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本文深入分析了线热源探针及测试条件与线热源的解析解及求解边界条件之间的差异,探讨了探针和实验应具备什么样的条件,解析解中的指数积分函数E_1(x)才能代之以对数函数ln(x)。从实验数据的线性回归直线式与实验记录之间的一些不吻合迹象,发现了探针的不等值蓄热形成的缺口;并提出了一个能弥合这一缺口,使实验关联式还原成理想线热源的解析解的“两点式还原法”。从而把探针的测量准确度和可靠性提高到了一个从未有过的高度,而且扩大了探针的适用范围。 相似文献
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热线探针测定液体的导热系数 总被引:1,自引:0,他引:1
本文分析了热线探针测定液体导热系数时产生误差的原因,指出了设计探针时应注意的问题。首次提出了利用实验数据对导热系数关联式进行校正的“两点式还原法”,从而提高了测量精度,与发表的文献数据相比,校正后的数据相对误差在±3%内。 相似文献
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研究了化学组成及显微结构对M1位NZP陶瓷导热系数的影响,随着M1位离子种类数的增加,NZP陶瓷的导热和降低。CMS的导热系数随着气孔率的增加而降低。 相似文献
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研究了瞬态圆球法测定有机溶液导热系数的方法,采用珠状热敏电阻来构成导热池,由测量导热池、参比导热池与两固定电阻组成测量电桥,导出了电桥的电压变化与被测液体导热系数之间的关系,通过测量电桥的电压值,测定了几种有机溶液的导热系数。 相似文献
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SiC纳米粉体悬浮液导热系数研究 总被引:12,自引:1,他引:11
本文作采用非稳态热丝法,测量了水中加平均粒为25nm的碳化硅粉(简称n-SiC),乙二醇中加n-SiC,水中加平均粒径为0.6μm的碳化硅粉(简称μ-SiC)和乙醇中加μ-SiC等4个系列不同固体积含量悬浮液的有效热系数,实验结果表明:对于所研究的悬浮液,其有效导热系数相对增加量随固相加入量的增加而线性增加;固相颗粒形貌对有效导热系数相对增加量有显著影响;基体液体虽对有效导热系数相对增加量无明显影响,但有效导热系数的绝对量由基体液体的导热系数决定。 相似文献
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热塑性聚酰亚胺复合材料导热性能研究 总被引:5,自引:0,他引:5
采用稳态热板法测定铜粉(Cu)填充热塑性聚酰亚胺(TPI)复合材料的热导率,研究了Cu填充量对复合材料的力学性能和导热性能的影响,初步探讨了温度与复合材料热导率的关系。通过扫描电子显微镜观察了复合材料的微观形态。在此基础上,理论计算复合材料热导率。研究表明,Cu填充TPI可有效提高复合材料力学性能和导热性能。当Cu体积分数提高到26%时,填料聚集形成导热链,Cu/TPI复合材料的热导率是纯TPI树脂的3.5倍;当填料含量低于10%时,Maxwell—Eucken模型适合预测复合材料热导率;基于导热链考虑的Y.Agan模型可较好地反映复合材料热导率随填料含量的变化情况;随着温度的升高,Cu/TPI复合材料热导率先增大后趋于平缓。 相似文献
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Amikam Birnboim Tayo Olorunyolemi Yuval Carmel 《Journal of the American Ceramic Society》2001,84(6):1315-1320
This work is devoted to the theoretical understanding of the microstructure and thermal conductivity relationships of compacted ceramic powders in the initial, nondensifying stage of sintering. A model based on surface diffusion of vacancies for the growth of the neck between particles is combined with numerical fully three-dimensional code calculations, which solve for the effective heat conductivity coefficient of lightly sintered particles. The predictions of the model are in agreement with experimental observations. The approach presented can be applied to solve a series of related problems, like dielectric properties, with arbitrary microstructure and multicomponent composite of the powders. 相似文献
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Ran-Rong Lee 《Journal of the American Ceramic Society》1991,74(9):2242-2249
AIN ceramics with densities varying from 3.18 to 3.30 g/cm3 and room-temperature thermal conductivities varying from 88 to 193 W/m K were produced. Different sintering conditions, packing powders, AIN powder sources, carbon additive, and sintering times were evaluated, and the key processing parameters which cause the differences in density and thermal conductivity were identified. SEM, TEM, and EDS were used to characterize the correlation between thermal conductivity, microstructure, and processing parameters. The important parameters which control the thermal conductivity of AIN ceramics are discussed. 相似文献
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Highly Porous Zirconia Ceramic Foams with Low Thermal Conductivity from Particle‐Stabilized Foams 下载免费PDF全文
Wen‐Long Huo Xiao‐Yan Zhang Yu‐Gu Chen Yu‐Ju Lu Wen‐Ting Liu Xiao‐Qing Xi Ya‐Li Wang Jie Xu Jin‐Long Yang 《Journal of the American Ceramic Society》2016,99(11):3512-3515
Zirconia ceramic foams with ultra‐high porosity of 96%–98% have been fabricated using sodium dodecyl sulfate (SDS) as the particle stabilizer of zirconia particles for the first time. The wet foams stabilized by zirconia particles are ultra‐stable due to partially hydrophobic zirconia particles modified by SDS. Zirconia foams exhibit close cells with thin cell wall and small grain size. Increasing SDS concentration favors the foamability of the suspension, and further increases the porosity of ceramic foams. Zirconia ceramic foams with porosity of 98.1% have compressive strength of 0.26 ± 0.05 MPa. Decreasing solid loading leads to the porosity of ceramic foams. The compressive strength could be improved significantly by increasing the sintering temperature. Zirconia ceramic foams with porosity of 97.9% has low thermal conductivity of 0.027 ± 0.004 W·(m·K)?1, which could be used as thermal insulation and refractory material. 相似文献
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以NZP族低热膨胀陶瓷Ca1-xBaxZr4(PO4)6(0≤x≤1)系列中的零膨胀组成Ca0.85Ba0.15Zr4P6O24为例,着重研究了不同添加剂对该零膨胀陶瓷的热膨胀异向性、平均热膨胀系数和导热性能的影响规律。实验结果表明,在烧结过程中添加质量分数1%SiO2或3%SiC均能够降低Ca0.85Ba0.15Zr4P6O24的热膨胀异向性,但与此同时,第二相的加入使Ca0.85Ba0.15Zr4P6O24的热膨胀系数有所上升。质量分数为1%~7%SiC晶须的加入反而导致NZP族陶瓷导热性能进一步降低,原因是SiC抑制了晶粒生长。 相似文献