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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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    Si_3N_4/BN Composite Ceramics with Nd_2O_3-Al_2O_3-Y_2O_3 Ternary Additives by Pressureless Sintering

    Ping LiuYongfeng LiXiangdong WangHaiyun Jin...
    106-108页
    查看更多>>摘要：Si_3N_4/BN composite ceramics with 25vol% h-BN were prepared by pressure-less sintering process with Nd_2O_3/Al_2O_3/Y_2O_3 as sintering additives. The effects of these ternary additives on the densification behaviors and mechanical properties were investigated. XRD and FES EM were used to investigate the α- β phase transformation and microstructure. The XRD results showed that α-Si_3N_4 has transformed to β-Si_3N_4 completely in all the samples during the pressureless sintering process. The line shrinkage increased with the Nd_2O_3 contents increasing, and the highest line shrinkage (7.75%) was observed when 4wt% Nd_2O_3 was added, then decreased. The same trends were observed in flexural strength and fracture toughness testing. The ternary additives of Y_2O_3-Al_2O_3-Nd_2O_3 could improve the density, strength and fracture toughness of the material effectively.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Oxidation Resistance Behave of Stainless Steel /TiC Nano Powders

    Chen WenyiZhou JianLiu Ying
    109-112页
    查看更多>>摘要：Stainless steel/TiC nanocomposite powder were prepared by high-energy ball-milling method using 316 stainless steel powder, carbon and titanium powder as raw materials. Microstructure of the nanocomposite powder was investigated with XRD and TEM techniques. The results showed that the stainless steel/TiC nanocomposite powder obtained when the ball-milling time was more than 40 hours. DSC analysis method was used to study the characteristics of oxidation resistance and the oxidation reaction kinetics of the nanocomposites powder. Results show that the oxidant resistance of nanocomposite powder was improved, the activation energy of oxidation reaction increased.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Impact Properties of TiC/Fe at Elevated Temperatures

    Bao Yan-rongLi BinLiu Zong-deBao Zhi-jian...
    113-115页
    查看更多>>摘要：The impact properties of TiC-Fe composite at different temperatures prepared by SHS / PHIP technique were investigated by impact test which was conducted in air from 20℃ to 100020℃. Morphology of the impact fracture surface was observed by scanning electron microscope (SEM) and phase composition before and after the impact test was analyzed with X-Ray Diffraction. The results indicate that the impact toughness of TiC-Fe composite increases significantly with the temperature increasing above 700℃, representing a minimum value at 700℃. The impact fracture of TiC-Fe composite at room temperature, 700℃, 900℃ and 1000℃ is mainly brittle, showing certain plasticity with morphology of dimples as the temperature increases above 700℃. A small amount of Fe_2O_3 exists in the fracture surface, indicating TiC-Fe composite is oxidized partially during the impact test at elevated temperatures.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Oxidation Behavior of TiC/ Fe Ceramics Produced by Self-Propagating High-Temperature Synthesis

    Li BinLiu Zong-deZhao Li-pingBao Yan-rong...
    116-119页
    查看更多>>摘要：The key problem about the application of TiC/Fe composite ceramics in high temperature is the oxidation resistance. With an aim to investigate oxidation properties, the high density TiC/Fe ceramics was produced by self-propagating high-temperature synthesis method combined with pseudo hot iso-static pressing (SHS/PHIP). The oxidation kinetics of TiC/Fe ceramics were investigated by means of conducting the isothermal oxidation experiments in air at temperature of 550℃ ～ 900℃ for up to 150 hours, and measuring the variations of the weight gains of the composites with the oxidation times. The microstructure evolution of the composites during the oxidation processing was studied by using SEM/EDS and XRD. Experimental results show that TiC/Fe ceramics basically follows a parabolic rule at high temperature. A detailed characterization of the microstructure and distribution of the phases within the scale following oxidation studies has been undertaken to suggest the possible mechanism for the oxidation of TiC/Fe ceramics.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Wear Resistance of TiC Ceramic Particulate-reinforced Metal Matrix Cermets

    Liu Zong-deLi BinZhao Li-pingChen Yong...
    120-122页
    查看更多>>摘要：To characterize wear behaviors of TiC ceramic particulate-reinforced metal matrix cermets in abominable condition, wear-resistance test was practiced in grain abrasive wear with the TiC-xNi cermets in-situ fabricated by self-propagating high-temperature synthesis method combined with pseudo hot iso-static pressing. Grain abrasion test was conducted with the MLS-225 type tester. Wear resistance was evaluated as weight loss obtained after each period of 10 minutes. Wear resistance of the cermets increased with the increase of TiC content in the composites. SEM was employed to analyze the wear process and wear mechanism. SEM examination of the wear tracks in the worn surface suggests that abrasive wear mechanisms of different binder content cermets are similar. The worn surface is characterized by long and deep parallel grooves. The fracturing of bigger carbide grains and carbide framework by a fatigue process under repeated abrasion is followed by weight loss of the material.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Thermal Conductivities of LaPO_4/Al_2O_3 Composites Fabricated by SPS

    Aibing DuRuifen WuZhixue QuChunlei Wan...
    123-125页
    查看更多>>摘要：The thermal conductivities of the LaPO_4/Al_2O_3 composites that were fabricated by spark plasma sintering (SPS) were determined. The results revealed that their thermal conductivities displayed nearly a slow decrease with increasing temperature from 25℃ to 800℃, having the classic I/T dependence. In addition, the conductivities of the composites decrease monotonously with increasing the LaPO_4 content because of the lower thermal conductivity of LaPO_4. The calculated conductivities of the composites using Maxwell equation match well the experimental values at both the end members of LaPO_4 and Al_2O_3 being the continuous phase, but showing a little deviation at intermediate composition.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Preparation and Antibacterial Effect of Silver-Carrying Nano-Hydroxyapatite Powder

    Jinxia HuangJianrong WangJinghe LiuBin Liu...
    126-129页
    查看更多>>摘要：Hydroxyapatite (HA) has attracted many attentions because it has a similar structure to that of human bones and favorable biocompatibility. However, the antibacterial effect of HA must be improved. In this paper, HA nanoparticles were prepared by a simple method. Then, Ag-carrying HA powder (Ag-HA) was prepared by an ion-solution reaction and its antibacterial property was investigated. The results showed that Ag-HA powder had excellent ability in inhibiting the growth of two species of bacteria, namely E. coli and S. aureus. Ag ion was believed to play a key role in killing bacteria.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Thermal Shock Behavior of Nd-Doped α-Sialon Ceramics

    Chunfeng LiuFeng YeYu ZhouYudong Huang...
    130-133页
    查看更多>>摘要：Nd-α-sialons with the stoichiometric composition of Nd_(0.333)Si_(10)Al_2ON_(15) were obtained by hot-press sintering at 1800℃ for lh. The thermal shock behavior of the Nd-α-sialons was examined by a water-quenching technique. The influence of the thermal shock temperature difference (ΔT) and cycle times on the residual strength was evaluated. Equiaxed a-sialon grains formed together with a small amount of intergranular phase M' (Nd_2Si_(3-x)Al_xO_(3+x)N_(4-x)) and β-sialon phase. The residual strength after a thermal shock tended to decrease gradually with increasing ΔT above 500℃. However, the specimens exhibited an improved residual strength (～94% of the room temperature strength) after a thermal shock of ΔT=1100℃. The residual strength presented a gradual decrease with increasing the thermal shock cycle times at ΔT=1100℃, and was still remained ～55% of the room temperature strength after 11-time cycle. It is contributed to the surface oxidation which may results in the healing of surface cracks and the generation of surface compressive stresses.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Effect of Silica Coating on the Thermal Stability of Tantalum Based Nitrides Pigments

    Jong-Chul ParkJae-Hwan PeeYooJin KimWoo-Seok Cho...
    134-137页
    查看更多>>摘要：The colored TaON and Ta_3N_5 were synthesized by ammonolysis of amorphous Ta(OH)_5 in the temperature range of 800-1000℃. Ta(OH)_5 were prepared by titration process from TaCl_5. TaON were synthesized at 900℃ for 2 hr, and Ta_3N_5 were synthesized at 1000℃ for 5 hr. In general, Ta_3N_5 powders were easily oxidized at 500℃ with changing colority from red to white. To minimize the oxidation problem of Ta_3N_5 powders, we proposed silica coated system using TEOS and APTES as a surfactant. Tonality of silica coated Ta_3N_5 has very little changing which means silica coating actually minimizes the oxidation of the Ta_3N_5 particles.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Influences of SrSO_4 and Ag on High Temperature Tribological Properties of Spark-Plasma-Sintered ZrO_2(Y_2O_3)-Al_2O_3 Composites

    Y.F. LiJ.H. OuyangY.M. WangY. Zhou...
    138-143页
    查看更多>>摘要：ZrO_2(Y_2O_3)-Al_2O_3-SrSO_4 nanocomposites incorporated with and without Ag addition have been fabricated by spark plasma sintering (SPS) to evaluate their friction and wear properties in sliding against alumina ball from room temperature to 600℃. X-ray diffraction (XRD), scanning electron microscope (SEM) and Raman spectroscopy were used to investigate microstructure and self-lubrication mechanisms of nanocomposites after wear tests at different temperatures. The ZrO_2(Y_2O_3)-Al_2O_3-SrSO_4 nanocomposite exhibits low and stable friction coefficients of 0.2 to 0.3 and wear rates in the order of 10~(-6) mm~3/Nm at high temperatures. With the addition of Ag into the composite, the intermediate temperature lubricating property is greatly improved. Plastic deformation of SrSO_4 and sliver during sliding plays an important role in formation of lubricating films on worn surfaces of nanocomposites. These lubricating films reduce the friction and wear of the ZrO_2(Y_2O_3)-Al_2O_3 matrix composites.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd