共查询到20条相似文献,搜索用时 15 毫秒
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Huijie Cheng Yali Li Edwin Kroke Stefanei Herkenhoff 《Journal of the European Ceramic Society》2013,33(11):2181-2189
In situ synthesis of Si2N2O/Si3N4 composite ceramics was conducted via thermolysis of novel polysilyloxycarbodiimide ([SiOSi(NCN)3]n) precursors between 1000 and 1500 °C in nitrogen atmosphere. The relative structures of Si2N2O/Si3N4 composite ceramics were explained by the structural evolution observed by electron energy-loss spectroscopy but also by Fourier transform infrared and 29Si-NMR spectrometry. An amorphous single-phase Si2N2O ceramic with porous structure with pore size of 10–20 μm in diameter was obtained via a pyrolyzed process at 1000 °C. After heat-treatment at 1400 °C, a composite ceramic was obtained composed of 53.2 wt.% Si2N2O and 46.8 wt.% Si3N4 phases. The amount of Si2N2O phase in the composite ceramic decreased further after heat-treatment at 1500 °C and a crystalline product containing 12.8 wt.% Si2N2O and 87.2 wt.% Si3N4 phases was obtained. In addition, it is interesting that residual carbon in the ceramic composite nearly disappeared and no SiC phase was observed in the final Si2N2O/Si3N4 composite. 相似文献
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反应烧结法制备氮化硅 总被引:1,自引:0,他引:1
1前言Si3N4制品以其优良的物理化学性能,如热震稳定性好、高温强度高、抗氧化、抗侵蚀等而受到人们的重视。作为生产Si3N4制品的主要原料———Si3N4粉,近年的需求不断上升。反应烧结法制备Si3N4是一种比较简单实用的方法,其纯度可达到96%,又可以形成大规模工业化生产。2实验2.1原料选择原料选择工业硅粉的指标如表1,粒度分布如表2。2.2成型为了满足装炉的要求,先要把硅粉成型为疏松多孔的坯体,结合剂选取用聚乙烯醇水溶液,其浓度为聚乙烯醇:水=2:100;原料混练选用普通混砂机。硅粉:锯末:醇液=100:3:10,配好的原料放入混砂机中混练15min… 相似文献
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Ning Liu Tengfei Hu Yusen Duan Jingxian Zhang Xiaoguang Li Shaoming Dong 《International Journal of Applied Ceramic Technology》2022,19(3):1255-1264
In this paper, silicon nitride (Si3N4) ceramics with black color and high toughness were fabricated by gas pressure sintering and characterized by X-ray diffraction, Raman, scanning electron microscopy, EDS, and transmission electron microscopy. The in situ formed cobalt silicide was confirmed to contribute to the black color through the introduction of CoO. Due to the addition of CoO, the growth of β-Si3N4 grains is promoted, forming elongated grains, and eventually forms the self-reinforcing microstructure. However, with adding excessive CoO, interfacial debonding is found between cobalt silicide and Si3N4 matrix and a decrease in strength was resulted. The optimum composition is 1 mol% CoO in Si3N4, with the fracture toughness of 9.9 ± 0.3 MPa m1/2, flexural strength of 826.1 ± 46.0 MPa, and a much darker black color. The mechanism of color formation is discussed where the black color derives mainly from the metallic silicon and additionally the porosity. 相似文献
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采用α-Si3N4或混合的β/α-Si3N4原始粉末,借助于气体压力烧结可使掺入Y-Ce的富氮多倍阳离子α-SiAlON(赛隆)陶瓷致密化。用不同的烧结周期可以研究α-SiAlON成核和长大机理的作用。烧结后的X射线衍射表明,除α-SiAlON基质相外,还有21R多种类型相。在原始组份中采用α-Si3N4粉末制备的烧结材料的显微结构特性表明,如所预料的,如果颗粒长大前未应用α-SiAlON成核过程,则呈现典型的等轴颗粒形态。然而,如果在最终烧结前进行成核,则可观察到针状α-SiAlON颗粒。在含有混合β/α-Si3N4的原始粉末中,也观察到针状颗粒形态。讨论了不同的Si3N4原始粉末和烧结条件对颗粒形态和机械性能的影响。 相似文献
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研究了采用Si,N4与Al的混合粉,经压制、烧结制备AIN/Al-Si复合材料的技术方法。试验结果表明:AIN的反应生成机制属于一种连续渐进式反应形成过程,即于高温下液相Al中的Al原予渗入Si3N4的晶体点阵取代Si原予而逐渐使之向AIN晶体点阵转化的过程。被取代的Si原予从固相Si3N4中析出,扩散溶入液相Al中,冷却后形成Al-Si舍金固溶体,一般呈网状分布于AIN晶体相的周围。新生成的AIN与Al-Si合金相之间表现出很好的界面亲和性。 相似文献
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Studying the Role of Gelation Agents in Gelcasting Non-porous Si3N4 Bodies by Pressureless Sintering
Sharifi Omid Alizadeh Siavash M. Golmohammad Mohammad Golestanifard Farhad 《SILICON》2022,14(16):10447-10457
Silicon - The monomer content in the gelcasting process affects the kinetics of cross-linking reactions which determines the quality of the gel network structure and the final properties of the... 相似文献
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Mechanical and dielectric properties of porous Si2N2O–Si3N4 in situ composites fabricated for use as radome by gel-casting process were investigated. The flexural strength of the Si2N2O–Si3N4 ceramics is 230.46 ± 13.24 MPa, the complex permittivity of the composites varies from 4.34 to 4.59 and the dissipation factor varies from 0.00053 to 0.00092 from room temperature to elevated temperature (1150 °C) at the X-band. In the porous regions, some Si2N2O fibers (50–100 nm in diameter) are observed which may improve the materials properties. 相似文献
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利用氧化镁(MgO)和氧化铝(Al2O3)作为烧结助剂,采用放电等离子烧结(SPS)方法制备α-Si3N4陶瓷材料。讨论了SPS方法制备氮化硅材料的烧结行为和烧结机理,分析了烧结助剂添加量和烧结温度等影响因素与材料致密度的关系,利用XRD分析了样品的物相组成,SEM观察了样品断口的显微结构,并且测试了样品的力学抗弯强度。结果表明当烧结温度为1300~1500℃,烧结助剂含量为6%~10%时,可以制备出致密度变化范围为64%~96%的α-Si3N4陶瓷材料;当烧结助剂含量为10%时,材料在1400℃即可烧结致密,致密度可达到95%以上。烧结机理为SPS低温液相烧结。材料的力学强度为50~403MPa,并且与密度关系密切。 相似文献