용융 Si 침윤 방법에 의한 다공성 RBSC 제조

서기식,박상환,권혁보 한국세라믹학회 2000 한국세라믹학회지 Vol.37 No.11

용융 Si 침윤 방법에 의한 새로운 다공질 RBSC 제조공정이 개발되었으며, 용융 Si 침윤공정 방법으로 제조된 다공질 RBSC의 최대 3-점 파괴 강도는 18 MPa, 최대 기공율은 46% 범위이었다. 용융 Si 침윤방법으로 제조된 다공질 RBSC의 기계적 특성 및 기공율은 성형체내 SiC 입자 표면의 카본 source의 양 및 침윤시 사용된 Si의 양에 직접적으로 영향을 받는 것으로 나타났다. 침윤시 상대 Si 양은 40%를 사용하였으며, SiC 입자 표면에 graphite와 phenol resin을 함께 코팅한 성형체를 사용하여 제조된 다공질 RBSC에서 최대 파괴강도 값을 얻었다. 상대 Si의 양의 증가는 다공질 RBSC의 파괴강도를 감소시켰으며, SiC 입자 표면의 카본 source 코팅층은 graphite와 phenol resin을 같이 사용하였을 때 다공질 RBSC의 파괴강도는 증가되었으나, RBSC 내 기공율은 감소되었다.

RBSC/Graphite 복합재료의 기계적 특성에 관한 연구

서기식,박상환,하조웅,정윤중 한국세라믹학회 1998 한국세라믹학회지 Vol.35 No.6

반응소결 SiC/Graphite 복합체에서 Graphite 입자의 크기에 따른 마찰마모특성

백용혁,서영현,최웅,이종호,Baik, Yong-Hyuck,Seo, Young-Hean,Choi, Woong,Lee, Jong-Ho 한국세라믹학회 1997 한국세라믹학회지 Vol.34 No.8

The tribological property of ceramics is very important for use in seal rings, pump parts, thread guides and mechanical seal, etc. In the present study, which RBSC/graphite composites were manufactured by adding graphite powders with different particle sizes to mixtures of SiC powder, metallic silicon, carbon black and alumina, effects on the tribological property of each RBSC/graphite composite was investigated in accordance with the particle size of the added graphite powder. The water absorption, the bending strength and the resistance for the friction and wear were measured, and the crystalline phase and the microstructure were respectively examined by using XRD and SEM. In case that the particle size of the graphite powder was fine(2${\mu}{\textrm}{m}$), the formation of $\beta$-SiC was accelerated, thereby making the increase of the bending strength and the decrease of the water absorption, but no improvement for the tribological properties. Furthermore, in case that the particle size of the graphite powder was some large(88~149${\mu}{\textrm}{m}$), the formation of $\beta$-SiC was not accelerated, to thereby make the decrease of the bending strength and the increase of the water absorption, but the improvement for the tribological property of only the composite having the graphite powder of 20 vol%. In addition, in case that the particle size distribution of the graphite powder was large (under 53 ${\mu}{\textrm}{m}$), there was no improvement for every properties. However, the composites, which the graphite powder with the particle size of 53~88 ${\mu}{\textrm}{m}$ was added in 10~15 vol%, had the most increased resistance for the friction and wear which show the worn out amount of 0.4~0.6$\times$10-3 $\textrm{cm}^2$, and the value of the bending strength is 380~520 kg/$\textrm{cm}^2$.

반응소결 SiC-graphite 복합체의 마찰마모특성

백용혁,신종윤,곽효섭,박용갑 한국세라믹학회 1996 한국세라믹학회지 Vol.33 No.5

The tribological properties of ceramics are very important in the application to engineering ceramic parts such as mechanical seal slurry valve disc and so on. In this study the effect of graphite addition on the mechanical and tribological properties of RBSC/graphite composites were investigated. The composites were prepared by adding graphite powder to the mixture of SiC powder metallic siliconcarbon black and alumina. Bending strength water absorption friction coefficient the amount of worn out material at a certain time and maximum surface roughness(Rmax) of the prepared composites were measured and crystalline phases were examined with XRD. The composite containing 5 vol% graphite powder showed improved bending strength due to high green density and decreased friction coefficient and wear resistance. The friction coefficient and the wear resistance of the composite were increased by adding graphite powder up to 10 vol% They decreased however as increasing the amount of graphite powder more that 10vol% There was no linear relationship between the tribological properties and bending strength of the composites.

다층 기공구조를 갖는 다공성 반응소결 탄화규소 다공체 제조

조경선,김규미,박상환,Cho, Gyoung-Sun,Kim, Gyu-Mi,Park, Sang-Whan 한국세라믹학회 2009 한국세라믹학회지 Vol.46 No.5

Reaction Bonded Silicon Carbide(RBSC) has been used for engineering ceramics due to low-temperature fabrication and near-net shape products with excellent structural properties such as thermal shock resistance, corrosion resistance and mechanical strength. Recently, attempts have been made to develop hot gas filter with gradient pore structure by RBSC to overcome weakness of commercial clay-bonded SiC filter such as low fracture toughness and low reliability. In this study a fabrication process of porous RBSC with multi-layer pore structure with gradient pore size was developed. The support layer of the RBSC with multi-layer pore structure was fabricated by conventional Si infiltration process. The intermediate and filter layers consisted of phenolic resin and fine SiC powder were prepared by dip-coating of the support RBSC in slurry of SiC and phenol resin. The temperature of $1550^{\circ}C$ to make Si left in RBSC support layer infiltrate into dip-coated layer to produce SiC by reacting with pyro-carbon from phenol resin.

반응소결 탄화규소 다공체의 기계적 특성

황성식,박상환,한재호,한경섭,김찬목,Hwang, Sung-Sic,Park, Sang-Whan,Han, Jae-Ho,Han, Kyung-Sop,Kim, Chan-Mook 한국세라믹학회 2002 한국세라믹학회지 Vol.39 No.10

차세대 발전 시스템에서 사용되는 고온 가스 필터용 지지층 소재를 제조하기 위하여 용융 Si 침윤 방법으로 기공율이 32∼36%, 주기공 크기가 37∼90 ${\mu}m$ 범위를 갖는 고강도 다공질 반응소결 탄화규소(RBSC)를 개발하였다. 반응소결 탄화규소 다공체의, 최대 파괴강도는 120MPa이었으며, 용융 Si 침윤 방법으로 제조된 반응소결 탄화규소 다공체에서는 SiC 입자 사이에 SiC/Si로 이루어진 기지상이 형성되어 있기 때문에 파괴 강도 및 열충격 특성이 점토 결합 탄화규소 다공체 보다 우수하였다. 반응소결 탄화규소 다공체의 기공율 및 기공 크기는 잔류 Si의 양 및 성형체에 사용한 SiC 입자 크기에 따라 다르게 나타났다. Porous reaction bonded SiC with high fracture strength was developed using Si melt infiltration method for use of the support layer in high temperature gas filter that is essential to develop the next generation power system such as integrated gasification combined cycle system. The porosity and pore size of porous RBSC developed in this study were in the range of 32∼36% and 37∼90 ${\mu}m$ respectively and the maximum fracture strength of porous RBSC fabricated was 120 MPa. The fracture strength and thermal shock resistance of porous RBSC fabricated by Si melt infiltration were much improved compared to those of commercially available porous clay bonded SiC due to the formation of the strong SiC/Si interface between SiC particles. The characteristics of pore structure of porous RBSC was varied depending on the amounts of residual Si as Well as the size of SiC particle used in green body.

튜브형상 반응소결 탄화규소 부품의 시편크기에 따른 강도평가 유용성 고찰

김성원,이소율,오윤석,이성민,한윤수,신현익,김영석,Kim, Seongwon,Lee, Soyul,Oh, Yoon-Suk,Lee, Sung-Min,Han, Yoonsoo,Shin, Hyun-Ick,Kim, Youngseok 한국분말야금학회 2017 한국분말재료학회지 (KPMI) Vol.24 No.6

Reaction-bonded silicon carbide (RBSC) is a SiC-based composite ceramic fabricated by the infiltration of molten silicon into a skeleton of SiC particles and carbon, in order to manufacture a ceramic body with full density. RBSC has been widely used and studied for many years in the SiC field, because of its relatively low processing temperature for fabrication, easy use in forming components with a near-net shape, and high density, compared with other sintering methods for SiC. A radiant tube is one of the most commonly employed ceramics components when using RBSC materials in industrial fields. In this study, the mechanical strengths of commercial RBSC tubes with different sizes are evaluated using 3-point flexural and C-ring tests. The size scaling law is applied to the obtained mechanical strength values for specimens with different sizes. The discrepancy between the flexural and C-ring strengths is also discussed.

반응소결 탄화규소 세라믹스의 열물성과 기계적 특성에 미치는 SiC 크기의 영향

권창섭,오윤석,이성민,한윤수,신현익,김영석,김성원,Kwon, Chang-Sup,Oh, Yoon-Suk,Lee, Sung-Min,Han, Yoonsoo,Shin, Hyun-Ick,Kim, Youngseok,Kim, Seongwon 한국분말야금학회 2014 한국분말재료학회지 (KPMI) Vol.21 No.6

RBSC (reaction-bonded silicon carbide) represents a family of composite ceramics processed by infiltrating with molten silicon into a skeleton of SiC particles and carbon in order to fabricate a fully dense body of silicon carbide. RBSC has been commercially used and widely studied for many years, because of its advantages, such as relatively low temperature for fabrication and easier to form components with near-net-shape and high relative density, compared with other sintering methods. In this study, RBSC was fabricated with different size of SiC in the raw material. Microstructure, thermal and mechanical properties were characterized with the reaction-sintered samples in order to examine the effect of SiC size on the thermal and mechanical properties of RBSC ceramics. Especially, phase volume fraction of each component phase, such as Si, SiC, and C, was evaluated by using an image analyzer. The relationship between microstructures and physical properties was also discussed.

Y2O3 첨가 탄소 프리폼에 Si 용융 침투에 의해 제조한 반응 소결 탄화규소

장민호,조경식 한국분말야금학회 2021 한국분말재료학회지 (KPMI) Vol.28 No.1

The conversion of carbon preforms to dense SiC by liquid infiltration is a prospectively low-cost and reliable method of forming SiC-Si composites with complex shapes and high densities. Si powder was coated on top of a 2.0wt .% Y2O3-added carbon preform, and reaction bonded silicon carbide (RBSC) was prepared by infiltrating molten Si at 1,450oC for 1-8 h. Reactive sintering of the Y2O3-free carbon preform caused Si to be pushed to one side, thereby forming cracking defects. However, when prepared from the Y2O3-added carbon preform, a SiC-Si composite in which Si is homogeneously distributed in the SiC matrix without cracking can be produced. Using the Si + C → SiC reaction at 1,450oC, 3C and 6H SiC phases, crystalline Si, and Y2O3 were generated based on XRD analysis, without the appearance of graphite. The RBSC prepared from the Y2O3-added carbon preform was densified by increasing the density and decreasing the porosity as the holding time increased at 1,450oC. Dense RBSC, which was reaction sintered at 1,450oC for 4 h from the 2.0wt.% Y2O3-added carbon preform, had an apparent porosity of 0.11% and a relative density of 96.8%.

용융 Si 침윤방법에 의한 반응소결 탄화규소 고온가스 필터의 제조 및 특성

황성식,김태우 한국세라믹학회 2003 한국세라믹학회지 Vol.40 No.9

IGCC 발전 시스템에 사용되는 고온 가스 필터에 대하여 용융 Si 침윤공정 방법을 사용한 고강도 반응소결 탄화규소 고온 가스 필터 제조 공정이 개발되었다. 용융 Si 침윤 반응으로 제조된 반응소결 탄화규소의 상온 및 고온 파괴강도는 약 50-123, 60-66 MPa이었으며, 반응소결 탄화규소 다공체의 평균기공크기 및 기공율의 범위는 각각 60- 70 $\mu\textrm{m}$ 및 약 34 vol%이었다. 용융 Si 침윤 방법으로 제조된 반응 소결 탄화 규소 다공체에서는 SiC 입자 사이에 SiC/Si으로 이루어진 기지 상이 형성되어 고온 파괴 강도가 점토 결합 탄화 규소 다공체보다 우수하였다. 소결된 지지층 위에 Si 분말이 첨가되지 않은 slurry를 사용하여 여과층을 제조하였다. 여과층에 사용된 Sic 입자의 크기가 10$\mu\textrm{m}$에서 34 $\mu\textrm{m}$로 증가됨에 따라 SiC 입자 사이에 형성된 기지상의 두께가 증가하였다. 분진이 포함된 유체의 face velocity 변화에 따른 압손의 관계는 US filter사 Schumacher type 20 filter의 기체 유동 특성과 비슷하게 나타났으며, 분진여과 측정시 4분 내에 누출 분진의 크기가 1 $\mu\textrm{m}$ 크기 이하로 감소되었다. Novel fabrication technique was developed for high strength Reaction-Bonded SiC (RBSC) hot gas filter for use in IGCC (Integrated Gasification Combined Cycle) system. The room and high temperature fracture strengths for Si-melt infiltrated reaction-bonded SiC were 50-123, and 60-66 MPa, respectively. The average pore size was 60-70 $\mu\textrm{m}$ and the porosity was about 34 vol%. RBSC infiltrated with molten silicon showed improved fracture strength at high temperature, as compared to that of clay-bonded SiC, due to SiC/Si phase present within SiC phase. The thickness for SiC/Si phase was increased with increasing powder particle size of SiC from 10 to 34 $\mu\textrm{m}$. Pressure drop with dust particles showed similar response as compared to that for Schumacher type 20 filter. The filter fabricated in the present study showed good performance in that the filtered powder size was reduced drastically to below 1 $\mu\textrm{m}$ within 4 min.