• 한국세라믹학회지
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• 제26권1호
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• pp.7-12
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• 1989

The effects of composition ratios and sintering conditions in Co1-xMgxO ceramics on the sintering characteristics, electrical properties and oxygen sensing characteristics were investigated. In the same sintering conditions, porosity decreased with increase of MgO contents. The relationshiop of temperature and resistance in Co1-xMgxO ceramics showed NTC(negative temperature coefficient) characteristics at the temperature range from $700^{\circ}C$ to 1,10$0^{\circ}C$. In the case of pure CoO, however, the PTC(positive temperature coefficient) characteristics were shown over about 90$0^{\circ}C$. The electrical conductivity of Co1-xMgxO ceramics decreased proportionally with decrease of oxygen partial pressure at the range from 1 to 10-4(atm). Particularly, Co0.5Mg0.5O ceramics showed the highest sensitivity to oxygen gas.

• 한국분말재료학회지
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• 제22권3호
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• pp.175-180
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• 2015

In this study, ternary compound Max Phase $Ti_2AlC$ material was mixed by 3D ball milling as a function of ball milling time. More than 99.5 wt% pure $Ti_2AlC$ was synthesized by using spark plasma sintering method at 1000, 1100, 1200, and $1300^{\circ}C$ for 60 min. The material characteristics of synthesized samples were examined with relative density, hardness, and electrical conductivity as a function of sintering temperature. The phase composition of bulk was identified by X-ray diffraction. On the basis of FE-SEM result, a terraced structures which consists of several laminated layers were observed. And $Ti_2AlC$ bulk material obtained a vickers hardness of 5.1 GPa at the sintering temperature of $1100^{\circ}C$.

• 한국전기전자재료학회논문지
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• 제15권11호
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• pp.946-952
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• 2002

The electrical and dielectric characteristics of ZPCCY-based varistor ceramics were investigated in the sintering time range of 1∼3 h. Increasing sintering time deteriorated the nonlinearity, in which nonlinear exponent is decreased from 51.2 to 23.8 and leakage current is increased from 1.3 to 5.6 $\mu$A. As sintering time increases, the donor concentration was decreased in the range of (1.25∼l.73)$\times$10$\^$18/cm$\^$-3/ and the density of interface states is (3.64∼94.19)$\times$10$\^$12/cm$\^$-2/ with increasing sintering time. The increase in sintering time caused tan $\delta$ to increase in the range of 0.043 to 0.062 and relaxation time to increase in the range of 1.55 to 2.23 ㎲.

• 한국분말재료학회지
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• 제5권2호
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• pp.89-97
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• 1998

Sintering behavior of nanostructured(NS) W-Cu powders prepared by mechanical alloying (MA) was investigated as a function of sintering temperature. MA NS W-2owt%Cu and W-3owt%Cu composite powders with the crystal size of 20-30 nm were annealed at 90$0^{\circ}C$, and thermal characteristics of those powders were investigated by DSC. Sintering behavior of MA NS W-Cu composite powders was investigated during the solid-state sintering and the Cu-liquid phase sintering. The new nanosintering phenonenon of MA W-Cu powders at solid-state sintering temperature was suggested to explain the W-grain growth in the inside of MA powders. The sintering densification of MA NS W-Cu powders was enhanced at Cu melting temperature by arrangement of MA powders, i.e., the first rearrangement of MA powders was occurred, and then the rearrangement of W-grains in the sintered parts was also took place during liquid-phase sintering, i.e., the second rearrangement was happened. Due to the double rearrangement process of MA NS W-Cu powders, the high sintered density with more than 96%o was obtained and the fine and high homogeneous state of W and Cu phases was achieved by sintering at 1200 $^{\circ}C$.

• 한국기계연구소 소보
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• 통권20호
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• pp.89-104
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• 1990

This study was carried out to obtain the most optimum conition in vacuum sintering of M2 HSS powder, by analysis of sintering characteristics and fracture strength in several conditions. The conclusion deduced from this study are as follows; -Boron was more effective element than graphite; at this time, the optimum amount of addition was 0.05 wt% -The optimum condition of sintering temperature and time were 1190- $1200^{\circ}C$ and 1-1.25hr, respectively -Fracture strength of vacuum sintered and heat-treated specimen in the most optimum condition was 2-2.5KN/ $mm^2$

• 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.

• 센서학회지
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• 제30권3호
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• pp.148-153
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• 2021

During the manufacture of a ZnS lens with excellent transmittance in the mid-infrared region (3-5 ㎛) by the hot-press process, a single-layer sintering method is used in which one lens is manufactured in one process. Additional research is required to improve this single-layer sintering method because of its low manufacturing efficiency. To solve this problem, the variation in optical properties of ZnS lenses with change in sintering temperature was investigated by introducing a Stack sintering method that can sinter multiple lenses simultaneously. A carbon paper was placed between the molded lenses and sintered into five layers. The average permeability of 67% at medium infrared wavelengths of 3-5 ㎛ was excellent under the following sintering conditions: pressure of 50 MPa and temperature of 850℃. This value is 1% less than the average permeability in the case of single-layer sintering of the ZnS lens. It was confirmed that the stack sintering method developed in this study can be used to manufacture a large number of lenses with excellent characteristics in a single process.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 C
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• pp.1582-1584
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• 2004

The microstructure, electrical, and clamping voltage characteristics of ZPCCY-based varistor ceramics were investigated in the sintering time range of 1${\sim}$3 h. Increasing sintering time promoted the densification, in which the average grain size and density are increased in the range of $11.4{\sim}16.0{\mu}m$ and $5.34{\sim}5.54g/cm^3$, respectively. The nonlinear exponent decresed in the range of 60${\sim}$26 and the leakage current increased in the range of $1.3{\sim}10.7{\mu}A$ with increase of sintering time. The clamping voltage ratio was less than 2 for ratio surge current of 10 A over sintering times.

• 한국유체기계학회 논문집
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• 제17권5호
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• pp.72-77
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• 2014

Because of overload working condition of sintering cooler, the cooler fan often suffers the break or damage of rotor blade and fixing shaft. Therefore, internal flow characteristics of a steelworks sintering cooler fan by the duct shape of the cooler fan outlet, such as duct outlet opening ratio, duct height and dividing wall shape on the duct outlet flow pattern are examined in detail. The results show that relatively short duct wall height and attachment of dividing wall shape improves flow patterns considerably.

• 한국생산제조학회지
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• 제23권2호
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• pp.152-156
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• 2014

Lightweight materials such as aluminum and magnesium have recently received much attention in the automotive industries because of environmental and fuel-efficiency concerns. Using the powder metallurgy (PM) process for these materials creates significant opportunities for the cost-effective manufacture of lightweight automotive parts. In the present study, an Al-Cu-Mg alloy was fabricated using conventional PM processes. Primarily, the effects of the alloying elements on the sintering characteristics and mechanical behavior after heat treatment were investigated. A microstructural analysis was performed using an optical microscope and a scanning electron microscope to investigate the behavior of liquid phase sintering, including the formation of precipitates. The dependence of the mechanical behavior on the alloying elements was evaluated based on the transverse rupture strength.