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Synthesis of ZrN-Si_3N_4 Composite by Carbothermal Reduction and Nitridation of Zircon
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作者 MA Beiyue YU Jingkun +1 位作者 LI Hezheng WANG Zhenming 《China's Refractories》 CAS 2010年第1期16-19,共4页
Zircon ( ≤44 μm) and carbon black (≤30μm) were used as starting materials and mixed for 24 h using anhydrous ethanol as medium with the mass ratio of 100:40, dried fully at 60 ℃ and then dry mixed for 10 h. ... Zircon ( ≤44 μm) and carbon black (≤30μm) were used as starting materials and mixed for 24 h using anhydrous ethanol as medium with the mass ratio of 100:40, dried fully at 60 ℃ and then dry mixed for 10 h. Specimens with size of Ф20 mm × 5 mm were pressed under 60 MPa, then dried fully at 120 ℃ , put into a furnace with 1. 0 L ·min^-1 nitrogen gas and fired at 1 400, 1 450, 1 480 and 1 500℃ for 6, 9 and 12 h, respectively. The phase composition and microstructure of the specimens were studied by XRD and SEM, and the carbothermal reduction and nitridation reaction process was thermodynamically analyzed. The results show that using zircon and carbon black as starting materials, ZrN - Si3N4 composite is synthesized by carbothermal reduction and nitridation reaction in nitrogen atmosphere. The composites with different compositions are obtained by controlling the firing temperature and partial pressure of CO gas. The proper firing temperature and holding time to synthesize ZrN - Si3N4 composite are 1 500 ℃ for 12 h. 展开更多
关键词 carbothermal reduction and nitridation ZIRCON Zirconium nitride -silicon nitride composite
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Influences of Technological Parameters on Carbothermal Reduction and Nitridation of Titanium Dioxide
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作者 YU Renhong ZHANG Xiaohui JIANG Mingxue 《China's Refractories》 CAS 2010年第2期25-29,共5页
The particle size of starting materials, the homogeneity of the carbon/oxide mixtures, and the carbon content are important parameters for a rapid reaction. The influences of technological parameters(carbon particle... The particle size of starting materials, the homogeneity of the carbon/oxide mixtures, and the carbon content are important parameters for a rapid reaction. The influences of technological parameters(carbon particle size, oxide particle size, mixing method, carbon content) on the reaction rate of carbothermal reduction and nitridation of titanium dioxide (TiO2 ) were investigated by a continuous thermo-gravimetric analyzer for large size specimen. The carbon particle size is the most impor tant parameter for a rapid reaction, but carbon particle may have no influence on the morphology of titanium nitride (TiN) powder. Oxide particles are the precursors of TiN powder, but the TiO2 particles size has very little influence on the reaction rate. The carbon content not only influences the reaction rate to some degree, but also influences the purity of TiN powder. The mixing method of the specimen has very little influence on the reaction rate. These results are suitable for other nitrides and carbides prepared by carbothermal reduction method. 展开更多
关键词 Titanium dioxide Titanium nitride carbothermal reduction and nitridation Technological parameters
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Synthesis of high-quality ferrovanadium nitride by carbothermal reduction nitridation method
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作者 Ying-cong Zhou Yu Wang +1 位作者 Kuo-chih Chou Guo-hua Zhang 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2021年第3期255-262,共8页
High-quality ferrovanadium nitride(FeV45N,FeV55N and Fe65N)was fabricated using the raw materials of Fe_(3)O_(4),V_(2)O_(5) and graphite via carbothermal reduction nitridation method.Compared with the traditional meth... High-quality ferrovanadium nitride(FeV45N,FeV55N and Fe65N)was fabricated using the raw materials of Fe_(3)O_(4),V_(2)O_(5) and graphite via carbothermal reduction nitridation method.Compared with the traditional methods,it shortens the production process of ferrovanadium nitride by avoiding the preparation of ferrovanadium.The effects of C/O molar ratio and reaction temperature on phase transition,density,carbon,oxygen and nitrogen contents and microstructure were investigated.The appropriate C/O molar ratio is crucial to obtain the products with high nitrogen content.It is also found that a higher temperature is beneficial for the densification,and the density of the products obtained at 1550℃ is much higher than that at 1500℃.Moreover,a higher temperature contributes to the increase in nitrogen content owing to the higher reaction kinetics.The carbothermal reduction nitridation method is proved to be a facile route to fabricate cost-effective ferrovanadium nitride and is possible to be applied for industrial production. 展开更多
关键词 Ferrovanadium nitride carbothermal reduction nitridation High nitrogen content DENSIFICATION
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Preparation of Sialon Powder from Coal Gasification Slag 被引量:3
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作者 汤云 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2010年第6期1044-1046,共3页
X-ray fluorescence spectrometry(XRF),X-ray powder diffractometry(XRD) and scanning electron microscopy(SEM) were used to characterize the chemical composition,phase constituent and microstructure of the coal gas... X-ray fluorescence spectrometry(XRF),X-ray powder diffractometry(XRD) and scanning electron microscopy(SEM) were used to characterize the chemical composition,phase constituent and microstructure of the coal gasification slag.Sialon powders were synthesized by carbothermal reduction and nitridation using the coal gasification slag as raw materials.The experimental results showed that glass and amorphous carbon were the main phases,quartz and calcite as minor crystalline phases were also presented in porous coal gasification slag.Main constituents of coal gasification slag were SiO2,Al2O3,CaO and residual carbon.Sialon powder with Ca-α-Sialon as main crystalline phase can be synthesized when coal gasification slag powders were reduced and nitrided at 1500 ℃ for 9 h using nitrogen flow of 500 ml/min.The coal gasification slag is a valuable and economic starting material for preparing Sialon powders. 展开更多
关键词 coal gasification slag CHARACTERIZATION MICROSTRUCTURE SIALON carbothermal reduction and nitridation
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Effect of Zircon Addition on Properties of Low Carbon AL_2O_3-C Refractories
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作者 ZHANG Feifei YU Renhong ZHOU Ningsheng 《China's Refractories》 CAS 2014年第1期38-42,共5页
Using tabular alumina as aggregate,tabular alumina fines,reactive alumina ultra-fines,aluminum powders,silicon powders,carbon black,flake graphite,B4 C and zircon fines as matrix,low carbon Al2O3-C refractories were p... Using tabular alumina as aggregate,tabular alumina fines,reactive alumina ultra-fines,aluminum powders,silicon powders,carbon black,flake graphite,B4 C and zircon fines as matrix,low carbon Al2O3-C refractories were prepared.Influences of zircon powders additions (0,3%,5% and 7%,in mass,the same hereinafter) on properties,phase composition and microstructure were investigated.The results show that the ZrO2-nitride can be in-situ formed through carbothermal reduction and nitridation in Al2O3-C refractories.With the increase of zircon powder,the oxidation resistance of the Al2O3-C refractories improves obviously,the oxidized layer thickness decreases from 7.94 mm without zircon to 2.71 mm with 5% zircon.HMOR at 1 400 ℃ of the Al2O3-C refractories reaches the maximum 14.9 MPa when zircon addition is 5%.With the increase of zircon powder,the apparent porosity and bulk density change a little,CMOR and CCS increase. 展开更多
关键词 carbothermal reduction and nitridation ZIRCON alumina-carbon refractories zirconia-nitride oxidation resistance
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UNITECR 2011
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《China's Refractories》 CAS 2010年第4期29-29,共1页
Hosted by The Technical Association of Refractories, Japan, 12th Unified International Technical Conference on Refractories (UNTECR) will be held in Kyoto, Japan from Oct. 31 to Nov. 2, 2011.
关键词 Titanium dioxide Titanium nitride carbothermal reduction and nitridation Technological parameters
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Anisotropic, biomorphic cellular Si_(3)N_(4) ceramics with directional well-aligned nanowhisker arrays based on wood-mimetic architectures 被引量:2
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作者 Songsong XU Xiaonan ZHOU +6 位作者 Qiang ZHI Junjie GAO Liucheng HAO Zhongqi SHI Bo WANG Jianfeng YANG Kozo ISHIZAKI 《Journal of Advanced Ceramics》 SCIE EI CAS CSCD 2022年第4期656-664,共9页
Inspired by the transport behavior of water and ions through the aligned channels in trees,we demonstrate a facile,scalable approach for constructing biomorphic cellular Si_(3)N_(4) ceramic frameworks with well-aligne... Inspired by the transport behavior of water and ions through the aligned channels in trees,we demonstrate a facile,scalable approach for constructing biomorphic cellular Si_(3)N_(4) ceramic frameworks with well-aligned nanowhisker arrays on the surface of directionally aligned microchannel alignments.Through a facile Y(NO_(3))_(3) solution infiltration into wood-derived carbon preforms and subsequent heat treatment,we can faultlessly duplicate the anisotropic wood architectures into free-standing bulk porous Si_(3)N_(4) ceramics.Firstly,α-Si3N4 microchannels were synthesized on the surface of CB-templates via carbothermal reduction nitridation(CRN).And then,homogeneous distributed Y–Si–O–N liquid phase on the walls of microchannel facilitated the anisotropicβ-Si3N4 grain growth to form nanowhisker arrays.The dense aligned microchannels with low-tortuosity enable excellent load carrying capacity and thermal conduction through the entire materials.As a result,the porous Si_(3)N_(4) ceramics exhibited an outstanding thermal conductivity(TC,k_(R)≈6.26 W·m^(−1)·K^(−1)),a superior flexural strength(σ_(L)≈29.4 MPa),and a relative high anisotropic ratio of TC(k_(R)/k_(L)=4.1).The orientation dependence of the microstructure–property relations may offer a promising perspective for the fabrication of multifunctional ceramics. 展开更多
关键词 silicon nitride ANISOTROPIC carbothermal reduction nitridation(CRN) WOOD nanowhisker arrays
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Incorporation of europium (Ⅱ) nanostructures into the channels of mesoporous silicon oxy-nitride for enhanced photoluminescence
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作者 D. Suresh M. Yamashita T. Akai 《Journal of Rare Earths》 SCIE EI CAS CSCD 2018年第5期449-455,共7页
Divalent europium(Ⅱ)-doped mesoporous silicon oxy-nitride materials, as a novel type of nanoscopic photoluminescent material, are studied in which the optically active luminescent centers are isolated within the po... Divalent europium(Ⅱ)-doped mesoporous silicon oxy-nitride materials, as a novel type of nanoscopic photoluminescent material, are studied in which the optically active luminescent centers are isolated within the pores. Colorless and transparent blue emitting luminous Eu2+-doped mesoporous silicon oxy-nitride materials were prepared from mesoporous silica via impregnation, nanocasting and nitrogen-assisted carbothermal reduction and nitridation method. The morphology and porosity of the silica remain unchanged during the synthesis process as revealed by SEM images and by nitrogen sorption studies. Photoluminescence studies reveal a strong blue emission band for Eu2+ centered at 425 nm with a quantum efficiency of 47%. The luminescent intensity is greatly influenced by the amount of co-dopant, AI3+ ions. 展开更多
关键词 Blue luminescence Divalent europium Mesoporous silicon oxy-nitride carbothermal reduction and nitridation(CRN) Rare earths
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