共查询到18条相似文献,搜索用时 62 毫秒
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泡沫陶瓷由于具有一系列优异的性能,使得其应用范围越来越广泛,其制备方法也在不断地发展.先驱体转化法制备泡沫陶瓷是20世纪末才出现的一种新型工艺.它具有制备温度低、陶瓷组成和结构町设计、容易成型复杂构件等优点,成为目前泡沫陶瓷制备方法中的一个研究热点.根据泡沫陶瓷制备过程中成孔原理的不同,先驱体转化法制备泡沫陶瓷大致町以分为三类:(1)直接发泡法;(2)有机泡沫浸渍法;(3)添加造孔剂法.本文详细地介绍了由这三类先驱体转化法制备泡沫陶瓷的研究现状,并分析了其优缺点以及亟待解决的问题. 相似文献
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A process for the production of SiOC ceramic foams has been for the first time developed through melt foaming of a siloxane preceramic polymer with the help of a blowing agent, followed by pyrolysis under an inert atmosphere. The raw material consisted of a methylsilicone resin, a catalyst (which accelerated the cross-linking reaction of the silicone resin) and a blowing agent (which generated gas above 210°C). Methylsilicone resin foams were obtained through controlling the melt viscosity around 210°C, temperature where the blowing agent started to decompose, by varying the initial molecular weight of the preceramic polymer and the amount of the catalyst. The obtained SiOC ceramic foams exhibited excellent oxidation stability up to 1000°C, as shown by thermal gravimetric analysis (TGA). As expected, the mechanical properties of the SiOC ceramic foams varied as a function of their bulk density, possessing a flexural strength up to 5.5 MPa and a compression strength up to 4.5 MPa. The main steps in the process, namely foaming and pyrolysis, were analyzed in detail. The viscosity change was analyzed as a function of temperature by the dynamic shear measurement method. The pyrolysis process of foams was analyzed by TGA coupled with infrared spectroscopy (IR). 相似文献
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探讨了一种新的非化学反应直接凝聚固化成型方法。利用高分子电解质分散剂可以制备固体含量高、流动性良好的陶瓷泥浆。这种泥浆注入非多孔性模具后 ,无需生物酶催化反应 ,只需将温度升至70~80℃ ,泥浆便由分散状态转为凝聚状态 ,泥浆即达到固化成型。这种方法具有工艺简单、容易控制的特点 ,并且可以获得高致密、高均匀性的陶瓷成型体。通过对氧化铝 -高分子电解质 -水系统的吸附及流动特性进行的系统的研究 ,提出了覆盖率理论 ,解释了用经典的DLVO理论难以解释的胶体稳定性与温度敏感特性之间的关系 相似文献
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Preparation of ultra-high temperature SiC–TiB2 nanocomposites from a single-source polymer precursor
《Ceramics International》2020,46(12):19928-19934
SiC–TiB2 ceramic nanocomposites are valuable ultra-high temperature materials, which are rarely prepared from preceramic polymers. In this work, we synthesized SiC–TiB2 nanocomposites from a new preceramic polymer called titanium- and boron-modified polycarbosilane (TB–PCS). The polymer structure was characterized by Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance (NMR) spectroscopy. The structure, composition, and morphology of the resulting ceramic products were investigated by FT-IR, X-ray diffraction, and transmission electron microscopy. The elements of titanium and boron were incorporated into the preceramic polymer, and nanoscale TiB2 and β-SiC grains generated in situ were detected in the pyrolyzed ceramic products at temperatures higher than 1400 °C. The new preceramic polymer presents a novel approach to preparing SiC–TiB2 nanocomposites. 相似文献
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本文根据陶瓷料浆的三种稳定机制(静电稳定机制、空间位阻稳定机制、空缺稳定机制),详细阐述了高分子聚合物对浆料的不同作用机理,同时,从对陶瓷原料粒子表面改性的角度出发,介绍几种陶瓷粉体表面改性技术用以制备出稳定、均匀及高固相含量的陶瓷料浆。 相似文献
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《Journal of the European Ceramic Society》2022,42(13):5476-5483
In this study, we present a DLP 3D-printing strategy for the fabrication of SiCN ceramic matrix composites (CMCs). The polysilazane-based preceramic polymer containing inert fillers was UV-cured into a green body and then converted to SiCN CMCs after pyrolysis. The introduced fillers (Si3N4 particles and Si3N4 whiskers) as reinforcements are well dispersed in the matrix, which can not only effectively reduce the linear shrinkage and weight loss, but also greatly improve the mechanical properties of the SiCN CMCs. The bending strength of the SiCN CMCs reinforced with 10 wt% Si3N4 whiskers (without surface polished) reached 180.7 ± 15.6 MPa. Furthermore, the effect of fillers content on microstructure and porosity of the SiCN CMCs are discussed, and it was found that the excessive fillers led to increased pore defects and decreased continuity of the matrix, thereby reducing the mechanical properties of the SiCN CMCs. This strategy provides a promising ceramic manufacturing technique to fabricate polymer‐derived CMCs with complex-shaped and high-performance for potential demanding applications. 相似文献
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Organosilanes are often used in commercial sizings for glass fibres to provide wettability with the resin and promote strong interfacial adhesion to the matrix in a fibre reinforced polymer composite. The silane treatment is introduced as part of a complex deposition from an aqueous emulsion immediately at the spinaret and determines the optimum properties of the cured composite. To understand the interaction of organosilanes contained in sizings for glass surfaces, XPS was used to investigate the adsorption of γ-aminopropyltriethoxysilane (APS) from a simple sizing system containing a polyurethane (PU) film former. It has been found that both APS and the sizing (containing APS and PU) deposits on E-glass fibre surfaces contained components of differing hydrolytic stability. The differences observed in the AFM images of APS coated E-glass fibres before and after water extraction also confirmed that the APS deposit contained components with different water solubility. 相似文献
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Organosilanes are often used in commercial sizings for glass fibres to provide wettability with the resin and promote strong interfacial adhesion to the matrix in a fibre reinforced polymer composite. The silane treatment is introduced as part of a complex deposition from an aqueous emulsion immediately at the spinaret and determines the optimum properties of the cured composite. To understand the interaction of organosilanes contained in sizings for glass surfaces, XPS was used to investigate the adsorption of γ-aminopropyltriethoxysilane (APS) from a simple sizing system containing a polyurethane (PU) film former. It has been found that both APS and the sizing (containing APS and PU) deposits on E-glass fibre surfaces contained components of differing hydrolytic stability. The differences observed in the AFM images of APS coated E-glass fibres before and after water extraction also confirmed that the APS deposit contained components with different water solubility. 相似文献