排序方式: 共有68条查询结果,搜索用时 453 毫秒
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多晶铁纤维的合成与微波吸收性能的研究 总被引:19,自引:0,他引:19
The preparation and microwave-absorbing behavior of polycrystalline iron fibers modified with the thermal decomposition of carbonyl iron were studied in this paper. Through preparation of α-FeOOH fiber precursor, dehydration, reduction with hydrogen, modification with the thermal decomposition of carbonyl iron and passivation, polycrystalline iron fibers were yielded. α-FeOOH fiber precusor with optimum diameter and aspect ratio was made by using uniform seed crystal with optimum concentration and controlling the reaction time. Lacunas from procedure of dehydration and reduction were well modified with carbonyl iron. The sample with 1.95 mm thickness containting 60 % by weight of modified polycrystalline iron fibers showed reflection loss over 10 dB within the frequency range of 8.5~14.6 GHz, and the maximum reflection loss was 21.8 dB at 11.3GHz, while the sample of nonmodified polycrystalline iron fiber showed less reflection loss under same conditions. 相似文献
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聚硅氮烷包敷纳米铁磁粉PSZFe的合成及其雷达波吸收性能研究 总被引:8,自引:0,他引:8
金属磁性材料是一类很重要的雷达波吸收材料 ,而纳米铁磁粉是其中的姣姣者 ,具有质量轻、居里温度高、磁化强度高 (可以是铁氧体磁性材料的 2~ 3倍 ) [1,2 ] 、矫顽力大、雷达波吸收性能好和频带宽等优点[3 ] ;但由于其颗粒太细 ,暴露在空气中即被强烈氧化 ,实际应用很困难 ,对其进行包敷处理是一种很有效的抗氧化腐蚀方法 .聚硅氮烷(PSZ)做为纳米铁磁粉包敷层有很多优点 :包敷层所要求的化学和力学性能可以通过调整氯硅烷单体的比例以及反应条件而实现[4] ;包敷层具有高致密性、高疏水性 ,从而使潮气、水和氧气很难侵入 ;包敷层耐热性好… 相似文献
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用偏光显微镜、DSC和WAXD对新的主链型聚甲亚胺醚系列的液晶行为进行了表征,发现7种聚合物均显示向错和条带织构,其熔点呈奇偶变化规律. 相似文献
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The observation of disclination cores of high strength S= -2, -3, -4, -5, -6, -7, -8 in a smectic C phase of Schiff-base type liquid crystal (LC) is reported. The results of polarizing optical microscope (POM), differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD) prove that the sample exhibits smectic C phase. It is suggested that the formation of the high strength disclination is mainly ascribed to the stronger anchoring of LC molecules on the substrate due to the formation of hydrogen bonds between the pendent hydroxyl of the LC molecule and the substrate. 相似文献
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硅碳烷树枝状液晶的研究 总被引:4,自引:2,他引:4
树技状化合物具有规整的结构,其分子体积、形状和功能基团可在分子水平上精确控制[1],迄今国内只有综述报道[2].传统的液晶分子为刚性棒状,按经典液晶理论,树枝状分子难以存在液晶态,迄今仅见3例多技聚合物显示热致或液致液晶性D-“.nercec[’咱称首次合成热致液晶树枝状聚合物TPD-bx,但据Ringsdorf[51分类,因其未采用逐步发散或收敛法,而用一锅煮法合成,产品结构不规整,分子量不单一.故仍属于多技聚合物.本文首次合成了液晶硅碳烷树技状化合物.1硅碳烷树技状化合物的结构树枝状化合物的结构见图1,主干为硅碳烷,含12… 相似文献
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三代树状碳硅烷液晶研究——端基含丁氧基偶氮苯介晶基元 总被引:5,自引:3,他引:5
用发散法合成周边含丁氧基偶氮苯介晶基元(M5)端基新的三代树状碳硅烷(D3) 液晶,并用元素分析,核磁共振,激光解吸电离飞行时间质谱(MALDI-TOF-MS),红外、 紫外、偏光显微镜、差示扫描量热(DSC)和广角X射线衍射(WAXD)表征,D3为向 列相与M5相同,树状物相态由介晶基元相态决定,D3相行为;K79N1261116N,D3熔 点比M5降低33℃,D3清亮点比M5增加2℃,D3液晶态温区比M5加宽35℃。 相似文献
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