• 전자공학회논문지A
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• 제30A권5호
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• pp.30-35
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• 1993

We have investigated microwave dielectric properties of TiO$_{2}$ added (Pb$_{1-x}$Ca$_{x}$)ZrO$_{3}$ Ceramics with x=0.33, 0.35, and 0.37 sintered at 1400$^{\circ}C$ for 2 h. For additions of up to 3wt% of TiO$_{2}$ in (Pb$_{0.63}$ Ca$_{0.37}$)ZrO$_{3}$ (x=0.37), TiO$_{2}$ was completely soluble in (Pb, Ca)ZrO3 phase and did not affect the grain size of ceramics. Dielectric constant and temperature coefficient of resonant frequency increased due to the formation of solid solution, whereas Q value decreased linearly as TiO$_{2}$ increased up to 1 wt%. However, the dielectric loss was very high as TiO$_{2}$ exceeded 2 wt%. It was also shown that as Ca ion content in 0.5 wt% TiO$_{2}$ added (Pb$_{1-x}$,Ca$_{x}$)ZrO$_{3}$ decreased from x=0.37 to x=0.33, dielectric constant increased and Q value decreased.

• 한국세라믹학회지
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• 제24권5호
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• pp.423-430
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• 1987

Characteristics of Al2O3-ZrO2 powders prepared by sol-gel process and their sintering behavior were investigated as a function of calcination temperature. The sol-gel processed powders were calcined at 800, 900, 1000, 1100, 1200$^{\circ}C$, and analyzed by X-ray diffraction technique. Pore size and distribution of green compact of the calcined powders were measured by mercury porosimeter. It is suggested that the optimal temperature of calcination for the sintering of Al2O3-ZrO2 powder prepared by sol-gel process is 1100$^{\circ}C$. In the Al2O3-17vol.% ZrO2 sintered specimen, which was sintered at 1600$^{\circ}C$ for 2hrs in air, 69vol.% tetragonal phse existed.

• 한국결정성장학회지
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• 제7권3호
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• pp.377-383
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• 1997

이트리아 안정화 지르코니아(Y-TZP)에 5가 산화물$(Ta_2O_5,\;Nb_2O_5)$을 첨가하여 $1500^{\circ}C$온도에서 상압소결한 삼성분계중 quasi-binary system인 $ZrO_2-YTa(Nb)O_4$의 조성영역안에서 상 안정성을 관찰하기 위해 상태도를 작성하였으며, 결정립 크기나 annealing 온도에 상관없이 상 안정성을 유지하는 non-transformable $t-ZrO_2$ solid solution$(NT_{ss}$ )영역을 확인하고 안정화 mechanism을 조사하였다. $NT_{ss}$ 의 상 안정성은 정방정 fergusonite 구조를 갖는 $YTa(Nb)O_4$의 안정화로 상 변태를 억제하여 우수한 상 안정성을 유지하는 것으로 추정되었다. 기계적 특성을 향상시키기 위해 상 변태율이 가장 좋은 transformable-TZP $(T_{ss/})$ 를 에 첨가하여 조사한 결과 mixture의 조성이 $NT_{ss}$ 영역밖의 $NT_{ss}$영역에 위치하여도 상 안정성과 우수한 기계적 특성을 갖는다는 것이 발견되었다.

• 한국세라믹학회지
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• 제38권2호
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• pp.117-121
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• 2001

본 연구에서는 Zr $O_2$첨가가 Ba(Zn$_{1}$3/Ta$_{2}$3/) $O_3$(BZT)세라믹의 구조와 고주파 유전특성에 미치는 영향을 조사하였다. 모든 시료에서 $Ba_{5}$Ta$_4$ $O_{15}$ 이차상이 발견되었으며 Zr $O_2$의 첨가량이 증가하면 $Ba_{5}$Ta$_4$ $O_{15}$ 상의 양은 감소하였다. 반면에 Zr $O_2$의 첨가량이 1.5 mol% 이상인 시료에서는 $Ba_{0.5}$Ta $O_3$상이 발견되었다. BZT의 입자 크기는 약 1$mu extrm{m}$ 정도였지만, Zr $O_2$를 첨가하면 입자 크기가 증가하였다. SEM 및 TEM 분석에 의하여 Zr $O_2$가 첨가되면 액상이 존재하는 것을 알 수 있었으며, 이로 인하여 입자가 성장되는 것이 발견되었다. 시편의 밀도는 소량의 Zr $O_2$를 첨가하면 증가하지만 Zr $O_2$첨가량이 증가하면 감소하였다. 유전율은 모든 시료가 27에서 30 사이의 값을 가지고 있었다. 공진주파수 온도계수는 소량의 Zr $O_2$을 첨가하였을 때는 변화하지 않았지만 첨가량이 2.5 mol% 이상에서는 증가하였다. Q$\times$f 값은 Zr $O_2$을 첨가하면 증가하였고, 입자 성장이 완료되는 조성에서 최대 값을 보였다. 본 연구에서는 Zr $O_2$를 2.0 mol% 첨가하고 15$50^{\circ}C$에서 10시간 소결한 시료에서 최대의 Q$\times$f 값(164,000)을 얻을 수 있었다.다.다.

• 한국재료학회지
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• 제20권10호
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• pp.518-523
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• 2010

In this study, partially stabilized zirconia was synthesized using a chemical $Y_2O_3$ stabilizer and hydrothermal method. First, $YCl_3-6H_2O$ and $ZrCl_2O-8H_2O$ was dissolved in distilled water. Y-TZP (a $Y_2O_3$-doped toughened zirconia polycrystalline precursor) was also prepared by conventional co-precipitates in the presence of an excess amount of $NH_4OH$ solution under a fixed pH of 12. The Y-TZP precursors were filtered and repeatedly washed with distilled water to remove $Cl^-$ ions. $ZrO_2$-Xmol%$Y_2O_3$ powder was synthesized by a hydrothermal method using Teflon Vessels at $180^{\circ}C$ for 6 h of optimized condition. The powder added with the Xmol%- $Y_2O_3$ (X = 0,1,3,5 mol%) stabilizer of the $ZrO_2$ was synthesized. The crystal phase, particle size, and morphologies were analyzed. Rectangular specimens of $33mm{\times}8mm{\times}3$ mm for three-point bend tests were used in the mechanical properties evaluation. A teragonal phase was observed in the samples, which contains more than 3 mol% $Y_2O_3$. The $3Y-ZrO_2$ agglomerated particle size was measured at $7.01{\mu}m$. The agglomerated particle was clearly observed in the sample of 5 mol % $Y_2O_3-ZrO_2$, and and the agglomerated particle size was measured at 16.4 um. However, a 20 nm particle was specifically observed by FE-SEM in the sample of 3 mol% $Y_2O_3-ZrO_2$. The highest bending fracture strength was measured as 321.3 MPa in sample of 3 mol% $Y_2O_3-ZrO_2$.

• 한국재료학회지
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• 제14권6호
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• pp.394-398
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• 2004

A Ti47Al1.7W-3.7Zr alloy was oxidized between $900^{\circ}C$ and $1050^{\circ}C$, and the oxide scales formed were studied. The oxide scales consisted primarily of an outer$TiO_2$ layer, an intermediate $Al_2$$O_3$-rich layer, and an inner mixed ($TiO _2$ + $Al_2$$O_3$) layer. Besides $TiO_2$ and $Al_2$$O_3$, oxidation led to the formation of some $Ti_2$AlN and TiN. Both W and Zr were preferentially segregated below the intermediate $Al_2$$O_3$-rich layer. Tungsten in the oxide scale was present as $WO_3$ and ${Ti}_{x}$$W_{1-x}$, whereas zirconium as monoclic-$ZrO_2$ and tetragonal-$ZrO_2$.

• 한국세라믹학회지
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• 제27권8호
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• pp.1064-1070
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• 1990

ZrO2 fine powders were prepared by hydrolysis, adding 0.1, 0.2, 0.3, 0.4, 0.5, 0.6mol/1H2O/ethanol to 0.1 mol/l Zr(OC3H7)4/ethanol. When hydrolized by adding 0.1mol/l Zr(OC3H7)4/ethanol to 0.1, 0.2mol/l H2O/ethanol., spherical monodispersed ZrO2 fine powders were obtained. And in this condition average sizes were about 0.5, 0.3${\mu}{\textrm}{m}$, respectively. The more H2O/ethanol concentration increased, the more the particle size decreased and the particles were agglomerated strongly. Prepared powders were amorphous and hydrates. The calcined powders with 43$0^{\circ}C$ and 100$0^{\circ}C$ were showed tetragonal and monoclinic phase, respectively.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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• pp.125.1-125.1
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• 2015

산업 자동화기술이 발달함에 따라 다양한 용도의 부품개발과 산업 장비들의 부품에 대한 수요가 날로 증가하게 되어 산업이 발달하게 된 반면, 장비의 성능을 저하시키는 마모에 대한 문제점이 제기되고 있다. 이에 대한 해결책으로 내열성 및 내마모성을 가지는 박막코팅기술이 요구되고 있다. 특히, Alumina (Al2O3)와 Zirconia (ZrO2)는 내식성과 내열성, 내마모성의 우수한 특성을 지닌 재료이며, 이들을 기어, 베어링, 실린더 등 각종 기계의 부품에 코팅하여 내마모성을 가지게 한다. 본 실험에서는 Al2O3 : ZrO2 = 50 : 50 wt% 의 비율로 혼합한 target이 사용되었다. 그리고 Al2O3-ZrO2 target을 사용하여 RF-magnetron sputtering 방법으로 박막을 제작 하였다. sputter시에 power를 20 W에서 80 W까지 변화를 주었다. AFM, SEM, XRD를 통하여 알루미늄 기판위에 증착된 Al2O3-ZrO2 박막의 구조적 특성을 알아보았으며, 내마모성 테스트 장비를 통하여 박막의 마찰마모 특성에 대하여 조사하였다.

• Journal of Electrochemical Science and Technology
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• 제9권3호
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• pp.176-183
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• 2018

In this study, a $Li_2ZrO_3$ coated $Li[Ni_{0.8}Co_{0.15}Al_{0.05}]O_2$ (NCA) cathode was applied to an all-solid-state cell employing a sulfide-based solid electrolyte. Sulfide-based solid electrolytes are preferable for all-solid-state cells because of their high ionic conductivity and good softness and elasticity. However, sulfides are very reactive with oxide cathodes, and this reduces the stability of the cathode/electrolyte interface of all-solid-state cells. $Li_2ZrO_3$ is expected to be a suitable coating material for the cathode because it can suppress the undesirable reactions at the cathode/sulfide electrolyte interface because of its good stability and high ionic conductivity. Cells employing $Li_2ZrO_3$ coated NCA showed superior capacity to those employing pristine NCA. Analysis by X-ray photoelectron spectroscopy and electron energy loss spectroscopy confirmed that the $Li_2ZrO_3$ coating layer suppresses the propagation of S and P into the cathode and the reaction between the cathode and the sulfide solid electrolyte. These results show that $Li_2ZrO_3$ coating is promising for reducing undesirable side reactions at the cathode/electrolyte interface of all-solid-state-cells.

• 한국세라믹학회지
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• 제24권5호
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• pp.477-483
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• 1987

Cr2O3 doped Pb(Zr0.525 Ti0.475)O3 piezoelectric ceramics were prepared from reagent grade oxide mixture, PbO, ZrO2, TiO2 and Cr2O3. Piezoelectric and aging properties of specimens were measured for various additions of Cr2O3. Generally, it has been known that aging rate decreased with Cr2O3 addition by stabilizing the domain wall. But hysteresis loops showed that the domain destabilization was occurred at high electric field (larger than 10KV/cm). In smaller additions of Cr2O3 (0-0.2mol%), aging rate increased and microcracks were created with increasing poling filed due to increasing internal stress. In larger additions of Cr2O3(0.4∼0.6mol%), aging rate decreased with increasing poling field.