• Journal of the Korean Ceramic Society
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• v.31 no.8
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• pp.874-878
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• 1994

To increase the anti-oxidation and anti-wear properties of graphite for the propellant-burning environment, SiC, Pt and Al2O3 multi-layer coatings were conducted succesisvely and the optimum condition was researched. The SiC layer was produced by pack cementation and SiC layer in thickness of 30 ${\mu}{\textrm}{m}$ coating was produced after coating for 6 hours. Pt layer was coated by sputtering, and the Al2O3 layer was coated by reactive sputtering. the thickness of Pt layer and Al2O3 layer was less than one-tenth of that of SiC layer. The pack coated specimens and multi-layer coated specimens were made using above conditions and test-fired. The test result showed that the wear rate of SiC layer is approximately 1/10 compared to that of uncoated graphite.

• Tribology and Lubricants
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• v.16 no.5
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• pp.365-372
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• 2000

Tribological behavior of novolac resin-based friction materials with three different relative amounts of graphite and zirconium silicate was investigated by using a pad-on-disk type friction tester. The goal of this paper is to examine the effects of the relative amount of a lubricant and an abrasive in the automotive friction material on friction and wear characteristics at elevated temperature. Friction and wear of friction materials were affected by the existence of transfer film(3$\^$rd/ body layer) at friction interface and the composition of friction material, especially lubricant amount. The friction material with higher content of graphite indicated homogenized and durable transfer film, and resulted in stable friction coefficient regardless of the increase in friction heat. The experimental result also showed that the higher concentration of ZrSiO$_4$ in friction material aggravated friction stability and wear resistance due to the higher friction heat generated at fiction interface during high temperature friction test.

• Journal of the Korean Ceramic Society
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• v.32 no.4
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• pp.429-435
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• 1995

Al2O3-SiC-C(ASC) refractory materials were prepared from kaolin using thermit reaction. The mixed powder (A-K) for the thermit reaction was composed of Hadong kaolin, C(graphite) and Al. A-S(SiO2＋C＋Al) composition was also employed to compare with A-K in respect to reactability. As a result of XRD patterns of A-K sample after thermit reaction, and firing at 140$0^{\circ}C$ for 3hrs in Ar atmosphere, it was possible to use as a ASC refractory materials.

• Journal of Korea Foundry Society
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• v.2 no.3
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• pp.16-24
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• 1982

For the purpose of development of domestic carburizer, when the basicity of ash in carburizer was changed from $Na_2O/Al_2O_3+SiO_2$ ; 0.06 to $Na_2O/Al_2O_3+SiO_2$ ; 0,196wt%, using $Na_2O$ as flux for domestic graphite resource (Bong Myung armorphous graphite), carburizing efficiency was improved as basicity increased, optimum basicity value was $Na_2O/Al_2O_3+SiO_2$ ; 0.151. This means that $Na_2O$ contributed to lower viscosity of slag and raise occurence probability of specific reaction surface between molten iron and carburizer. The experiment of effect of general characteristics offecting carburizing ability of this carburizer was performed, the result is that 10/30 mesh was optimum size of the carburizer and as carbon equivalent of molten iron was higher, carburizing ratio was lowered, but when si concentration was below 1.8% in general cast iron melting region, recovery showed 75-85%. As agitation rate of molten iron and temperature interval were higher, Carburizing ratio was increased and showed max, 94%. Desulfurizing phenomena of molten iron by $Na_2O$ in carburizer didn't appear.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.197-198
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• 2009

This paper describes the Raman scattering characteristics of polycrystalline (poly) 3C-SiC films, which were deposited on the thermally oxidized Si(100) substrate by the atmosphere pressure chemical vapor deposition (APCVD) method according to growth temperature. TO and LO phonon modes to 2.0m thick poly 3C-SiC deposited at $1180^{\circ}C$ were measured at 794.4 and $965.7\;cm^{-1}$ respectively. From the intensity ratio of $I_{(LO)}/I_{(TO)}$ 1.0 and the broad full width half maximum (FWHM) of TO modes, itcan be elucidated that the crystallinity of 3C-SiC forms polycrystal instead of disordered crystal and the crystal defect is small. At the interface between 3C-SiC and $SiO_2$, $1122.6\;cm^{-1}$ related to C-O bonding was measured. Here poly 3C-SiC admixes with nanoparticle graphite with the Raman shifts of D and G bands of C-C bonding 1355.8 and $1596.8\;cm^{-1}$. Using TO mode of 2.0 m thick poly 3C-SiC, the biaxial stress was calculated as 428 MPa.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1995.11a
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• pp.207-213
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• 1995

로켓트 노즐 재료로 사용되는 그라파이트의 내삭마 특성을 향상시키기 의해 다층코팅에 관한 연구를 하였으며 $AI_2$$O_3$/PT/pack-SiC/Graphite와 CVD-$Si_3$$N_4$/CVD-SiC/pack-SiC/Graphite의 두 다층코팅 구조를 제작하여 내삭마 효과를 알아 보았다. $AI_2$$O_3$와 Pt충은 스퍼터링 증착방식을, $Si_3$$N_4$와 SiC층의 CVD는 저압화학증착방식을 사용하였다. 코팅층의 내삭마 특성 평가는 직접 노즐에 코팅층을 입혀 소형고체 추진기관 연소모타에 장착, 지상연소시험을 통해 수행하였으며 코팅층이 없는 표준모타에 비해 각각 60%, 80% 이상의 내삭마 특성의 향상을 보였다.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2000.06a
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• pp.166-172
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• 2000

Friction characteristics of phenolic resin-based friction composites containing threedifferent relative amounts of graphite and zirconium silicate were investigated by using a pad-on-disk type friction tester. Constant temperature test and constant interval test at three different initial temperatures(100. 200, 300$^{\circ}C$) were performed to examine the effects of friction heat on friction characteristics at elevated temperature. The friction composite(FMO.7) with higher content of ZrSiO$_4$showed unstable friction force at higher temperature and resulted in larger fluctuations of vibration during friction test. The abrasive action of ZrSiO$_4$in friction composite impeded stable transfer film and induced higher friction heat at friction interface. Friction oscillations according to the temperature were associated with the formation of transfer film(i'd body layer) on the friction composite and the counter part.

• Journal of the Korean Ceramic Society
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• v.21 no.1
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• pp.11-18
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• 1984

$eta$-Sialon synthesis was investigated via the simultaneous reduction and nitridation of Hadong Pink Kaolin using the graphite as a reducing agent at 135$0^{\circ}C$ under 80% $N_2-20%H_2$ atmosphere. When Hadong Pink Kaolin-graphite-silicon nitride seed(molar ratio ; $SiO_2:C:Si_3N_4$=1;3.5:0.05) mixture was heated at 135$0^{\circ}C$ for as long as 20h in 80%$N_2-20%H_2$ atmosphere a homogeneous $eta$-Sialon$(Si_{3.5}Al_{2.5}O_{2.5}N_{2.5})$ was mainly formed together with a small amount of $\alpha$-$Si_3N_4$.

• Journal of the Korean Ceramic Society
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• v.33 no.7
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• pp.816-822
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• 1996

Dependence of graphitic structure on oxidation of carbon materials was discussed using furan resin-derived carbon with inorganic compounds such as SiC and TiO2 Oxidation of carbon was governed by active site. I. e surface area regardless of the degree of graphitization. When oxidation was considered for not unit weight but unit area graphitization was important factor for oxidation so that the degree of graphitization increased the oxidation rate was delayed. Graphite (tiO2 addition) and turbostratic graphite(SiC addition) were oxidized through the same mechanism. In carbon materials with different structure components more than 2 oxidation of each component was different and amorphous component without the influence of additives on the surface was selectively oxidized in the intial oxidation stage.

• Journal of the Korean Ceramic Society
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• v.34 no.11
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• pp.1151-1158
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• 1997

Fracture of uni-directional carbon fiber reinforced carbon matrix composite is strongly dependent on the orientation of basal plane in graphite matrix when it is limited within matrix. The orientation of basal planes are vertically stacked to carbon fiber which results in the weakness for applied tensile or shear force in thermosetting resin derived-carbon matrix composite. Microtextural control of the matrix was tried through chemical interaction between metal carbides and furan resin derived-carbon matrix. SiC and TiO2 addition made the orientation disordered. However, porosity increased due to decomposition of SiC. Interfacial bonding could be controlled by TiO2 addition, but carbon fiber was considerably reacted with TiC during thermal treatment higher than 2$600^{\circ}C$. Therefore, it is desirable to control the thermal treatment temperature at which decomposition of SiC was not serious and TiC/C was not formed eutectoid.