• Journal of the Korean Crystal Growth and Crystal Technology
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• v.6 no.2
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• pp.203-212
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• 1996

Applicability of SiC coating through CVD process and PCS(polycarbosilane) impregnation for the oxidation resistance and mechanical properties of C/C composite was studied. The SiC layer coated by CVD was deposited uniformly on the C/C composite, whereas the SiC converted from PCS impregnation wetted around individual carbon fiber. The PCS-impregnated C/C composite exhibited a significant increase of bending strength in comparison with as received C/C composite. This increase in the mechanical property could be attributed to the high bonding strength between fibers due to an impregnated SiC phase. The PCS-impregnated C/C showed 25% improvement in density, 3.5 times higher MOR and 2.8 times higher oxidation resistance compared to the as-received C/C. The increments due to PCS impregnation were more effective than CVD process.

• 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 the Korean Ceramic Society
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• v.28 no.6
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• pp.478-482
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• 1991

Numerous researchers have observed the bubble formation from C/C composite at high temperature (1300$^{\circ}C$∼1700$^{\circ}C$). According to thermodynamic calculation, the bubble can be formed at the temperatures above 1500$^{\circ}C$ in the case of SiC coated C/C composite. However, the bubble below 1500$^{\circ}C$ could not be explained. Therfore, in an effort to explain the low temperature bubble formation, the effects of inhibitors such as B, Al, Zr and Si were thermodynamically investigated along with hydrogen and water vapor impurities resolved in C/C composite and SiC coating layer.

• Journal of the Korean institute of surface engineering
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• v.40 no.2
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• pp.63-69
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• 2007

Ni-SiC composite coating layers were formed using two kinds of SiC nano-particles by DC electrodeposition in a nickel sulfamate bath containing SiC particles. The effect of stirring rate and SiC particle type on the microstructure and properties of Ni-SiC composite coating layers were investigated. Results revealed that the trend of deposition rate is closely related to the codeposition of SiC and the deposition rate. or nickel, and the codeposition behavior of SiC can be explained by using hydrodynamic effect due to stirring. The average roughness and friction coefficient are closely related to the codeposition of SiC and SiC particle size. It was found that the Victors microhardness of the composite coating layers increased with increasing codeposition of SiC. The composite coating layers containing smaller SiC particle showed higher hardness. This can be explained by using the strengthening mechanism resulting from dispersion hardening. Anti-wear property of the composite coating layers formed using 130 nm-sized SiC nano-particles has been improved by 2,300% compared with pure electroplated-nickel layer.

• 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.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.

• Journal of the Korean Ceramic Society
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• v.32 no.9
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• pp.1003-1008
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• 1995

CVD-Si3N4/CVD-SiC/pack-SiC/pyro-carbon/(3-D C/C composite) multilayer coating was performed to improve the oxdiation resistance and erosion resistance properteis of the 3-D carbon/carbon composite, and the plasma test was performed to measure the oxidation resistance and erosion resistance properties. The thicknesses of each film layer were about 10${\mu}{\textrm}{m}$ for pack-SiC, 5${\mu}{\textrm}{m}$ for CVD-SiC and 40${\mu}{\textrm}{m}$ for CVD-Si3N4. When the multilayer coated specimen was exposed to the plasma flame with temperature of 500$0^{\circ}C$ for 20 seconds, it showed the weight loss five times less than that of the only pyro-carbon coated specimen.

• Composites Research
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• v.33 no.5
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• pp.256-261
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• 2020

In this study, the ignition temperature of the Al-Ti-C reaction system, the microstructure and the mechanical properties of the TiC/Mg composite which produced by the self-propagating high-temperature synthesis (SHS) followed by stir casting process were investigated. Mg based composite with uniformly dispersed 0, 10, 20, and 30 vol.% TiC were fabricated, and higher volume fraction of TiC reinforced composite showed superior compressive strength and wear resistance as compared with Mg matrix. It is attributed to the less contamination, defects, impurities in TiC/Mg composite by the in-situ SHS yield effective load transfer from the matrix to the reinforcement.

• Composites Research
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• v.33 no.3
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• pp.101-107
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• 2020

This study investigates the characterization on the thermal insulation properties of silicon carbide coating on the C_f-C composites. The silicon carbide coatings by chemical vapor deposition on the C/C composites are prepared to evaluate thermal resistance. Firstly, we perform the basic insulation test by thermal shock at 1350℃ in air on the C/C composite and SiC-coated C/C composite. We also performed the burner tests on the surface of the composites at high temperatures such as 1700 and 2000℃, and the weight change after burner tests are measured. The damages on the surface of C/C composite and SiC-coated composite are observed. As a result, the SiC coating is beneficial to protect the C/C composite from high temperature even though damages such as defoliation, crack and voids are observed during burner test at 2000℃.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1303-1304
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• 2007

The composites were fabricated, respectively, using 61[vol.%]SiC-39[vol.%]$TiB_2$ and using 61[vol.%]SiC-39[vol.%]$ZrB_2$ powders with the liquid forming additives of 12[wt%] $Al_{2}O_{3}+Y_{2}O_{3}$ by hot pressing annealing at $1650[^{\circ}C]$ for 4 hours. Reactions between SiC and transition metal $TiB_2$, $ZrB_2$ were not observed in this microstructure. ${\beta}{\rightarrow}{\alpha}$-SiC phase transformation was occurred on the SiC-$TiB_2$ and SiC-$ZrB_2$ composite. The relative density, the flexural strength and Young's modulus showed the highest value of 98.57[%], 226.06[Mpa] and 86.38[Gpa] in SiC-$ZrB_2$ composite at room temperature respectively. The electrical resistivity showed the lowest value of $7.96{\times}10^{-4}[{\Omega}{\cdot}cm]$ for SiC-$ZrB_2$ composite at $25[^{\circ}C]$. The electrical resistivity of the SiC-$TiB_2$ and SiC-$ZrB_2$ composite was all positive temperature coefficient resistance (PTCR) in the temperature ranges from $25[^{\circ}C]$ to $700[^{\circ}C]$. The resistance temperature coefficient of composite showed the value of $6.88{\times}10^{-3}/[^{\circ}C]$ and $3.57{\times}10^{-3}/[^{\circ}C]$ for SiC-$ZrB_2$ and SiC-$TiB_2$ composite in the temperature ranges from $25[^{\circ}C]$ to $700[^{\circ}C]$.