• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1988년도 춘계학술대회 논문집
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• pp.88-91
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• 1988

In this paper, PLZT Ceramics were fabricated by two stage sintering method whose first stage vacuum hot pressing and second stage PbO atmosphere sintering. Using Graphite Mould instead of Alumina Mould in first stage prevented the adhision between PLZT substrate and the mould. The grain sizes of PLZT Ceramics were controlled by varying the hot pressing time and second sintering time.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2004년도 학술대회지
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• pp.266-270
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• 2004

SiC materials have been extensively studied for high temperature components in advanced energy system and advanced gas turbine because it has excellent high temperature strength, low coefficient of thermal expansion, good resistance to oxidation and good thermal and chemical stability etc. However, the brittle characteristics of SiC such as low fracture toughness and low strain-to fracture still impose a severe limitation on practical applications of SiC materials. For these reasons, SiC/SiC composites can be considered as a promising for various structural materials, because of their good fracture toughness compared with monolithic SiC ceramics. But, high temperature and pressure lead to the degradation of the reinforcing jiber during the hot pressing. Therefore, reduction of sintering temperature and pressure is key requirements for the fabrication of SiC/SiC composites by hot pressing method. In the present work, monolithic Liquid Phase Sintered SiC (LPS-SiC) was fabricated by hot pressing method in Ar atmosphere at $1800^{\circ}C$ under 20MPa using $Al_2O_3,\;Y_2O_3\;and\;SiO_2$ as sintering additives in order to low sintering temperature and sintering pressure. The starting powder was high purity $\beta-SiC$ nano-powder with all average particle size of 30mm. The characterization of LPS-SiC was investigated by means of SEM and three point bending test. Base on the composition of sintering additives-, microstructure- and mechanical property correlation, tire compositions of sintering additives are discussed.

• The Korean Journal of Ceramics
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• 제5권3호
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• pp.224-229
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• 1999

The preparation and toughening of SiC-AIN solid solution from powder mixtures of $\beta$-SiC, AIN and $\alpha$-SiC by hot-pressing were studied in the 1870 to $2030^{\circ}C$ temperature range. The reaction of AIN and $\beta$-SiC(3C) powders causing transformation to the 2H(wurtzite) structure appeared to depend on hot-pressing temperatures and an additive of $\alpha$-SiC. For the composition of 49wt% SiC with 2 wt% $\alpha$-SiC and 47.5 wt% AIN47.5wt% SiC with 5 wt % $\alpha$-SiC at 203$0^{\circ}C$ for 1 h, th complete solid solutions with a single phase of 2H could be obtained. The appreciable amount of $\alpha$-SiC could develop the columnar inter-grains of 4H phase and the stable 2H phase with the relatively uniform composition and grain size distributions. The effect of $\alpha$-SiC on the phases present and compositional microstructures with columnar inter-grains was invetigated using X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The fracture toughness and Vickers hardness of the hot-pressed solid solutions wre examined by the indentation-fracture-test method.

• 한국재료학회:학술대회논문집
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• 한국재료학회 1996년도 재료학회 춘계학술발표회
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• pp.112-112
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• 1996

• 한국재료학회:학술대회논문집
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• 한국재료학회 1998년도 추계학술발표강연 및 논문개요집
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• pp.51-51
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• 1998

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2002년도 동계연구발표회 논문개요집
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• pp.232-233
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• 2002

Nanostructed high energy Nd-Fe-B based bulk magnet can be prepared by hot-working process (hot press and die-upset) from melt-spun amorphous or nanocrystalline powder.[1] Recently, we have investigated a modified method, current-applied pressure-assisted (CAPA) process, to produce nanocrystalline isotropic and anisotropic NdFeB magnets. The process consists of current-applied pressing the melt-spun powders to obtain isotropic precursor subsequent current-applied deforming the precursor to obtain textured magnet.[2-3] (omitted)

• 한국세라믹학회지
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• 제36권2호
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• pp.107-115
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• 1999

용융탄산염 연료전지(Molten Carbonate Fuel Cell)용 알루미나 화이버 강화 ${\gamma}$-LiAlO2 매트릭스의 적층방법에 따른 미세구조 변화 및 강도 증진 효과에 대하여 연구하였다. 테이프 캐스팅법으로 제조한 green sheet 2장을 45$^{\circ}C$에서 1kg/$ extrm{cm}^2$의 압력으로 1분간 hot pressing 하여 제조한 적층 매트릭스와 double casting 시 1단계 캐스팅한 green sheet를 3.5 시간 정도 건조한 뒤 2 단계 캐스팅 하여 제조한 적층 매트릭스의 기공율은 모두 50% 이상이었다. 알루미나 화이버 강화 적층 매트릭스의 강도는 비적층 매트릭스(115gf/$ extrm{mm}^2$)에 비해 70% 이상 증진되었으며 적층에 의해 화이버 배향성에 따른 강도의 편향성을 제거할 수 있었다. Triple casting에 의한 적층 메트릭스의 강도는 double casting 시에 비해 약간 증진되었으나 캐스팅 방향에 따른 강도의 편향성이 존재할 뿐만 아니라 기공율도 50% 이하였다. Double casting에 의한 적층 매트릭스의 강도 (195 gf/$\textrm{mm}^2$)는 hot pressing 하여 제조한 매트릭스 (212gf/$\textrm{mm}^2$)에 비해 약간 낮지만 MCFC 매트릭스 제조공정 면에서 double casting 법이 효율적인 적층공정으로 평가되었다.

• 한국세라믹학회지
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• 제49권4호
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• pp.308-317
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• 2012

Reactive processing, such as reactive hot pressing (RHP) and reactive spark plasma sintering (R-SPS), is effective densification method to prepare $ZrB_2$-based ultra high temperature ceramics (UHTCs). The present paper reviewed some typical reactive processing of $ZrB_2$-based UHTCs. All the reactions from the starting materials in the reactive processing are thermodynamically favorable, which generate enough energy and driving force for the densification of the final products under a relatively low temperature. Besides, compared with non-reactive processing, anisotropic $ZrB_2$ grains, such as $ZrB_2$ platelets, can only be obtained in the reactive processing, resulting in an improvement of the mechanical properties.

• 한국결정성장학회지
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• 제12권5호
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• pp.253-258
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• 2002

나노 복합체는 제 2상의 크기가 나노 사이즈인 복합체를 의미한다. 이러한 복합체는 제 2상이 마이크론 사이즈인 경우와 다른 독특한 특성을 나타내는 것으로 보고되며, 특별히 기계적 특성이 많이 향상되는 것으로 보고되고 있다. 하지만 이러한 나노 복합체가 전자세라믹 재료의 특성을 어떻게 변화시키는지에 대한 연구는 아직 미비한 편이다 본 연구에서는 PNN-PZT/Ag나노복합체를 고온 고압 소결법에 의하여 제조하였으며, 미세구조적, 유전적 특성에 대하여 고찰하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2015년도 제46회 하계학술대회
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• pp.1151-1152
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• 2015

Silicon zinc oxide (SZO) thin films were deposited via co-sputtering. Two kinds of post-treatment, furnace annealing and hot pressing, were carried out on the deposited SZO films. The effects of the post-treatment on the chemical bond and surface roughness of the deposited SZO films were analyzed as functions of the post-treatment conditions that were used. It was observed from the X-ray photoelectron spectroscopy (XPS) results that the amount of Si-O bonds in the SZO film drastically increased after the low-temperature furnace annealing. The experiment results showed that the hot pressing method would be favorable as it could improve the electrical characteristics of the SZO-TFTs.