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Synthesis of nearly spherical AlN particles by an in-situ nitriding combustion route

Journal of Advanced Ceramics 2021年第2期10卷 291-300页

作者： Zhilei Wei Kang Li Bangzhi Ge Chaowei Guo Hongyan Xia Yajie Guo zhongqi shi State Key Laboratory for Mechanical Behavior of Materials Xi’an Jiaotong UniversityXi’an710049China Engineering Research Center of Transportation Materials of Ministry of Education School of Materials Science and EngineeringChang’an UniversityXi’an710064China

Spherical AlN powders with micrometer size have attracted great attention owing to their good fluidity and dispersity. However, the industrial preparation methods usually require high temperature and long soaking time, which lead to the high cost and limit the wide application of the products. Herein, nearly spherical AlN particles with the average size of 2.5 μm were successfully synthesized via an in-situ combustion synthesis method. The effect of N_(2) pressure, NH_(4)Cl content, and Al particle size on the combustion reaction procedure, phase composition, and microstructure of the products was systematically investigated. The results showed that the decreased N_(2) pressure, increased NH_(4)Cl content, and Al particle size led to the decreasing of combustion temperature and speed, which further affected the morphology of the products. As a result, low N_(2) pressure(0.2 MPa), a small amount of NH4Cl(0.5 wt%), and fine Al particles(~2.5 μm) contributed to a moderate combustion temperature and facilitated the formation of nearly spherical AlN particles. In addition, based on the gas-releasing assisted quenching experiments and thermo-kinetic analysis, a two-step growth mechanism for the nearly spherical AlN particles was rationally proposed. The present method shows the advantages of low cost and high efficiency for preparing nearly spherical AlN particles, which can be used as raw materials for electronic substrates and fillers for packaging materials.

关键词： combustion synthesis AlN microstructure growth mechanism

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Preparation of SiC coated graphite composite powders by nitriding combustion synthesis

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Journal of Advanced Ceramics 2023年第10期12卷 1930-1945页

作者： Biao Zhang Wenqi Xie Huaizhi Lin Zhilei Wei Zhichao Xiao Kai He zhongqi shi State Key Laboratory for Mechanical Behavior of Materials Xi’an Jiaotong UniversityXi’an 710049China China Nuclear Power Engineering Co. Ltd.Beijing 100840China

Ceramic-coated graphite powders are considered as effective raw materials to fabricate three-dimensional continuous ceramic skeleton-reinforced graphite matrix composites which can overcome their inherent poor densification and improve their mechanical and antioxidation ***,the morphology and thickness regulation of ceramic coatings on graphite particles are still a great ***,SiC-coated graphite(graphite@SiC)powders were prepared by nitriding combustion synthesis using Si and graphited mesocarbon microbead(MCMB)as raw powders with polytetrafluoroethylene(PTFE)as a *** effects of the PTFE content and the Si/MCMB molar ratio on the phase composition and coating morphology were *** phase transition and microstructure evolution of a combustion synthesis(CS)process were revealed by a gas-released quenching *** the Si/MCMB molar ratio was 1:3 and the PTFE content was 10 wt%,the thickness of the SiC coating synthesized under 2 MPa N_(2)reached 1.14μ*** corresponding sintered graphite@SiC composite had relative density of 99.2%and flexural strength of 231 MPa,accompanied by a significant improvement in high-temperature antioxidation *** as-synthesized graphite@SiC powders with good sinterability and antioxidation properties show great promise for applications in the nuclear industry and other extreme fields.

关键词： SiC-coated graphite powders nitriding combustion synthesis(CS) antioxidation properties

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Preparation and anisotropic thermophysical properties of SiC honeycomb/Al-Mg-Si composite via spontaneous infiltration

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Progress in Natural Science:Materials International 2019年第2期29卷 177-183页

作者： Zhejian Zhang zhongqi shi Biguo Yang Bangzhi Ge Xiaoyu Zhang Yajie Guo State Key Laboratory for Mechanical Behavior of Materials Xi'an Jiaotong University Engineering Research Center of Transportation Materials of Ministry of Education School of Materials Science and Engineering Chang'an University

The SiC honeycomb/Al-Mg-Si composite with interpenetrated microstructure was prepared by spontaneous infiltration of Al-8 wt%Mg-7 wt%Si alloy into directional porous SiC honeycomb served as reinforcement. The microstructure and anisotropic thermophysical properties of this composite were also examined. The results showed that the initial microstructure of the SiC honeycomb can be retained and the as-prepared SiC honeycomb/Al-Mg-Si composite exhibited significantly anisotropic characteristics. Meanwhile, the alloying treatment on the Al matrix can avoid the generation of Al;C;and promote the wettability between Al and ***,the directional porous SiC honeycomb with such a low ceramic content（19 vol.%） made it possible for the composite to have a higher thermal conductivity(138.3 W/（m?K）) in the axial direction and a lower coefficient of thermal expansion(11.40 × 10;/K) in the radial *** influences of the SiC honeycomb reinforcement on the anisotropic thermophysical properties were also studied by the theoretical models in comparing with the experimental results.

关键词： SiC honeycomb Al-Mg-Si alloy Spontaneous infiltration Anisotropy Thermophysical properties

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Mechanical and ablation properties of three-dimensional ZrC skeleton-reinforced graphite-based composites

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Journal of Advanced Ceramics 2024年第10期13卷 1553-1565页

作者： Wenqi Xie Biao Zhang Xiaoyu Zhang Zhilei Wei Wanli Yang Zhichao Xiao zhongqi shi State Key Laboratory for Mechanical Behavior of Materials Xi’an Jiaotong UniversityXi’an 710049China Chaoma Technology Co. Ltd.Xi’an Aerospace Composites Research InstituteXi’an 710025China

Graphite materials are promising aerospace structural materials owing to their low density,high thermal conductivity,and high temperature ***,the poor mechanical properties and inferior ablation resistance of graphite materials limit their application in advanced space *** address this problem,three-dimensional zirconium carbide(3D ZrC)skeleton-reinforced graphite composites(mesocarbon microbeads,MCMBs)were designed and fabricated by combination of molten salt coating and spark plasma sintering(SPS).The effects of ZrC content on the mechanical and ablation properties were investigated in *** the ZrC content of 45 vol%,the bending strength and fracture toughness of the MCMB@ZrC composite were 112 MPa and 1.72 MPa·m^(1/2),*** ablation at 2.4 MW·m^(-2)for 60 s,the MCMB@ZrC composites with 30 vol%ZrC exhibited the best ablation performance and remained intact after ablation,with linear and mass ablation rates of 2.13μm·s^(-1)and 4.24 mg·s^(-1),*** 3D ZrC skeleton with moderate content provides effective support for the graphite matrix and thermal protection during the ablation process to a certain extent.

关键词： composite graphite mechanical properties ablation performance

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Preparation of unidirectional porous AlN ceramics via the combination of freeze casting and combustion synthesis

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Journal of Materials Science & Technology 2022年第5期100卷 161-168页

作者： Zhilei Wei Zhejian Zhang Xiaoyu Zhang Zhiyuan Li Tao Li Jiabin Hu Shunjian Xu zhongqi shi State Key Laboratory for Mechanical Behavior of Materials Xi’an Jiaotong UniversityXi’an 710049China School of Mechanical and Electrical Engineering Xinyu UniversityXinyu 338000China

Unidirectional porous AlN ceramics(UP-AlNs)have attracted great attention for their wide applications in catalyst supports,filters and composite ***,traditional fabrication processes usually require high temperature and long production ***,UP-AlNs were successfully fabricated via the combination of tertiary butyl alcohol(TBA)-based freeze casting and combustion synthesis route using Al and AlN powders as raw *** microstructure,open porosity,thermal conductivity and compressive strength of UP-AlNs can be manipulated by synergistically regulating the AlN diluent content and Al/AlN solid loading of the freezing *** optimal UP-AlNs exhibited controllable structure wavelength(λ)and open porosity in a wide range of 21.1-47.1μm and 54.2%-86.0%,*** addition,the corresponding products also possessed anisotropic thermal conductivity and compressive *** novel route for the fabrication of UP-AlNs has the advantages of low cost,energy-saving and high efficiency,which shows significant promise for industrial applications.

关键词： AlN Freeze casting Combustion synthesis Thermal conductivity Compressive strength

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Continuous SiC skeleton reinforced highly oriented graphite flake composites with high strength and specific thermal conductivity

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Journal of Advanced Ceramics 2022年第3期11卷 403-413页

作者： Xiaoyu ZHANG Wenqi XIE Lan SUN Zhilei WEI Zhejian ZHANG Yuanyuan ZHU Jiabin HU Shenghe WANG zhongqi shi State Key Laboratory for Mechanical Behavior of Materials Xi’an Jiaotong UniversityXi’an710049China State Grid Anhui Electric Power Co. Ltd.Hefei230061China

Highly oriented graphite-based composites have attracted great attention because of their high thermal conductivity(TC),but the low mechanical properties caused by the inhomogeneous distribution and discontinuity of reinforcements restrict the wide ***,continuous SiC ceramic skeleton reinforced highly oriented graphite flake(SiC/GF)composites were successfully prepared by combining vacuum filtration and spark plasma *** effect of SiC concentration on the microstructure,flexural strength,and thermophysical properties of the composites was *** GF grains in the composites exhibited high orientation with a Lotgering factor of>88%when the SiC concentration was≤30 wt%,and the SiC skeleton became continuous with the SiC concentration reaching 20 wt%.The formation of continuous SiC skeleton improved the flexural strength of the composites effectively while keeping the TC in a high ***,the composites with 30 wt%SiC exhibited the flexural strength up to 105 MPa,and the specific TC reaching 0.118 W·m^(2)·K^(−1)·*** composites with excellent flexural strength and thermophysical properties showed significant promise for thermal management applications.

关键词： ceramics composite materials high orientation flexural strength heat conduction

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Anisotropic, biomorphic cellular Si_(3)N_(4) ceramics with directional well-aligned nanowhisker arrays based on wood-mimetic architectures

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Journal of Advanced Ceramics 2022年第4期11卷 656-664页

作者： Songsong XU Xiaonan ZHOU Qiang ZHI Junjie GAO Liucheng HAO zhongqi shi Bo WANG Jianfeng YANG Kozo IshiZAKI State Key Laboratory for Mechanical Behavior of Materials Xi’an Jiaotong UniversityXi’an 710049China High Voltage Switchgear Insulation Materials Laboratory of State Grid Pinggao Group Co.Ltd.Pingdingshan 467001China Department of Mechanical Engineering Nagaoka University of TechnologyNagaoka 940-2188Japan

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 *** 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) ***,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 *** dense aligned microchannels with low-tortuosity enable excellent load carrying capacity and thermal conduction through the entire *** 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.

关键词： silicon nitride anisotropic carbothermal reduction nitridation(CRN) wood nanowhisker arrays

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Enhanced figure of merit for famatinite Cu_(3)SbSe_(4)via band structure tuning and hierarchical architecture

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Journal of Materiomics 2023年第6期9卷 1263-1272页

作者： Lijun Zhao Haolin Ye Xinmeng Wu Jian Yang Lihua Yu zhongqi shi Shahid Hussain Guanjun Qiao Junhua Xu Bangzhi Ge Li Wang Chongjian Zhou School of Materials Science and Engineering Jiangsu University of Science and TechnologyZhenjiang212100JiangsuChina State Key Laboratory of Solidification Processing Key Laboratory of Radiation Detection Materials and DevicesMinistry of Industry and Information TechnologyNorthwestern Polytechnical UniversityXi'an710072ShaanxiChina School of Materials Science and Engineering Jiangsu UniversityZhenjiang212013JiangsuChina State Key Laboratory for Mechanical Behavior of Materials Xi'an Jiaotong UniversityXi'an710049ShaanxiChina

The p-type Te-free Cu_(3)SbSe_(4)with famatinite structure is a potential candidate for thermoelectric materials due to the low cost and eco-friendly constituent ***,its strong bipolar effect and high lattice thermal conductivity(klat)are the main challenges for its performance ***,we report a new strategy to enhance its figure of merit zT~0.86 at 673 K for Cu_(3)Sb_(0.95)Fe_(0.05)Se_(2.8)S_(1.2)via band structure tuning and hierarchical ***,S substituted Se atoms in lattice can widen the band gap to alleviate the bipolar ***,Fe doping in Sb site significantly increases the density of states,thus increasing the carrier effective mass,and obtaining a remarkably high Seebeck coefficient of~560 mV/K at 300 ***,the induced hierarchical architecture defects resulting in a minimum klat of~0.48 W·m^(-1)·K^(-1)at 673 ***,the improved Seebeck coefficient combined with low thermal conductivity leads to an enhanced zT.

关键词： Cu3SbSe4-Based materials Defects Band gap Thermoelectric properties Solid solution

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Preparation and Application Progress of Porous Alumina

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China's Refractories 2020年第4期29卷 10-18页

作者： WANG Tao WANG Bo HOU Baoqiang shi zhongqi YANG Jun XIA Hongyan WANG Jiping WANG Hongjie YANG Jianfeng State Key Laboratory for Mechanical Behavior of Materials Xi’an Jiaotong UniversityXi’an 710049China

Porous alumina ceramics are widely used in various fields because of their unique characteristics in structure and *** article mainly provided an overview of preparation techniques of porous alumina ceramics;besides,the principles and the characteristics of pore-forming agents processes,gel-casting processes,freeze-casting processes,anodizing processes and other common processes in obtaining the required properties of porous alumina ceramics were ***,the relevant applications and the performance of porous alumina ceramics were *** research prospects of porous alumina ceramics were put forward based on the research status at the end of this paper.

关键词： alumina porous ceramics preparation application

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内贴CFRP加固圆形隧洞弧形界面力学性能研究

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天津大学学报（自然科学与工程技术版） 2023年第3期56卷 323-331页

作者：施钟淇秦敢杨帆合肥工业大学土木与水利工程学院合肥230009 深圳市城市公共安全技术研究院有限公司深圳518038 城市安全风险监测预警应急管理部重点实验室深圳518038

内贴碳纤维增强复合材料(CFRP)加固圆形隧洞时,弧形加固界面的力学性能是影响CFRP与衬砌混凝土两种材料能够变形协调共同承载的重要因素.考虑弧形加固界面的黏结滑移,建立了界面应力理论分析模型,分析了界面曲率变化对界面应力状态的影... 详细信息

内贴碳纤维增强复合材料(CFRP)加固圆形隧洞时,弧形加固界面的力学性能是影响CFRP与衬砌混凝土两种材料能够变形协调共同承载的重要因素.考虑弧形加固界面的黏结滑移,建立了界面应力理论分析模型,分析了界面曲率变化对界面应力状态的影响;通过建立CFRP加固圆形隧洞数值分析模型,着重研究了胶层的弹性模量和厚度、CFRP的弹性模量和厚度、CFRP的粘贴层数等加固参数变化时,弧形加固界面应力状态的变化规律;最后结合具体工程案例,在兼顾隧洞衬砌满足加固条件的同时,从减小界面应力、防止结构出现剥离破坏的角度对上述参数的选择提出优化方案.计算分析与工程案例研究结果表明:界面曲率的存在使得加固界面上不仅存在环向应力,而且会存在径向应力,界面应力状态相比于加固界面为平面而言更为复杂;界面曲率的变化对界面环向应力无明显影响,但对界面径向应力影响显著,随着界面曲率半径的逐渐降低,界面径向应力水平会显著提高;选择弹性模量较小的胶层,适当减小胶层的涂刷厚度,可以显著降低弧形加固界面的应力水平,从而降低结构发生剥离破坏的潜在风险;在满足结构受力与承载要求的前提条件下,建议选择厚度较薄、弹性模量较小的碳纤维材料对圆形隧洞进行加固,同时尽可能地减少粘贴层数,对CFRP与衬砌混凝土的长期共同作用有利.

关键词：隧洞加固弧形界面界面应力黏结滑移有限元分析

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