• Journal of the Korean Ceramic Society
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• v.32 no.10
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• pp.1212-1218
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• 1995

Al2O3-coated SiC composite powder and mechanically mixed Al2O3-SiC composite powder were synthesized using Al-isopropoxide and commercial SiC as the starting materials. Experiment results showed that the sinterability of Al2O3-coated SiC composite powder was more improved than the mechanically mixed Al2O3-SiC composite powder by the effect of homogeneous coating of alumina around SiC particles. Hence, the mechanical properties of the former was also much more improved than the latter.

• Journal of the Korean Ceramic Society
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• v.30 no.4
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• pp.316-324
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• 1993

Three types of dispersed, coated and mechanically mixed SiC reinforced Al2O3 composite powders were used to investigate the effect of composite powder type on sintering characteristics and properties of Al2O3-SiC composites. Sinterability of coated type composite powders was superior to that of other composite powders when they were pressureless sintered at 1500~1$700^{\circ}C$ for 2h in Ar atmosphere. However, sinterabilities (>98% TD) of each type of composite powders were similar when they were hot pressed at 180$0^{\circ}C$ for 1h under 30MPa in N2 atmosphere. SiC powders were randomly distributed in the specimen prepared from dispersed type composite powders, whereas homogeneously distributed for coated type specimens. It was found that SiC powders inhibited the grain growth of Al2O3, and fracture toughness was increased by the increment of crack growth resistance due to residual stress by secondary SiC particles within Al2O3 grains.

• International Journal of Ocean System Engineering
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• v.2 no.4
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• pp.244-249
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• 2012

In this study, a monolithic MoSi2 matrix reinforced with 20 vol% SiC particles, a SiC/MoSi2 composite matrix reinforced with 20 vol% ZrO2 particles, and a ZrO2/MoSi2 composite were fabricated using hot press sintering at $1350^{\circ}C$ for 1 h under a pressure of 30 MPa. The Vickers hardness and sliding wear resistance of the monolithic MoSi2, ZrO2/MoSi2, and SiC/MoSi2 composite were investigated at room temperature. A wear behavior test was carried out using a disk-type wear tester with a silicon nitride ball. The ZrO2/MoSi2 composite showed an average Vickers hardness value and excellent wear resistance compared with the monolithic MoSi2 and SiC/MoSi2 composite at room temperature.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.04a
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• pp.102-105
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• 2005

The mechanical properties of $SiC_f/SiC$ composites reinforced with continuous SiC fiber have been investigated in conjunction with the detailed analysis of their microstructures. Especially, the effect of test temperature on the characterization of $SiC_f/SiC$ composites was examined. In this composite system, a braiding Hi-Nicalon SiC fibric was selected as a reinforcement. $SiC_f/SiC$ composites have been fabricated by the reaction sintering process, using the complex matrix slurry with a constant composition ratio of SiC and C particles. The characterization of $RS-SiC_f/SiC$ composites was investigated by means of SEM, EDS and three point bending test. Based on the mechanical property-microstructure correlation, the high temperature applicability of $RS-SiC_f/SiC$ composites was discussed.

• Advanced Composite Materials
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• v.18 no.1
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• pp.61-75
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• 2009

The effect of porous matrix on thermal fatigue behavior of 3D-orthogonally woven SiC/SiC composite was evaluated in comparison with that having relatively dense matrix. The porous matrix yields open air passages through its thickness which can be utilized for transpiration cooling. On the other hand, the latter matrix is so dense that the air passages are sealed. A quantity of the matrix was varied by changing the number of repetition cycles of the polymer impregnation pyrolysis (PIP). Strength degradation of composites under thermal cycling conditions was evaluated by the $1200^{\circ}C$/RT thermal cycles with a combination of burner heating and air cooling for 200 cycles. It was found that the SiC/SiC composite with the porous matrix revealed little degradation in strength during the thermal cycles, while the other sample showed a 25% decrease in strength. Finally it was demonstrated that the porous structure in 3D-SiC/SiC composite improved the thermal fatigue durability.

• Journal of Powder Materials
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• v.21 no.6
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• pp.460-466
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• 2014

Al-Si-SiC composite powders with intra-granular SiC particles were prepared by a gas atomization process. The composite powders were mixed with Al-Zn-Mg alloy powders as a function of weight percent. Those mixture powders were compacted with the pressure of 700 MPa and then sintered at the temperature of $565-585^{\circ}C$. T6 heat treatment was conducted to increase their mechanical properties by solid-solution precipitates. Each relative density according to the optimized sintering temperature of those powders were determined as 96% at $580^{\circ}C$ for Al-Zn-Mg powders (composition A), 97.9% at $575^{\circ}C$ for Al-Zn-Mg powders with 5 wt.% of Al-Si-SiC powders (composition B), and 98.2% at $570^{\circ}C$ for Al-Zn-Mg powders with 10 wt.% of Al-Si-SiC powders (composition C), respectively. Each hardness, tensile strength, and wear resistance test of those sintered samples was conducted. As the content of Al-Si-SiC powders increased, both hardness and tensile strength were decreased. However, wear resistance was increased by the increase of Al-Si-SiC powders. From these results, it was confirmed that Al-Si-SiC/Al-Zn-Mg composite could be highly densified by the sintering process, and thus the composite could have high wear resistance and tensile strength when the content of Al-Si-SiC composite powders were optimized.

• Journal of the Korean Ceramic Society
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• v.32 no.9
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• pp.1009-1018
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• 1995

(Ti.Si)C composite powders were synthesized by SHS method using microwave energy. Compositional and structural characterization of the powder were carried out by using scanning electron microscopy and X-ray diffraction. The average particle size of the synthesized (Ti.Si)C composite powders was smaller than that of the starting materials. From the results of the temperature profile, combustion temperature and velocity were decreased with increasing Si molar ratio. With increasing C molar ratio combustion temperature and velocity did not change. (Ti.Si)C composite was sintered at 185$0^{\circ}C$ for 60 min by using hot-pressing with 30 MPa. The best properties were obtained from the sintered specimen whose composition was 1 : 1 : 1.9 molar ratio of Ti : Si : C. The sintering density, flexural strength and vickers hardness of the sintered body were 4.71 g/㎤, 423 MPa and 21 GPa, respectively.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.11
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• pp.1016-1021
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• 2008

The development of the first wall whose major function is to withstand high neutron and heat fluxes is a critical path to fusion power. The materials database and the fabrication technology are being developed for design, construction and safety operation of the fusion reactor. The first wall was designed to consist of the plasma facing armor, the heat sink layer and the supporting plates. and Porous materials are of significant interest due to their wide applications in catalysis, separation, lightweight structural materials. In this study, the characteristics of the sintering process of SiC ceramic, $SiC_f$/SiC composite and porous $C_f$/SiC composite have been introduced order to study of the fusion blanket materials and heat-exchange pannel.

• The Korean Journal of Ceramics
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• v.3 no.1
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• pp.47-51
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• 1997

The dense sintered bodies of Si/SiC composite with various Si contents could be fabricated by changing the green density in the forming process. The Si/SiC/graphite composites with various graphite contents could be also fabricated by changing a graphite content in the starting composition. Their mechanical and tribological properties were characterized and wear mechanism was also studided. The hardness and strength of the Si/SiC and the Si/SiC/graphite were decreased with increasing the contents of free Si and graphite, respectively. However, the friction coefficient and specific wear rate had no specific relations to their hardness and strength. Adhesion of free Si was a main factor to determine a wear resistance of the Si/SiC composite. In the case of the Si/SiC/graphite, solid lubricationl and liquid reservoir of the graphite particles played the main role of the reduction of the friction force. In the torque test to estimate the possibility of practical of practical applications, the value of torque between the Al2O3 disk and Si/SiC/graphite disk was 1/6 lower compared with two $Al_2O_3$ disks on the basis of 100,000 cycles.

• Tribology and Lubricants
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• v.19 no.5
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• pp.274-279
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• 2003

$Al-SiC_{p}$ composite layer was prepared by plasma thermal spray on aluminum substrate. The homogeneously dispersed composite powder for thermal spray was fabricated by mechanical alloying with ball mill. The friction tests of the composite layers and commercial aluminum alloys for comparison were performed in the temperature range of 20∼$260^{\circ}C$ with the interval of $40^{\circ}C$ with steel counter-face. Friction coefficient was recorded during test sequence, and the microstructure of surface and debris was investigated by optical and scanning electron microscope. Friction coefficients of composite and aluminum alloys at room temperature were similar except pure aluminum. As the temperature increase, friction coefficient was increased rapidly in AC4C, AC2A. But friction coefficient of $Al-SiC_{p}$ composite was not increased so much up to $220^{\circ}C$. Consequently, the reinforcement of $SiC_{p}$ into aluminum matrix increased the stability of friction coefficient as well as wear resistance.