• Journal of Powder Materials
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• v.23 no.1
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• pp.1-7
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• 2016

Cu-Mn compacts are fabricated by the pulsed current activated sintering method (PCAS) for sputtering target application. For fabricating the compacts, optimized sintering conditions such as the temperature, pulse ratio, pressure, and heating rate are controlled during the sintering process. The final sintering temperature and heating rate required to fabricate the target materials having high density are $700^{\circ}C$ and $80^{\circ}C/min$, respectively. The heating directly progresses up to $700^{\circ}C$ with a 3 min holding time. The sputtering target materials having high relative density of 100% are fabricated by employing a uniaxial pressure of 60 MPa and a sintering temperature of $700^{\circ}C$ without any significant change in the grain size. Also, the shrinkage displacement of the Cu-Mn target materials considerably increases with an increase in the pressure at sintering temperatures up to $700^{\circ}C$.

• Journal of Technologic Dentistry
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• v.36 no.1
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• pp.9-15
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• 2014

Purpose: Generally dental technicians clinically decide the sintering temperature of zirconia artificial teeth to match the color of the teeth. However, the sintering temperature influence the microstructure and mechanical strength of ceramic body. In this study, to evaluate the free choice of sintering temperature which leads to color the problems in zirconia false teeth, the variation of microstructure, mechanical strength, and colortone of zirconia ceramics according to the change of sintering temperature was investigated. Methods: Bar type specimens were prepared from commercial zirconia blocks by cutting and polishing into $0.8cm(L){\times}1.0cm(W){\times}4.8cm(H)$. Specimens were fired from 1,400 to $1,700^{\circ}C$ at $50^{\circ}C$ intervals and held for 1hour at highest temperature. Apparent porosity, water absorption, firing shrinkage, bulk density, bend strength, whiteness were tested. Microstructures were observed by SEM. Results: When fired above $1450^{\circ}C$, all specimens showed 0% apparent porosity and water absorption, 20% firing shrinkage, and $6.1g/cm^3$ bulk density regardless of firing temperatures. SEM photomicrographs showed grain growth of zirconia occurred above $1,600^{\circ}C$. Whiteness was also largely changed above this temperature. Maximum bend strength of 1,05MPa was obtained at $1,550^{\circ}C$. Bend strength lowered slightly above this temperature and showed $950{\ss}\acute{A}$ at $1,700^{\circ}C$. Conclusion: In order to fit the colortone of zirconia artificial teeth, arbitrary choice of firing temperature higher than $1,500^{\circ}C$, up to $1,700^{\circ}C$ did not influence the mechanical strength.

• Journal of the Korea Institute of Building Construction
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• v.10 no.3
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• pp.49-56
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• 2010

The purpose of this study is to examine the effect of variations in the mix rate of PVA fiber and the replacement ratio of non-sintering Hwangtoh on non-sintering Hwangtoh mortar and concrete mixed with PVA fiber. For water to binder ratio, mortar and concrete were both 50%, and PVA fiber mix rate was 0% and 0.3%. The replacement ratio of non-sintering Hwangtoh was 0, 25, 50 and 75(%) for mortar, and 0, 15, 30 and 50(%) for concrete. The properties of the mortar and concrete were compared and analyzed in 4 different levels, and the results can be summarized as follows. The replacement ratio of 30% of the non-sintering Hwangtoh, and the PVA fiber mix rate of 0.3% is determined to result in concrete of high quality, including strength and fluidity, and crack control by plastic shrinkage.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1218-1219
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• 2006

The shrinkage variation of Low Temperature Cofired Ceramics(LTCC) limits the size of the substrates that impose limitations on embedded passive components. This paper focuses on the method of minimizing or controlling planar shrinkage and reducing distortion during firing. The laminated sheets of alumina and glass were sintered at varying temperature, and depending on the amount of the glass ceramics. When the sintered of multi-layer structure with $Al_2O_3/Glass/Al_2O_3$, the glass infiltrated entirely into $Al_2O_3$ layer at the temperature of about $950^{\circ}C$ or higher.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.357-360
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• 2005

This research investigates the drying shrinkage of non-sintering cement(NSC) matrix added phosphogypsum(PG) and waste lime(WL) to granulated blast furnace slag(GBFS) as sulfate and alkali activators with various curing condition. The experimental results are follow: When the moisture is fully supplied at the early curing age, there is effect which carries out abundant generation of the ettringite which is an expansion nature mineral, and compensates for contraction with a chemical prestress concept.

• Journal of the Korean Ceramic Society
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• v.29 no.11
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• pp.843-850
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• 1992

The purpose of this study was to describe the heterogeneity effects on Intermediate/Final microstructure in isothermal liquid phase sintering. Several kinds of pore shapes were made by the different in the heterogeneity stress level during Intermediate/Final stage. Specimen with 48% green density especially showed that the local regions of a sintered compact were subject to more rapid shrinkage than the surroundings. This densification limiting factors generally inhibited sintering and made the large isolated crack-like pore in heterogeneous microstructures.

• Journal of the Microelectronics and Packaging Society
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• v.5 no.2
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• pp.53-58
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• 1998

Sintering and dielectric characteristics of substrates were estimated by mixing rate of alumina and potashborosilicate glass(PBSG) powders. PBSG powders were used 7761(corning code)and alumina powders were used in extra pure rate(99.9%) and had 0.1 ${\mu}$m mean size. After ball milling with organic additives green sheets which were casted by doctor blade machine were sintered at 800$^{\circ}C$ for 1∼3hrs. Microstructure, linear shrinkage and dielectric constant of substrates were surveyed in order to fabricate low-dielectric and low tem-perature sintering substrate.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.05a
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• pp.507-511
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• 2008

LTCC (Low Temperature Co-fired Ceramic) has been successfully applied to ceramic substrates for circuits and micro-fluidic systems and has proven its superior performance in a variety of applications. The prediction of shrinkage in LTCC process is an important for dimensional control of micro LTCC products which has influences on electronic characteristics. For avoiding the unpredictable shrinkage of LTCC during the sintering which makes accurate placement of the circuit devices difficult, pre-processes such as WIP (Warm Isostatic Pressing) and lamination must be modified. The objective of the present investigation is to establish a proper WIP conditions for near net shape fabrication of LTCC products. This paper discusses the influence of WIP conditions on the dimensional change of LTCC sheet. In the investigation, it is shown that the shrinkage values of sheets depend on WIP conditions and sheet directions. This work is a quantitative evaluation of the effect of WIP pressure on shrinkage of LTCC sheet. Additionally, the results show anisotropic shrinkage behaviour of sheet during LTCC process.

• Journal of Powder Materials
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• v.9 no.1
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• pp.50-60
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• 2002

SPS(Spark Plasma Sintering ) is known to be an excellent sintering method for porous materials. In the present work an attempt has been made of fabricating porous 316L Stainless steel with good mechanical properties by using controlled SPS process Porosity was 21%~53% at sintering temperature of $600^{\circ}C$~100$0^{\circ}C$ The limit of porosity with available mechanical strength was 30% at given experimental conditions. Porosity can be controlled by manipulating the intial height of the compact by means of the supporter and punch length. The applied pressure can be exerted entirely upon the supporter, giving no influence on the specimen. The specimen is then able to be sintered pressurelessly. In this case porosity could be controlled from 38 to 45% with good mechanical strength at sintering temperature of 90$0^{\circ}C$. As the holding time increased, neck between the particles grew progressively, but shrinkage of the specimen did not occur, implying that the porosity remained constant during the whole sintering process.

• Journal of Korea Foundry Society
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• v.10 no.1
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• pp.64-70
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• 1990

In order to lower the cabon content of sintered products below the solubility of austenite, Fe-oxide was added to cast iron powder of which matrix was pearlite. And the effects of it on some sintering properties and mechanical properties were investigated. Roughly speaking, the linear shrinkage, density, and tensile strendth of sintered properties increased as the sintering temperature became higher, the size distribution of powder became finer, and the amount of Fe-oxide added became less. The maximum tensile strength of sintered products was $78㎏f/mm^2$ more or less, of which carbon content was 1.4% and sintering temperature was $1180^{\circ}C$.