首页期刊导航|Key engineering materials
期刊信息/Journal information
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
正式出版
收录年代

    Effects of CeO_2 on the Mechanical Property and Microstructure of 3Y-TZP Nanocomposite Ceramic Die Material

    Zhao ShikuiXu Chonghai
    42-44页
    查看更多>>摘要：Thermal stability and wear resistance of nanoceramic materials are excellent, so it is an ideal die material and has become one of the increasingly important topics in the field of die research. A new 3Y-TZP nanocomposite die material was prepared with hot pressing technique by using 3Y-TZP, CeO_2, Al_2O_3 and nanometer sized TiC as raw materials. Effects of CeO_2 on the mechanical property and microstructure of 3Y-TZP nanocomposite die material were investigated. The addition of CeO_2 has obvious effect on the flexural strength and fracture toughness. When the content of CeO_2 is 2mol%, the fracture toughness of the composite material reaches 11.22MPa·m~(1/2). With the increase of CeO_2 content, the fracture toughness becomes lower, the flexural strength and hardness first increase and then decrease. When the CeO_2 content is 6mol%, the maximum flexural strength reaches 866MPa. The reason for the improvement of mechanical property can be attributed to the effect of CeO_2 on the phase transformation of t-ZrO_2 and microstructure and the resulted phase transformation toughening mechanism.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Microstructure and Mechanical Property of Three-Dimensional Needled C/SiC Composites Prepared by Precursor Pyrolysis

    Cui-Lin HanDong-Lin ZhaoLei ZhangZeng-Min Shen...
    45-47页
    查看更多>>摘要：Three-dimensional needled carbon/silicon carbide (C/SiC) composites with pyrolytic carbon interfacial layer were fabricated by precursor pyrolysis. The microstructure and mechanical property of the three-dimensional needled C/SiC composites were investigated. A thin pyrolysis carbon layer (0.2± μm) was firstly deposited on the surface of carbon fiber as the interfacial layer with C_3H_6 at 850℃ and 0.1 MPa by chemical vapor infiltration. Polycarbosilane and divinylbenzene were selected as a precursor to silicon carbide ceramics and a cross-linking reagent for PCS, respectively. The density of the composites was 1.94 g cm~(-3). The flexural strength of the three-dimensional needled C/SiC composites was 135 MPa. The three-dimensional needled C/SiC composites with pyrolytic carbon interfacial layer exhibit good mechanical properties and a typical failure behavior involving fibers pull-out and brittle fracture of sub-bundle.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Property and Microstructure of CNTs/AlN Ceramics

    Wang HongleiZhou XinguiYu HaijiaoZhao Shuang...
    48-49页
    查看更多>>摘要：CNTs/AlN ceramics were fabricated by hot-pressing and their bulk density, flexural strength, thermal conductivity were characterized. The microstructure was also investigated. The fracture surface were analyzed by SEM. TEM was used for analyzing the microstructure. It is found that the density, mechanic and thermal-conductivity properties markedly decreased as the CNTs reinforced AlN ceramic; through microstructure observation, the conglomeration of CNTs mostly exist among the AlN grain boundary, and the CNTs were scathed by the high temperature and pressure of the hot-pressing.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Microstructures and Mechanical Properties of B_4C-TiB_2 Composite Prepared by Hot Pressure Sintering

    XinYan YueShuMao ZhaoLiang YuHongQiang Ru...
    50-53页
    查看更多>>摘要：B_4C-TiB_2 composite was prepared using hot pressure sintering. The microstructures and mechanical properties of the B_4C-TiB_2 composite were investigated. The B_4C-TiB_2 composite with 43 mass % TiB_2 showed the optimized properties. The relative density, hardness, flexural strength and fracture toughness of that were 98.2 %, 25.9 GPa, 458 MPa and 8.7 MPa·m~(1/2), respectively. A number of toughening mechanisms, including fine grain, crack deflection and grain pull-out, were observed during microstructural analysis of the composite. The fracture mode of the B_4C-TiB_2 composite was greatly affected by the existence of the second phase of TiB_2.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Effects of Adding SiC Powder on the Properties of Carbon Fiber Reinforced Si-O-C Composites Fabricated via Precursor Pyrolysis

    Jing-yu LiuKe JianZhao-hui ChenZhi-wei Fang...
    54-56页
    查看更多>>摘要：Three dimensional carbon fiber reinforced silicon oxycarbide (3D Cf/Si-O-C) composites with low cost silicon resin as precursors and 3D Cf as reinforcement. Effects of adding SiC powder (SiC_p) on the microstructure, mechanical properties and anti-oxidation properties of 3D Cf/Si-O-C composites were investigated. The results showed that adding SiC_p filler could reduce the porosity and improve the interface bonding, therefore the properties of composites increased. But when the SiC_p content was excessive, it was difficult to dense the matrix of composites at the further cycles and pores existed in the matrix. As a result, the mechanical properties of the composites decreased. It was found that when fabricated with 18.2 weight percent SiC_p the composites exhibited highest mechanical properties, and the flexural strength and fracture toughness reached 421.3MPa and 13.0 MPa·m~(1/2), respectively. And the anti-oxidation properties were improved with the increase of the SiC_P content. When fabricated with 25.0 weight percent SiC_p the composites exhibited best oxidation resistance properties, and the composites retained 89.5% of original flexural strength.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Damage Detection in Fibre Reinforced Ceramic and Metal Matrix Composites by Acoustic Emission

    Figen Kaya
    57-60页
    查看更多>>摘要：In this work damage micro-mechanisms of two different types of fibre reinforced composites are investigated by acoustic emission, AE. Ceramic based oxide fibre reinforced mullite matrix composite and metallic based SiC fibre reinforced titanium matrix composites exhibit different fracture mechanisms during loading and AE technique could pinpoint these damage mechanisms based on the AE responses detected simultaneously. The results show that in a ceramic matrix composite, the identification of fibre fracture and matrix cracking requires careful analysis of the AE data as both fibres and matrix break in brittle manner. Whereas the separation of fibre fracture from the ductile tearing of matrix ligaments could be easier in metallic based composites, such as titanium matrix composites.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Defects Analysis of Large Size Silicon Nitride Balls Sintered by Gas Pressure Sintering

    Feng SunWei-ru ZhangTing-yan TianXiang-hong Teng...
    61-63页
    查看更多>>摘要：The sections of Φ55mm silicon nitride balls, sintered by gas pressure sintering were analyzed. The results show that temperature gradient during of the sintering process from the surface to the core of large size silicon nitride balls occurred because of the lower thermal conductivity of Si_3N_4. With the diameter increasing, the temperature gradient was more visible. The impurity of raw materials, such as free Si, free C and other metal oxides, like the SiO_2 could produce gas, such as SiO, CO and so on, during the sintering process through the thermodynamic analysis. The producing gas exhausted more difficultly with the diameter of silicon nitride balls increasing. These factors were the most important to the defects of large size silicon nitride balls during the sintering process and made cracks and crescent on the surface of balls.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Effects of SiO_2 and Fe_2O_3 on Morphological of Mullite

    Cunshu HuangJiachen LiuAnran GuoLu Yang...
    64-65页
    查看更多>>摘要：Effects of SiO_2 and Fe_2O_3 on morphological of mullite were investigated for a special use related to mullite containing SiO_2 and Fe_2O_3. It was concluded that, when Al_2O_3/SiO_2 ratio near the theoretical component of mullite, the composites cannot been sintered at 1600℃. The normal morphology of mullite presents granule form with Fe_2O_3 addition, while takes a long column shape with the condition of excessive. SiO_2 presenting. Fe_2O_3 can promote sintering of mullite, as well as growing in needle-like morphology.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Preparation and Characterization of Fe/SiC Ceramic-Metal Composites

    Zhongsheng LiuGang ShaoDeliang ChenRui Zhang...
    66-68页
    查看更多>>摘要：SiC is a perfect reinforced material, characteristic of high hardness, high wear- and corrosion-resistant property, and low cost. SiC-reinforced iron-matrix composites show high wear resistance, high hardness, high inflexibility and high strength, with wide applications as superior wear-resistant and high temperature materials. This paper reported a heterogeneous precipitation method to coat SiC with copper particles. The vacuum hot-pressing method was used to sinter the Fe/SiC composites with Cu-coated SiC powders. The techniques of XRD and SEM were used to characterize the compositions and microstructures of the samples. The Archimedes method was used to test the density. The results showed that SiC and Cu were homogeneously mixed in the composite powders obtained by the heterogeneous deposition method, and that the composites with 5wt% of SiC (Cu) obtained at 950℃ have a high relative density of 96%, a high hardness of 4121 MPa and a high bending strength of 646 MPa. The enhanced properties of Fe/SiC composites could result from the improved interfacial consistency by using Cu-coated SiC powders, which could inhibit some adverse interfacial reactions.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Comprehensive Evaluation of Machinabilities of Dental Ceramics

    Cheng ZhangJi LuHui Huang
    69-71页
    查看更多>>摘要：Machinability of ceramics is a comprehensive behavior resulting from the interactions of several factors. In this paper, the fuzzy comprehensive evaluation system was applied to establish a model for machinabilities of several dental ceramics, including zirconia, empress feldspar, empress toughening leucite and lithium disilicate glass. The hardness (H_V), fracture toughness (K_(IC)) and elastic modulus (E) of ceramic samples were used in evaluation model with different weighted indexes. The ceramics could be thus divided into 4 groups of "easiest", "easy", "difficult" and "most difficult", based on evaluated results. Lithium disilicate glass belongs to "easiest", empress feldspar and empress toughening leucite are at the "easy" level, and zirconia is "difficult" to be machined compared with other counterparts. The evaluations by established model are well supported by the practical machining experiments while these dental ceramics being undergone cutting. This implies that the derived evaluation model is an easy and simple way to estimate machinability of dental ceramics.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd