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Effect of Mg/Al Ratios on Hydration Mechanism of Tabular Alumina Carbon Composites Reinforced by Al4C3 in situ Reaction

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Journal of Wuhan University of Technology(Materials Science) 2017年第4期32卷 800-805页

作者：杨依帆 jiang mingxue YANG Ding'ao YUAN Shouqian ZHAO Jizeng ZHAO Wei YANG Mengyao College of Materials and Mineral Resources Xi'an University of Architecture and TechnologyXi'an 710055China Beijing Lier High-Temperature Materials Co. LtdBeijing 102211China Fuzhou University Zhicheng College Fuzhou 350002China

Hydration mechanism of tabular alumina carbon composites reinforced by Al4C3 in situ reaction with Mg and Al was researched in water steam using super automatic thermostatic water bath from 25 ℃ to 85 ℃. It is shown that hydration mechanism of the composites is chemical reaction control at 44.3 ℃-84 ℃ in H2O（g）. The hydration was controlled by diffusion from 24.7 ℃ to 33 ℃. The ratio of added Mg/Al influences the HMOR of the *** mechanism of HMOR of the composites with different ratios of Mg/Al can be discovered by means of SEM analysis. The active Mg/Al powder and flake graphite inside give the composites outstanding hot strength resulting from the interlocking structure of Al4C3 crystals at high temperature. Besides, the matrix changes into the Al4C3 with high refractoriness. The method of preventing the hydration of tabular alumina carbon composites reinforced by Al4C3 in situ reaction was immersed in the wax at suitable temperature or storing them below 33 ℃ in a dry place or storing them with paraffin-coating.

关键词： hydration mechanism tabular alumina carbon Al4C3 Mg/Al ratios

Mechanical Properties and Electrical Conductivity of TiN-Al_2O_3 Composites

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China's Refractories 2008年第4期17卷 25-28页

作者： SHI Xiaoqi ZOU Ming jiang mingxue College of Materials Science and Engineering Xi＇ an University of Architecture ＆ Technology Xi＇ an 710055 China

TiN- Al2O3 composite powders with different TiN contents （0, 10 vol%, 20 vol%, 30 vol% and 40 vol% ）were prepared with micrometer TiN and α-Al2O3 powder （ their purities were 99% ） as starting materials by wet ball milling for 5 h. TiN-Al2O3 composite were then prepared by pressing the above composite powders, drying at 200 ℃ for 12 h and firing at 1 800 ℃ for 3 h in nitrogen atmosphere in hot-pressing furnace. The influences of TiN content on mechanical properties and electrical conductivity of TiN -Al2O3 composites were studied. The results showed that the mechanical properties of the composite increased with TiN content increasing, while the resistivity of composites decreased. A composite with 40% TiN had 498 MPa ben- ding strength, 4. 285 MPa· m1/2 fracture toughness, 1.34×10^-3 Ω· cm resistivity. The SEM analysis showed that the fine TiN crystals distributed among the crystal boundary of Al2O3 matrix. They bonded together forming a net-like structure which played a role of restraining Al2O3 grains from growing up, toughening and strengthening, so the mechanical properties of TiN -Al2O3 composite were enhanced.

关键词： Titanium nitride Alumina Titanium nitride -alumina composite Electrical conductivity

Thermodynamic Analysis for Carbothermal Reduction and Nitridation of TiO_2

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China's Refractories 2007年第1期16卷 11-14页

作者： YU Renhong jiang mingxue SHI Xiaoqi College of Material Science and Engineering Henan University of Science and Technology College of Material Science and Engineering Xi＇ an University of Architecture and Technology

The diagrams of stability relations（namely,Predominance area phase diagram,PAPD）of nitride,carbide and oxides in Ti-C-N-O system were plotted by thermodynamic *** optimum conditions and main influence factors for the synthesis of titanium nitride and titanium carbide by carbothermal reduction in nitrogen atmosphere were discussed.

关键词： Thermodynamic analysis Titanium nitride Titanium carbide Predominance area Phase diagram

Influences of Technological Parameters on Carbothermal Reduction and Nitridation of Titanium Dioxide

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China's Refractories 2010年第2期19卷 25-29页

作者： YU Renhong ZHANG Xiaohui jiang mingxue High Temperature Materials Institute Henan University of Science and Technology Luoyang 471003 China Sinosteel Luoyang Institute of Refractories Research Co. Ltd. Luoyang 471039 China College of Materials Science and Engineering Xi＇an University of Architecture and Technology Xi＇an 710055 China

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.

关键词： Titanium dioxide,Titanium nitride,Carbothermal reduction and nitridation Technological parameters

Effect of Atmosphere on Sintering of High Cr_2O_3 Bearing Refractories Considered from Thermodynamic Calculation

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China's Refractories 2009年第4期18卷 22-26页

作者： QIAN Yuejin jiang mingxue LI Liusheng School of Materials Science and Engineering Xi＇ an University of Architecture ＆ Technology Xi＇ an 710055 China Department of Material Science and Engineering Luoyang Institute of Science ＆ Technology Luoyang 471023 China

Pure Cr2O3 refractories and high Cr2O3 bearing refractories are difficult to sinter in oxidizing atmosphere, but they can be sintered easily in carbon embedded conditions. In the latter case it is attributed to the formation of liquid CrO in reducing atmosphere. The thermodynamic calculation shows that the Cr2O3 is reduced by CO at 1 550 ℃ to chromium carbides, which disproves the existence of liquid CrO. This is confirmed by further sintering experiment of the Cr2O3 refractories. Effect of atmosphere on sintering of high Cr2O3 bearing refractories and measures to accelerate the sintering process are discussed based on the experiment and thermodynamic calculation.

关键词： High chrome oxide bearing refractories Sintering Thermodynamic calculation Reducing atmosphere

基于有限元模拟研究不同形状磨料对高铝砖的冲蚀磨损

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硅酸盐学报 2014年第6期42卷 761-767页

作者：廉晓庆蒋明学西安建筑科技大学材料与矿资学院西安710055 西安科技大学材料科学与工程学院西安710054

以石英砂、棕刚玉、碳化硅为磨料,对III等高铝砖进行常温垂直冲蚀磨损。假定磨料为动能相同的球体、正方体和正四棱锥,建立单粒子冲蚀模型对冲蚀试验进行有限元模拟,采用线弹性材料模型分析不同形状磨料的冲击行为,采用JH-2材料模型计... 详细信息

以石英砂、棕刚玉、碳化硅为磨料,对III等高铝砖进行常温垂直冲蚀磨损。假定磨料为动能相同的球体、正方体和正四棱锥,建立单粒子冲蚀模型对冲蚀试验进行有限元模拟,采用线弹性材料模型分析不同形状磨料的冲击行为,采用JH-2材料模型计算靶材的冲蚀磨损率和最大等效应力。结果表明:正方体和正四棱锥磨料的接触时间、垂直压入深度、冲击效率均相当,且远大于球体磨料;冲蚀磨损率的模拟结果和试验结果、靶材最大等效应力三者均与磨料圆度成反比,模拟结果略低于试验结果。对靶材冲蚀前后表面进行显微结构分析,钝角磨料(石英砂)的主要冲蚀机制是缺陷部位的断裂和基质的切削,尖角磨料(碳化硅)的主要冲蚀机制是骨料的断裂和基质的犁削。

关键词：磨料形状冲蚀磨损有限元模拟冲蚀机制

Synthesis of SiC Whiskers from Silicon Nitride in Argon Atmosphere

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China's Refractories 2009年第1期18卷 21-25页

作者： ZHANG Ying jiang mingxue ZHANG Junzhan CUI Xiwen School of Materials Science and Engineering Xi＇an University of Architecture and Technology Xi＇an 710055 China

SiC whiskers were synthesized by carbothermal reduction of silicon nitride, α-Si3N4 and β-Si3N4 powders were used as silicon sources, and graphite, active carbon and black carbon as carbon sources, as well as boron oxide as catalyst. The synthesized SiC whiskers were characterized by XRD and SEM. The results showed that the synthesizing temperature should be above 1716 K; the decomposition of Si3N4 was the limited step in the synthesis of SiC whiskers; and catalyst not only offered the liquid condition, but also restricted the growth of SiC whiskers along one dimension. LS mechanism seems to explain well the growth of SiC whiskers.

关键词： Silicon carbide whiskers Silicon nitride Growth mechanism

Effect of Magnesia-Chrome Synthetic Materials on Magnesia-Alumina-Chrome Ramming Mixes

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China's Refractories 2006年第3期15卷 24-27页

作者： WANG Li ZHANG Xiaohui ZHANG Chenqian jiang mingxue Xi＇ an University of Architecture and Technology Xi＇ an 710055 China Sinosteel Luoyang Refractories （Group） Co. Ltd. Luoyang 471039 China Sinosteel Luoyang Instiute of Refractories Research Luoyang 471039 China

Magnesia-alumina-chrome ramming mixes with same chemical compositions were prepared by using different raw materials such as fused magnesia-chrome synthetic materials and sintered one, wasted bricks and magnesia-alumina spinels. Their physical properties were tested and microstructures were analyzed. The results show that the ramming mixes made of different raw materials bring about different microstructures and properties although the mixes have the same chemical composition, binder content and aggregate size composition.

关键词： Magnesia-chrome synthetic materials Ramming mix Magnesia-alumina-chrome

Effects of Anti-explosion Agents on Low-cement Castables

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China's Refractories 2010年第4期19卷 12-15页

作者： XU Jilong jiang mingxue LI Fang ZHANG Ronghui College of Materials Science and Engineering Xi＇an University of Architecture and Technology Xi＇an 710055 China Beijing Allied Rongda Engineering Material Co. Ltd. Beijing 101400 China

Effects of three anti-explosion agents：fiber,azo amide,and metal aluminum powder,on the anti-explosion property of Al2O3-SiC-C low-cement castables were researched. The mechanism of the anti-explosion agents was studied by observing the microstructure of the castables. The results show that all these agents can improve the anti-explosion performance of the low-cement castables. The anti-explosion performance of the castables is the best by composite adding 0.12% fiber,0.05% azo amide,and 0.1% metal aluminum powder. The main anti-explosion mechanism is that these three agents form apparent pores which increase the permeability.

关键词： Low-cement castables Anti-explosionagent Apparent pore