• 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.

• 열처리공학회지
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• 제14권2호
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• pp.96-102
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• 2001

$Al_2O_3$-copper alloy has been successfully made by gas atomization, mechanical alloying and hot pressing. In order to investigate microstructure and phase, it has been studied by using scanning electron microscope, transmission electron microscope and X-ray diffractometor. Mechanical properties have been examined using hardness tester and compressive tester according to annealing temperature. Although comparatively large Cu-Al powders are milled, the reaction between Cu-Al and $Cu_2O$ occurs and very fine $Al_2O_3$ particles in the matrix particles (5-10nm) are obtained. Compressive strength of this alloy is more than that of GlidCop Al60.

• 한국세라믹학회지
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• 제33권4호
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• pp.464-470
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• 1996

Toughening mechanism of boron carbide ceramics by the addition of titanium boride was investigated. Speci-men was prepared by hot pressing of boron carbide with upto 30vol% of titanium boride particulates. Toughness of boron carbide ceramics was increased from 4.7 MPa m1/2 to 6.3 MPa m1/2 with 15 vol% TiB2 addition. But further increase of TiB2 content results in slow decrease of toughness. From microstructure evaluation and crack propagation behavior it is concluded that the major toughening mechanism is crack deflection pheno-mena.

• 한국세라믹학회지
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• 제45권10호
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• pp.594-599
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• 2008

Hydroxyapatite(HA) was prepared from waste tuna bone, and its sintering property and dissolution behavior were investigated. Tuna bone derived-HA powder consisted of mainly HA and small amount of MgO. Porous HA ceramics with sintered density of 79% was obtained by pressureless sintering at $1200^{\circ}C$. Meanwhile, HA ceramics prepared by hot pressing at $1000^{\circ}C$ showed dense microstructure with sintered density of 95%. Immersion test revealed that both porous and dense HA ceramics were stable in liquid environment without distinct evidence of surface dissolution. It may be assumed that the presence of Mg in tuna bone-derived HA may improve dissolution resistance of HA.

• 소성∙가공
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• 제18권8호
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• pp.616-624
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• 2009

In this work we demonstrate the hot-embossing process under different forming conditions such as forming temperature, load, and holding time in pressing, in order to determine the suitable conditions required for linear patterning on polymer plates (PC). Results showed that the replicated pattern depth increased in proportion to an increase in the forming temperature, load, and time. The reduction of the workpiece thickness increased according to the holding time in the pressing process. In the process of time, the reduction ratio of the workpiece thickness decreased due to the surface area increment of the workpiece, while the pressure on the workpiece declined. In order to reduce the bulging ratio we introduced a temperature difference between the upper and the lower punch.

• Journal of the Korean Wood Science and Technology
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• 제23권3호
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• pp.33-39
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• 1995

To accelerate the cure of phenolic resin adhesives for plywood, the complexation with melamine resin and the addition of cure-accelerating agents were discussed. The hot-pressing temperature and time of phenol resin could be decreased by complexation with melamine resin. but the wet glue-joints strength of phenol melamine resin was lower than that of ordinary phenol resin in case of plywood using spruce veneer at core layer. Among the tested cure-accelerating agents. the sodium carbonate showed the greatest effect on shortening gelation time of phenolic resin. In addition, in the manufacturing scale test, the hot-pressing time of phenol resin with the addition of 5 parts sodium carbonate could be shortened about 20% compared with ordinary phenol resin which had same glue-joints properties.

• The Korean Journal of Ceramics
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• 제4권3호
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• pp.171-175
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• 1998

$Al_2O_3$-TiC composites were prepared from aluminum, titanium oxide, and carbon fibers by self-propagating high-temperature synthesis(SHS). After the SHS reaction, the TiC phase in the sample was found either fibrous or non-fibrous shape. The fraction of the fibrous TiC phase varied with the amount of $Al_2O_3$ diluent addition. The optimum amount of diluent to make fibrous carbide was determined to be 30%. The fibers were hollow inside and made of multiple grains with a composition of titanium carbide. The hollow fiber formation mechanism was suggested and discussed. The synthesized powders were consolidated to dense composites by hot pressing at $1750^{\circ}C$ under 30 MPa.

• 한국세라믹학회지
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• 제40권7호
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• pp.667-671
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• 2003

테이프 캐스팅법을 이용하여 알루미나/지르콘(반응결합 뮬라이트/지르코니아 유도)을 내부층으로 하고 알루미나/지르코니아 혹은 뮬라이트/지르코니아를 외부층으로 하는 산화물 층상 복합체를 고온가압소결법으로 제조하였다. 나노압입시험법을 이용하여 층상 산화물 복합체의 기계적 성질(경도 및 탄성계수)을 측정하고, SEM을 통하여 복합체의 미세구조를 관찰하였다. 산화물 층상 복합체의 제조를 위한 가열·냉각시 유도된 구성 산화물간의 열팽창 계수의 차이로 인하여 생성된 잔류응력을 하중-변위곡선을 이용하여 확인할 수 있었다.

• 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.