• Title/Summary/Keyword: Y2O3

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Joining Behavior of YSZ Ceramics to Al2O3-ZrO2-SiO2-R2O and Al2O2-ZrO2-SiO2-La2O3-R2O Glass Systems (Al2O3-ZrO2-SiO2-R2O와 Al2O3-ZrO2-SiO2-La2O3-R2O계 유리와 부분안정화 지르코니아간의 접합거동)

  • Choi, Jinsam;Bae, Won Tae
    • Journal of the Korean Ceramic Society
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    • v.52 no.1
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    • pp.19-22
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    • 2015
  • The joining behavior of YSZ ceramics to the glasses used in the $9Al_2O_3-24ZrO_2-51SiO_2-16R_2O$ and $9Al_2O_3-24ZrO_2-51SiO_2-7La_2O_3-9R_2O$ (wt%) glass systems was investigated. The glass transition and softening temperatures were determined to be $430^{\circ}C$ and $760^{\circ}C$, respectively. The behavior of the contact angle was inversely proportional to an increase in the temperature. The Zr element in YSZ acted as a nucleation agent and contributed to the bonding behavior at the interface.

Solid-state reaction kinetics for the formation of mullite($3Al_2O_3{\cdot}2SiO_2$) from amorphous $SiO_2$ and ${alpha}-Al_2O_3$ (비정질 $SiO_2$${alpha}-Al_2O_3$부터 Mullite를 합성하기 위한 고체상태 반응속도)

  • 김익진;곽효섭;고영신
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.8 no.2
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    • pp.332-341
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    • 1998
  • Reaction kinetics for the solid - state reaction of ${\alpha}-Al_2O_3$with amorphous $SiO_2$to produce mullite ($3Al_2O_3;{cdot};2SiO_2$) was studied in the temperature range of 1450~$1480^{\circ}C$. Rate of kinetic reaction were determined by using $SiO_2$- coated $Al_2O_3$ compact containing 28.16 wt.% $SiO_2$and heating the reactant mixtures in MgO at definite temperature for various times. Amount of products and unreacted reactants were determined by X-ray diffractometry. Data from the volume fraction and ratio of peak intensities of mullite indicated that the reaction of ${\alpha}-;Al_2O_3$ with $SiO_2$to form $3Al_2O_3\;{\cdot}\;2SiO_2$ start between 1450 and $1480^{\circ}C$. The activation energy for solid-state reaction was determined by using the Arrhenius equation; The activation energy was 31.9 kJ/mol.

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Experimental Verification of the Decomposition of Y2O3 in Fe-Based ODS Alloys During Mechanical Alloying Process

  • Byun, Jong Min;Park, Chun Woong;Kim, Young Do
    • Metals and materials international
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    • v.24 no.6
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    • pp.1309-1314
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    • 2018
  • In this study, we investigated the state of $Y_2O_3$, as a major additive element in Fe-based ODS alloys, during mechanical alloying (MA) processes by thermodynamic approaches and experimental verification. For this purpose, we introduced $Ti_2O_3$ that formed different reaction products depending on the state of $Y_2O_3$ into the Fe-based ODS alloys. In addition, the reaction products of $Ti_2O_3$, Y, and $Y_2O_3$ powders were predicted approximately based on their formation enthalpy. The experimental results relating to the formation of Y-based complex oxides revealed that $YTiO_3$ and $Y_2Ti_2O_7$ were formed when $Ti_2O_3$ reacted with Y; in contrast, only $Y_2Ti_2O_7$ was detected during the reaction between $Ti_2O_3$ and $Y_2O_3$. In the alloy of $Fe-Cr-Y_2O_3$ with $Ti_2O_3$, $YTiO_3$ (formed by the reaction of $Ti_2O_3$ with Y) was detected after the MA and heat treatment processes were complete, even though $Y_2O_3$ was present in the system. Using these results, it was proved that $Y_2O_3$ decomposed into monoatomic Y and O during the MA process.

Mechanical and Electrical Characteristics of $Al_2O_3-ZrO_2/A_2O_3$-TZP Structural Ceramics ($Al_2O_3-ZrO_2/A_2O_3$-TZP 세라믹스의 제조 및 기계적.전기적 특성)

  • 박재성;남효덕;이희영
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1999.11a
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    • pp.335-338
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    • 1999
  • The effect of monoclinic $ZrO_2$(pure) and tetragonal $ZrO_2$ containing 5.35wt% $Y_2$$O_3$(Y-TZP) addition on the mechanical properties and thermal shock resistance of $Al_2$$O_3$ ceramic were investigated. The addition of $ZrO_2$(m) and Y-TZP increased sintering density of $Al_2$$O_3$. The vickers hardness increased with increasing the volume fraction of Y-TZP going through a maximum at 20wt%. The hardness of the specimens was found to be depend on the sintering density. With increasing the volume fraction of $ZrO_2$(m) and Y-TZP, the fracture toughness of the composite is increased. This result may be taken as evidence that toughening of ${Al_2}{O_3}$ can also be achieved by the transformation toughening and microcrack toughening of $ZrO_2$. The property of the& shock for ${Al_2}{O_3}$-$ZrO_2$ composites was improved by increasing the volume fraction of monoclinic $ZrO_2$(pure).Grain size increased with increasing the volume fraction of $ZrO_2$.

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Effect of In2O3 Doping on the Properties of ZnO Films as a Transparent Conducting Oxide (투명전도성 ZnO 박막의 특성에 미치는 In2O3 첨가에 따른 영향)

  • Lee, Choon-Ho;Kim, Sun-Il
    • Journal of the Korean Ceramic Society
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    • v.41 no.1
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    • pp.57-61
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    • 2004
  • Zinc Oxide (ZnO) have the crystal structure of wurtzite which is semiconducting oxide with band gap energy of 3.3eV. $In_2O_3$-doped ZnO films were fabricated by electron beam evaporation at $400^{\circ}C$ and their characteristics were investigated. The content of $In_2O_3$ in ZnO films had a marked effect on the electrical properties of the films. As $In_2O_3$ content decreased. $In_2O_3$-doped ZnO films was converted amorphous into crystallized films and showed a better characteristics generally as a transparent conducting oxide. As $In_2O_3$-doped ZnO films were prepared by $In_2O_3$-doped ZnO pellet with 0.2at% of $In_2O_3$ content, the value of resistivity was about $6.0 {\times} 10^{-3} {\Omega}cm$. The transmittance was higher than 85% throughout the visible range.

Effect of Composition of Bond Coating on the Durability of the Plasma Sprayed $\textrm{ZrO}_2$-$\textrm{CeO}_2$-$\textrm{Y}_2\textrm{O}_3$ Thermal Barrier Coating (금속결합층의 조성이 $\textrm{ZrO}_2$-$\textrm{CeO}_2$-$\textrm{Y}_2\textrm{O}_3$ 단열층의 내구성에 미치는 영향)

  • Kim, Hye-Seong;Kim, Byeong-Hui;Seo, Dong-Su
    • Korean Journal of Materials Research
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    • v.9 no.1
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    • pp.73-80
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    • 1999
  • The effect of alloy compositions of the bond coating on the plasma sprayed-thermal barrier coatings was investigated. The performance of the coating composed of Rene80/NiCrAl/ZrO$_2$-CeO$_2$-Y$_2$O$_3$ and Rene80/CoNiCrAlY/ZrO$_2$-CeO$_2$-Y$_2$O$_3$was evaluated by isothermal and thermal cyclic test in an ambient atmosphere at 115$0^{\circ}C$. The failure of Rene80/NiCrAl/ZrO$_2$-CeO$_2$-Y$_2$O$_3$ coatings was occurred at the bond coating/ceramic coating interface while Rene80/CoNiCrAlY/ZrO$_2$-CeO$_2$-Y$_2$O$_3$ coating was failed at the substrate/bond coating interface after thermal cyclic test. The lifetime of Rene80/NiCrAl/ZrO$_2$-CeO$_2$-Y$_2$O$_3$coatings was longer than Rene80/CoNiCrAlY/ZrO$_2$-CeO$_2$-Y$_2$O$_3$coating. The oxidation rate of the NiCrAl bond coating examined by TGA was lower than CoNiCrAlY bond coatings. In summary, these results suggest that Rene80/CoNiCrAlY/ZrO$_2$-CeO$_2$-Y$_2$O$_3$system as thermal barrier coating be not suitable considering the durability of the coating layer for high temperature oxidation and thermal stress.

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Comparisons on Dielectric and Peizoelectric Proeprties of Rhombohedral, Tetragonal and Morphotropic Phase Boundary in Pb(Ni1/3Nb2/3)O3-PbTiO3-PbZrO3 System with MnO2 Addition (Pb(Ni1/3Nb2/3)O3-PbTiO3-PbZrO3계의 삼방정, 정방정 및 상경계조성에서의 MnO2 첨가에 따른 유전 및 압전특성에 비교)

  • 전구락;손정호;김정주;조상희
    • Journal of the Korean Ceramic Society
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    • v.25 no.5
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    • pp.488-494
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    • 1988
  • Effects of MnO2 addition on themicrostructure, dielectric and piezoelectric properties of Rhombohedral, Tetragonal and Morphotropic phase boundary(MPB) in Pb(Ni1/3Nb2/3)O3-PbTiO3-PbZrO3 system were investigated and respectively the amount of MnO2 addition was 0, 0.2, 0.5, 1.0, 3.0wt%. In the tetragonal region, compared with the Rhombohedral and Morpotropic phase boundary, Mechanical quality factor(Qm), Curie temperature(Tc) and Dissipation factor were promoted by addition of MnO2. According to the results of the microstructure, dielectric and piezoelectric properties, the solid solution range of MnO2 addition in this system was 0.2-0.5wt%.

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Effect of ${Gd_2}{O_3}$ Addition on the Sintered Density and Resintered Density in <${UO_2}-{Gd_2}{O_3}$ Pellets (${UO_2}-{Gd_2}{O_3}$소결체에서 ${Gd_2}{O_3}$첨가가 소결 및 재소결밀도에 미치는 영향)

  • Baek, Jong-Hyeok
    • Korean Journal of Materials Research
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    • v.5 no.3
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    • pp.364-370
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    • 1995
  • ex-AUC U$O_{2}$ 분말과 $Gd_{2}$O_{3}$ 분말을 기계적으로 혼합하여 소결한 U$O_{2}$-$Gd_{2}$O_{3}$ 소결체의 밀도 변화와 재소결 후 밀도변화를 기공크기 및 분포의 변화로 서술하였다. 수소분위기에서 175$0^{\circ}C$, 4시간 동안 소결하였을 때, 순수 U$O_{2}$의 소결밀도는 97.2% T.D.였으나 6wt% $Gd_{2}$O_{3}$ 첨가까지는 U$O_{2}$-$Gd_{2}$O_{3}$의 소결밀도는 $U^{+4}$와 $Gd^{+4}$의 상호확산 때문에 약 90% T.D.로 급격히 감소하였다. 그러나 6wt% 이상의 $Gd_{2}$O_{3}$가 첨가되면 우라늄이온 산화아와 산소침입으로 인하여 소결밀도는 오히려 증가하였다. 1$700^{\circ}C$에서 재소결시킬 때 순수 U$O_{2}$ 소결체에서는 재소결 시간에 따라 밀도증가가 발생하였다. U$O_{2}$-$Gd_{2}$O_{3}$ 소결체 경우에는 재소결시 밀도가 감소하였으나 재소결 시간이 증가함에 따라 다시 밀도는 증가하였고, 6wt%$Gd_{2}$O_{3}$가 첨가된 U$O_{2}$-$Gd_{2}$O_{3}$ 소결체에서 밀도가 가장 많이 감소하였다.

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Fabrication of $BaTiO_3-PTCR$ Ceramic Resister Prepared by Direct Wet Process (습식 직접합성법을 이용한 PTCR 소자개발 연구)

  • 이경희;이병하;이희승
    • Journal of the Korean Ceramic Society
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    • v.22 no.4
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    • pp.61-65
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    • 1985
  • $BaTiO_3$ powders doped with $BaTiO_3$ and $Nb_2O_5$ at 9$0^{\circ}C$ for 1hr. were synthesized by Direct Wet Process. These powders were very homogeneous and fine particle size. To obtain the highe PTCR effect AST($1/3Al_2O_3$.$3/4SiO_2$.$1/4TiO_2$) and $MnO_2$ were added in the semiconduc-ting $BaTiO_3$. In this case $Bi_2O_3$ and $MnO_2$ were used in the form of $Bi(NO)_3$ and $MnCl_2$.$4H_2O$ solution for Direct Wet Process. $BaTiO_3$ doped Nb2O5 and $MnO_2$ demostrated greater PTCR effect than $BaTiO_3$ doped $Nn_2O_5$ only.

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The Effects of $MnO_2$ and $Cr_2O_3$ on Piezoelectric Properties of $Pb(Mg_{1/2}W_{1/2})_{0.3} Ti_{0.4} Zr_{0.3}O_3$ Ceramics ($MnO_2$$Cr_2O_3$$Pb(Mg_{1/2}W_{1/2})_{0.3} Ti_{0.4} Zr_{0.3}O_3$ Ceramics의 압전성질에 미치는 영향)

  • 안영필;박종상
    • Journal of the Korean Ceramic Society
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    • v.19 no.4
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    • pp.293-299
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    • 1982
  • The effects of $MnO_2$ and $Cr_2O_3$ on the Piezoelectrictric properties of Pb(Mg1/2W1/2)0.3 Ti0.4 Zr0.3O3 Ceramics. Electromechanical properties in the system in connection with the sintering temperature and the effects of $MnO_2$ and $Cr_2O_3$ addition. The dielectric constant of the ceramics decreased with the additions of $MnO_2$ while the additions of $Cr_2O_3$ increased the value. The Planar coupling factor (Kp) of the ceramics with 0.2wt% $MnO_2$ and with 0.2wt% $Cr_2O_3$ gave the highest value of 0.52 and 0.513 as sintered at 106$0^{\circ}C$, 108$0^{\circ}C$, respectively. The value of mechanical Q-factor were in parallel with the fired density of the ceramics. The optical micrography of the sintered bodies showed that the additions of $MnO_2$ promoted the grain growth, while the additions of $Cr_2O_3$ retarded the grain growth.

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