Several methods are currently used to produce Al/SiC MMC.
These include stir casting, preform infiltration, powder
metallurgy and spray forming [5–8]. Stir casting involves
mixing SiC particles with aluminum while it is in a liquid or
semi-liquid state. Stirring is required in this process due to the
difference in density between the two materials (ρAl=2400 kg/
m3 and ρSiC=3200 kg/m3). Without stirring, SiC particles tend
to settle to the bottom of the melt causing an uneven distribution
of the particles [5]. In addition, it has been observed that the
solidification front can push particles during cooling [6,7]. This
leads to agglomerations of particles, which can be detrimental to
the mechanical properties of the composite.
The preform infiltration method of producing Al/SiC MMC
involves filling the cavities of a rigid porous SiC structure with
molten aluminum via the capillary action. The aluminum can be
pulled into the preform with a vacuum or pushed into the
preform with a high-pressure flow [5]. The resulting composites
typically have volume fractions of SiC greater than 55% and
have low coefficients of thermal expansion. These composites
have applications in electronic packaging [8].
The powder metallurgy method of producing Al/SiC MMC
involves mixing aluminum powder with SiC, compacting and
sintering. Mixing of the powders may involve dry blending, wet
(slurry) blending or ball milling [9]. Agglomeration of the SiC
particles is often a problem in blend processing. The small size
of SiC particles cause them to become electrically charged,
Several methods are currently used to produce Al/SiC MMC.
These include stir casting, preform infiltration, powder
metallurgy and spray forming [5–8]. Stir casting involves
mixing SiC particles with aluminum while it is in a liquid or
semi-liquid state. Stirring is required in this process due to the
difference in density between the two materials (ρAl=2400 kg/
m3 and ρSiC=3200 kg/m3). Without stirring, SiC particles tend
to settle to the bottom of the melt causing an uneven distribution
of the particles [5]. In addition, it has been observed that the
solidification front can push particles during cooling [6,7]. This
leads to agglomerations of particles, which can be detrimental to
the mechanical properties of the composite.
The preform infiltration method of producing Al/SiC MMC
involves filling the cavities of a rigid porous SiC structure with
molten aluminum via the capillary action. The aluminum can be
pulled into the preform with a vacuum or pushed into the
preform with a high-pressure flow [5]. The resulting composites
typically have volume fractions of SiC greater than 55% and
have low coefficients of thermal expansion. These composites
have applications in electronic packaging [8].
The powder metallurgy method of producing Al/SiC MMC
involves mixing aluminum powder with SiC, compacting and
sintering. Mixing of the powders may involve dry blending, wet
(slurry) blending or ball milling [9]. Agglomeration of the SiC
particles is often a problem in blend processing. The small size
of SiC particles cause them to become electrically charged,
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