤x≤2.0)的Ca-α-Sialon陶瓷。本文报道了它的反应过程、相组成、晶胞参数随组份的变化和显微结构的研究结果.研究结果表明,当x≥1.0时,制备的Ca-α’样品的物相由α-Sialon和AIN多型体21R组成,其中21R的含量随x值的增加而变大.TEM的观察结果与物相分析相符,并进一步揭示了在Ca-α-Sialon样品中长颗粒形貌的α-Sialon的存在. 相似文献
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采用化学共沉淀法成功地制备出适用于彩电显象管内荧光体着色的CoxR1-xAl2O4(R=Zn、 Mg, x=0.8~1.0)钴蓝颜料: 450nm波长处反射率最大提高18.2%, 600nm处反射率最大降低5%。通过对该颜料反射率的影响因素,如掺杂离子类型、掺杂浓度和Co2+离子浓度的探讨,结论如下:Zn2+、Mg2+改变钴蓝颜料反射性能的作用机理为晶格畸变引起Co2+3d轨道电子能级分裂程度的变化;对于掺杂离子Zn2+、Mg2+,x下限值分别约为0.85和0.8. 相似文献
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To study the effect of the microstructure of natural fiber on the transverse thermal conductivity of unidirectional composite, abaca and bamboo fibers were unidirectionally aligned to fabricate epoxy composites by a resin transfer molding (RTM) technique. The transverse thermal conductivity of these two types of composites was measured in a steady-state platform. X-ray diffractometer and scanning electron microscopy were applied to analyze the microstructure and morphology of both fibers and composites. The results indicated that the transverse thermal conductivity showed two types of tendencies with fiber content increasing: increasing for bamboo fiber composites, and decreasing for abaca fiber composites. The microstructure and theoretical analysis suggest that the lumen structure plays a great role rather than crystal structures and chemical compounds on the transverse thermal conductivity of unidirectional composites, which is useful for further development and design of natural fiber reinforced composites with better thermal insulation property for people’s daily life. 相似文献
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研究了碳纳米管纤维的微观结构和拉伸性能,并进一步分析了其与环氧树脂形成界面剪切强度及微观结构。采用单丝断裂试验测试了碳纳米管纤维/环氧树脂复合材料体系的界面剪切强度,结合单丝断裂过程中的偏光显微镜照片、复合材料的拉曼谱图和断口扫描电镜照片,研究了碳纳米管纤维/环氧树脂复合材料界面的微观结构。结果表明: 碳纳米管纤维/环氧树脂复合材料的界面剪切强度约为14 MPa;在碳纳米管纤维和环氧树脂形成界面的过程中,环氧树脂可以浸渍纤维,形成具有一定厚度的复合相,这种浸渍过程和界面相的形成都有利于碳纳米管纤维与基体之间的连接。 相似文献
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Tada J Kono T Suda A Mizuno H Miyawaki A Midorikawa K Kannari F 《Applied optics》2007,46(15):3023-3030
Selective fluorescence excitation of specific molecular species is demonstrated by using coherent control of two-photon excitation with supercontinuum pulses generated with a microstructure fiber. Pulse shaping prior to pulse propagation through the fiber is controlled by a self-learning optimization loop so that the highest fluorescence signal contrast between two fluorescent proteins is obtainable. The self-learning optimization loop successfully controls both the optical nonlinarity of the microstructure fiber and the two-photon excitation of the fluorescent proteins. 相似文献
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聚丙烯腈是炭纤维的重要原材料。高质量的聚丙烯腈才有可能生产出高质量的原丝,而高质量的原丝是保证高质量炭纤维的必在条件。聚丙烯腈的分子量及其分布、等规度、共聚结构单元的比例及分布上的缺陷直接影响着聚丙烯腈的质量,进而影响原丝及其炭纤维的性能。从调整聚丙烯腈分子量及分布、等规度、共聚结构单元的比例及分布入手,论述了提高聚丙... 相似文献
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聚丙烯腈是炭纤维的重要原材料.高质量的聚丙烯腈才有可能生产出高质量的原丝,而高质量的原丝是保证高质量炭纤维的必要条件.聚丙烯腈的分子量及其分布、等规度、共聚结构单元的比例及分布直接影响着聚丙烯腈的质量,进而影响原丝及其发纤维的性能.从聚丙烯腈分子链的微观结构(分子量及其分布、等规度、共聚结构单元的比例及分布)阐述了对炭... 相似文献
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A new concept in optical-fiber chemical sensors, the active fiber core optical sensor (AFCOS), is presented. In this sensor, the fiber core acts as a transducer. The sensitivity of an AFCOS sensor is compared with that of an active coating [evanescent wave (EW)] based optical-fiber sensor. Requirements for a fiber core to act as a chemical sensor are discussed. Novel techniques for making a porous sol-gel silica fiber, doping chemical reagents into the fiber, and constructing a chemical sensor using the porous fiber as a transducer have been developed. The microstructure of the fabricated sol-gel silica fiber and the effect of the fiber's microstructure on the capability of the porous sol-gel silica fiber for guiding light are discussed. A humidity sensor employing a CoCl/sub 2/-doped porous sol-gel fiber as a transducer has been constructed as an example. The test results for the humidity sensor verified a theoretical analysis indicating that an optical-fiber chemical sensor using an active fiber core as a transducer has a much higher sensitivity than that of an EW-based sensor. 相似文献
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利用透射电镜观察了δ-Al2O3短纤维增强Al-5.5Mg合金复合材料界面在不同环境温度下的微观结构特征。 同时, 基于该类复合材料的单纤维模型, 利用弹塑性有限元分析方法, 研究了在不同温度下界面热残余应力的大小和分布情况, 并讨论了热残余应力对界面行为的影响。 最后, 讨论了界面的微观结构和热残余应力特征对复合材料整体性能的影响。 研究表明, 不同环境温度下, 界面具有不同的微观结构和热残余应力特征, 这些特征的变化将引起复合材料整体性能的明显变化。 相似文献
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以戊二醛为增强改性剂,利用湿法纺丝制备含有预埋增强剂的南极磷虾蛋白/海藻(AKP/SA)初生纤维,通过初生纤维纺丝线在线热交联技术实现热交联反应从而制得高强度南极磷虾蛋白/海藻(HAKP/SA)复合纤维。利用旋转黏度计确定了增强交联反应的热交联温度,研究了交联度对复合纤维微观结构以及吸湿性能的影响,测试了增强后复合纤维力学性能和结晶性能的变化。结果表明:80℃时戊二醛能有效发生热交联反应;AKP/SA复合纤维具有较好的吸湿性能,吸湿率为7.3%,随着交联度的提高,复合纤维的吸湿性能降低,吸湿平衡时间缩短;HAKP/SA复合纤维仍以非晶形态存在,表面存在不均匀的沟槽结构;力学性能测试表明增强后的纤维断裂强度提高了13%。 相似文献
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We demonstrate tapering of a high air-fill fraction photonic crystal fiber by using the flame-brushing technique. Transverse probing along the taper allows us to ascertain how the microstructure is preserved during tapering. Experimental results are compared with numerical simulations performed with the finite-difference time-domain and plane-wave expansion methods. Through this investigation we find that the fiber geometry is well preserved throughout the tapering process and we resolve the apparent discrepancies between simulation and experiment that arise through the finite extent of the fiber microstructure. 相似文献