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微滤、超滤分离技术在中药提取及纯化中的应用进展 总被引:11,自引:0,他引:11
综述了微滤和超滤技术在中药提取及纯化中的应用进展,如提取中药有效成分、制备中药注射剂、制备中药口服液、制备中药浸膏等;分析其工艺优点、存在的问题和解决的对策,并指出其发展前景。 相似文献
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综述了水热(溶剂热)法制备纳米材料的特点以及用此法制备ZnS纳米球、纳米线、纳米棒的研究进展,分析了纳米材料制备中表面活性剂对其形貌的重要作用,指出了水热(溶剂热)法制备纳米材料存在的问题和发展前景。 相似文献
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通过添加阴离子表面活性剂,制备了稳定性能优异的炭黑分散液;然后将其添加到天然胶乳(NRL)中,采用胶乳共沉法制备NRL/炭黑复合材料,并对其物理性能、动态力学性能和内生热等进行了探讨。研究结果表明:当炭黑类型相同时,由胶乳共沉法制备的硫化胶之力学性能普遍优于由机械法制备的硫化胶;当采用炭黑N375补强时,由胶乳共沉法制备的硫化胶之力学性能相对最佳,其拉伸强度、撕裂强度和硬度分别比由机械法制备的硫化胶提高了6.5%、4.6%和8.8%;由胶乳共沉法制备的硫化胶之损耗因子(tanδ)小于由机械法制备的硫化胶,故前者的滞后损失更小、内生热更少且温升更低。 相似文献
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聚乙酸乙烯酯(PVAc)作为常用的胶黏剂之一,其制备方法和工艺研究具有重要意义。叙述了PVAc制备方法和工艺,包括PVAc优缺点、搅拌强度、反应温度、分散介质、保护胶体、引发剂、乳化剂、交联剂和添加剂等在PVAc制备和工艺中的效用与改性。制备方法和工艺只是PVAc性能改善或者改性研究中的一部分,它决定着PVAc的生产成本,影响到PVAc的应用前景。只有充分掌握PVAc制备方法和工艺,熟悉其中各个环节,才能缩减其生产成本。 相似文献
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从碳微球的制备方法着手,综述了各方法的制备原理、原料、影响因素以及所得碳微球的结构性能和形貌特征,并归纳了各方法的优缺点,得出了溶剂热法、化学气相沉积法和模板法3种相对有效的制备方法,由于溶剂热法的突出优点,在碳微球的多种制备方法中优势凸显,将成为未来制备碳微球的主要方法。详细评述了不同结构和性能的碳微球在各个领域的应用,深入开发碳微球的性能和拓展其应用领域将会成为今后的研究重点;进一步讨论了碳微球的结构对其性质和应用的影响,通过设计碳微球的结构来改变其性质,是碳微球制备研究领域未来的发展方向。 相似文献
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制备了钨铜酸锶掺杂PZT三元体系压电陶瓷,测量了不同烧结温度和不同组成的材料的压电常数值,以压电常数为依据,确定了不同组成的材料的最优烧结温度及在最优烧结温度下材料的压电常数.研究了钨铜酸锶的掺杂量对材料机电耦合系数和机械品质因数的影响.并对不同组成的材料进行了XRD和SEM分析,研究了材料的物相组成和微观结构对材料性能的影响.讨论了Sr2+,W6+,Cu2+离子对PZT压电陶瓷进行改性的作用机理.实验结果表明,钨铜酸锶可对PZT材料进行较好的改性作用,使材料的压电常数提高到570pC/N. 相似文献
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Processing of 1-3 Piezoelectric Ceramic/Polymer Composites 总被引:1,自引:0,他引:1
Victor F. Janas Thomas F. McNulty Francis R. Walker Robert E Schaeffer Ahmad Safari 《Journal of the American Ceramic Society》1995,78(9):2425-2430
Several methods of forming fine-scale 1–3 piezoelectric ceramic/polymer composites for possible transducer applications were demonstrated. These methods include tape casting, honeycomb dicing, and ceramic fiber weaving. In the tape casting technique, laminated structures were formed using thin PZT tapes. The tapes were stacked, with spacers separating the layers, and the stack embedded in polymer. Dicing the stack resulted in a composite with 1–3 connectivity. The thin tape technique can be used to develop composites with ceramic or polymer volume fraction gradients and multifunctional ceramics. Dicing of PZT honeycombs yields 1–3 composites with uniquely shaped rods. Shapes included +, T, and L. In the ceramic fiber weaving technique, green PZT fibers were woven through a PZT honeycomb support structure. The structure was fired to sinter the PZT fibers, and embedded with polymer to yield 1–3 composites. All 1–3 composites showed high and uniform piezoelectric coefficients across the electroded area. 相似文献
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锆钛酸铅(PZT)粉体合成的研究进展 总被引:1,自引:0,他引:1
锆钛酸铅(PbZrxTi1-xO3,PZT)陶瓷是一类重要的铁电、压电、介电材料,其粉体的相组成、化学组成、热稳定性和烧结活性影响着陶瓷制品的铁电、压电和介电性能。本文详细综述了合成PZT粉体的固相反应法和湿化学方法的发展现状,并对几种合成方法的特点进行了评介,为低温合成纯相PZT粉体和PZT一维纳米结构指出了可能的方法。 相似文献
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Yan Chen Xiulan Bao Chi-Man Wong Jian Cheng Haidong Wu Haizhu Song Xuanrong Ji Shanghua Wu 《Ceramics International》2018,44(18):22725-22730
The PZT ceramics with different weight content from 78% to 89% were printed using the stereolithography method. The piezoelectric properties as well as the microstructure of the ceramics were investigated in detail. X-ray patterns and Raman spectra demonstrate that the steady PZT tetragonal phase has already formed in these sintered ceramics. Besides, the piezoelectric constant and dielectric constant were 212–345 pC/N and 760–1390, which were sligthly lower than that of the dry pressing disk. Furthermore, a two-dimensional ultrasound transducer array (8?×?8) was designed and developed to evaluate the properties of the 3D-printed PZT ceramics. 相似文献
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Ceramic/polymer composites are attracting increasing interest in materials research and practical applications due to the combination of excellent electric properties of piezoelectric ceramics and good flexibility of polymer matrices. In this case, the crystallization of the polymer has a significant effect on the electric properties of ceramic/polymer composites. Based on different heat treatment methods, the crystallization of poly(vinylidene fluoride) (PVDF) in composites of lead zirconate titanate (PZT) and PVDF can be controlled effectively. PZT/PVDF composites with various PVDF crystallizations exhibit distinctive dielectric and piezoelectric properties. When the crystallization of PVDF is 21%, the PZT/PVDF composites show a high dielectric constant (ε) of 165 and a low dielectric loss (tan δ) of 0.03 at 103 Hz, and when the crystallization of PVDF reaches 34%, the piezoelectric coefficient (d33) of PZT/PVDF composites can be up to ca 100 pC N?1. By controlling the crystallization of PVDF, PZT/PVDF composites with excellent dielectric and piezoelectric properties were obtained, which can be employed as promising candidates in high‐efficiency capacitors and as novel piezoelectric materials. Copyright © 2010 Society of Chemical Industry 相似文献