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连续SiC纤维最主要的制备方法是先驱体转化法, 目前已发展到第三代, 它主要作为SiC基复合材料(SiCf/SiC)的增强体。SiCf/SiC具有优异的耐高温、抗氧化和高温抗蠕变性, 及其在中子辐照条件下的低放射性, 成为高温、辐射等苛刻条件下结构部件的优先候选材料。本文首先对国内外SiC纤维的发展, 尤其是对第三代SiC纤维的不同制备思路和特征进行了介绍。然后, 对SiCf/SiC制备工艺和性能的进展进行了综述, 突出了制备工艺创新与SiC纤维发展的关系。最后, 对近几年SiCf/SiC在高性能航空发动机、聚变反应堆领域的应用进展进行了总结, 并对国内连续SiC纤维和SiCf/SiC复合材料的发展进行了展望。 相似文献
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以连续SiC纤维为增强体,采用前驱体浸渍裂解工艺,在复合材料基体中引入SiC晶须制备出多级增强的SiCf/SiC-SiCw复合材料,并采用化学气相渗透工艺在SiC晶须表面制备BN界面层,研究了SiC晶须及其表面BN界面层对复合材料的性能影响.结果表明:在复合材料中引入SiC晶须后,由于晶须的拔出、桥连及裂纹偏转等作用增加了裂纹在基体中传递时的能量消耗,使SiCf/SiC复合材料的压缩强度有明显提高,当引入体积分数为20%的SiC晶须时,复合材料压缩强度提高了22.6%,可达673.9 MPa.通过化学气相渗透工艺在SiC晶须表面制备BN界面层后,复合材料的拉伸强度、弯曲强度和断裂韧度分别为414.0,800.3 MPa和22.2 MPa·m1/2,较SiC晶须表面无界面层时分别提高了13.9%,8.8%和19.0%. 相似文献
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PP-g-MAH/羽绒粉体共混膜的力学性能 总被引:1,自引:0,他引:1
采用不同增塑剂对羽绒粉体处理,制备了不同羽绒含量的马来酸酐接枝聚丙烯(PP-g-MAH)/羽绒粉体共混膜,分析了粉体含量、PP种类及不同增塑剂对共混膜力学性能的影响。结果表明随着粉体含量的增加,共混膜拉伸强度呈下降趋势,而在相同粉体含量的情况下,PP-g-MAH/羽绒粉体共混膜力学性能优于PP/羽绒粉体共混膜,用甘油处理后共混膜的力学性能较优。 相似文献
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通过熔融纺丝的方法成功制备了紫外/红外双波长荧光防伪纤维。分别采用X射线衍射、差示扫描量热分析、荧光光谱、纤维强伸度、扫描电镜等方法对制备的荧光纤维进行表征,探讨了荧光粉含量对纤维的力学性能、结晶性能和荧光性能的影响。结果表明,该纤维能在254 nm紫外光的激发下发出红色荧光,也能在980 nm红外光的激发下发射出绿色荧光,具有双重防伪效果。随着荧光粉含量的增加,双波长荧光防伪纤维的荧光强度不断增强,但荧光粉的团聚情况加剧。此外,随着荧光粉含量的增加,纤维的拉伸强度与断裂伸长率不断减小,但是当荧光粉含量≤10%时,对纤维拉伸强度的影响很小。 相似文献
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《Advanced Powder Technology》2023,34(1):103885
Fabrication of parts with high mechanical properties heavily depend on the quality of powder deployed in the fabrication process. Copper powder in three different powder types were spheroidized using radio-frequency inductively coupled plasma (ICP) spheroidization process (TekSphero-15 system). The characterized powders include virgin powder as purchased from the powder manufacturer, powder used in electron beam powder bed fusion (EB-PBF) process, and reconditioned powder, which was used powder that underwent an oxygen-reduction treatment. The goal of spheroidizing these powder types was to evaluate the change in powder morphology, the possibility of enhancing the powder properties back to their as-received conditions, and assess oxygen reduction of the powder lots given their initial oxygen contents. Also, to investigate the impact of re-spheroidization on powder properties, the second round of spheroidization was performed on the already used-spheroidized powder. The impact of powder type on powder sphericity and particle size distribution was evaluated using the image analysis of scanning electron microscope (SEM) micrographs and laser diffraction, respectively. The spheroidized powder showed higher sphericity and more uniform particle size distribution overall. Depending on the powder collection bin, second round of spheroidization affected the powder sphericity differently. The possibility of deploying the plasma spheroidization process as an alternative oxygen-reduction technique was also investigated through tracking the powders’ oxygen content using inert gas fusion method before and after the spheroidization. The plasma spheroidized powder showed less oxygen content than the hydrogen-treated powder. The second round of spheroidization caused no change in oxygen content. The correlation between oxygen-reduction and created cracks was discussed and compared between plasma spheroidization and hydrogen-treatment. The plasma spheroidization process created a powder with higher sphericity, uniform particle size, and less oxygen content. 相似文献
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苄基化改性杉木粉的制备表征及对PP复合材料力学性能的影响 总被引:1,自引:0,他引:1
以甲苯为溶荆、NaOH为催化剂,使用氯化苄对杉木粉进行改性,制备了增重率(WPG)不同的改性木粉;用双辊筒炼塑机将改性木粉与聚丙烯(PP)共混,制备了木粉/PP复合材料.研究了工艺条件对改性木粉增重率的影响.通过红外光谱(FT-IR)、X射线衍射(XRD)和热重分析(TG)等方法,研究了改性木粉的结构和热性能.并研究了... 相似文献
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有机硅耐高温涂料的防腐蚀性能研究 总被引:2,自引:0,他引:2
以有机硅树脂为成膜物,制备出一种具有良好耐热性和耐蚀性,在500℃下可长期使用的耐高温防腐蚀涂料.研究了氧化铁红粉,复合磷酸锌粉,TiO_2粉对涂层性能的影响.结果表明,3种填料均能提高涂层的耐水性及耐盐水性,其中,复合磷酸锌粉的效果最为明显,且随着复合磷酸锌粉加入量的增加,涂层的耐水性及耐盐水性得以进一步提高.当磷酸锌粉的加入量为15%时,涂层可耐500℃高温,并具有较好的防腐蚀性能. 相似文献
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《Cement and Concrete Composites》2007,29(9):656-666
This paper describes the use of electrical conductivity to characterize plain and coarse glass powder modified cement pastes. It is observed that the glass powder addition facilitates improved hydration of the cement grains. For the proportions investigated in this study, and the particle size of glass powder, this advantage is negated by the reduced amount of hydration products, i.e., the dilution effect. The variation of electrical conductivity and its derivative with time can be related to the various phases in the microstructural development of the paste. It is observed from the time derivative of conductivity plots that the addition of glass powder results only in minor changes in the setting time of the pastes. Higher the glass powder content, higher the normalized conductivity (ratio of conductivity at a certain glass powder content to that of plain paste) at very early times, and then it falls to a value closer to or less than 1.0 at later times. A parallel model is used to represent effective conductivity as a function of the pore solution conductivity, porosity, and pore connectivity factor. The pore solution conductivity increases with increase in glass powder content. The porosity of the pastes reduces with increase in glass powder content at early ages and increases at later ages. A reduced pore connectivity factor is observed for pastes with higher glass powder content at later times. However, this does not imply increased volume of hydration products as is commonly interpreted for normal pastes, but the electrical conduction pathways are made more tortuous by the relatively large volume of un-reacted filler material in the pore structure. 相似文献
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Blending a mixture of powders to a homogeneous system is a crucial step in many manufacturing processes. To achieve a high quality of the end product, powder mixtures should be made with high content uniformity. For instance, producing uniform tablets depends on the homogeneous dispersion of active pharmaceutical ingredient (API), often in low level quantities, into excipients. To control the uniformity of a powder mixture, the first required step is to estimate the powder content information during blending. There are several powder homogeneity evaluation techniques which differ in accuracy, fundamental basis, cost and operating conditions. In this article, emerging techniques for the analysis of powder content and powder blend uniformity, are explained and compared. The advantages and drawbacks of all the techniques are reviewed to help the readers to select the appropriate equipment for the powder mixing evaluation. In addition, the paper highlights the recent innovative on-line measurement techniques used for the non-invasive evaluation of the mixing performance. 相似文献