• Title/Summary/Keyword: ZrB22

Search Result 345, Processing Time 0.027 seconds

The Electric Properties of Multilayer Ceramic Capacitors with (Ba,Ca)(TiZr)O3(Ba,Ca)(TiZr)O3 Ceramics ((Ba,Ca)(TiZr)O3(Ba,Ca)(TiZr)O3 세라믹을 적용한 적층 칩 커패시터의 전기적 특성)

  • Yoon Jung-Rag;Yeo Dong-Hun;Lee Heun-Young;Lee Suk Won
    • The Transactions of the Korean Institute of Electrical Engineers C
    • /
    • v.55 no.1
    • /
    • pp.1-5
    • /
    • 2006
  • The effect of A/B moi ratios and sintering temperatures on dielectric properties and microstructure of (Ba0.93Ca0.07)m(Ti0.82Zr0.18)O3(Ba0.93Ca0.07)m(Ti0.82Zr0.18)O3 ceramics were investigated. The dielectric constant decreased with increasing the A/B mol ratio. However, the dielectric loss is improved. As the dielectric properties of A/B mol ratio with m = 1.009 at sintered temperature 1260C1260C, we obtained dielectric constant 12,800, dielectric loss 3.5%3.5% and Y5V temperature characteristics. Highly reliable Ni-MLCCs, 1.6mm(length)\time0.8mm(width)\time0.8mm(length)\time0.8mm(width)\time0.8mm(height) with capacitance of 1.23 μFμF and 야ssipation loss of 5.2%5.2% were obtained employing dielectric material composed of (Ba0.93Ca0.07)1.009(Ti0.82Zr0.18)O3(Ba0.93Ca0.07)1.009(Ti0.82Zr0.18)O3 - MnO20.2wt%Y2O30.18wt%,SO20.15wt%(Ba0.4Ca0.6)SiO31wt%MnO20.2wt%Y2O30.18wt%,SO20.15wt%(Ba0.4Ca0.6)SiO31wt%.

Phase Evolution and Thermo-physical Properties of La2(Zr1-xHfx)2O7 Oxides for Thermal Barrier Coatings (열차폐코팅용 La2(Zr1-xHfx)2O7 산화물의 상형성과 열물성)

  • Kim, Seong-Won;Lee, Sung-Min;Oh, Yoon-Suk;Kim, Hyung-Tae;Jang, Byung-Koog
    • Journal of Powder Materials
    • /
    • v.18 no.6
    • /
    • pp.568-574
    • /
    • 2011
  • As operating temperatures of engines or turbines continually increase for higher efficiency, significant amounts of researches have been focused on finding new materials, which would be alternatives to conventional yttria-stabilized zirconia (YSZ) for thermal barrier coatings (TBCs). In this study, phase evolution and thermo-physical properties of La2(Zr1xHfx)2O7La2(Zr1xHfx)2O7 pyrochlore systems are investigated for TBC applications. La2(Zr1xHfx)2O7La2(Zr1xHfx)2O7 systems are comprised by selecting La3+La3+ as A-site ions and Zr4+/Hf4+Zr4+/Hf4+ as B-site ions in A2B2O7A2B2O7 pyrochlore structures. For the developed phases in La2(Zr1xHfx)2O7La2(Zr1xHfx)2O7 compositions, thermo-physical properties such as thermal conductivity, thermal expansion coefficient are examined. The potential of these La2(Zr1xHfx)2O7La2(Zr1xHfx)2O7 compositions for TBC application is also discussed.

Effects of Calcination Process and ZrO2ZrO2 Addition on the Electrical Properties of BaTiO3BaTiO3 Ceramics (하소공정과 ZrO2ZrO2 첨가량이 BaTiO3BaTiO3의 전기적 특성에 미치는 영향)

  • 차진이;박재관;오태성;김윤호
    • Journal of the Korean Ceramic Society
    • /
    • v.28 no.11
    • /
    • pp.935-941
    • /
    • 1991
  • Effects of calcination process and ZrO2 addition on the electrical properties of [(Ba0.82Sr0.08Ca0.1)O]m(Ti1-χχZrχχ)O2 ceramics have been investigated. With the variation of A/B-site ratio m of the dielectric formulations, sintering behavior and the resistivity after sintering in a reducing atmosphere have been affected by the calcination process. When the dielectric formulations of m=1.01 were sintered in a reducing atmosphere, the room-temperature resitivity of 109 {{{{ OMEGA }}.cm was obtained for samples processed with two-step calcination, which was much lower than 1012 {{{{ OMEGA }}.cm of samples calcined once. It was confirmed that high resistivity of Ca-doped BaTiO3 ceramics, after sintering in a reducing atmosphere, is maintained by acceptor-like behavior of CaTi" which is formed by Ca substitution to Ti-site. It was also found out that the critical amount of B-site Ca substitution for reduction inhibition of BaTiO3 is around 0.005 mol. With the increasing amount of ZrO2 addition to dielectric formulations, Curie peak was depressed and Curie temperature was lowered due to the enhanced diffuse phase transition.tion.

  • PDF

Fabrication of ZrB2/SiC/WC composites via spark plasma sintering and enhancement of oxidation resistance

  • Jae-Seok Choi;Jung-Hun Kim;Jae Uk Hur;Sung-Churl Choi;Gye-Seok An
    • Journal of Ceramic Processing Research
    • /
    • v.21 no.3
    • /
    • pp.351-357
    • /
    • 2020
  • To prevent the oxidation of ultra-high-temperature ceramic zirconium diboride (ZrB2) at high temperatures, this study fabricated sintered composites containing silicon carbide and tungsten carbide, and examined the properties related to hightemperature oxidation. Spark plasma sintering was employed for rapid sintering, and a high-temperature torch test was conducted on samples to determine their surface oxidation behaviour. The composites oxidised at high temperature showed different surface oxidation behaviour according to the type of carbide-based additive. Composites containing both carbides, which have different oxidation mechanisms, exhibited better resistance to oxidation than those containing a single carbide.

A Study on Optimum Spark Plasma Sintering Conditions for Conductive SiC-ZrB2 Composites

  • Lee, Jung-Hoon;Ju, Jin-Young;Kim, Cheol-Ho;Shin, Yong-Deok
    • Journal of Electrical Engineering and Technology
    • /
    • v.6 no.4
    • /
    • pp.543-550
    • /
    • 2011
  • Conductive SiC-ZrB2ZrB2 composites were produced by subjecting a 40:60 (vol%) mixture of zirconium diboride (ZrB2) powder and ββ-silicon carbide (SiC) matrix to spark plasma sintering (SPS). Sintering was carried out for 5 min in an argon atmosphere at a uniaxial pressure and temperature of 50 MPa and 1500C1500C, respectively. The composite sintered at a heating speed of 25C25C/min and an on/off pulse sequence of 12:2 was denoted as SZ12L. Composites SZ12H, SZ48H, and SZ10H were obtained by sintering at a heating speed of 100C100C/min and at on/off pulse sequences of 12:2, 48:8, and 10:9, respectively. The physical, electrical, and mechanical properties of the SiC-ZrB2ZrB2 composites were examined and thermal image analysis of the composites was performed. The apparent porosities of SZ12L, SZ12H, SZ48H, and SZ10H were 13.35%, 0.60%, 12.28%, and 9.75%, respectively. At room temperature, SZ12L had the lowest flexural strength (286.90 MPa), whereas SZ12H had the highest flexural strength (1011.34 MPa). Between room temperature and 500C500C, the SiC-ZrB2ZrB2 composites had a positive temperature coefficient of resistance (PTCR) and linear V-I characteristics. SZ12H had the lowest PTCR and highest electrical resistivity among all the composites. The optimum SPS conditions for the production of energy-friendly SiC-ZrB2ZrB2 composites are as follows: 1) an argon atmosphere, 2) a constant pressure of 50 MPa throughout the sintering process, 3) an on/off pulse sequence of 12:2 (pulse duration: 2.78 ms), and 4) a final sintering temperature of 1500C1500C at a speed of 100C100C/min and sintering for 5 min at 1500C1500C.

Effects of Bi2Bi2O3O3 additions on the dielectric and piezoelectric properties in Pb(Zr0.54Zr0.54, Ti0.46Ti0.46)O3O3 (Bi2Bi2O3O3첨가량이 Pb(Zr0.54Zr0.54, Ti0.46Ti0.46)O3O3의 유전, 압전특성에 미치는 영향)

  • 배이열;서동수
    • Electrical & Electronic Materials
    • /
    • v.6 no.3
    • /
    • pp.207-213
    • /
    • 1993
  • Pb(Z r0.54r0.54, Ti0.46Ti0.46) O3O3에 B i2i2 O3O3를 0.0wt%까지 첨가하여 미세구조, 유전, 압전, 성질에 미치는 영향을 고찰하였다. B i2i2 O3O3의 고용범위는 약 0.5~0.7wt%정도 이었고 B i2i2 O3O3 첨가량이 증가함에 따라서 결정립의 크기가 감소하였다. B i2i2 O3O3첨가량이 증가함에 따라 고용한계까지는 d33d33 , tan .delta., .xi.rr(분극후)값이 증가하였으며 Qm값과 밀도는 감소하였다. KpKp 값은 B i3+i3+ 가 P b2+b2+를 치환하므로 형성되는 Pb공공의 형성에 의해 자발분극이 증가됨에 따라 증가하였다.다.

  • PDF

Application of Taguchi Method and Orthogonal Arrays for Optimization of Adhesion of SrZrO3SrZrO3 Coatings on Ag/Bi(2223) Tapes

  • Lee, Se-Jong;Lee, Deuk-Yong;Song, Yo-Seung;Kim, Bae-Yeon
    • Progress in Superconductivity and Cryogenics
    • /
    • v.5 no.1
    • /
    • pp.13-16
    • /
    • 2003
  • Adhesion of SrZrO3SrZrO3 resistive oxide barrier on Ag sheathed Bi(2223) tapes prepared by the sol-gel and dip-coating method was evaluated with an aid of Taguchi method and Lie(21×3721×37) orthogonal arrays to determine the optimal process combination of levels of factors that best satisfy the bigger is better quality characteristic (QC=B). For analyses of results statistical calculations such as average and analysis of variance (ANOVA) were employed to analyze the results for improving the performance qualities of the dip-coated SrZrO3SrZrO3 film. Experimentally, the performance of the films was evaluated in terms of bond strength by varying Sr/Zr moi ratio (A), amount of organic vehicle additives (B), drying temperature (C) and time (D), heat treatment temperature (E) and time (F), respectively. The optimal combination of levels of factors was determined to be A3B2C3D2E1F3A3B2C3D2E1F3 having a 90% confidence level.

Effect of Sintering Temperature on Properties of ββ-SiC-ZrB2ZrB2 Composites Manufactured by Pressureless Sintering (상압소결법에 의해 제조한 ββ-SiC-ZrB2ZrB2 복합체의 특성에 미치는 소결온도의 영향)

  • Ju, Jin-Young;Shin, Yong-Deok
    • Proceedings of the KIEE Conference
    • /
    • 2001.07c
    • /
    • pp.1436-1438
    • /
    • 2001
  • The ββ-SiC + ZrB2ZrB2 ceramic electroconductive composites were pressureless-sintered and annealed by adding 12wt% Al2O3Al2O3 + Y2O3Y2O3 (6 : 4wt%) powder as a function of sintering temperature. The relative density showed the highest value of 81.1% at 1900CC sintering temperature. The phase analysis of the composites by XRD revealed of αα-SiC(6H), TiB2TiB2, Al5Y2O12Al5Y2O12 and ββ-SiC(15R). Flexural strength showed the highest value of 230 MPa for composites sintered at 1900CC. The vicker's hardness and the fracture toughness showed the highest value of increased with increasing sintering temperature and showed the highest of 9.88 GPa and 6.05 MPam1/2MPam1/2 at 1900CC. The electrical resistivity was measured by the Pauw method from 25CC to 700CC. The electrical resistivity of the composites showed the PTCR (Positive Temperature Coefficient Resistivity).

  • PDF

Inclusion and mechanical properties of ODS-RAFM steels with Y, Ti, and Zr fabricated by melting

  • Qiu, Guo-xing;Wei, Xu-li;Bai, Chong;Miao, De-jun;Cao, Lei;Li, Xiao-ming
    • Nuclear Engineering and Technology
    • /
    • v.54 no.7
    • /
    • pp.2376-2385
    • /
    • 2022
  • Two groups of oxide dispersion-strengthened reduced-activation ferritic/martensitic steels (A and B) were prepared by adding Y, Ti, and Zr into steels through vacuum induction melting to investigate the inclusions, microstructures, mechanical properties of the alloys. Results showed that particles with Y, Ti, and Zr easily formed. Massive, Zr-rich inclusions were found in B steel. Density of micron inclusions in A steel was 1.42 × 1014 m-3, and density of nanoparticles was 3.61 × 1016 m-3. More and finer MX carbides were found in steel tempered at 650 ℃, and yield strengths (YS) of A and B steel were 714±2 and 664±3.5 MPa. Thermomechanical processing (TMP) retained many dislocations, which improved the mechanical properties. YSs of A and B treated by TMP were 725±3 and 683±4 MPa. The existence of massive Zr-rich inclusions in B steels interrupted the continuity of the matrix and produced microcracks (fracture), which caused a reduction in mechanical properties. The presence of fine prior austenite grain size and inclusions was attributed to the low DBTTs of the A steels; DBTTs of A650 and A700 alloy were -79 and -65 ℃. Tempering temperature reduction and TMP are simple, readily useable methods that can lead to a superior balance of strength and impact toughness in industry applications.

Effects of A-site Ca and B-site Zr Substitution on the Dielectric Characteristics and Microstructure of BaTiO3-CaTiO3 Composite (A-site Ca 및 B-site Zr 첨가에 의한 BaTiO3-CaTiO3복합체의 유전특성 및 미세구조에 미치는 영향)

  • 윤만순;박영민
    • Journal of the Korean Ceramic Society
    • /
    • v.40 no.1
    • /
    • pp.37-45
    • /
    • 2003
  • The dielectric and sintering characteristics of composites made by substituting Ca ion to Ba-site and Zr ion to Ti site in $(Ba{1-x}Ca_x)(Ti{0.96-yZr_ySn_{0.04})O_3$ (0.15x0.20,0.09y0.14)(0.15x0.20,0.09y0.14) were investigated. As the content of Ca was more than 15 mol%, composite was formed by precipitating the second phase whose main element was CaTiO3CaTiO3 and the fraction of the second phase was increased. The curie temperature of composites was depended on Ca concentration, 1.7C per mol% and the maximum dielectric constant of composite was decreased by the rate of 200/mol%. The substitution of Zr ion decreased the curie temperature by the rate of 10C per mol% and the maximum dielectric constant was decreased by 217/mol% due to the increase of diffuse phase transition. The density and insulation breakdown characteristics were improved by suppressing the abnormal grain growth due to the increase of second phase. We developed the composition of Y5U (EIA standard) condenser which had high breakdown voltage and dielectric constant by controlling diffuse phase transition by the addition of Zr ion into composite.