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Key engineering materials
Trans Tech Publications Ltd.
Key engineering materials

Trans Tech Publications Ltd.

半月刊

1013-9826

Key engineering materials/Journal Key engineering materials
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    Mechanical Property and Ballistic Performance of Silicon Carbide

    Tian MaHeng DuZili YanZhengcao Li...
    72-75页
    查看更多>>摘要：Two groups of silicon carbide ceramics were prepared by pressureless sintering processing with a small amount of boron and carbon as sintering additives. The flexural strength, Vickers hardness, fracture toughness and compressive strength of the samples were measured and compared. Sample A achieved much higher flexural strength (389.4MPa) than that of sample B (250.3MPa) due to the difference of additive dosage. However, the two groups of samples attained comparable values for the other three mechanical properties. SEM observation revealed that the stoichiometric ratio of the Si/C atom in the sintered body is an important factor to affect the mechanical performance of the silicon carbide. The ballistic performance of the samples was also evaluated in this study. The results showed that sample B exhibited more excellent ballistic property, which is probably related to the high flexural strength. The detailed influencing factors need to be studied further.
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    • NSTL
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    Effect of Ball Milling on Microstructure and Flexural Strength of Ti(C,N)-Ni Cermets

    Xiaoyan WangJian LiRuifen WuWei Pan...
    76-78页
    查看更多>>摘要：Ti(C,N) cermets were prepared by SPS method. The effects of nickel salt coating as well as ball milling times on the microstructure and mechanical properties of the cermets were investigated. SEM images shows that the nickel was coated homogeneously on the surface of Ti(C,N) powders by mixing Ni salt and Ti(C,N) powder. The grains of Ti(C,N)-based cermets became finer with increasing ball milling time. The flexural strength increased when the balling milling was below 48h, and then decreased with increasing of ball milling time, which was due to the decrease of the flake structure in cermets.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Preparation of Porous SiO_2 Ceramics by Gelcasting

    Sha LiHaiyan DuDuo YangJiping Guo...
    79-80页
    查看更多>>摘要：Porous SiO_2 ceramics had been successfully prepared by gelcasting. The open porosity of obtained samples was between 0.40 and 0.46, which reached its maximum at 1100℃. The change of line shrinkage rate was opposite to the open porosity. The microstructure was investigated though X-ray diffraction (XRD) and scanning electronic microscope (SEM).
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    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Preparation of Porous Mullite Ceramics by Fly Ash/Al Compositions

    Qihui JiaJiachen LiuJiping GuoXiongwei Du...
    81-84页
    查看更多>>摘要：Porous mullite was prepared from a reactive mixture of Al metal powder and the fly ash produced by power plant. The sintering ceramics was characterized for the pore structure and phase identification studies. It was found that the sintered specimen expands at first (1300-1400℃) and then shrinks which was correspondence to the changing of open porosity. The expansion was attributed to the fact that the alumina produced from the oxidation reaction of Al powder made the volume larger than the starting mixtures. At 1550℃, it was inferred that the alkaline element in the fly ash made the mullite decomposed then destroyed the mullite structure. The SEM photographs suggested us that the pore diameter of the sintered ceramics might be adjusted by adding Al powder with different grain sizes. Moreover, because of the rod-like mullite produced in the pores, Mg metal addition could develop the further modification of the pore structure with similar porosity (47% at 1400℃/4h) compared with that (53%) with Owt % Mg metal powders.
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    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Preparation of Mullite by Coating Al(OH)_3 on the Surface of Fly Ash

    Rui XuHaiyan DuShihui LiXiongwei Du...
    85-87页
    查看更多>>摘要：Porous mullite were prepared by coating Al(OH)_3 on the surface of the particles of waste fly ash. The effects of content of urea on formation of mullite and sintering temperature on microstructure of mullite were investigated by XRD and SEM analysis. It was showed that two kind mullite were obtained, one was growing from original Needle-like mullite existing in original ashfly, and the other was formed through by the reaction between glassy phase and Al_2O_3 coated on spherical waste fly ash.
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    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Preparation of Complicated SiC Green Bodies via Aqueous Slip Casting

    Yuan LiJiqiang GaoJianfeng Yang
    88-91页
    查看更多>>摘要：Two domestic silicon carbide powders with different particle size distribution and one petroleum coke powder were blended in proportion and then dispersed in aqueous medium. Green bodies were solidified from these suspensions via conventional slip casting. The effects of pH, solid loading, and the amount of dispersant on the formability and packing ability were evaluated. The results showed that the pH within 9.5-10.5, solid loading of 42vol%, aging time more than 24h, and 0.3wt% of dispersant were optimal. Complicated green bodies with height of 300mm and thickness of 3.5mm were obtained. The corresponding suspension viscosity was 1200mPas and the relative packing density was 64.8%. The density is 3.01gcm~(-3) and the flexural strength is 305±15 MPa after reaction sintering. These results may be attributed to accurately using of dispersant and in-depth study of processing parameter.
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    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Influence of Calcination Time on Pozzolanic Activity of Metakaoline Base on a Novel Evaluation Method

    Meirong WangTiesong LinPeigang HeDechang Jia...
    92-94页
    查看更多>>摘要：A novel evaluation method of pozzolanic activity of metakaoline is studied. The pozzolanic activity can be evaluated by the measurement of the content of AlO_4 tetrahedra. Base on this method, the influence of calcination time on pozzolanic activity of metakaoline is studied. The results indicate that the pozzolanic activity increases with the calcination time when calcination time is below 4 hours, and it decreases with the calcinations time increasing when the calcination time is 4-8 hours.
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    • NETL
    • NSTL

    The Microstructure and Tribological Properties of Carbon Fibre Reinforced Carbon/SiC Dual Matrix Composites

    Xiao PengLi ZhuanXiong Xiang
    95-98页
    查看更多>>摘要：Carbon fibre reinforced carbon and silicon carbide dual matrix composites (C/C-SiC) are new type of high performance brake materials, and possess a series of outstanding advantages. In the present study, the C/C-SiC brake composites were fabricated by the combination of chemical vapor infiltration with liquid silicon infiltration. The fabric preforms were prepared by three dimension needling method. Results show the SiC form inside the short-cut fabric, around the needing fibre and among the fibre bundles in the non-woven web of the C/C-SiC composites. The average static friction coefficient of the C/C-SiC materials was 0.61. The average dynamic friction coefficient were between 0.41 and 0.54 with the increase of brake speed, and the wear rates are not sensitive to the brake speed and maintained about 0.02 cm~3·MJ~(-1) all along.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Synthesis and Properties of Al_4SiC_4 by Carbothermal Reduction

    Jianli ZhaoChang-An WangAkira YamaguchiJialin Sun...
    99-102页
    查看更多>>摘要：Al_4SiC_4 is probably used as non-oxide raw material for high-temperature ceramics. Al_4SiC_4 was synthesized by using starting materials of metal-carbon, metal-oxide- carbon or carbides. In this paper, Al_4SiC_4 has been synthesized by using oxides (Al_2O_3 and SiO_2) and carbon as starting materials through carbothermal reduction process. The oxidation properties in air and O_2 atmosphere by TG method and the stability of the synthesized Al_4SiC_4 heated in moisture were investigated. Pure Al_4SiC_4 phase was synthesized when heating the mixture powder of Al_2O_3, SiO_2 and C (C : Al_2O_3 : SiO_2 =8:2: 0.8, in molar ratio) at 1700℃ for 8h in flowing Ar atmosphere. The synthesized Al_4SiC_4 powder consists of platelet shape grains with size of 6～8μm length, 3～5μm width and 1μm thickness. Al_4SiC_4 obviously oxidized from 800℃ when heated in flowing air or O_2 atmosphere. When keeping Al_4SiC_4 powder in moisture, it was not observed to be reacted with water by XRD and SEM analysis.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Preparation of C_f/SiC Composites by Liquid Silicon Infiltration

    Chunpeng WangJie TangHailin LiuYanli Huo...
    103-105页
    查看更多>>摘要：The C_f/SiC made from carbon fiber preforms infiltrated by phenol resin, pure carbon slurry and aqueous C/SiC slurry showed different binding strength between carbon fiber and SiC matrix, thus influenced the fracture behavior of the composite. The fracture toughness of the C_f/SiC composites with the value of 9.82MPa·m~(1/2),improved remarkably compared with reaction- bonded silicon carbide (RBSC). But the flexural strength was less than 100 MPa, because of the existence of considerable amount of pores in C/SiC composites.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd