• Proceedings of the Korean Environmental Sciences Society Conference
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• 2006.05a
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• pp.340-341
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• 2006

입자분포가 서로 다른 분체를 소수화 및 친수화 표면을 갖도록 표면개질을 하여 solid casting으로 성형하여 소결함으로써 계면장력에 의한 전기적 반발로 자기배열 구조를 갖는 다층 다공질 구조의 세라믹 담체의 제조가 가능하였다.

• Proceedings of the Materials Research Society of Korea Conference
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• 2005.05a
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• pp.315-315
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• 2005

• Proceedings of the Materials Research Society of Korea Conference
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• 1999.05a
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• pp.60-60
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• 1999

• Proceedings of the Materials Research Society of Korea Conference
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• 2005.05a
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• pp.88-88
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• 2005

• Proceedings of the Materials Research Society of Korea Conference
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• 2005.05a
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• pp.306-306
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• 2005

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.323-324
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• 2006

저온동시 소결용 세라믹스, LTCC를 사용한 RF/MW용 고유전율 세라믹을 개발하기 위하여 300이상의 고유전율과 낮은 손실 계수를 가지는 것으로 알려진 $Ag(Nb_{1/4}Ta_{3/4})O_3$ 고용체와 $CaTiO_3$, $TiO_2$를 각각 혼합하여 공진주파수의 온도 계수가 0에 가까운 안정된 유전체 특성을 얻고자 하였다. 유전율의 온도 안정성을 도모하기 위해 음의 온도 계수를 갖는 $CaTiO_3$, $TiO_2$와 양의 온도계수를 갖는 $CaTiO_3$ 및 $TiO_2$를 일정 분율로 혼합한 복합체 구조의 시편을 제작하였다. LTCC 소자로의 적용을 위해 3wt.%의 CuO를 첨가하여 소결 온도를 낮추었으며, 소결 시편의 상 분석, 미세구조 및 전기적 특성을 조사하였다.

• Journal of the Korean Ceramic Society
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• v.40 no.8
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• pp.751-757
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• 2003

Rapid densification of a SiC-30 wt% TiC powder with additive 10 wt% A1$_2$O$_3$-Y$_2$O$_3$-CaO was conducted by Spark Plasma Sintering(SPS). The fully-densified materials can be obtain through the SPS process with very fast heating rate and short holding time. In the present work, the heating rate and applied pressure were kept to be $100^{\circ}C$/min and 40 MPa, while sintering temperature varied from $1600^{\circ}C$ to $1800^{\circ}C$ for 10 min. The full densification of SiC-30 wt% TiC composites with the addition of $Al_2$O$_3$, $Y_2$O$_3$ and CaO was achieved at the temperature above $1700^{\circ}C$ by spark plasma sintering. The XRD found that 3C-SiC and TiC were maintained the entire SPS process temperature, without phase transformation of SiC and formation of YAG phase to $1800^{\circ}C$. The microstructures of the rapidly densified SiC-30 wt% TiC composites consisted of smaller equiaxed SiC grains and larger TiC grains. The biaxial strength of 635.2 MPa and fracture toughness of 6.12 MPaㆍ$m^{1/2}$ were found for the specimen prepared at $1750^{\circ}C$.

• Journal of the Korean Ceramic Society
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• v.41 no.5
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• pp.375-380
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• 2004

Pb(Ni$\_$1/3/Nb$\_$2/3/)O$_3$-PbZrO$_3$-PbTiO$_3$ thick films were screen-printed on platinized alumina substrates and fired at 800-1000$^{\circ}C$. Two kinds of powders with different particle size were prepared by attrition and ball milling methods. Effects of particle size of starting material on the microstructure and electrical properties of the thick films were investigated. Average particle size of attrition milled-powder (0.44 ${\mu}$m) was much smaller than that of ball milled-powder (2.87 ${\mu}$m). Average grain size of the thick film prepared from attrition-milled powder was smaller than that of the thick film prepared from ball-milled powder at the sintering temperature of 800$^{\circ}C$. However, the difference in average particle size became smaller with increasing the sintering temperature. Thick films prepared from attrition-milled powders showed more uniform and denser microstructures at all firing temperatures. Thick films prepared from attrition-milled powders had better electrical properties at the firing temperature above 900$^{\circ}C$ than thick films prepared from ball-milled powders. Dielectric constant, remanent polarization and coercive field of the thick film prepared from attrition-milled powders and fired at 900$^{\circ}C$ were 559, 16.3 ${\mu}$C/cm$^2$, and 51.3 kV/cm, respectively.

• Journal of the Korean Ceramic Society
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• v.41 no.2
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• pp.165-169
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• 2004

Microwave dielectric properties and the behavior of low-temperature sintering of $Zn_{1-x}(Li_{1/2}La_{1/2})_xTiO_3$ ($0.01{\leq}x{\leq}0.05$) with 4 wt% $H_3BO_3$ were investigated as a function of $(Li_{1/2}La_{1/2})^{2+}$ content. The sintering temperature of the specimens can be reduced from $1150^{\circ}C$ to $875^{\circ}C$ with the addition of 4 wt% $H_3BO_3$ as a sintering agent. Dielectric constant (K) and Temperature Coefficient of resonant Frequency (TCF) with the substitution of ($(Li_{1/2}La_{1/2})^{2+}$ ion depended on dielectric mixing rule. Quality factor (Qf) depended on density and microstructure. Typically, K of 26.5, Qf of 19,030 GHz and TCF of 7.5 ppm$/^{\circ}C$ were obtained for the specimens with x=0.03 sintered at $875^{\circ}C$ for 3 h.

• Journal of the Korean Ceramic Society
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• v.40 no.7
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• pp.677-682
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• 2003

The physical properties of sintered body made from 3 kinds of slip, F (Flocculated), M (Moderate), and D (Dispersed) for coal fly ash 70-clay 30 (wt%) were studied in terms of slip states and pore size distribution of sintered bodies. The floc particle size distribution for slip F was wider than slip D and the slip F contained flocs larger than 11 $\mu\textrm{m}$. The pore size distribution of the green body of all slips ranged over 1∼4 $\mu\textrm{m}$. The pores smaller than 1 $\mu\textrm{m}$ almost disappeared during the sintering process, while the larger pore of 2.5∼3 $\mu\textrm{m}$ growed by 1 $\mu\textrm{m}$. The pore distribution for the green body of slip F became a narrow in width and high in height after sintering and the large pore limit in a slip F sintered body was 5.1 $\mu\textrm{m}$ which is smaller than that of other slip. The slip F rather flocculated was favorable over slip D well dispersed, in offering a higher compressive strength. From these results, the mechanical strength of sintered body is dependent on the pore distribution which could be controlled by dispersion state of the slips.