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纳米-纳米复相陶瓷的制备 总被引:4,自引:0,他引:4
本文结合作者的工作对纳米—纳米复相陶瓷的制备方法进行了评述。纳米—纳米复相陶瓷的粉体由于既要求粒子大小为纳米量级,又要求不同组分均匀分布,一般以化学法制备为主。在烧结过程既要获得高的致密度,又要防止晶粒的长大,烧结过程通常要采取如原位合成、热压烧结等方法。 相似文献
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Al2O3—AIN—TiC复合陶瓷的制备与微观结构 总被引:6,自引:1,他引:6
用反应烧结和气氛烧结技术制备Al2O3-AIN-TiC复合陶瓷,用XRD,SEM等测试手段进行了微观结构的研究,结果表明,用该技术制备的复相陶瓷含有纳米级的AIN晶粒,从而使得在较低的烧结温度下可以制得比较致密的Al2O3-AIN-TiC复合陶瓷。 相似文献
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纳米复相结构陶瓷的原位反应合成 总被引:1,自引:0,他引:1
简要介绍了原位反应合成纳米复相陶瓷的原理及其可行性,认为此方法是制备纳米复相结构陶瓷的有效方法. 同时讨论了氮化硼(h-BN)复相陶瓷的特点及其性能改善的关键因素,认为采用传统方法难以获得高性能的BN复相陶瓷. 提出了一系列原位化学反应,并采用热压或无压烧结获得了细小而均匀分散的非氧化物?氮化硼(Nobn)复相陶瓷,纳米级的BN片晶主要分布在基体晶粒的晶界处,当BN体积含量适当时即可获得一种全新的部分弱晶界陶瓷复合材料(PWICs),这种材料具有很好的综合力学性能. 相似文献
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以水基喷雾造粒而成含5%(质量分数)纳米氮化钛(TiN)颗粒的碳化硅(SiC)造粒粉为原料,采用无压烧结制备纳米复合SiC陶瓷。分析了烧结温度及保温时间对复合陶瓷烧结特性与显微结构的影响规律。结果表明:采取二步烧结可以实现SiC陶瓷在晶粒不明显长大的前提下实现致密化,二步烧结,即先升温到1950℃保温15min后迅速降至1850℃烧结1h,制备的SiC陶瓷具有较高收缩率、较低质量损失以及较高的致密度;纳米TiN颗粒加入后能与基体(SiC,Al2O3)部分发生反应生成TiC和AlN,明显改善SiC陶瓷的烧结性能,获得等轴状、细晶显微结构和优越的力学性能。 相似文献
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《Journal of the European Ceramic Society》2019,39(15):4957-4964
Y2O3-MgO nanocomposite has attracted attention for use in infrared windows and domes. However, the large difference in refractive index between the two phases of this materials phases induces inevitable grain boundary scattering. To overcome this drawback, it is indispensable to greatly reduce the grain size and eliminate residual pores. Two-step sintering has been extensively used to produce fine-grained ceramics, but long incubation time and an additional process are required. As a robust approach, pressure-assisted two-step consolidation of Y2O3-MgO nanocomposite ceramics is investigated to achieve full density while retaining domain size. A sintering path for pressure-assisted two-step sintering and related kinetic window are obtained for the first time. By effectively suppressing grain growth and eliminating residual pores via two-step hot-pressing, outstanding mid- and near-infrared transmittance were achieved. The results indicate that pressure-assisted two-step sintering is a promising alternative strategy that can decrease the domain size and achieve full density of ceramics. 相似文献
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Mixtures based on a nanocomposite powder (SiC – C) for hot pressure molding of ceramics are prepared. Micromechanical properties of the sintered ceramics are shown to depend on the technique by which the sintering activator is introduced to the mixture. Results of a study of the structure and phase composition of the sintered ceramics by transmission electron microscopy and x-ray diffractometry are reported. 相似文献
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《Journal of the European Ceramic Society》2023,43(4):1385-1396
The polymer-derived ceramics (PDCs) technique enables relatively low-temperature fabrication of Si-based ceramics, with silicon carbide fiber as a representative product. Polycarbosilane (PCS) has Si-C backbone structures and can be converted to silicon carbide. In the PDCs method, residual or excess carbon is generated from the precursor (C/Si ratio = 2 for polycarbosilane). Because of the non-stoichiometry of SiC, the physicochemical properties of polymer-derived SiC are inferior to those of conventional monolithic SiC. Herein, a silicon carbide-hafnium carbide nanocomposite fiber was optimized by crosslinking oxygen into the PCS fiber by regulating the oxidation curing time. During pyrolysis, carbothermal reduction, and sintering, carbon was removed by reaction with hydrogen and cross-linked oxygen. Non-destructive techniques (X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, and high-temperature thermomechanical analysis) were used to investigate the effects of excess carbon. The microstructure of the near-stoichiometric SiC-HfC nanocomposite fiber was more densified, with superior high-temperature properties. 相似文献
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V. Sadykov V. Usoltsev N. Yeremeev N. Mezentseva V. Pelipenko T. Krieger V. Belyaev E. Sadovskaya V. Muzykantov Yu. Fedorova A. Lukashevich A. Ishchenko A. Salanov Yu. Okhlupin N. Uvarov O. Smorygo A. Arzhannikov M. Korobeynikov Ma.K.A. Thumm 《Journal of the European Ceramic Society》2013,33(12):2241-2250
This work reviews results of research aimed at design and characterization of mixed ionic–electronic conducting perovskite–fluorite nanocomposite oxide ceramics. Nanocrystalline oxides were prepared via Pechini route, nanocomposites – via ultrasonic dispersion of their mixture in organic solvents with addition of surfactants. Genesis of the real structure of nanocomposites at sintering by conventional as well as advanced (microwave or e-beam treatment) techniques was studied in details by structural methods. Applied preparation procedures ensured nano-sizes of perovskite/fluorite domains even in dense ceramics and a high spatial uniformity of their distribution. Redistribution of elements between perovskite and fluorite domains without formation of new phases was revealed. Characterization of nanocomposite transport properties by oxygen isotope heteroexchange and conductivity or weight relaxation demonstrated that perovskite–fluorite interfaces are paths for fast oxygen diffusion. Best perovskite–fluorite combinations tested as cathode layers or dense oxygen separation layers in asymmetric supported membranes demonstrated performance promising for the practical application. 相似文献
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综述了烧成制度、原料组成及粒径、制备方法等对纳米复合陶瓷显微结构的影响及纳米复合陶瓷不同于传统陶瓷的增韧机制。 相似文献
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Toru Nagai Hae Jin Hwang Masaki Yasuoka Mutsuo Sando Koichi Niihara 《Journal of the American Ceramic Society》1998,81(2):425-428
Ceramic nanocomposites with a perovskite-type ferroelectric dispersoid were studied, to introduce ferroelectricity into structural ceramics. Barium titanate (BaTiO3) was found to be phase compatible with magnesia (MgO) during sintering, and a MgO matrix/BaTiO3 nanocomposite was successfully fabricated by a conventional powder mixing and sintering method. The mechanical strength of the nanocomposite was not degraded, although weak BaTiO3 was incorporated into the composite. The BaTiO3 dispersoid was tetragonal or possibly orthorhombic, although the tetragonality, c/a, was decreased from the starting powder. 相似文献
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堇青石基玻璃陶瓷研究进展 总被引:9,自引:1,他引:9
介绍了制备堇青石基玻璃陶瓷的三种方法:熔融法、烧结法和溶胶-凝胶法,综述了玻璃组成、添加剂和晶核剂对堇青石基玻璃陶瓷的烧结特性及性能的影响,并对其未来的发展进行了展望. 相似文献