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| Content Provider | IEEE Xplore Digital Library |
|---|---|
| Author | Chen Zhang Xinbo He Qian Liu |
| Copyright Year | 2014 |
| Description | Author affiliation: Sch. of Mater. Sci. & Eng., Univ. of Sci. & Technol. Beijing, Beijing, China (Chen Zhang; Xinbo He; Qian Liu) |
| Abstract | High-performance mesophase pitch-based graphite fiber reinforced metal matrix composites offer a good thermal conductivity and tailorable coefficient of thermal expansion. These composites are regarded as a promising heat dissipation materials for electronic packaging application. It is reported that short graphite fiber/Al composites were fabricated by vacuum pressure infiltration, which is a suitable procedure for the fabrication of complex shaped components at high production rates and low cost. The thermal conductivity of short fiber/Al composites is lower than 230 W $m^{-1}$ $K^{-1}.$ It is expected that the composites using copper as the matrix, which has a higher thermal conductivity and lower coefficient of thermal expansion than aluminum, may have a better thermal properties. However, there is few investigation on fabrication of graphite fiber/Cu composites since copper does not wet graphite. This work focuses on the fabrication of short graphite fiber/Cu composites for thermal management application by vacuum pressure infiltration technique. A $Mo_{2}C$ coating was synthesized on the surface of graphite fiber through molten salts method for improving the wetting between graphite fibers and copper. Certain Grfs reacted with molybdenum oxides powders in a molten salts mixture composed of NaCl-KCl at 1000 °C for 30 min under a flowing argon atmosphere. The obtained coating is compact and homogenous with the thickness of 0.3 μm. Copper was infiltrated into $Mo_{2}C-coated$ graphite preform at 1150 °C with low pressure and Cu matrix composites with 20 vol%-40 vol% fibers were fabricated. Due to the unidirectional compression in the perform and infiltration process, the fibers were uniform distribution in the plane perpendicular to the press direction (X-Y plane) and showed a two dimensional orientation. The interface of composites was examined by EDS line-scan. Results show that there was copper infiltrated into the $Mo_{2}C$ interlayer. A good adhesion was observed in composites in which the $Mo_{2}C$ interlayer tightly adhered to both fiber and Cu matrix. The obtained composites present high relative density above 99.5%. With increasing volume fraction of fiber from 20% to 40%, the thermal conductivity of composites in X-Y plane slightly decreased from 356 W $m^{-1}$ $K^{-1}$ to 311 W $m^{-1}$ $K^{-1}.$ The coefficient of thermal expansion in X-Y plane decreased from 14× $10^{-6}$ to 7 × $10^{-6}$ $K^{-1}.$ The experimental values of thermal conductivities of composites were compared with the theoretical calculation. With the introduction of $Mo_{2}C$ interlayer, the interface thermal conductance of graphite $fiber/Mo_{2}C$ interlayer/copper matrix had to be taken into consideration. So the effective thermal conductivity of coated fiber was firstly calculated by using the acoustic mismatch model (AMM). Then, a model of Maxwell-Garnett effective medium approach on the anisotropic short fiber reinforcement was used to estimate the thermal conductivity of composites. The result showed that the theoretical predictions are in good agreement with the experimental values. The thermal conductivity of composites could be further improved if perform with single axile orientation fiber was infiltrated. |
| Starting Page | 172 |
| Ending Page | 176 |
| File Size | 536885 |
| Page Count | 5 |
| File Format | |
| ISBN | 9781479947072 |
| DOI | 10.1109/ICEPT.2014.6922630 |
| Language | English |
| Publisher | Institute of Electrical and Electronics Engineers, Inc. (IEEE) |
| Publisher Date | 2014-08-12 |
| Publisher Place | China |
| Access Restriction | Subscribed |
| Rights Holder | Institute of Electrical and Electronics Engineers, Inc. (IEEE) |
| Subject Keyword | Thermal conductivity Conductivity Graphite Copper Optical fiber dispersion Thermal expansion Electronic packaging thermal management infiltration metal matrix composites thermal conductivity coefficient of thermal expansion |
| Content Type | Text |
| Resource Type | Article |
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