共查询到20条相似文献,搜索用时 46 毫秒
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采用有机前驱体制备Si3N4/SiC纳米复相陶瓷 总被引:9,自引:0,他引:9
本研究采用有机前驱体为主要原料,通过热解及烧结制备了两类Si3N4/SiC纳米复相陶瓷,研究了这些材料的微结构特点,讨论了材料强化的机制及力学性能与显微结构的关系。 相似文献
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Si3N4/纳米SiC复相陶瓷的研究 总被引:10,自引:0,他引:10
采用纳米SiC粉体制备了Si3N4/纳米SiCp复相陶瓷。研究了制备工艺、纳米SiC含量对材料性能及显微结构的影响,并对材料显微结构特点与强韧化机制进行了分析 。结果表明:添加20vo%〈100nm的SiC粉体时,复相陶瓷的室温抗弯强度达856MPa,当添加10vo%上述SiC粉体时,复相陶瓷的增韧效果最佳,断裂韧性达8.27MPam^1/2,比基体材料提高了23%。 相似文献
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纳米SiC—Ca—α—Sialon复相陶瓷的研究 总被引:5,自引:0,他引:5
研究了用表面活性剂有效地分散纳米SiC粉体中的聚集体的实验过程,发现分散状态取于表面活性剂用量、PH值和浸 Si3N4,AlN,CaCO33和纳β-SiC为原料粉料,用反应热压法制备了不同SiC含量的纳米SiC-Ca-αsialon复相陶瓷,并分别其相组成,力学性能和显微结构等进行了研究。 相似文献
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纳米SiC—Si3N4复合超细粉末的研制 总被引:7,自引:0,他引:7
用热化学气相反应法制备了纳米级SiC-Si3N4复合超细粉末,讨论了工艺参数对复合超细粉末颗粒度、组成、结构等的影响,并制备出颗粒呈球形、颗粒尺寸均匀、分散性好、最小颗粒尺寸为89A的纳米级SiC-Si3N4复合超细粉末。 相似文献
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T. V. Barinova I. P. Borovinskaya 《International Journal of Self-Propagating High-Temperature Synthesis》2009,18(1):30-33
Combustion of silicon powders containing organic dopants in nitrogen gas under pressure was found to yield a mixture of α-Si3N4, β-Si3N4, SiC, and Si2N2O. Relative amount of these compounds in combustion product was found to depend on the pressure of nitrogen gas, type and
concentration of dopants, combustion geometry, and cooling rate. The formation of α-Si3N4 was found to occur in the presence of oxygen-containing dopants. The type of dopant was also found to affect the morphology
of product particles.
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Krishan L. Luthra 《Journal of the American Ceramic Society》1991,74(5):1095-1103
This study provides new perspectives on why the oxidation rates of silicon carbide and silicon nitride are lower than those of silicon and on the conditions under which gas bubbles can form on them. The effects on oxidation of various rate-limiting steps are evaluated by considering the partial pressure gradients of various species, such as O2 , CO, and N2 . Also calculated are the parabolic rate constants for the situations when the rates are controlled by oxygen and/or carbon monoxide (or nitrogen) diffusion. These considerations indicate that the oxidation of silicon carbide and silicon nitride should be mixed controlled, influenced both by an interface reaction and diffusion. 相似文献
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Nitridation behavior of silicon powder compacts of various thicknesses with Y2O3 and MgO as sintering additives
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Chika Matsunaga You Zhou Dai Kusano Hideki Hyuga Kiyoshi Hirao 《International Journal of Applied Ceramic Technology》2017,14(6):1157-1163
The effects of the nitriding temperature (1300 and 1350°C), holding time (0‐4 hours), and thickness of Si powder compacts on the nitridation behavior of silicon were investigated by examining the nitridation rates, analyzing phase compositions, and observing the microstructures of nitrided compacts. Si powder compacts doped with Y2O3 and MgO as sintering additives were prepared with thicknesses of 3, 6, and 9 mm. The phases of nitrided compacts were transformed from Si to α‐Si3N4 and β‐Si3N4 with an increase in the nitriding temperature and holding time. The degree of nitridation increased with the nitriding temperature and holding time. The β/(α+β) ratio increased with the nitriding temperature and holding time, and with a decrease in the thickness of the Si powder compacts. However, all compacts exhibited the same tendency for a higher β/(α+β) ratio at the compact surface than in the bulk of the compact. The variation in the β/(α+β) ratio for each compact decreased with an increase in the nitriding temperature and holding time. 相似文献
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Takayuki Narushima Michihisa Kato Shin Murase Chiaki Ouchi Yasutaka Iguchi 《Journal of the American Ceramic Society》2002,85(8):2049-2055
The oxidation behavior of a silicon wafer, chemically vapor-deposited SiC, and single-crystal SiC was investigated in an oxygen—2%–7% ozone gas mixture at 973 K. The thickness of the oxide film that formed during oxidation was measured by ellipsometry. The oxidation rates in the ozone-containing atmosphere were much higher than those in a pure oxygen atmosphere. The parabolic oxidation kinetics were observed for both silicon and SiC. The parabolic rate constants varied linearly with the ozone-gas partial pressure. Inward diffusion of atomic oxygen formed by the dissociation of ozone gas through the SiO2 film apparently was the rate-controlling process. 相似文献
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Volatility Diagrams for Silica, Silicon Nitride, and Silicon Carbide and Their Application to High-Temperature Decomposition and Oxidation 总被引:1,自引:0,他引:1
Volatility diagrams—isothermal plots showing the partial pressures of two gaseous species in equilibrium with the several condensed phases possible in a system—are discussed for the Si-O and Si-N systems, and extended to the Si-N-O and Si-C-O systems, in which the important ceramic constituents SiO2 , Si3 N4 , Si2 N2 O, and SiC appear as stable phases. Their use in understanding the passiveactive oxidation transitions for Si, Si3 N4 , and SiC are demonstrated. 相似文献
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Amiya S. Sanyal Joydeb Mukerji Siddhartha Bandyopadhyay 《Journal of the American Ceramic Society》1991,74(9):2312-2314
Mössbauer spectra of the products obtained by carbothermal reduction and distribution of silica in the presence of iron in the temperatures range 1200o to 1540o were studied. The preponderance of β- Si3 N4 over the α form at a higher reaction temperature were assumed to be related to the formation of an Fe-Si-N liquid. The liquid did not alter its composition with the variation of reduction-temprature, Iron had no effect on the reaction mechanism below 1300o C. 相似文献
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Rong-Jun Xie Mamoru Mitomo Guo-Dong Zhan Hideyuki Emoto 《Journal of the American Ceramic Society》2000,83(10):2529-2535
Starting with a mixture of ultrafine β-Si3 N4 and a SiO2 -containing additive, a superplastic Si3 N4 -based composite was developed, using the concept of a transient liquid phase. Significant deformation-induced phase and microstructure evolutions occurred in the nonequilibrium, fine-grained Si3 N4 material, which led to the in situ development of a Si3 N4 –22-vol%-Si2 N2 O composite and strong texture formation. The unusual ductility of the composites with elongated Si2 N2 O grains was attributed to the fine-grained microstructure, the presence of a transient liquid phase, and the alignment of the elongated Si2 N2 O grains. The mechanical properties of the resultant composite were enhanced rather than impaired by superplastic deformation and subsequent heat treatment; the resultant composite exhibited both high strength (957 MPa) and high fracture toughness (4.8 MPa·m1/2 ). 相似文献
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Rong-Jun Xie Mamoru Mitomo Wonjoong Kim Young-Wook Kim 《Journal of the American Ceramic Society》2000,83(12):3147-3152
Silicon nitride–silicon oxynitride (Si3 N4 –Si2 N2 O) in situ composites have been fabricated via either the annealing or the superplastic deformation of sintered Si3 N4 that has been doped with a silica-containing additive. In this study, quantitative texture measurements, including pole figures and X-ray diffraction patterns, are used in conjunction with scanning electron microscopy and transmission electron microscopy techniques to examine the degree of preferred orientation and texture-development mechanisms in these materials. The results indicate that (i) only superplastic deformation can produce strong textures in the β-Si3 N4 matrix, as well as Si2 N2 O grains that are formed in situ ; (ii) texture development in the β-Si3 N4 matrix mainly results from grain rotation via grain-boundary sliding; and (iii) for Si2 N2 O, a very strong strain-dependent texture occurs in two stages, namely, preferred nucleation and anisotropic grain growth. 相似文献
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硅是化妆品生产不可缺少的原料之一。介绍了硅粉、硅悬浮液用于化妆品生产的最新技术, 特别是毛发调理产品中的应用。硅粉作为固体原料有望成为化妆品中新产品的生产原料。 相似文献