• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2018년도 춘계학술대회 논문집
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• pp.121-121
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• 2018

Copper is a promising electronic material due to low cost and high electrical conductivity. However, the oxidation problem in an ambient condition makes a crucial issue in practical applications. In here, we developed a simple and cost-effective Cu patterning method on a flexible PET film by combining a solution processable Cu nanoparticle patterning and a low temperature post-processing using acetic acid treatment, laser sintering process and acid-assisted laser sintering process. Acid-assisted laser sintering processed Cu electrode showed superior characteristics in electrical, mechanical and chemical stability over other post-processing methods. Finally, the Cu electrode was applied to the flexible electronics applications such as flexible and transparent heaters and touch screen panels.

• 소성∙가공
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• 제16권5호통권95호
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• pp.396-400
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• 2007

LTCC(Low Temperature Co-fired Ceramic) which offers a good performance to produce multilayer structures with electronic circuits and components has emerged as an attractive technology in the electronic packaging industry. In LTCC module fabrication process, the lamination and the sintering are very important processes and affect the electrical characteristics of the final products because the processes change the permittivity of ceramics and the dimension of the circuit patterns which have influences on electronic properties. This paper discusses the influence of lamination pressure and sintering temperature on the permittivity and the dimensional change of LTCC products. In the present investigation, it is shown that the permittivity increases along with increasing of the lamination pressure and the sintering temperature.

• 한국분말재료학회지
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• 제19권5호
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• pp.373-378
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• 2012

Sintered bulks of $ZrO_2$ nanopowders were fabricated by magnetic pulsed compaction (MPC) and subsequent two-step sintering employed in this study and the formability effects of nanopowder on mixing condition, pressure and sintering temperature were investigated. The addition of PVA induced and increase in the formability of the sintered bulk. But cracked bulks were obtained on sintering with addition of over 10 wt% PVA due to generation of crack during sintering. The optimum compaction pressure during MPC was 1.0 GPa and mixing conditions included using 5.0 wt% PVA. The optimum processing condition included MPC process, followed by two-step sintering (first at 1000 and then at $1450^{\circ}C$). The sintered bulks with the diameter of 30 mm under these conditions were found to have non crack, ~99% density.

• 한국생산제조학회지
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• 제21권3호
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• pp.516-524
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• 2012

Selective Laser Sintering(SLS) system consists of various element technologies. Main components of the system include a position control system, a speed control system of the roller, and nitrogen atmosphere furtherance for the powdered sintering. Other systems which make the core of the SLS system are build room and the feed room for powder epitaxial, a temperature control system, and a scan path generator for the laser. The powder material for laser sintering is necessary to produce prototypes in Solid Freeform Fabrication(SFF) based on SLS process. This powder material is sintered in powder room using $CO_2$ laser after spreading evenly using roller to reproduce mold via SFF. This study addresses an SFF system by using the SLS process which applies single laser system to enable manufacturing of 3D shape. And to evaluate applicability of the single laser system, experiments were conducted with optimal fabricating process.

• 한국결정성장학회지
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• 제25권1호
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• pp.6-12
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• 2015

율속제어소결은 소결 공정 중 실시간으로 측정되는 시편의 팽창/수축거동을 이용해 일정한 수축거동을 하도록 로의 파워를 조정하는 소결방법으로, 온도를 조절하기 위해 로의 파워를 제어하는 일반적인 소결에 비해 시편의 소결 과정을 세밀히 제어할 수 있으며, 특히 소결공정의 최적화를 이룰 수 있는 장점이 있다. 본 연구에서는 탄화붕소의 소결에 율속 제어소결을 적용해 각 공정변수의 조절에 따른 소결온도 및 입자성장의 변화를 조사하여 그 상관관계를 규명하고 이를 기존의 이론에 맞추어 해석함으로써 율속제어소결을 어떻게 소결공정 최적화에 이용할 수 있는지 그 가능성을 알아보았으며 이를 통해 향후 미지 소재의 소결공정에 율속제어공정을 어떻게 적용할 수 있는지 고찰해 보았다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1994년도 춘계학술대회 논문집
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• pp.149-158
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• 1994

Powder forged Connecting Rods have become attractive for use in automotive engines. The powder forging process offers beneficial material utilization as well as the minimization of finishing operations over that of conventionally forged rods. In the present work, the sintering behavior of Fe-2Cu-0.6C, optimum preform design and forgeability of various forging variables were investigated. Our data were generated using a newly proposed sub-scale con-rod developed specifically to simulate the powder forging process. We obtain optimum condition of sintering and powder forging process.

• 한국세라믹학회지
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• 제50권3호
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• pp.226-230
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• 2013

We performed high pressure high temperature (HPHT) sintering for the 20 nm MgO powders at the temperatures from $600^{\circ}C$ to $1200^{\circ}C$ for only 5 min under 7 GPa pressure condition. To investigate the microstructure evolution and physical property change of the HPHT sintered MgO samples, we employed a scanning electron microscopy (SEM), density and Vickers hardness measurements. The SEM results showed that the grain size of the sintered MgO increased from 200 nm to $1.9{\mu}m$ as the sintering temperature increased. The density results showed that the sintered MgO achieved a more than 95% of the theoretical density in overall sintering temperature range. Based on Vickers hardness test, we confirmed that hardness increased as temperature increased. Our results implied that we might obtain the dense sintered MgO samples with an extremely short time and low temperature HPHT process compared to conventional electrical furnace sintering process.

• 한국분말재료학회지
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• 제14권1호
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• pp.32-37
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• 2007

Using spark plasma sintering process (SPS), Ti-6Al-4V alloy powders were successfully consolidated without any contamination happened due to reaction between the alloy powders and graphite mold. Variation of microstructure and mechanical properties were investigated as a function of SPS temperature and time. Compared with hot isostatic pressing (HIP), the sintering time and temperature could be lowered to be 10 min. and $900^{\circ}C$, respectively. At the SPS condition, UTS and elongation were about 890 MPa and 24%, respectively. Considering the density of 98.5% and elongation of 24%, further improving the tensile strength would obtain by increasing the SPS pressure.

• 한국세라믹학회지
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• 제46권5호
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• pp.478-483
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• 2009

Thermal shock and hot corrosion resistance of silicon nitride ceramics are investigated in this study. Silicon nitrides are fabricated by nitride pressureless sintering (NPS) process, which process is the continuous process of nitridation reaction of Si metal combined with subsequent pressureless sintering. The results of thermal shock test show it sustains 400MPa of initial strength during test in the designated condition of ${\Delta}T=700{\sim}25^{\circ}C$ up to maximum 4,800 cycles. Hot corrosion tests also reveal that the strength degradation of NPS silicon nitride did not occur at $700^{\circ}C$ with an exposure in Ar, $H_2$, Na and K for 1,275 h.

• 한국결정성장학회지
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• 제12권2호
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• pp.80-86
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• 2002

$Al_{2}O_{3}/SiC$ nanocomposites were made by infiltrating partially sintered alumina bodies with polycarbosilane (PCS) solutions, which is a SiC polymer precursor, with pressureless sintering. The SiC content, densification, phases, strength, and microstructure were investigated with the processing parameters such as PCS solution concentration and heat treatment condition for PCS pyrolysis and sintering. The results were compared with those for pure alumina and nanocomposite samples made by the existing polymer precursor route (i.e. the PCS addition process). The SiC contents of up to 1.5 vol% were obtained by the PCS infiltration. PCS pyrolysis, followed by air heat treatment, was needed before sintering to avoid a cracking problem and to attain a densification as high as 98 % of theoretical. The nanocomposites exhibited significantly higher strength than pure alumina and those prepared by the PCS addition process despite larger grain size. Besides $\alpha-Al_{2}O_{3}/SiC$ and $\beta-SiC$ phases, mullite was present a little in the nanocomposites, which resulted from the reaction of $SiO_{2}$ in the pyrolysis product of PCS with the $Al_{2}O_{3}$ matrix during sintering. The nanocomposites had intagranular particles believed to be SiC, which is a typical feature of $Al_{2}O_{3}/SiC$ nanocomposites.