• 제목/요약/키워드: ZrO_2$

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Surface acoustic wave characteristics of Pb(Sn1/2Sb1/2)O3PbZrO3PbTiO3 ceramics (Pb(Sn1/2Sb1/2)O3PbZrO3PbTiO3 세라믹스의 탄성 표면파 특성)

  • 홍재일;김준한;유주현;강진규;위규진;박창엽
    • Electrical & Electronic Materials
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    • v.4 no.3
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    • pp.220-228
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    • 1991
  • 본 연구에서는 핫프레스법으로 제작된 0.05Pb(Sn12/Sb12/)O3-0.60PbZrO3-0.35PbTiO3+x[wt%]MnO2 세라믹스에 대해 구조적, 전기적 특성 및 탄성 표면파 특성을 조사하였다. x가 0.4인 조성을 1150[.deg.C]에서 45분간 소성한 시편의 경우 탄성표명파의 전기 기계 결합 계수 ks 2가 2.8[%], 기계적 품질 계수 Qm 이 1976으로 탄성 표면파 소자용 기판으로서 응용 가능함을 보였다.

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Electrical Conductivities of [(ZrO2)1x(CeO2)x]0.92(Y2O3)0.08 Solid Solution ([(ZrO2)1x(CeO2)x0.92(Y2O3)0.08 고용체의 전기전도도)

  • 이창호;최경만
    • Journal of the Korean Ceramic Society
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    • v.35 no.12
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    • pp.1323-1328
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    • 1998
  • The electrical conductivities of the yttria (8mol%) stabilizedzirconia-ceria solid solutions were measured as a function of oxygen partial between 800C and 1000C using 4-probe d.c. method Under pure oxygen atmosphere the oxygen ionic conductivity of CeO2-ZrO2 decreased with the concentration of CeO2 Under reducing condition electronic conduction due to the redox equilibrium of Ce ion was observed. Total ionic and electronic conductivities fitted by a defect model enabled to determine the electronic transference number(tei) which increased with the concentration of CeO2 and with the degree of reduction.

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Study on Sliding Wear Characteristics and Processing of MoSi

  • Park, Sungho;Park, Wonjo;Huh, Sunchul
    • International Journal of Ocean System Engineering
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    • v.2 no.4
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    • pp.244-249
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    • 2012
  • In this study, a monolithic MoSi2 matrix reinforced with 20 vol% SiC particles, a SiC/MoSi2 composite matrix reinforced with 20 vol% ZrO2 particles, and a ZrO2/MoSi2 composite were fabricated using hot press sintering at 1350C for 1 h under a pressure of 30 MPa. The Vickers hardness and sliding wear resistance of the monolithic MoSi2, ZrO2/MoSi2, and SiC/MoSi2 composite were investigated at room temperature. A wear behavior test was carried out using a disk-type wear tester with a silicon nitride ball. The ZrO2/MoSi2 composite showed an average Vickers hardness value and excellent wear resistance compared with the monolithic MoSi2 and SiC/MoSi2 composite at room temperature.

Syngas and Hydrogen Production from CeO2/ZrO2 coated foam device under concentrated solar radiation (고온 태양열을 이용한 합성가스 및 수소 생산에서 CeO2/ZrO2가 코팅된 다공성 폼의 영향)

  • Jang, Jong-Tak;Yoon, Ki-June;Han, Gui-Young
    • 한국태양에너지학회:학술대회논문집
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    • 2011.11a
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    • pp.307-313
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    • 2011
  • 금속산화물을 이용한 2단계 산화/환원 반응은 GTL, CTL 의 반응원료인 합성가스 및 수소 생산기술이다. 이 기술은 메탄을 환원제로 사용함으로써 비교적 저온에서 산화/환원 반응을 할 수 있는 장점이 있다. 하지만 반복 사이클의 시연에서 금속산화물의 소결현상으로 인한 활성저하가 이 기술의 문제점 중의 하나이다. 본 연구에서는 2.5 kW Xenon arc lamp 가 설치된 solar simulator를 사용 하였으며, 무기물 다공성 폼 (SiC foam)및 유기물 다공성 폼 (Ni, Cufoam)에 CeO2/ZrO2 를 코팅하여 연속적인 합성가스 및 수소 생산 가능성을 알아보았다. 반응 전 후의 CeO2/ZrO2 의 결정 구조를 SEM 과 XRD 를 통해 분석하였다.

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Impact of ZrO2 nanoparticles addition on flexural properties of denture base resin with different thickness

  • Albasarah, Sara;Al Abdulghani, Hanan;Alaseef, Nawarah;al-Qarni, Faisal D.;Akhtar, Sultan;Khan, Soban Q.;Ateeq, Ijlal Shahrukh;Gad, Mohammed M.
    • The Journal of Advanced Prosthodontics
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    • v.13 no.4
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    • pp.226-236
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    • 2021
  • PURPOSE. This study aimed to evaluate the effect of incorporating zirconium oxide nanoparticles (nano-ZrO2) in polymethylmethacrylate (PMMA) denture base resin on flexural properties at different material thicknesses. MATERIALS AND METHODS. Heat polymerized acrylic resin specimens (N = 120) were fabricated and divided into 4 groups according to denture base thickness (2.5 mm, 2.0 mm, 1.5 mm, 1.0 mm). Each group was subdivided into 3 subgroups (n = 10) according to nano-ZrO2 concentration (0%, 2.5%, and 5%). Flexural strength and elastic modulus were evaluated using a three-point bending test. One-way ANOVA, Tukey's post hoc, and two-way ANOVA were used for data analysis (α = .05). Scanning electron microscopy (SEM) was used for fracture surface analysis and nanoparticles distributions. RESULTS. Groups with 0% nano-ZrO2 showed no significant difference in the flexural strength as thickness decreased (P = .153). The addition of nano-zirconia significantly increased the flexural strength (P < .001). The highest value was with 5% nano-ZrO2 and 2 mm-thickness (125.4 ± 18.3 MPa), followed by 5% nano-ZrO2 and 1.5 mm-thickness (110.3 ± 8.5 MPa). Moreover, the effect of various concentration levels on elastic modulus was statistically significant for 2 mm thickness (P = .001), but the combined effect of thickness and concentration on elastic modulus was insignificant (P = .10). CONCLUSION. Reinforcement of denture base material with nano-ZrO2 significantly increased flexural strength and modulus of elasticity. Reducing material thickness did not decrease flexural strength when nano-ZrO2 was incorporated. In clinical practice, when low thickness of denture base material is indicated, PMMA/nano-ZrO2 could be used with minimum acceptable thickness of 1.5 mm.

Electrical Properties of PZT/BT Mulitilayered Films (PZT/BT 박막의 전기적 특성)

  • Lee, Sang-Heon;Nam, Sung-Pil;Lee, Young-Hie;Park, Jae-Jun
    • Proceedings of the KIEE Conference
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    • 2005.11a
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    • pp.189-190
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    • 2005
  • Ploycrystalline $Pb(Zr_{0.5},Ti_{0.5))O_3$ and BaTiO3 powder were prepared by sol-gel process. The alumina substrate were sintered at 1400C with bottom electrode of Pt for 2 hours. The Pb(Zr0.5,Ti0.5)O3 / BaTiO3 multilayered thick films with laminating times were fabricated on alumina substrate by screening printing method. The obtained thick films were sintered at 800C with upper electrode of Ag paste for 1 hour. Structural properties of Pb(Zr0.5,Ti0.5)O3 / BaTiO3 multilayered thick films were investigated. As a result of the Differential Thermal Analysis(DTA) of Pb(Zr0.5,Ti0.5)O3, exothermic peak was observed at around 650 C. The X-ray diffraction (XRD) patterns indicated that BaTiO3 and Pb(Zr0.5,Ti0.5)O3 phases and porosities were formed in the interface of Pb(Zr0.5,Ti0.5)O3 / BaTiO3multilayered thick films.

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Structural Properties of PZT BT Mulitilayered Films (PZT BT 이종 박막의 구조적 특성)

  • Lee, Sang-Heon;Lim, Sung-Soo;Lee, Young-Hie
    • Proceedings of the KIEE Conference
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    • 2005.07c
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    • pp.1960-1961
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    • 2005
  • Ploycrystalline Pb(Zr0.5,Ti0.5)O3 and BaTiO3 powder were prepared by sol-gel process. The alumina substrate were sintered at 1400C with bottom electrode of Pt for 2 hours. The Pb(Zr0.5, Ti0.5)O3/BaTiO3 multilayered thick films with laminating times were fabricated on alumina substrate by screening printing method. The obtained thick films were sintered at 800C with upper electrode of Ag paste for 1 hour, Structural properties of Pb(Zr0.5,Ti0.5)O3/BaTiO3 multilayered thick films were investigated. As a result of the Differential Thermal Analysis(DTA) of Pb(Zr0.5,Ti0.5)O3, exothermic peak was observed at around 650C. The X-ray diffraction (XRD) patterns indicated that BaTiO3 and Pb(Zr0.5,Ti0.5)O3 phases and porosities were formed in the interface of Pb(Zr0.5,Ti0.5)O3 / EaTiO3 multilayered thick films.

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Characteristics of PZT/BT Multilayered thick film using Sol-gel Process (PZT/BT 이종 세라믹의 특성)

  • Lee, Sang-Heon;Lee, Young-Hie;Lee, Sung-Gap
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2005.07a
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    • pp.365-366
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    • 2005
  • PZT films are the most intensively investigated because PZT has advantages such as low processing temperature and large remnant values. In this paper, the microstructure and electric properties of Pb(Zrx,Ti(1x))O3/BaTiO3 heterolayered thick films with Zr mole ranging from 30 to 70 % screen printed onto a alumina substrate were studied. Pb(Zrx,Ti(1x))O3 and BaTiO3 powders were prepared by the sol-gel method. The BaTiO3 powders were calcined at 700C for 2 hours. Structural properties of Pb(Zrx,Ti(1x))O3/BaTiO3 multilayered thick films were investigated. As a result of the X-ray diffraction (XRD) analysis, Pb(Zrx,Ti(1x))O3/BaTiO3 exhibited a perovskite polycrystalline phase without pyrochlore phase or any preferred orientation.

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Zr-Nb 합금의 산과거동 및 Oxide 분석

  • 주기남;권상철;김성수;안상복;김영석
    • Proceedings of the Korean Nuclear Society Conference
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    • 1998.05b
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    • pp.99-104
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    • 1998
  • 400C H2O steam 분위기에서 Zr-2,5wt%Nb 및 Zr-20wt%Nb 합금의 산화거동을 열처리조건에 따른 미세조직 관점에서 고찰하였으며, 형성된 oxide를 분석하여 산화기구를 규명하고자 하였다. Zr-Nb 합금의 산화거동은 열처리에 따라 협성된 조직상에 매우 민감하였는데, 주 조직인 a-Zr 상 보다는 β상들에 (β-Zr, β-Nb) 보다 큰 영향을 받는 것으로 보인다. β-Zr 상은 α-Zr 상에 비해 부식저항성이 낮으며, 그 양에 관계없이 유사한 정도의 부식거동을 보인다. β-Nb 상의 경우, 미세한 크기로 적은양이 존재하는 경우 부식저항성에 별다른 영향이 없어 보이는 반면, 상당량의 β-Nb 상이 조대한 크기로 (약 0,2μm) 존재하는 경우 매우 불안정한 부식거동을 보였다. 이들 β상들의 낮은 산화저항성은 Nb2O5 을 포함한 Nb 계 oxide의 형성에 주로 기인한 것으로 추정된다.

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