• Title/Summary/Keyword: ZrB22

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The Properties of βSiCZrB2βSiCZrB2 Electroconductive Ceramic Composites with Al2O3+Y2O3Al2O3+Y2O3Contents (Al2O3+Y2O3βSiCZrB2계 전도성 복합체의 특성)

  • Shin, Yong-Deok;Ju, Jin-Young;Hwang, Chul
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.49 no.9
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    • pp.516-522
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    • 2000
  • The mechanical and electrical properties of the hot-pressed and annealed βSiCZrB2 electroconductive ceramic composites were investigated as a function of the liquid forming additives ofAl2O3+Y2O3 Phase analysis of composites by XRD revealed αSiC(6H)ZrB2andYAG(Al5Y3O12) The relative density of composites were increased with increased Al2O3+Y2O3 contents. The Flexural strength showed the highest value of 390.6MPa for composites added with 20wt% Al2O3+Y2O3 additives at room temperature. Owing to crack deflection crack bridging phase transition and YAG of fracture toughness mechanism the fracture toughness showed the highest value of 6.3MPa.m1/2 for composites added with 24wt% Al2O3+Y2O3 additives at room temperature. The resistance temperature coefficient showed the value of2.46×103,2.47×103,2.52×103/C for composite added with 16, 20, 24wt% Al2O3+Y2O3 additives respectively. The electrical resistivity of the composites was all positive temperature coefficient resistance(PTCR) in the temperature range of 256Cto900C.

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Composition Control of YSZ Thin Film Prepared by MOCVD

  • Matsuzaki, Tomokazu;Okuda, Norikazu;Shinozaki, Kazuo;Mizutani, Nobuyasu;Funakubo, Hiroshi
    • The Korean Journal of Ceramics
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    • v.6 no.2
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    • pp.134-137
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    • 2000
  • Zirconia films stabilized b Y2O3, YSZ, films were deposition by metal organic chemical vapor deposition (MOCVD) onto various kind of substrates. Y2O3, ZrO2and the mixtures of these two were deposited and characterized. The deposition rate, the film composition and the structure could be systematically varied through the Y(C11H19O2)3, Zr(O.t-C_H_9)_4source gas ratios and the deposition temperature. The Y/Zr ratio in YSZ film could be adjusted by controlling the ratio of Y(C11H19O2)3, Zr(O.t-C4H9)4partial pressures. This is because the ratios of the deposition rates of Y and Zr atoms in Y2O3and ZrO2films to those in YSZ films, Ф, are constant irrespective of the input gas concentration. However, the Y/Zr ratio was found to be smaller than that estimated based on the deposition rates of un-mixed Y2O3and ZrO2films. This is because the Фs of Y and Zr atoms are not equal. The activation energy of Y2O3component in YSZ films was similar to that of ZrO2component in YSZ films. These YSZ values were more than 4 times larger than those of un-mixed Y2O3or ZrO2films.

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Ferroelectric properties of the Ba(La1/2Nb1/2)O3Pb(ZryTi1y)O3ceramics with PbZrO3 contents (투광성 Ba(La1/2Nb1/2)O3Pb(ZryTi1y)O3 세라믹의 PbZrO3조성에 따른 강유전 특성)

  • 류기원;이성갑;배선기;이영희
    • Electrical & Electronic Materials
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    • v.6 no.3
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    • pp.241-247
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    • 1993
  • 본 연구에서는 투광성 0.085Ba(L a12/N b12/) O3- 0.915Pb(Z ry Ti1y) O3(0.45.leq.y.leq.0.70)세라믹을 2단 소성법으로 제작한 후, PbZr O3조성 및 온도에 따른 구조적, 강유전적특성을 측정하였다. XRD측정 결과, PbZr O3조성이 감소할수록 결자상수 및 단위격자 체적은 감소하였으며 시편의 결정구조는 입방정계에서 능면체정계, 정방정계로 변화되었다. 8.5/60/40시편의 경우 포화분극, 잔류분극 및 항전계가 각각 33.28[.mu.C/cm2], 4.15[kV/cm]로 전형적인 메모리 특성을 나타내었으며 PbZr O3조성이 증가함에 따라 강유전 이력곡선은 slim loop특성을 나타내었다. 잔류분극은 온도가 증가함에 따라 감소하였으며 특히 PE-FE상경계 부근에 위치한 조성의 경우, 상전이 온도 이하의 온도에서 급격히 감소하는 경향을 나타내었다.다.

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Effect of YAG on the Fracture Toughness and Electrical Conductivity of βSICZrB2 Composites (βSICZrB2복합체의 파괴인성과 전기전도도에 미치는 YAG의 영향)

  • Shin, Yong-Deok;Ju, Jin-Young;Yoon, Se-Won;Hwang, Chul;Park, Mi-Lim
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2000.07a
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    • pp.839-842
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    • 2000
  • The mechanical and electrical properties of the hot-pressed and annealed β-SiC-ZrB2 electroconductive ceramic composites were investigated as function of the liquid forming additives of Al2O3+Y2O3. Phase analysis of composites by XRD revelled α -SiC(6H), ZrB2, and YAG(Al5 Y3O12 ). Owing to crack deflection, crack bridging, phase transition and YAG of fracture toughness mechanism, the fracture toughness showed the highest value of 6.3MPa.m12/ for composites added with 24wt% Al2O3+Y2O3additives at room temperature. The resistance temperature coefficient respectively showed the value of 2.46×103 , 2.47×103 , 2.52× 103 C for composite added with 16, 20, 24wt% A12O3+Y2O3additives. The electircal resistivity of the composites was all positive temperature coefficient resistance(PTCR) in the temperature range of 25C to 900C.

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Determination of SiO2 and ZrO2 in Zircon Sand by Optical Emission Spectrometer (직독식 방출분광기를 이용한 지르콘사 중의 SiO2ZrO2의 분석)

  • Kim, Young Man;Jeong, Chan Yee;Han, Bong Han;Choi, Beom Suk
    • Analytical Science and Technology
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    • v.6 no.3
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    • pp.275-282
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    • 1993
  • A direct and simultaneous method to determine the SiO2 and ZrO2 in zircon sand of raw mineral and its treated one were studied by optical emission spectrometer using DC arc source. The synthetic standard was prepared by mixing with pure metal oxide, and it was diluted with buffer(graphite) and flux(Li2B4O7). The mixing ratio of buffer and flux and its dilution ratio to sample was investigated in order to choose the best excitation conditions. The optimum mixing and dilution ratios were 0.22:1 and 40, and the standard deviations of analytical results were 1.9% for SiO2 and 4.7% for ZrO2.

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Magnetic Properties of Nylon 6 based Nd-Fe-Co-Zr-B Pellets for Injection Molding (사출성형용 Nylon 6계 Nd-Fe-Co-Zr-B 펠렛의 자기특성)

  • 최승덕;이우영;양충진
    • Journal of the Korean Magnetics Society
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    • v.3 no.1
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    • pp.34-40
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    • 1993
  • Nylon 6 based magnetic pellets for injection molding were produced using plasma arc melt-spun Nd10.5Fe79Co2Zr1.5B7 powders. Two sorts of bonded magnets made of two different sizes of particles (38 75μm and 75 150μm) were prepared to determine critical volume fraction of magnet powders, and the magnetic prop erties of the magnets were discussed as a function of density. For the nylon fi based Nd-Fe-Co-Zr-B pellets made of 38 75μm particles, the critical volume fraction of powders 0.7 was obtained with the pellet density which is 90% of theoretical density while the magnets of 75 150μm showed the density of 87% of the theoretical value with the same volume fraction. The nylon (i magnets with the addition of 0.5 wt. % silicon oil only exhibited the best magnetic properties to have iHc=8.8kOe,Br=5.1kG and (BH)max=5.2MGOe which are of world class. An empirical relationship in predicting the magnet density with a known fraction (Vs) of loading powders was obtained such as ρ(g/cm3)=1.1+K.Vs where the K ranges over 5.3~5.6 be ing dependent upon the particle size loaded.

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The Magnetic Properties of Fe87Zr7B5Ag1(at.%) Amorphous Alloy (Fe87Zr7B5Ag1 비정질합금의 연자기 특성)

  • 김병걸;송재성;김현식;오영우
    • Journal of the Korean Magnetics Society
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    • v.5 no.1
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    • pp.8-14
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    • 1995
  • The magnetic properties of an Fe87Zr7B5Ag1(at.%) amorphous alloy have been investigated as a function of annealing temperatures to clarify its application potential as a core material for high-frequency use by adding a small amount of insoluble element of Ag. A new excellent soft magnetic material was developed. The amorphous alloy produced by relatively low temperature annealing at Ta=400C exhibited very high initial permeability(μi) of 288,000 at 1kHz and 2mOe, very low coercivity(Hc) of 15mOe and low core loss(Wc) of 50W/kg at 100kHz and 1,000G which is comparable with Co-based amorphous alloys, respectively. It is notable that the values obtained in the present study are the best magnetic properties among various kinds of Fe-based soft amorphous materials reported up to date. The reasons for the achievement of good soft magnetic properties are presumably due to the homogeneous formation of very fine α-Fe clusters with the size of 2~3nm in an amorphous matrix, which can be deduced from the increase of resistivity and the TEM observation. The very fine α-Fe clusters embedded in an amorphous matrix had a great influence on reduction of magnetostriction and refinement of magnetic domain.

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Effect of YAG on β-Sic-ZrB2 Composites (β-Sic-ZrB2계 복합체에 미치는 YAG의 영향)

  • Hwang, Chul;Ju, Jin-Young;Shin, Yong-Deok;Lee, Jong-Doc;Jin, Hong-Bum
    • Proceedings of the KIEE Conference
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    • 2000.07c
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    • pp.1474-1476
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    • 2000
  • The mechanical and electrical properties of the hot-pressed and annealed β-Sic-ZrB2 electroconductive ceramic composites were investigated as function of the liquid forming additives of Al2O3+Y2O3. Phase analysis of composites by XRD revealed α-SiC(6H), ZrB2, and YAG(Al5Y3O12). The relative density of composites were increased with increasing Al2O3+Y2O3 contents. The flexural strength showed the highest value of 390.6MPa for composites added with 20wt% Al2O3+Y2O3 additives at room temperature. Owing to crack deflection, crack bridging. phase transition and YAG of fracture toughness mechanism. the fracture toughness showed the highest value of 6.3MPam1/2 for composites added with 24wt% Al2O3+Y2O3 additives at room temperature. The electrical resistivity of the composites was all positive temperature coefficient resistance (PTCR) in the temperature range of 25C to 900C.

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Properties of the β-Sic+39vol.%ZrB2 Composites Prepared by the Pressureless-Sintering (상압소결에 의해 제조한 β-Sic+39vol.%ZrB2 복합체의 특성)

  • Shin, Yong-Deok;Ju, Jin-Young;Yoon, Se-Won;Hwang, Chul;Lim, Seung-Hyuk;Song, Joon-Tae
    • Proceedings of the KIEE Conference
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    • 1999.11d
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    • pp.894-896
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    • 1999
  • The β-SiC+ZrB2 ceramic composites were pressureless-sintered and annealed by adding 4, 8, 12wt% Al2O3+Y2O3(6 : 4wt%) powder as a liquid forming additives at 1800C for 4h. The relative density is over 79.3% of the theoretical density and phase analysis of the composites by XRD revealed of α-SiC(6H, 4H), ZrB2, Al5Y2O12 and β-SiC(15R). Flexural strength showed the highest of 301.33MPa for composites added with 8wt% Al2O3+Y2O3 additives at room temperature. Owing to crack deflection and crack bridging of fracture toughness mechanism, the fracture toughness showed the highest of 3.6979MPam1/2 for composites added with 8wt% Al2O3+Y2O3 additives at room temperature. The electrical resistivity was measured by the Pauw method from 25C to 700C. The electrical resistivity of the composites showed the PTCR(Positive Temperature Coefficient Resistivity).

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Texture Study in HDDR-treated Nd-Fe-B-type Particles

  • Kim, Jung-Hwan;Kwon, H.W.
    • Journal of Magnetics
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    • v.10 no.4
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    • pp.152-156
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    • 2005
  • Effects of the disproportionating hydrogen pressure and alloy composition on the texture in the HDDR-treated Nd-Fe-B particles were examined using the Nd12.6Fe81.4B6 and Nd12.6Fe68.7B6Co11.0Ga1.0Zr0.l alloys. Disproportionation kinetics of the Nd2Fe14B phase in the Nd-Fe-B alloy was retarded significantly by the addition of Co, Ga and Zr. The retarded disproportionation kinetics of the Nd2Fe14B phase ensured a wider processing win­dow in terms of disproportionating hydrogen pressure for achieving a texture in the HDDR-treated Nd-Fe-B alloy particles.