J. Liu et al. / Journal of Alloys and Compounds 465 (2008) 239–243
243
W–15Cu alloy (ranging from 160 to 190 W m−1 K−1) [22]. As
its density is less than one fifth of that of W–15Cu alloy, Al/SiC
composite has tremendous potential to substitute W–Cu alloys
used in the electronic heat package.
Acknowledgements
This work has been financially supported by Innovation
Groups Foundation (103-037016) and Development Foundation
(103-037508) of Hefei University of Technology, China.
4. Summary and conclusion
References
SiC preforms with different Porosity were obtained by the
oxidation process, which used W28 yellow-green SiC powders
in abrasive grade as the starting material and W10 super-pure
graphite powders as the pore-forming agents. There are two
types of pores in SiC preforms. The first type is the clearance
between adjacent SiC particles; the second is the voids left by
burned out graphite particles. Pores were all connected mutu-
ally to form an open pore-net for liquid AlSi7Mg infiltrating
in. Liquid Al alloy spontaneously infiltrated into porous SiC
preforms enhanced by interface reaction between solid SiO2
film derived from the oxidation of SiC and magnesium in liquid
Al alloy. The mean thermal expansion coefficient of sintered
SiC preforms increased from 2.4% to 4.4% with the increase
of graphite volume fraction from 0% to 20%. Nevertheless, the
expansion did not cause the preforms to deform. There was no
change in shape and dimension for SiC preforms during the
pressureless infiltration process. The tolerance for products of
SiC/Al composites could be accurately controlled by careful
mould designing to achieve near-net-shape after sintering. As
SiC volume fraction increased from 39% to 62% with decreas-
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the thermal conductivity of SiC/Al composites with bending
strength beyond 360 MPa and elastic modulus beyond 140 GPa
decreased from 146 to 118 W m−1 K−1 at room temperature. In
corresponding, the mean linear coefficient of thermal expansion
from room temperature to 373 K decreased from 10 × 10−6 to
7.69 × 10−6 K−1, agreeing better with Turner’s model.
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