• 한국세라믹학회:학술대회논문집
• /
• 한국세라믹학회 2002년도 추계총회 및 연구발표회 초록집
• /
• pp.101.1-101
• /
• 2002

• 한국전기전자재료학회논문지
• /
• 제16권6호
• /
• pp.454-459
• /
• 2003

We investigate the structure and properties of SiC (Silicon Carbide) nanotubes using molecular dynamics simulation based on the Tersoff bond-order potential. For small diameter tubes, the Si-C bond distance of SiC nanotubes decreases as the nanotube diameter is decreased, due to curvature of the nanotube surface. We find that Young's modulus of SiC nanotubes is somewhat smaller than that of the other nanotubes considered so far. However, Young's modulus for SiC nanotubes is larger than that of ${\beta}$-SiC and almost equal to the experimental value for SiC nanorod and SiC whisker. The strain energy of the SiC nanotubes is also lower than that of the other nanotubes. The lower strain energy of SiC nanotubes raises the possibility of synthesis of SiC nanotubes.

• 마이크로전자및패키징학회지
• /
• 제10권3호
• /
• pp.67-71
• /
• 2003

실리콘 주괴(ingot)에서 실리콘 웨이퍼를 제조할 때 사용되는 슬러리는 SiC 연마재와 절삭유를 포함한다. 실리콘 웨이퍼 제조 시 생긴 폐슬러지에서 SiC 연마재와 절삭유는 분리되어 재활용된다. 본 연구는 폐슬러지 Si 분말에 C분말을 혼합하여 SiC를 합성하는 것에 관한 것이다. 다양한 크기의 SiC 분말과 휘스커가 제조되었으며 기존의 휘스커의 크기보다 작은 나노미터 크기의 휘스커도 발생하였다. 일반적으로 휘스커는 금속 불순물을 첨가하여 제조되는데, 본 연구에서 나노미터 크기의 휘스커 발생은 폐슬러지에 첨가되어있는 미세한 크기의 금속불순물의 영향으로 판단된다.

• 한국세라믹학회지
• /
• 제19권2호
• /
• pp.121-126
• /
• 1982

This paper deals with the $Si_3N_4$-bonded SiC refractory in terms of its microstructure development during nitridation. When mixture of SiC grains and fine Si power is fired under nitrogen atmosphere, an interlocking network of $Si_3N_4$ whiskers is formed by nitridation of Si. It is found that the strength of $Si_3N_4$-bonded SiC refractory is soley due to the physical nature of this interlocking whiskers. At the initial stage of nitridation, $Si_3N_4$ whisker forms in very thin and long shape and, with further nitridation, it becomes thicker with diameters up to 0.35$\mu\textrm{m}$. It is found that the mechanical strength of $Si_3N_4$-bonded SiC refractory depends on the degree of nitridation and the development of microstructure.

• 한국세라믹학회지
• /
• 제37권9호
• /
• pp.864-870
• /
• 2000

알루미나 단미의 기계적 성질을 향상시키고자, 185$0^{\circ}C$에서 1시간 동안 열간 가압소결에 의하여 SiC 입자 및 SiC 휘스커를 단독으로 혹은 동시에 첨가한 알루미나 복합재료를 제조하여 기계적 성질과 미세조직을 조사하였다. 20vol%의 SiC 입자 혹은 휘스커 첨가에 의하여, 알루미나 복합재료의 강도는 단미의 360 MPa에서 각각 640 MPa, 650 Mpa로 향상되었다. 20vol%의 SiC 입자 혹은 휘스커를 첨가한 복합재료의 파괴인성은 각각 3.5 MPa.m$^{1}$2/, 5.5 MPa.m$^{1}$2/를 나타내었다. 20vol%의 SiC 휘스커와 2vol%의 SiC 입자를 동시 첨가한 다중강화 복합재료의 강도와 파괴인성은 각각 790 MPa, 5.0 MPa.m$^{1}$2/ 로 증가하였다. 이와 같이 알루미나 단미에 비해 강도 및 파괴인성이 향상된 것은 입자에 의한 결정립 미세화 효과와 휘스커에 의한 균열편향, pull-out의 영향으로 생각된다.

• 한국세라믹학회:학술대회논문집
• /
• 한국세라믹학회 2004년도 추계총회 및 연구발표회 초록집
• /
• pp.94.4-94.4
• /
• 2004

• 대한기계학회논문집
• /
• 제17권10호
• /
• pp.2498-2508
• /
• 1993

$Al/SiC/Al_{2}O_{3}$ hybrid composites are fabricated by squeeze infiltration method. From the misconstructive of $Al/SiC/Al_{2}O_{3}$ hybrid composites fabricated by squeeze infiltration method, uniform distribution of reinforcements and good bondings are found. Hardness value of $Al/SiC/Al_{2}O_{3}$ hybrid composites increases linearly with the volume fraction of reinforcement because SiC whisker and $Al_{2}$O$_{3}$ fiber have an outstanding hardness. Optimal aging conditions are obtained by examining the hardness of $Al/SiC/Al_{2}O_{3}$ hybrid composites with different aging time. Tensile properties such as Young's modulus and ultimate tensile strength are improved up to 30% and 40% by the addition of reinforcements, respectively. Failure mode of $Al/SiC/Al_{2}O_{3}$ hybrid composites is ductile on microstructural level. Through the abrasive wear test and wear surface analysis, wear behaviour and mechanism of 6061 aluminum and $Al/SiC/Al_{2}O_{3}$ hybrid composites are characterized under various testing conditions. The addition of SiC whisker to $Al/SiC/Al_{2}O_{3}$ composites gives rise to improvement of the wear resistance. The wear resistance of $Al/SiC/Al_{2}O_{3}$ hybrid composites is superior to that of Al/SiC composites. The wear mechanism of aluminum alloy is mainly abrasive wear at low speed range and adhesive and melt wear at high speed range. In contrast, that of $Al/SiC/Al_{2}O_{3}$ hybrid composites is abrasive wear at all speed range, but severe wear when counter material is stainless steel. As the testing temperature increases, wear loss of aluminum alloy decreases because the matrix is getting more ductile, but that of $Al/SiC/Al_{2}O_{3}$ hybrid composites is hardly varied. Oil lubricant is more effective to reduce the wear loss of aluminum alloy and $Al/SiC/Al_{2}O_{3}$ hybrid composites at high speed range.

• 한국세라믹학회지
• /
• 제35권12호
• /
• pp.1249-1256
• /
• 1998

${\beta}$-Silicon carbide(${\beta}$-SiC) whiskers could be synthesized by the carbothermal reduction of kaolin at tem-peratures between 1400 and 1500$^{\circ}C$. The whiskers were grown up to about 1150 of aspect ratio by VS mechanism (showing tapering tips) and to about 45 of that by VLS mechanism (showing round droplet tips) respectively. Hydrocarbon like methane in the reaction atmosphere promoted the formation of gaseous il-icon monoxide(SiO) from silicon dioxide(SiO2) and subsequently reacted with it to form whiskers. The for-mation of ${\beta}$-SiC whiskers increased with increasing carbon content(to 30 wt%) and reaction temperatures. The max. yield of ${\beta}$-SiC whiskers was 15% at 1500$^{\circ}C$ under 20%CH4/80%H2.

• 한국분말재료학회지
• /
• 제9권1호
• /
• pp.11-18
• /
• 2002

The 6061 Al alloy based composites reinforced with 10 vol% SiC whiskers were prepared by powder metallurgy with the powders having the different sizes, i.e. < $30{\mu}m$ and > $30{\mu}m$ The composites were subjected to equal channel angular pressing (ECAP) at various conditions and the microstructural changes during ECAP were examined In the composites SiC whiskers were clustered and randomly aligned. The clusters were relatively well distributed in the composite with the smaller initial powder size. After ECAP, the clusters were aligned parallel to flow direction and became smaller. In addition, the shape of clusters was changed from irregular to round. The microstructure of the ECAPed samples were compared with those of the conventionally hot-extruded composites. The uniform microstructure and enhanced microhardness could be obtained by using the powders having the smaller size, decreasing ECAP temperature and repeating ECAP.

• 한국세라믹학회지
• /
• 제32권2호
• /
• pp.189-196
• /
• 1995

Materials retaining electrolyte of a phosphoric acid fuel cell (PAFC) have been prepared with SiC powder to SiC whisker mixing ratios of 1:1, 1:2, 1:3, 1:4, 0:1 by a tape casting method. When 3wt% dispersant (sorbitan monooleate) is added to a matrix, the porosity of the matrix decreases a little while the bubble pressure and area of the matrix increase remarkably in comparison with no dispersant content. Effect of the electrolyte resistance and the polarization resistance on perfomance of a PAFC has been investigated using A.C. impedance spectroscopy. With the increase of whisker content, the electrolyte resistance decreases due to the increase of porosity and acid absorbancy, and the polarization resistance increases due to the increase of surface roughness. The polarization resistance affects current density predominantly at the higher potential than 0.7V becuase the polarization resistance is considrably larger than the electrolyte resistance. Both the electrolyte resistance and the polarization resistance affect current density near 0.7V of the fuel cell operating potential because they have similar values. The electrolyte resistance affects current density predominantly at the lower potential than the fuel cell operating potential because the electrolyte resistance is larger than the polarization resistance.