Wenhuai Tian

Tsinghua University, Beijing, Beijing Shi, China

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Publications (3)0 Total impact

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    ABSTRACT: A novel particles-compositing method was used for the first time to disperse different contents of multi-walled carbon nanotubes (CNTs) in micron sized copper powders, which were subsequently consolidated into CNT/Cu composites by spark plasma sintering (SPS). Microstructural observations showed that the homogeneous distribution of CNTs and dense composites could be obtained for 0–10 vol.% CNT contents. The CNT clusters were appeared in the powder mixture with 15 vol.% CNTs, which resulted in an insufficient densification of the composites. The effective thermal conductivity of the composites was analyzed both theoretically and experimentally. The addition of CNTs showed no enhancement in overall thermal conductivity of the composites due to the interface thermal resistance associated with the low phase contrast of CNT to copper and the random tube orientation. Besides, the composite containing 15 vol.% CNTs led to a rather low thermal conductivity due possiblely to the combined effect of unfavorable factors induced by the presence of CNT clusters, i.e. large porosity, lower effective conductivity of CNT clusters themselves and reduction of SPS cleaning effect. The CNT/Cu composites may be a promising thermal management material for heat sink applications.
    Composites Science and Technology. 02/2010;
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    ABSTRACT: Cu/diamond composites have been considered as a next generation of thermal management material for electronic packages and heat sinks applications. The major challenge in the development of these composites is to obtain a well bonded interface between the copper and the diamond. In this study, an effective way to apply a vapor deposited chromium coating onto diamond particles was used to overcome this interface problem. The Cu/diamond composites were produced by spark plasma sintering (SPS) technique. The results showed that the densification, interfacial bonding and thermal conductivity of coated composites were evidently enhanced compared to that of uncoated composites. A maximum thermal conductivity of 284 W/m K, 31% increase with that of uncoated composite was obtained in the coated composite containing 50 vol.% particles sintered at 920 °C. However, the thermal conductivity of coated composites was still far below the theoretical value. The possible reasons for this deviation were discussed and the methods for further improvement in thermal conductivity of Cu/diamond composites were proposed.
    Journal of Alloys and Compounds. 01/2010;
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    ABSTRACT: A simple model was introduced for describing the effect of porosity on the effective thermal conductivity of spark plasma sintered (SPS) consolidated SiCp/Al composites in terms of an effective medium approximation (EMA) scheme. Numerical results of the present model were compared to an existing model of two-step Hasselman–Johnson approach and experimental data. Both models yielded very close predictions, which provided a satisfactory agreement to the experimental data, especially for the composites with porosity below 10%. At high levels of porosity the model predictions were slightly higher than the experimental values. These two models were further extended to account for the thermal conduction properties of porous composites with a multimodal size distribution or multiphase reinforced mixtures.
    Composites Part A: Applied Science and Manufacturing. 01/2010;

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27 Citations

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Institutions

  • 2010
    • Tsinghua University
      • School of Materials Science and Engineering
      Beijing, Beijing Shi, China
    • General Research Institute for Nonferrous Metals (GRINM)
      Peping, Beijing, China
    • University of Science and Technology, Beijing
      • School of Materials Science and Engineering
      Peping, Beijing, China