Boming ZHANG
,
Shuyuan ZHAO
,
Xiaodong HE
,
Shanyi DU
材料科学技术（英文）
The thermal properties of high-alumina fibrous insulation which filled in metallic thermal protection system were investigated. The effective thermal conductivities of the fibrous insulation were measured under an atmospheric pressure from 10-2 to 105 Pa. In addition, the changes of the specific heat and Rosseland mean extinction coefficient were experimentally determined under various surrounding temperatures up to 973 K. The spectral extinction coefficients were obtained from transmittance data in the wavelength range of 2.5– 25 μm using Beer’s law. Rosseland mean extinction coefficients as a function of temperature were calculated based on spectral extinction coefficients at various temperatures. The results show that thermal conductivities of the sample increase with increasing temperature and pressure. Specific heat increases as temperature increases, which shows that the capacity of heat absorption increases gradually with temperature. Rosseland mean extinction coefficients of the sample decrease firstly and then increase with increasing the temperature.
关键词:
Effective thermal conductivity
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Chuncheng ZHU
,
Xinghong ZHANG
,
Xiaodong HE
,
Qiang XU
材料科学技术（英文）
TiC-TiB2-Cu composites were produced by self-propagating high-temperature synthesis combined with pseudo hot isostatic pressing using Ti, B4C and Cu powders. The microstructure and mechanical properties of the composites were investigated. The X-ray diffraction (XRD) and scanning electron microscopy (SEM) results showed that the final products were only TiC, TiB2 and Cu phases. The clubbed TiB2 grains and spheroidal or irregular TiC grains were found in the microstructure of synthesized products. The reaction temperature and grain size of TiB2 and TiC particles decreased with increasing Cu content. The introduction of Cu into the composites resulted in a drastic increase in the relative density and flexual strength, and the maximum values were obtained with the addition of 20 wt pct, while the fracture toughness was the best when Cu content was 40 wt pct.
关键词:
Composite
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Liping SHI
,
Yao LI
,
Xiaodong HE
材料科学技术（英文）
The preparation technology of microlayer composite material by the electron beam physical vapor deposition (EBPVD) technique was briefly introduced. Taking the advantage of the large-scale commercial software of finite element analysis, a reasonable physical model was built up during the deposition processing and the distribution of residual stress was analyzed between substrate and deposition layer or among deposition layers. The results show that: with the increasing substrate preheating temperature, the interlaminar shear stress increases but the axial residual stress decreases. The probability of curling up after de-bonding tends to enhance as the thickness of deposition film increases.
关键词:
Microlayer composite material
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