• 한국세라믹학회지
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• 제38권8호
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• pp.687-692
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• 2001

Silicon nitride-La-silicon oxynitride ceramics were fabricated by Spark Plasma Sintering (SPS). The density, crystalline phase and microstructure were compared with those obtained by Hot Pressing (HP). The full density was achieved within 40 min by spark plasma sintering at 1$650^{\circ}C$, whereas the same result was required by hot pressing with a dwell time of 500 min at higher temperature. There were some differences in the microstructure and second phases in the sintered ceramics, which are attributed to the rapid densification in the spark plasma sintering. The fine and acicular grain microstructure appeared in spark plasma sintering.

• E2M - 전기 전자와 첨단 소재
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• 제8권5호
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• pp.544-550
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• 1995

In this paper, the anode for molten carbonate fuel cell have been prepared by doctor blade method and microstructure, pore distribution, sintering test of the electrode were investigated. Component analysis were done by Scanning Electron Micrograph, porosimeter and sintering test apparatus. As a result, median pore size was 11.mu.m order at the major specimen and porosity was about 70%. And thickness loss of the electrode was 1.5% at Ni-10Co anode after sintering test.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
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• pp.307-310
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• 2009

In order to develop SOFC cell performance, many kind of things were investigated. Electrode microstructure is the one of them therefore we focus on electrodes fabrication easily and efficiently. We can fabricate electrodes easily with Pt using DC magnetron sputtering and sintering. However sputtering is difficult to handle and to grow porous electrodes what we require. On the other hand sintering is much easier than sputtering to make porous and adhesive electrodes. So in this paper we deal with sintering and optimize to deposit electrodes conditions by analyzing electrode microstructure with sacnning electron microscopy(SEM) micrograph. Also, we compare electrochemical performance of cells fabricated by sputtering and sintering.

• 한국세라믹학회지
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• 제27권3호
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• pp.337-344
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• 1990

As a function of sintering temperature and time, the electrical properties of ruthenium based thick film resistors were investigated with microstructure. The variatio of resistivity and TCR(temperature coefficient of resistance)trends of sintered speciman at various sintering temperature were different low resistivity paste(Du Pont 1721) from high one(Du Pont 1741). These phenomena are deeply relative to microstructure of sintered film. With increasing the sintering temperature for 1721 system, the electrical sheet resistivity decreased, but again gradually increased above 80$0^{\circ}C$. And TCR trends in 1721 system are all positive. On the other hand the electrical sheet resistivity of 1741 resistor system decreased with sintering temperature. And TCR trends variable according to sintering temperature. TCR of speciman sintered at $700^{\circ}C$ was negative value, and TCR of 80$0^{\circ}C$ sintered speciman coexisted negative and positive value. But in case of speciman sintered at 90$0^{\circ}C$, TCR was positive value. As results of this fact, it was well known that the charge carrier contributied to electrical conduction in 1741 resistor system varied with sintering temperature.

• 한국재료학회지
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• 제19권12호
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• pp.680-685
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• 2009

Using a polyurethane foam replica method, porous hydroxyapatite scaffolds (PHS) were fabricated using conventional and microwave sintering techniques. The microstructure and material properties of the PHS, such as pore size, grain size, relative density and compressive strength, were investigated at different sintering temperatures and holding times to determine the optimal sintering conditions. There were interconnected pores whose sizes ranged between about 300 ${\mu}m$ and 700 ${\mu}m$. At a conventional sintering temperature of 1100$^{\circ}C$, the scaffold had a porous microstructure, which became denser and saw the occurrence of grain growth when the temperature was increased up to 1300$^{\circ}C$. In the case of microwave sintering, even at low sintering temperature and short holding time the microstructure was much denser and had smaller grains. As the holding time of the microwave sintering was increased, higher densification was observed and also the relative density and compressive strength increased. The compressive strength values of PHS were 2.3MPa and 1.8MPa when conventional and microwave sintering was applied at 1300$^{\circ}C$, respectively.

• 대한치과기공학회지
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• 제37권4호
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• pp.235-242
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• 2015

Purpose: The aims of this study are compare with microstructure and mechanical properties of Co-Cr-Mo alloys fabricated by powder metallurgy(P/M) process and casting process respectively. Methods: Microstructure and micro-hardness were tested by SEM and Vickers Hardness Tester. The sintered specimen was produced by furnace-coolling after sintering, however the casting specimen were produced thru air-cooling and water-cooling after the casting. For observation of phase transformation during sintering, DSC analyzing was carried out. Results: Mean pore size of sintered Co-Cr-Mo alloy was $4.32{\mu}m$ and that of casting alloy was $1.63{\mu}m$. Hardness of sintered alloy was lower than water-quenched casting alloy. Conclusion: Proper sintering temperature of Co-Cr-Mo alloy was above $1,200^{\circ}C$ and pore size of casting specimen were finer than sintered specimen, but hardness were similar.

• 한국세라믹학회지
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• 제32권11호
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• pp.1308-1314
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• 1995

Changes in phase and microstructure were investigated in the SiC-AlN ceramics prepared by pressureless sintering using yttrium aluminum garnet (YAG) as a sintering aid at 200$0^{\circ}C$ and 210$0^{\circ}C$. The SiC/AlN ratio made a remarkable difference in densification, phase relations and the morphology of grains. In the AlN-rich composition, major phase was 2H and microstructure was composed of the densified equiaxed grains irrespective of the sintering temperatures. While those sintered at 200$0^{\circ}C$ were porous with major phase being 3C, the rod-like and the equiaxed grains were coexisted when sintered at 210$0^{\circ}C$ in the SiC-rich composition.

• 한국세라믹학회지
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• 제39권9호
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• pp.818-821
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• 2002

The grain boundary resistivity of a 1-mol%-$Al_2O_3$-dopedd CaO-Stabilized Zirconia(CSZ) specimen was determined by impedance spectroscopy using sub-millimeter-scale electrodes. At the initial stage of sintering, the grain-boundary resistivity of the specimen interior was observed to be higher than that of the surface. However, upon further sintering the boundary resistivity of the specimen interior became lower than that of the surface. The results were explained in terms of a redistribution of the intergranular liquid phase. The liquid phase was predicted to initially coagulate at the interior of the specimen then spread outward during sintering.

• 한국분말재료학회지
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• 제17권1호
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• pp.13-22
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• 2010

The unique features of spark plasma sintering process are the possibilities of a very fast heating rate and a short holding time to obtain fully dense materials. $\beta$-SiC powder with 0, 2, 6, 10 wt% of $\alpha$-SiC particles (seeds) and 4 wt% of Al-B-C (sintering aids) were spark plasma sintered at $1700-1850^{\circ}C$ for 10 min. The heating rate, applied pressure and sintering atmosphere were kept at $100^{\circ}C/min$, 40 MPa and a flowing Ar gas (500 CC/min). Microstructural development of SiC as function of seed content and temperature during spark plasma sintering was investigated quantitatively and statistically using image analysis. Quantitative image analyses on the sintered SiC ceramics were conducted on the grain size, aspect ratio and grain size distribution of SiC. The microstructure of SiC sintered up to $1700^{\circ}C$ consisted of equiaxed grains. In contrast, the growth of large elongated SiC grains in small matrix grains was shown in sintered bodies at $1750^{\circ}C$ and the plate-like grains interlocking microstructure had been developed by increasing sintering temperature. The introduction of $\alpha$-SiC seeds into $\beta$-SiC accelerated the grain growth of elongated grains during sintering, resulting in the plate-like grains interlocking microstructure. In the $\alpha$-SiC seeds added in $\beta$-SiC, the rate of grain growth decreased with $\alpha$-SiC seed content, however, bulk density and aspect ratio of grains in sintered body increased.

• 대한치과기공학회지
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• 제42권2호
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• pp.73-79
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• 2020

Purpose: The aim of this study was to investigate the influence of short and long duration sintering on microstructure and flexural strength of zirconia. Methods: To conduct three-point bending test, Zirconia specimens are milled according to ISO 6872 guidelines(N=18, n=9 per group). Two specimens group(n=8) is sintered for 10 hours(Standard schedule) and 3 hours(Speed schedule) at the peak temperature of 1550℃ with silicon carbide sintering furnace. Flexural strength of specimens are measured by instron. After coating each specimen(n=1), microstructure of specimens is observed using Scanning Electron Microscope(SEM). T-test was utilized to statistically assess the data. Results: The mean and standard deviation value of the flexural strength for standard schedule group are 578.15±57.48Mpa, that of speed schedule are 465.9±62.34Mpa. T-test showed significant differences in flexural strength between two zirconia specimen group which applied standard schedule and speed schedule respectively(p<0.05). Conclusion: The result of this study showed that the increase in sintering time led to increased grain size, and also to a positive effect on the flexural strength.