共查询到14条相似文献,搜索用时 78 毫秒
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设计了由两根交叉微米线构成的点接触测量装置,推导了接触热阻测量的实验原理,分析了微米线的表面形貌,实现了不同作用力下接触热阻和接触电阻的同时测量。结果表明:两微米线刚接触时,接触热阻和接触电阻均比相对位移大于5μm时的结果大近一个数量级,且两者的比值满足Wiedemann-Franz定律;随着相对位移增大,绝缘层对导热的贡献增大,接触热阻减小,但接触电阻几乎不变;继续增加相对位移,得到的接触热阻和接触电阻几乎均与作用力无关,Lorenz数为(4~5)×10-8 W·Ω·K-2。 相似文献
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设计了由两根交叉微米线构成的点接触测量装置,推导了接触热阻测量的实验原理,分析了微米线的表面形貌,实现了不同作用力下接触热阻和接触电阻的同时测量。结果表明:两微米线刚接触时,接触热阻和接触电阻均比相对位移大于5 μm时的结果大近一个数量级,且两者的比值满足Wiedemann-Franz定律;随着相对位移增大,绝缘层对导热的贡献增大,接触热阻减小,但接触电阻几乎不变;继续增加相对位移,得到的接触热阻和接触电阻几乎均与作用力无关,Lorenz数为(4~5)×10-8 W·Ω·K-2。 相似文献
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使用微滴拉伸试验研究碳纤维、聚乙烯纤维/基体界面的微观力学性能,着重分析树脂微滴端部角大小分别对两种纤维/树脂微滴的界面微观力学行为的影响。发现在不同端部角下,两种纤维/树脂微滴界面的应力分布和应力传递不同。碳纤维/树脂微滴中的残余应力分布呈"W"型、外载拉伸应力分布呈"M"型,界面应力传递效率达到70%;而聚乙烯纤维/树脂微滴中的残余应力分布呈"M"型,外载拉伸应力分布呈"W"型,界面应力传递效率只有13%。根据力学模型得到的相应的剪应力分布都呈反对称分布,在纤维嵌入端存在剪应力集中,且碳纤维所受的剪应力远大于聚乙烯纤维。 相似文献
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提出了应用基于谐波探测技术的3ω法进行液体导热性能测量的方法。设计了3ω测试系统,测试了不同浓度和不同温度下纳米流体的热导率和热扩散系数,与文献中的测试结果进行了对比。实验中测试的热波信号较好地满足频域内的导热方程,说明采用交流电流加热可使流体的微对流作用得到有效减弱。采用基于多颗粒布朗运动的微对流(MSBW)模型预测了纳米流体的热导率。浓度比较低时TiO2+蒸馏水、Al2 O3+蒸馏水纳米颗粒流体的热导率随温度增加呈线性增大,并且与液体的Prandtl数有关,在测试温度为18~65℃范围内,水的热导率随温度升高以及纳米颗粒的布朗运动所引起周围基液的微对流作用是纳米流体强化传热的两个重要机理。 相似文献
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Dong Huang Ruixuan Tan Ling Liu Chong Ye Shipeng Zhu Zhen Fan Peng Zhang Huang Wu Fei Han Hongbo Liu Jinshui Liu 《Journal of the European Ceramic Society》2021,41(8):4438-4446
The novel three dimensional highly thermal conductive carbon/carbon-silicon carbide (C/C-SiC) composite was successfully prepared using the mesophase-pitch-based carbon fibers and pyrocarbon as the thermal diffusion channels. The results show that the highly thermal conductive C/C-SiC composite with 221.1 W m?1K?1 in the ablation direction exhibits a smaller temperature gradient, and the surface temperature is 470 °C lower than that of the lowly thermal conductive C/C-SiC composite. The mass and linear ablation rates of the highly thermal conductive C/C-SiC composite are 0.56 mg·cm?2 s?1 and 0.11 μm·s?1, respectively. 相似文献
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The poor interlaminar properties restrict the application of carbon fiber reinforced polymer (CFRP) composites. In this work, a novel method for fabricating a graded interface structure is developed to improve the through-thickness thermal conductivity of CFRP composites. High-strength graphene nano-plates (GnP) and phenolic resin (PF) were selected to deposit on the surface of carbon fiber to design a novel CF/Epoxy laminates, where a simultaneous improvement of interlaminar shear strength (ILSS) and through-thickness thermal conductivity was observed. With addition of 1 wt % of GnP-PF in CF, 37.04% increase of the ILSS, and 16.67% enhancement of thermal conductivity compared to the original CFRP. The mechanism for improvement of both ILSS and thermal conductivity was studied by scanning electron microscopy and nano-indentation, where a better interface formed by GnP-PF has been clearly observed. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47061. 相似文献
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An experimental study was conducted to investigate the fouling process of calcium carbonate on the heat transfer surface, during forced convective heat transfer. The dynamic monitoring apparatus of fouling resistance was set up for the present experiments. The fouling behavio(s were examined under different factors including fluid velocity, hardness,alkalinity, solution temperature, and wall temperature. Asymptotic fouling curves varying with time were obtained. The fouling rate and asymptotic fouling resistance increased and the induction periods were shortened with the fluid velocity decreasing, hardness andalkalinity increasing, and solution temperature and heat transfer surface temperature increasing. Thecomponents of fouling that formed on the heat transfer surface included crystallization fouling and particulate fouling. The thermal performance parameter of fouling,ρfhf, varied from 380 to 2600 kg·W·(m^4·K)^-1, increasing with growing velocity and decreasing solution temperature, hardness or alkalinity. Furthermore, the thermal conductivity of fouling, λf, varied from 1.7 to 2.2 W·(m·K)^-1 . 相似文献
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Fiber length distribution and thermal,mechanical and morphological properties of thermally conductive polycarbonate/chopped carbon fiber composites 下载免费PDF全文
Zhixing Yu Yu Bai Yingcheng Li Xiaoyu Wang Wei Wang Junyan Liu 《Polymer International》2018,67(8):1137-1144
Chopped carbon fibers (CCFs) coated by poly(ethylene terephthalate) (PET) were treated using 3‐aminopropyltriethoxysilane (Si), and then used for fabricating thermally conductive polycarbonate/CCF (PC/(Si + PET)@CCFi) composites with various filler contents. Optical microscopy measurements indicated that CCF fillers in the composites had a wide length distribution and, with CCF content increasing, the mean fiber length and mean fiber aspect ratio steadily decreased. Compared to PC/(Si + PET)@CCF0, the molten flowability of composites declined. Thermogravimetric analysis and pyrolysis–gas chromatography–mass spectrometry characterizations showed that introducing CCFs could enhance the thermal stability of the composites and restrict the pyrolytic degradation of the polymer matrix. Moreover, both in‐plane and through‐thickness thermal conductivities increased with increasing CCF content. These conductivities at 50% CCF content reached 2.45 and 0.59 W m?1 K?1, and were improved by 11.25 and 1.95, respectively. Furthermore, the tensile and flexural properties of the composites continuously enhanced, accompanying decreased impact strength and elongation at break. Fractography revealed that fillers dispersed in matrix uniformly and a great many fiber cross‐sections and circular cavities coexisted in fracture surface, besides a clear interface and reduced long fibers. And the fracture behavior was mainly the breaking and peeling of fibers from matrix. © 2018 Society of Chemical Industry 相似文献
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碳纤维的表面改性对导热顺丁橡胶性能的影响 总被引:4,自引:0,他引:4
研究了碳纤维的表面改性方法对碳纤维/顺丁橡胶(BR)复合材料的硫化特性、门尼粘度、导热性能和力学性能的影响.实验结果表明,碳纤维/顺丁橡胶复合材料与顺丁橡胶空白样相比,其硫化速度、导热系数与力学性能都有明显的提高.而碳纤维的表面改性对碳纤维/顺丁橡胶复合材料的硫化特性数据、门尼粘度和导热系数影响并不明显,加入碳纤维后的未改性的碳纤维/顺丁橡胶复合材料的导热性能最佳,其导热系数为0.527 W/(m·K),为顺丁橡胶空白样的1.7倍;经过高温氧化后碳纤维填充复合材料力学性能有所提高,其拉伸强度为2.39 MPa. 相似文献
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炭黑对轮胎胎面胶热物性的影响 总被引:1,自引:0,他引:1
研究了炭黑品种和用量对轮胎胎面胶热扩散系数(α)、导热系数(λ)及比热容(C)3种热物性参数的影响规律。结果表明,随着炭黑填充量的增加,胎面胶的α及λ均逐渐增大,C逐渐减小。炭黑的结构性对胎面胶α的影响程度大于炭黑的粒径;温度相同时,炭黑的结构性越高,其填充胎面胶的α越大;随着炭黑填充量的增加,3种炭黑填充胎面胶α之间的差距呈现先增大后减小的变化趋势。炭黑的结构性及粒径对胎面胶C的影响没有固定的规律,但在低温区,炭黑的粒径越大,其填充胎面胶的C越大,且炭黑填充量对此差距无影响。炭黑的结构性对胎面胶λ的影响程度大于炭黑的粒径;温度相同时,炭黑的结构性越高,其填充胎面胶的λ越大;当炭黑用量较低时,其对胎面胶λ的影响程度相对较小,随着炭黑填充量的增加,3种炭黑填充胎面胶λ之间的差距呈现先增大后减小的变化趋势。 相似文献