Abstract: SiC powder was synthesized by carbothermal reduction method using silica sol and amylum as
reactants in closed and open graphite crucibles, respectively. The phase composition and morphology of
the powders were characterized. Formation of phase-pure silicon carbide can be achieved at 1700°C for
1h. Increasing reaction temperature and extending holding time can greatly promote the production of
SiC. The products synthesized in open graphite crucibles are mainly composed of equiaxial β-SiC
particles while those synthesized in closed graphite crucibles are β-SiC particles and nanorods.
Abstract: A new method for producing silicon carbide platelets with low cost and high yield was
introduced. The silicon carbide platelets were synthesized by double-heating technique with carbon black
and SiO2 powder as raw materials without using any catalysts. The starting mixtures were heated at a
temperature in the range of 1800-2000°C for the duration of about 2-4h to produce substantially
completely unagglomerated silicon carbide platelets with the thickness of 5-15μm and the average
diameter of 50-150μm. Compared to the conventional heating, double-heating technique has different
heating mechanism and has advantages of less investment for equipment, easy to manufacture and
convenient to operate. Furthermore, it is very suitable for realizing the scaled production because of the
lower synthesizing temperature, shorter reaction time and greater output.
Abstract: SiC fibers containing Y and Al were prepared by sintering the amorphous KD-Y fibers at
different temperatures from 1200 to 1800 °C. The tensile strength of fibers increases when the sintering
temperature increases from 1200 to 1400 °C due to the dispersion strengthening of β-SiC microcrystal
and decreases to the lowest point when being sintered at 1600 °C, then rose again with the further increase
of temperature to 1800 °C. The tensile strength reached to 2.15 GPa. The oxygen content of KD-Y fibers
determined the properties of the sintered SiC fibers and sintering process. Through chemical vapor curing
(CVC), the oxygen content was controlled below 7.0 wt% and the tensile strength of KD-Y fibers reached
to 3.08 GPa. Further-more, the sintering process of KD-Y fibers was discussed and the grain size of β-SiC
grew up with the heat treatment temperature.
Abstract: A new heating apparatus for synthesizing SiC whiskers was introduced. SiC whiskers were
synthesized in electric field furnace with carbon black and SiO2 powders as raw materials and some
influencing factors were discussed. SiC whiskers with diameter of 0.1-0.4μm, length of 5-70μm and
average purity of 99.6% were acquired at lower temperatures of 1200-1400°C for a shorter holding time
of 2-4h. The results showed that the high voltage field has great catalysis action on synthetic of SiC
whiskers by reducing activation energy and enhancing reaction speed.
Abstract: In this paper, green bodies of RBSC were prepared through the gel-casting process. The effects
of monomer concentration and ratio of MBAM to AM on the strength and microstructure of the green
bodies were studied. When the monomer content increased from 10wt% to 20wt %( relative to water in
the slurry), the flexural strength increases efficiency. However, the flexural strength decreases when the
monomer content was above 20wt%. Similarly, when the ratio of MBAM to AM increased from 1/19 to
1/9, it had the same effects on the flexural strength of green bodies. It was found that silicon carbide
particles were packaged by the carbon particles with gel. When the monomer content was 20wt% and the
ratio of MBAM to AM was 1/9, the green body showed the best homogeneous microstructures and its
flexural strength achieved 8MPa.
Abstract: The application and the transpirational behavior of oriented porous SiC as transpiration cooling
materials in a simulating test were studied. The test sample was shaped by freeze-casting process and
reaction sintered. The testing device was composed by an electric arc combustor and a hydrogen coolant
providing system. It was found that the permeability, the amount of coolant required and the uniformity of
coolant infiltration were all effected by the microstructure of porous SiC, which furthermore influced the
cooling efficiency of the testing system. In this test, the inner face temperature of the combustion chamber
was maintained less than 400K throughout the thermal testing period contrasting with the fire temperature
up to 3600K by the utilization of oriented porous SiC transpiration cooling materials.
Abstract: Using the coat mix process, porous SiC ceramics are fabricated using commercially available
silicon powders and phenolic resin as the starting materials. The phase composition, morphology, pore
size and pore size distribution of the obtained products are characterized by X-ray diffraction, scanning
electron microscopy and mercury intrusion porosimeter. The results show that high porosity SiC ceramics
with a narrow pore size distribution can be fabricated at 1500°C in vacuum by the coat mix process. The
open pore porosity can reach up to 60%. The pore size varies in the range of 1-6 'm.
Abstract: Polyacrylonitrile (PAN) based carbon fiber felt which contains abundant various SiC microthreads
and some other microstructures was prepared through sintering the pretreated felt at high
temperature at low nitrogen pressure. XRD, SEM, TEM, HRTEM analyses for the sintered felt were
carried out to study its components and microstructures. There are SiC nanothreads, SiC submicron
threads, SiC micron threads and a few SiO2 two- or three-dimensional microstructures (possibly intermix
with the similar form of SiC) existed within the inner hollow spaces of the felt. The complex permittivity,
complex permeability of the sample in the X-band frequency range were obtained.
Abstract: The effects of deposition temperature on the growth characteristics of CVD SiC coatings were
investigated. CVD SiC coatings were made by pyrolysis of methyltrichlorosilane (MTS) in hydrogen at a
low pressure of 5kPa. The ratio of MTS to hydrogen was 1/12. The deposition temperatures were varied
from 1373K to 1503K. Optical microscope and SEM were used to observe the surface morphology and
microstructure of the coatings. XRD was used for characterization of the phase composition. Results
indicated that the deposition rate and the surface roughness varied with deposition temperature. At
1373K, the deposited grains were mainly equiaxed with the crystallite size of 22 nm. However, when the
deposition temperature was 1503K, the SiC grains were mainly showed faceted columnar structure with
the crystallite size of 32 nm. Grain size increased with the increase of deposition temperature.
Abstract: 2D-C/SiC composites with high performance were prepared at temperatures as low as 900 °C.
The flexural strength of the composites reached 329.61MPa, the same level as the composites prepared at
1200°C, and shear strength and fracture toughness were 32.14MPa and 14.65MPa·m1/2, respectively. The
microstructure and mechanical properties of the composites after heat-treatment at 1600°C were also
investigated to determine the potential applications at high temperature.