• 한국세라믹학회지
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• 제35권3호
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• pp.303-309
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• 1998

The fabrication of Al2O3/Al composite by pressureless infiltration was investigated by the change of Mg and Si content in Al alloy infiltration process and infiltration atmosphere. The effect of alloying elements infiltration atmosphere and interfacial reactants between Al alloy matrix and Al2O3 particles were in-vestigated in terms of bendingstrength and harness test,. The fabrication of Al2O3/Al composite by the vestigated in terms of bending strength and hardness test. The fabrication of Al2O3/Al composite by the pressureless infiltration was done in nitrogen atmosphere with Mg in Al alloy. It was successfully fabricated at $700^{\circ}C$ according to Mg contents in Al alloy and infiltration condition. Because Mg in the Al alloy and ni-trogen atmosphere of infiltratio condition produced Mg-N compound(Mg3N2) it decreased the wetting an-gle between molten Al alloy and Al2O3 particles by coating on surface of Al2O3 particles. The fracture strength of Al2O3/Al-Mg composite was 800MPa and Al2O3/Al-Si-Mg composite was 400MPa. Si in Al alloy decreased the interfacial strength between Al alloy matrix and Al2O3 particles.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2001년도 추계 학술발표강연 및 논문개요집
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• pp.133-133
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• 2001

• 한국세라믹학회지
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• 제32권8호
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• pp.909-914
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• 1995

From alumina powder and TEOS, $\alpha$-Al2O3/SiO2 composite powder for reaction-sintered mullite was synthesized by heterogeneous coagulation and surface coating, and investigated the mullitization reaction and sintering behavor of these powders. In $\alpha$-Al2O3/SiO2 composite powder prepared by heterogeneous coagulation, each alumina particles were surrounded by silica particles of 50~60 nm in size. And the alumina particles in composite powder prepared by surface coating were coated by uniform silica layer with thickness of 50 nm. In both methods, mullitization reaction was completed at 1$650^{\circ}C$ for 3h, and specimen sintered above 145$0^{\circ}C$ was about 95% fo the theoretical relative density. Mullite grains formed from the reaction with composite powders showed spherical shape with a size of 1~2${\mu}{\textrm}{m}$.

• 한국분말재료학회지
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• 제11권3호
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• pp.259-264
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• 2004

Aluminum based metal matrix composite reinforced with SiC particles was fabricated by the powder-in sheath rolling method. A stainless steel tube with outer diameter of 12 mm and wall thickness of 1mm was used as a sheath. Mixture of aluminum powder and SiC particles of which volume content was varied from 5 to 20vol.% was filled in the tube by tap filling and then rolled to 75% reduction at ambient temperature. The rolled specimen was sintered at 56$0^{\circ}C$ for 0.5hr. The tensile strength of the (SiC)$_{p}$/Al composite increased with the volume content of SiC particles, and at 20vol.% it reached a maximum of 100㎫ which is 1.6 times higher than unreinforced material. The elongation decreased with the volume content of $Al_{2}$O$_{3}$ particles. The mechanical properties of the (SiC)$_{p}$/Al composite fabricated by the powder-in sheath rolling is compared with that of (Al$_{2}$O$_{3}$)$_{p}$/Al composite by the same process.ess.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제55권11호
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• pp.505-513
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• 2006

The present study investigated the influence of the content of $Al_2O_3+Y_2O_3$ sintering additives on the microstructure, mechanical and electrical properties of the pressureless-sintered $SiC-ZrB_2$ electroconductive ceramic composites. Phase analysis of composites by XRD revealed mostly of ${\alpha}-SiC(4H),\;ZrB_2,\;{\beta}-SiC(15R)$ and In Situ $YAG(Al_5Y_3O_{12})$. The relative density and the flexural strength showed the highest value of 86.8[%] and 203[Mpa] for $SiC-ZrB_2$ composite with an addition of 8[wt%] $Al_2O_3+Y_2O_3$ as a sintering aid at room temperature respectively. Owing to crack deflection and crack bridging of fracture toughness mechanism, the fracture toughness showed 3.7 and $3.6[MPa{\cdot}m^{1/2}]\;for\;SiC-ZrB_2$ composites with an addition of 8 and 12[wt%] $Al_2O_3+Y_2O_3$ as a sintering aid at room temperature respectively. Abnormal grain growth takes place during phase transformation from ${\beta}-SiC\;into\;{\alpha}-SiC$ was correlated with In Situ YAG phase by reaction between $Al_2O_3\;and\;Y_2O_3$ additives during sintering. The electrical resistivity showed the lowest value of $6.5{\times}10^{-3}[({\Omega}{\cdot}cm]$ for the $SiC-ZrB_2$ composite with an addition of 8[wt%] $Al_2O_3+Y_2O_3$ as a sintering aid at room temperature. The electrical resistivity of the $SiC-ZrB_2$ composites was all positive temperature coefficient(PTCR) in the temperature ranges from $25[^{\circ}C]\;to\;700[^{\circ}C]$. The resistance temperature coefficient showed the highest value of $3.53{\times}10^{-3}/[^{\circ}C]\;for\;SiC-ZrB_2$ composite with an addition of 8[wt%] $Al_2O_3+Y_2O_3$ as a sintering aid in the temperature ranges from $25[^{\circ}C]\;to\;700[^{\circ}C]$. In this paper, it is convinced that ${\beta}-SiC$ based electroconductive ceramic composites for heaters or ignitors can be manufactured by pressureless sintering.

• 한국결정성장학회지
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• 제7권4호
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• pp.626-631
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• 1997

하동고령토($Al_2O_3-SiC-C$)를 출발원료로하여 AlSiCa내화재 원료를 합성하였다. 하동고령토와 탄소분말을 혼합하여 수소분위기하에서 반응시킨결과, $1300^{\circ}C$에서$Al_2O_3-SiC-C$ 복합체가 힙성되기 시작하여$1400^{\circ}C$에서 완전 합성되었고, $SiO_2$에 대한 최적carbon량은 mole비로 1:4이었다. 합성시 알루미나 용기에 탄소분말을 충전시키지 않을 때는 미합성부분이 없이 밝은 녹색을 띈 $\beta$-SiC(cubic form) 를 형성함을 확인하였다.

• 에너지공학
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• 제20권3호
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• pp.171-177
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• 2011

본 연구에서는 폴리비닐알코올(PVA)을 전해질 막으로 이용하기 위하여 가교제로서 글루타르알데히드(GLA)와 무기물 첨가제로 알루미늄실리케이트($Al_2O_3{\cdot}3SiO_2$)를 사용하여 PVA/GLA/$Al_2O_3{\cdot}3SiO_2$ 복합막을 제조하였다. PVA/GLA/$Al_2O_3{\cdot}3SiO_2$ 복합막은 GLA의 비율이 증가함에 따라 함수율이 감소되었고, 알루미늄실리케이트 함량이 증가함에 따라 함수율 향상이 예상되어 수소이온 전도도가 향상되는 경향을 보였다. 제조된 고분자의 가교결합은 IR과 함수율의 경향성으로 확인되었다. 제조된 고분자의 열분석은 TGA에 의해 수행되었다. TGA의 분석결과 PVA/GLA 복합막은 가교결합으로 인하여 PVA보다 열안정성이 우수하였으며, 복합막의 알루미늄실리케이트의 비율이 증가할수록 열안정성이 더욱 증대되는 것을 알 수 있었다. 본 연구에서 제조된 복합막은 열안전성을 갖으며 $60^{\circ}C$까지는 양이온전도도가 증가하는 경향을 갖지만 $90^{\circ}C$로 온도가 높아짐에 따라 성능이 낮아지는 경향을 보였다. 따라서 보다 적극적인 노력을 통하여 향후 이온전도성 복합 전해질막으로 적용 가능성을 타진해야 할 것으로 기대된다.

• 한국세라믹학회:학술대회논문집
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• 한국세라믹학회 2000년도 추계총회,초청강연,특별강연,연구발표회
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• pp.165.2-165
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• 2000

• 한국결정성장학회지
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• 제7권4호
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• pp.610-618
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• 1997

반응용침법으로 제조된 $Al_2O_3$/Al 복합재료는 900-$1200^{\circ}C$의 온도범위에서 $Al_2O_3$ 분말성형체에 용융Al을 침투시켜 제조하였다. 용융침투는 각 온도에서 잠복기를 거친후 발생하였으며, 복합재료의 성장속도는 시간에 따라 선형적으로 비례하였다. 제조된 복합재료의 주성분은 $Al_2$O$_3$와 Al이었고 소량의 Si이 탐지되었다. 복합재료의 상대밀도는 $Al_2O_3$ 입자크기가 증가함에 따라 증가하였고 용융 침투온도가 높을수록 감소하였다.

• 한국세라믹학회지
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• 제50권6호
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• pp.364-371
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• 2013

The sintering behavior of monolithic SiC is examined using the binary sintering additive of $Al_2O_3$-rare earth oxide ($RE_2O_3$, where RE = Sc, Nd, Dy, Ho, or Yb). Through hot pressing at 20 MPa and $1750^{\circ}C$ for 1 h in an Ar atmosphere for 52 nm fine ${\beta}$-SiC powder added with 5 wt% sintering additive, a SiC density of > 97% is achieved, which indicates the effectiveness of $Al_2O_3-RE_2O_3$ system as a sintering of additive for SiC. Based on this result, 7 wt% of $Al_2O_3-Sc_2O_3$ is tested as an additive system for the fabrication of a continuous SiC fiber-reinforced SiC-matrix composite ($SiC_f$/SiC). Electrophoretic deposition combined with the application of ultrasonic pulses is used to efficiently infiltrate the matrix phase into the voids of $Tyranno^{TM}$-SA3 fabric. After hot pressing, a composite density of > 97% is obtained, along with a maximum flexural strength of 443 MPa.