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Journal of Wuhan University of Technology(Materials Science) 2015年第3期30卷 478-483页

作者：邹爱华周贤良 LI Duosheng ZHANG Jianyun School of Materials Science and Technology Nanjing University of Aeronautics and Astronautics School of Material Science and Engineering Nanchang Hangkong University Research School of Engineering Australian National University

The preforms with high SiC volume fraction （〉50%） were successfully fabricated by two bonding methods. Moreover, the dimensional change, compressive strength, and microstructure of SiC preforms were investigated, and the bonding mechanism among SiC particulates in preforms was also discussed. Results show that, after heating to 1 100 ~C and holding for 2 h, a uniform and interconnected structure in the SiC preforms can be obtained by using starch, stearic acid, and graphite respectively as the pore-forming agents, which benefits the subsequent infiltration by the molten metals. More neck-like-jointing among SiC particulate by using graphite as the pore-forming agent improves the dimensional accuracy and compressive strength of the preform. Besides, the properties of the preforms by the binder bonding are better than those by the oxidation bonding, which is mainly because the mixed neck-like-jointing and binder at high temperature provide effective bonding together.

关键词： SiC preforms pore-forming agent bonding methods properties

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Effects of pore-forming agents on Properties of Silicon Carbide Porous Ceramics Prepared from Crystalline Silicon Cutting Waste

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China's Refractories 2019年第4期28卷 12-16页

作者： MA Beiyue WU Hua GAO Zhi REN Xinming ZHANG Yaran School of Metallurgy Northeastern University

SiC powder was rapidly synthesized in an induction furnace with crystalline silicon cutting waste and active carbon as raw materials,and then SiC porous ceramics were prepared at 1600 t for 4 h with carbon embedded using the powder as raw material,the starch and the graphite as pore-forming *** of additions of different pore-forming agents on the phase composition,microstructures,physical properties,and cold crushing strength of the porous ceramics were *** results show that the main crystalline phases of the synthetic powder areα-S iC(6H-SiC)andβ-SiC(3C-SiC).The phase composition of the porous ceramics includesα-S iC(6H-SiC),β-SiC(3C-SiC),FeSi,quartz and *** apparent porosity and closed porosity of the porous ceramics prepared by adding starch are higher,and the cold compressive strength of the porous ceramics added with graphite is *** increasing the additions of the starch,the apparent porosity,closed porosity and linear shrinkage ratio of the porous ceramics increase,and the bulk density decreases *** 20 mass%starch is added,the apparent porosity,closed porosity,linear shrinkage ratio and cold compressive strength are 57.05%,2.03%,5.10%and 10.20 MPa,respectively.

关键词： silicon carbide porous ceramics pore-forming agent crystalline silicon cutting waste

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Innovative construction of macroporous–mesoporous structured spherical alumina and its hydrothermal stability

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Particuology 2024年第7期90卷 429-435页

作者： Yufan Mo Chunli Li Huiyu Li Wei Han He Wen Yinghong Han Chunxia Che Yongjun Feng State Key Laboratory of Chemical Resource Engineering Beijing Engineering Center for Hierarchical CatalystsCollege of ChemistryBeijing University of Chemical TechnologyBeijing100029China Lanzhou Petrochemical Research Center Petrochemical Research InstitutePetroChinaLanzhou730060China

The pore structure of spherical alumina supports is closely related to the dispersion of catalytically active components and the diffusion of *** excellent pore structure under strict reaction conditions is of utmost *** this work,sphericalγ-Al_(2)O_(3)support with a bimodal pore structure,composed of macropores and mesopores,was successfully synthesized using dodecane as the pore-forming agent through the oil–ammonia column-shaping *** morphology and internal pore structure of the alumina were found to be influenced by the amount of surfactant added and ultrasound treatment ***,when concentration of surfactant was 4‰and ultrasound voltage of 20 V was applied,the resultingγ-Al_(2)O_(3)-4‰-20 displayed a highly concentrated distribution of macropores with an average pore size of 100 nm,resulting in an impressive porosity of 69.21%.In contrast,the untreated sample ofγ-Al_(2)O_(3)-0-0 only exhibited a mesoporous distribution with a porosity of 54.03%.Moreover,after being subjected to a hydrothermal treatment in a high temperature(600°C)and high humidity(water vapor)environment for 120 h,theγ-Al_(2)O_(3)-4‰-20 sample maintained a high BET specific surface area of 170.9 m^(2)g^(−1)and mercury intrusion porosimetry specific surface area of 263.3 m^(2)g^(−1).

关键词： Spherical alumina supports pore-forming agent Oil-ammonia column shaping method Hydrothermal treatment Hydrothermal stability

Influence of pore size optimization in catalyst layer on the mechanism of oxygen transport resistance in PEMFCs

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Progress in Natural Science:Materials International 2020年第6期30卷 839-845页

作者： Shumeng Guan Fen Zhou Jinting Tan Mu Pan State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Hubei Provincial Key Laboratory of Fuel Cells Wuhan University of Technology

In PEMFC, the oxygen transport resistance severely hinders the cell from achieving high performance. In this paper, pore-forming agent was used to optimize the pore size distribution of the catalyst layer(CL), and to study its effect on the mechanism of oxygen transport resistance, including molecular diffusion resistance, Knudsen diffusion resistance, and local O2resistance in CL. The results showed that with the pore formation the cell performance had a significant improvement at high current density, mainly due to its better oxygen transport properties, especially under low platinum conditions. The addition of pore-forming agent moved the pore diameter toward a larger pore diameter with a range from 70 to 100 nm, and also obtaining a higher cumulative pore volume. It was found that the increase of the cumulative pore volume and larger pore size were conducive to the diffusion of oxygen molecules in CL, and the resistance caused by which was the dominant part in total transport resistance. Further tests indicated that the improvement of molecular diffusion resistance was much larger than that of Knudsen diffusion resistance in the catalyst layer after pore formed. In addition, the optimized pore structure will also get a higher number of effective pores, which resulted in an increased effective area of the ionomer on the Pt surface. The higher effective area of the ionomer was particularly beneficial for the reduction of local O2resistance with low Pt loading.

关键词： pore size optimization pore-forming agent Oxygen transport resistance PEMFC

Phase evolution and properties of novel Al2O3-based poly-hollow microsphere (PHM) ceramics

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Journal of Advanced Ceramics 2016年第2期5卷 176-182页

作者： Jia-Min WU Ying CHEN Xiao-Yan ZHANG Qian HUANG Jin-Long YANG Yu-Sheng SHI State Key Laboratory of Materials Processing and Die & Mould Technology School of Materials Science and Engineering Huazhong University of Science and Technology Wuhan 430074 ChinaState Key Laboratory of New Ceramics and Fine Processing School of Materials Science and Engineering Tsinghua University Beijing 100084 China State Key Laboratory of Materials Processing and Die & Mould Technology School of Materials Science and Engineering Huazhong University of Science and Technology Wuhan 430074 China State Key Laboratory of New Ceramics and Fine Processing School of Materials Science and Engineering Tsinghua University Beijing 100084 China

In this paper, novel Al2O3-based poly-hollow microsphere (PHM) ceramics were prepared using Si3N4 and Al2O3 PHMs as pore-forming agents. The effect of Si3N4 and Al2O3 PHMs with different percentages on properties of Al2O3-based PHM ceramics was investigated. Through adjusting percentage of Al2O3 PHMs, Al2O3-based PHM ceramics with enhanced properties are achieved. X-ray diffraction (XRD) results show that main phases of Al2O3-based PHM ceramics vary from beta-SiAlON (z value increases from 2.9 to 4) to Al2O3 with the increase of percentage of Al2O3 PHMs from 10% to 100%. The different phase compositions result in different properties of Al2O3-based PHM ceramics. With the increase of percentage of Al2O3 PHMs, porosity of Al2O3-based PHM ceramics gradually decreases, while their shrinkage, flexural strength, and fracture toughness firstly decrease and then increase. Using different kinds of ceramic PHMs as pore-forming agents, various novel and high-performance porous ceramics could be prepared via optimizing percentage of ceramic PHMs in the future.

关键词： porous ceramics poly-hollow microsphere (PHM) pore-forming agent phase evolution mechanical properties

Preparation and characterization of the porous ceramics from fly ash

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Journal of Coal Science & Engineering(China) 2007年第1期13卷 95-98页

作者：任祥军张学斌孟广耀刘杏芹 Department of Materials Science and Engineering University of Science and Technology of China Hefei 230026 China Hefei Coal Science Research Institute Hefei 230001 China

Porous ceramics was made from coal fly ash, and the microstructure and other properties were characterized as a function of the amount of the pore-forming agent and firing temperature. The results indicated that the proper sintering temperature for the useful ceramic materials is 1 250℃, and a liquid-phase was involved in the densification process.

关键词： fly ash porous ceramics pore-forming agent porosity permeability

Preparation of SiC Porous Ceramics by Crystalline Silicon Cutting Waste

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China's Refractories 2018年第4期27卷 46-50页

作者： ZHANG Yaran MA Beiyue YU Jingyu SU Chang REN Xinming QIAN Fan LIU Guoqi LI Hongxia YU Jingkun School of Metallurgy Northeastern University State Key Laboratory of Advanced Refractories Sinosteel Luoyang Institute of Refractories Research Co.Ltd.

SiC porous ceramics were prepared at 1 400 ℃ for4 h with crystalline silicon cutting waste and activated carbon as main starting materials and NH4HCO3 as the pore-forming agent. Effects of NH4HCO3 additions( 0,20%,30%,40%,by mass) on the phase composition,microstructure,sintering properties,cold compressive strength and thermal shock resistance of as-prepared Si C porous ceramics were investigated. The results show that:( 1) addition of NH4HCO3 remarkably influences the apparent porosity and cold compressive strength of specimens. The apparent porosity achieves its maximum value( 63. 40%) when 40% NH4HCO3 is added,while the minimum cold compressive strength is 4. 77 MPa;( 2) the specimen with 40% NH4HCO3 has the best thermal shock resistance. The thermal cycling times between1 000 ℃ to room temperature reach 62;( 3) the addition of NH4HCO3 does not remarkably affect the phase composition of the specimens;( 4) the specimens include a large number of SiC particles and a small amount of SiC whiskers.

关键词： crystalline silicon cutting waste silicon carbide porous ceramics pore-forming agent sintering properties cold compressive strength thermal shock resistance

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