共查询到18条相似文献,搜索用时 93 毫秒
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采用固相和液相反应法在泡沫碳化硅陶瓷骨架表面原位生长碳化硅晶须,研究了催化剂和反应温度的影响.结果表明,催化剂氯化镍的作用使硅与碳直接反应生长出细长的碳化硅晶须.在适当的反应温度下生长的碳化硅晶须的表面光滑,线径比较大,有少量的呈弯曲状或竹节状;反应温度过高使得硅晶须的缺陷较多.在泡沫碳化硅陶瓷骨架的表面原位生长出碳化硅晶须属于LS生长机理.具有表面晶须的碳化硅陶瓷以深床体积过滤的方式用于过滤柴油机汽车尾气中的碳颗粒,表面晶须既能提高泡沫陶瓷过滤器的过滤能力,又有利于过滤器的再生. 相似文献
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碳化硅泡沫陶瓷浆料成分与烧结性能 总被引:11,自引:0,他引:11
将用于制备碳化硅泡沫陶瓷的浆料烘干、制粉、干压、烧结,从而探讨浆料的成分与 烧结性能的关系.样品的抗弯强度与烧结助剂的含量之间存在最佳搭配关系,烧结对强度的贡 献主要来自于新相莫来石的生成和玻璃相对碳化硅颗粒的包覆、连接作用.同种成分的样品开 气孔率随着烧结温度的升高表现出单调下降的趋势,而抗弯强度与开气孔率的变化并没有表现 出完全相反趋势;不同成分样品的耐火度均保持在1730℃没有变化.采用最佳配方的浆料和 最佳烧结温度制备的碳化硅泡沫陶瓷抗弯强度可达到0.72MPa. 相似文献
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由多孔陶瓷材料制备的过滤元件在分离、净化领域得到日益广泛的应用,陶瓷过滤器的过滤机理和过滤效率的研究、表征日益受到重视.综述了泡沫陶瓷、普通多孔陶瓷管、陶瓷过滤膜过滤机理的研究进展.泡沫陶瓷主要通过滤饼机制、表面效应、整流效应来达到净化金属液的效果. 相似文献
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为拓展铁尾矿的资源化利用途径,本研究分别以细颗粒高硅铁尾矿、铁尾矿+石墨粉以及铁尾矿+石墨粉+碳化硅粉为原料,采用泡沫注凝成形-常压烧结、泡沫注凝成形-反应烧结和模压成形-反应烧结工艺制备了铁尾矿多孔陶瓷和三种以碳化硅为主晶相的多孔陶瓷。通过DSC-TG和XRD分析,研究了铁尾矿自身的烧结过程以及铁尾矿与石墨之间的碳热还原反应烧结过程,对比分析了四种多孔陶瓷材料的孔隙率、压缩强度、热导率等性能。结果表明,以铁尾矿为原料可制备具有较高孔隙率(87.2%)、压缩强度(1.37 MPa)和低热导率(0.036 W/(m·K))的铁尾矿多孔陶瓷,它是一种高效保温隔热材料;利用铁尾矿与石墨之间的碳热还原反应可获得碳化硅多孔陶瓷,其热导率显著提高,但强度偏低;而在原料中加入部分碳化硅,可以明显改善多孔陶瓷的压缩强度,获得具有高孔隙率(91.6%)、较高压缩强度(1.19MPa)和热导率(0.31W/(m·K))的碳化硅多孔陶瓷,它可作为轻质导热材料或复合相变材料的载体使用;与泡沫注凝成形工艺相比,采用模压成形工艺制备的碳化硅多孔陶瓷虽然孔隙率有所降低(79.3%),但热导率得到显著提升(1.15 ... 相似文献
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高活性的光催化二氧化钛纳米材料与高气孔率的三维多孔泡沫陶瓷材料复合,得到的光催化泡沫陶瓷过滤器,具备高活性、大表面积、大通量、以及陶瓷的耐高温、耐化学腐蚀、循环适用性,在大气/水净化领域率先得到了广泛应用。在工业领域的废气脱臭处理、在农业领域的农药废水太阳光降解、在医疗卫生领域的实验室医院空气杀菌处理、在交通领域的高速列车空气净化等,已经展开应用。综述了国内外光催化泡沫陶瓷过滤器的应用研究现状、问题及其发展趋势。 相似文献
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采用有机泡沫浸渍法制备碳化硅泡沫陶瓷时, 通过对聚氨脂泡沫进行不同改性剂的表面处理来改善其挂浆性能, 利用一种更加合理的表征方法, 即测量挂浆后泡沫陶瓷素坯孔筋尺寸和表征孔筋挂浆后形貌来衡量挂浆性能. 试验结果表明, 在所选用的四种改性剂中, 羧甲基纤维素(CMC)的改性作用最好, 其次是硅溶胶, 而聚乙烯醇(PVA)效果最差. CMC的改性效果主要来源于pH值>7 条件下形成的疏水基团与有机泡沫结合而亲水基团与水基浆料结合的结构, 这种结构可以显著改善有机泡沫与水基浆料的润湿性. 相似文献
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Aligned silicon carbide whiskers were prepared from porous carbon foams by thermal evaporation of silicon. High-density silicon carbide whiskers were vertically deposited on the surface of siliconizing carbon foam. The whiskers were straight and hexagon-shaped with diameter of 1-2 μm and length of about 40 μm. They consisted of a single-crystalline zinc blende structure crystal in the [111] growth direction. The pore structure of carbon foam played an important role in determining distribution of the whiskers on the surface of siliconizing carbon foam. When carbon foam with higher porosity and larger pore size was employed, distributions of the whiskers were more ordered and more intensive. The whiskers were grown by the vapor-solid (VS) mechanism. 相似文献
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Yongheng Zhang 《Materials Research Bulletin》2004,39(6):755-761
Silicon nitride bonded silicon carbide foams have been produced by nitridation of the foamed compacts containing silicon carbide and silicon powders. When no nitridation additive was used the ceramic foams nitrided at all temperatures studied contained a significant amount of whisker phase α-Si3N4 formed both inside and outside the cell walls leading to a loose microstructure and a low mechanical strength. When the Al2O3 and Y2O3 were used as nitridation additives, the ceramic foams nitrided at temperatures of 1360 and 1395 °C containing certain amount of Si2N2O and whisker α-Si3N4 phases that are bonded by a glassy phase and behave as reinforcements for the ceramic foams exhibited a much higher mechanical strength. At nitridation temperature of 1430 °C, the ceramic foam showed the locally formed β-Si3N4 as the main nitrided phase that caused no increase in bonding area between the nitrided phase and the silicon carbide particles. Thus, a relatively lower mechanical strength was observed for the ceramic foam. 相似文献
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介绍了泡沫陶瓷材料的性能表征及其发展现状和存在问题,总结了制造中的材料选取、制造工艺以及技术性能指标。 相似文献
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以泡沫碳化硅载体内的残余硅为硅源,在泡沫碳化硅载体上自转化合成silicalite-1型沸石晶体.用残余硅含量为16.7%的泡沫碳化硅作为载体,町制备出负载均匀、耐热性好,抗热冲击、比表面积为36 m2g-1的silicalite-1型沸石晶体/泡沫碳化硅复合材料.研究了泡沫碳化硅载体的残余硅含量和水热合成溶液的组成等因素对沸石晶体的自转化合成及其形貌的影响.结果表明,泡沫碳化硅载体中的残余硅含量是影响沸石晶体层结晶的关键因素.当载体中硅的含量过低时,溶液中的硅酸根浓度过低,不具备形成沸石晶体的条件;而当载体中硅的含量过高时,溶液中的硅酸根浓度过高,沸石晶体优先在残余硅的表面形核,随着这些硅的溶解,在其上形成的沸石晶体也随之脱落.增加模板剂的含量可促进沸石晶体形核,从而使沸石晶体的尺寸变小. 相似文献
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泡沫陶瓷填料直接蒸发冷却换热性能实验研究 总被引:1,自引:1,他引:0
介绍了泡沫陶瓷填料的直接蒸发冷却换热性能实验方法,探讨了泡沫陶瓷填料换热效率和过流阻力的影响因素及其影响规律。实验结果表明:新型泡沫陶瓷材料可用作直接蒸发冷却换热填料,其换热效率接近纸质湿帘,高于金属填料,在温室空气调节领域有着广阔的应用前景。 相似文献
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A replication process for producing fine open-celled ceramic foam from preceramic polymers is presented and analysed. In this process a porous sodium chloride compact formed by sintering was first infiltrated with polycarbosilane. After dissolution of the salt, the resulting polymer foam was cured by oxidation in air and pyrolysed to form a silicon carbide foam. The curing stage is the most critical step, and was investigated using a series of controlled curing experiments and finite-difference modelling of heat transfer during curing. Good agreement has been found between theory and experiment. The model was then used to investigate the limits of the process and to provide stategies for successful curing of the foams without melting or cracking. 相似文献