• 한국안광학회지
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• 제8권1호
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• pp.17-22
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• 2003

$PbO-Bi_2O_3-B_2O_3-SiO_2$ 유리계의 DTA 곡선과 FT-IR 스펙트럼을 조사하였다. 유리전이 온도의 조성비 의존성은 60 mol% $Bi_2O_3$에서 유리계의 구조가 변화하는 것으로 나타났다. 높은 비스무스 함량을 가지는 시료의 FT-IR 스펙트럼 조사에서 무거운 양이온 $Bi^{3+}$의 단위구조와 관계되는 결합이 우세했으며 그리고 고함량의 $Bi_2O_3$ 시료에서도 역시 붕소원자의 3배위와 4배위 진동이 있었다. PbO함량이 높은 유리계의 경우, 비가교 산소밴드의 낮은 강도는 PbO의 망목형성제 역할에 기인 한 것으로 생각된다. 유리의 흡수대는 결정화상태에서 강도가 매우 큰 변화를 보였다.

• 한국재료학회지
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• 제5권2호
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• pp.246-250
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• 1995

$MgTiO_{3}$에 $CaTiO_{3}$, MgO, CaO를 첨가하여 고주파 유전특성을 조사하였다. 온도계수가 zeo $ppm/^{\circ}C$에 접근하는 ($Mg_{0.915}Ca_{0.085})TiO_{3}$ 조성에서 유전상수값은 22, Qxf 값은 50000, MgO를 0.1mol 첨가한 조성에서는 유전상수는 17, Qxf값은 131000, CaO를 8mol% 첨가한 조성에서 유전상수는 20, Qxf 값은 52000을 나타내엇다. $MgTiO_{3}$에 $CaTiO_{3}$를 단독으로 첨가하는 경우보다 MgO와 CaO를 동시에 첨가할 때 보다 높은 Q값을 갖는 $MgTiO_{3}$계 세라믹스를 제조할 수 있었다.

• 한국대기환경학회지
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• 제20권4호
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• pp.451-463
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• 2004

The performance of disk-type catalytic filters impregnated by TiO$_2$ or TiO$_2$-3Al$_2$O$_3$ㆍ 2SiO$_2$ supports and V$_2$O$_{5}$ catalyst was evaluated for selective catalytic reduction (SCR) of NO with ammonia as a reductant. XRD, FT -IR, BET and SEM were used to characterize the catalytic filters prepared in this work. Optimal V$_2$O$_{5}$ loading and reaction temperature for V$_2$O$_{5}$/TiO$_2$ catalytic filters were 3-6 wt.% and 350-40$0^{\circ}C$ at GHSV 14,300 $hr^{-1}$ in the presence of oxygen, respectively. With increasing the V$_2$O$_{5}$ loading from 0.5 to 6 wt%, NO conversion increased from 24 to 96% at 40$0^{\circ}C$ and 14.300$hr^{-1}$, and maintained at 80% over in the V$_2$O$_{5}$ loading range of 3-6 wt.% and then dropped at V$_2$O$_{5}$ loading of 7wt.% over. In comparing V$_2$O$_{5}$/ TiO$_2$ and V$_2$O$_{5}$/ TiO$_2$-3Al$_2$O$_3$ㆍ2SiO$_2$ catalytic fillers, which have same 3wt.% V$_2$O$_{5}$ loading, the V$_2$O$_{5}$/ TiO$_2$-3A1$_2$O$_3$ㆍ2SiO$_2$ catalytic filter showed higher activity than V$_2$O$_{5}$/ TiO$_2$ catalytic filter, but higher differential pressure drops owing to its low air permeability. low air permeability.

• 한국세라믹학회지
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• 제35권9호
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• pp.905-910
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• 1998

• 한국세라믹학회지
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• 제34권11호
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• pp.1129-1138
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• 1997

Al2O3/20 vol%YAG composite containing equiaxed grains and Al2O3/20 vol%LaAl11O18 composite containing elongated grains were fabricated using Al2O3-Y2O3 composition and Al2O3-La2O3 composition, respectively, by hot-pressing. In order to investigate the influence of microstructural control of second phase on toughening effect of toughened ceramic composites, AE (acoustic emission) measurements have been coupled with fracture toughness experiments(SENB and SEPB method). A separation of the fracture toughness and analysis of toughening mechanism was possible using the AE technique. The fracture toughness of hot-pressed materials was estimated to be 3.2 MPam0.5 for monolithic alumina, 4.7 MPam0.5 for Al2O3/20 vol%YAG composite and 6.2 MPam0.5 for Al2O3/20 vol%LaAl11O18 composite. In monolithic Al2O3, toughening does not occur as a result of either microcracking or grain bridging, whereas, composites exhibit toughening effects by both microcracking in the frontal zone and gain bridging in the wake zone, resulting in an improvement of fracture toughness as compared with monolithic Al2O3. The fracture toughness of Al2O3/20 vol%LaAl11O18 composite is higher than that of Al2O3/20 vol%YAG composite. It may be attributed to the elongated microstructure of Al2O3/20 vol%LaAl11O18 composite, resulting relatively greater bridging effect.

• 한국세라믹학회지
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• 제33권11호
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• pp.1209-1216
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• 1996

MoSi2-Al2O3 composites were prepared by thermal explosion mode of self-propagating high temperature syn-thesis (SHS) using element powders of MoO3 Mo Si and Al. The combustion products of MoSi2 which have 10, 20, 30 and 40 wt% Al2O3 showed the molten state in the range of Mo to MoO3 6:1-9.5:1, 2:1-8:1, 1:1-5:1, and 1:1-3:1 (molar ratio) respectively. The combustion products which made least seperation the molten phase from the slag phase were in Mo/MoO3=9, 5:1, 8:1, 5:1 and 3:1 (molar ratio) respectively. Particles size of MoSi2 and Al2O3 in the combustion product were decreased as the molar ratio of Mo to MoO3 increase. By XRD analysis only MoSi2 and $\alpha$-Al2O3 peaks were identified in the combusion products, In case of MoSi2 containing 20wt% Al2O3 5.1wt% Al existed into MoSi2 grains and 30.7wt% Si and 7.7wt% Mo existed into Al2O3 grains. The relative density of MoSi2 containing 10, 20, 30 and 40 wt% Al2O3 were 82.7, 85.2, and 81.9% respectively. The fracture strength of MoSi2-Al2O3 composites increased with increasing Al2O3 and that of MoSi2-20wt% Al2O3 composite was 195 MPa.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2018년도 춘계 학술논문 발표대회
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• pp.238-239
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• 2018

This paper presents the synthesis results of CaO-Al₂O₃ system clinker using the CaCO₃ and the Al₂O₃ according to the synthesis methods dependent on the temperature. The purpose of this study is the formation of the CaO-Al₂O₃ system clinker containing high ratio of CaO·2Al₂O₃ (CA₂). The maximum sintering temperature for the synthesis of CaO-Al₂O₃ compounds was 1250℃, 1300℃ and 1400℃. The CaO-Al₂O₃ compounds was sintered at the maximum sintering temperature for three hours. After sintering, the compounds was analyzed using X-ray diffraction method. The 12CaO·7Al₂O₃ (C1₂A₇) and CaO·Al₂O₃ (CA) increased as elevating the maximum sintering temperature whereas the CA₂ decreased. Especially, at the 1250℃ of maximum sintering temperature, the un-reacted CaO and Al₂O₃ was identified.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1998년도 추계학술대회 논문집
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• pp.45-48
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• 1998

A BaTiO$_3$ was annexed to SrTiO$_3$, (x)BaTiO$_3$-(1-x)SrTiO$_3$ (0.7$\leq$X$\leq$1) ceramics with stable dielectric and electrical properties in high voltage were manufactured. Structural, dielectric and electrical properties were surveyed with the contents of SrTiO$_3$. The open porosity and sintering density were excellent in 0.9BaTiO$_3$-0.1SrTiO$_3$, the grain size of 0.9BaTiO$_3$-0.1SrTiO$_3$ was maximum at 12.40[${\mu}{\textrm}{m}$]. Increasing SrTiO$_3$ mol ratio, the curie temperature was shifted low temperature and the supreme permittivity was increased. In line with increasing of supplied voltage, permitivity was decreased slightly.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
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• pp.400-403
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• 2004

The dielectric properties of $BaTiO_3/SrTiO_3$ multilayered thick films with printing times were investigated. $BaTiO_3/SrTiO_3$ thick films were deposited by Screen-printing method on alumina substrates. The obtained films were sintered at $1400^{\circ}C$ with bottom electrode(Pt) for 2hours. The structural and the dielectric properties were investigated for various printing times. The BST phase appeared in all of the $BaTiO_3/SrTiO_3$ mutilayered thick films. The $BaTiO_3/SrTiO_3$ multilayered thick film thickness, obtained by one printings, was $50{\mu}m$. The dielectric constant and dielectric loss of the $BaTiO_3/SrTiO_3$ multilayered thick film, obtained by five printings, were about 266, 0.8% at 1Mhz, respectively.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.19-20
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• 2007

At first the $Ba_{0.5}Sr_{0.5}TiO_3$-MgO powder with $B_2O_3-Li_2CO_3$ were made by the Sol-Gel method. The thick films of BST-MgO with $B_2O_3-Li_2CO_3$ were fabricated on the $Al_2O_3$ substrates coated with Pt by the screen printing method. The structural and dielectric properties of the BST-MgO thick film with $B_2O_3-Li_2CO_3$, addition were investigated. The structure of the BST-MgO with $B_2O_3-Li_2CO_3$ thick films were dense and homogeneous with no pores. The dielectric constant was increased and dielectric loss was decreased with increasing the sintering temperature.