• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2003년도 춘계학술대회 논문집
• /
• pp.1911-1915
• /
• 2003

Today optical communication industry is developed; demand of optical communication part is increased. ZrO$_2$ ceramic ferrule is very significant part which determines transmission efficiency and quality of information in the optical communication part by connector of optical fibers. Being different from metal grinding, material removal through brittle fracture plays an important role in ZrO$_2$ ceramic grinding. Most of ZrO$_2$ ceramic ferrule processes are grinding which request high processing precision. Particularly, concentricity and cylindricity of inner and outer diameter are very important. The co-axle grinding process of ZrO$_2$ ceramic ferrule is to make its concentricity all of uniform before centerless grinding. Surface integrity of ZrO$_2$ ceramic ferrule is affected by grinding conditions, and equipment. In this study, surface integrity of workpiece according to such as a change of grinding wheel speed, feed rate, regulating wheel speed and grinding force is investigate to improve the concentricity and roundness of ZrO$_2$ ceramic ferrule from many experiments. Thus, if possible be finding highly efficient and quality grinding conditions.

• 대한치과기공학회지
• /
• 제33권1호
• /
• pp.7-14
• /
• 2011

Purpose: As the demand and importance of aesthetic aspects in dental treatment become higher, much attention is paid to materials used for dental prostheses. Thus, the marginal fidelity of most-commonly used alloy, IPS - Empress and ZrO2 ceramic is compared. Methods: The alloy core made by casting, IPS - Empress core made by pressing and ZrO2 ceramic core made by CAD/CAM are used to make 10 samples respectively. For each core, three points were measures and the optical microscope (Axio Imager.Alm,Zeiss co., Oberkochen, Germany) was used to observe the cores with a magnification of 100. Results: As for alloy, IPS - Empress and ZrO2 ceramic, the average and deviation of their marginal distance are $29.91\;{\pm}11.93{\mu}m$ for alloy, $33.45\;{\pm}8.61{\mu}m$ for IPS - Empress, and $31.55\;{\pm}9.85{\mu}m$ for ZrO2. The one-way ANOVA test was conducted to compare them. However, there was no statistically significant difference among them. Conclusion: The study on marginal fidelity of alloy, IPS - Empress, and ZrO2 ceramic shows they have no marginal fidelity problem clinically. Therefore, if a system is selected based on the patient's condition or treatment method, there will be no problem.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
• /
• pp.170-171
• /
• 2008

The etching characteristics of Zirconium Oxide ($ZrO_2$) and etch selectivity of $ZrO_2$ to Si in HBr/$SF_6$ plasma were investigated. It was found that $ZrO_2$ etch rate shows a non-monotonic behavior with increasing both HBr fraction in $SF_6$ plasma, Source power, Bias Power, gas pressure. The maximum $ZrO_2$ etch rate of 54.8 nm/min was obtained for HBr(25%)/$SF_6$(75%) gas mixture. From these data, the suggestions on the $ZrO_2$ etch characteristics were made.

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

• 한국진공학회지
• /
• 제12권S1호
• /
• pp.83-87
• /
• 2003

Zirconium oxide films have been synthesized by radio-frequency magnetron sputtering deposition on n-Si(001) substrate with metal zirconium target at variant $O_2$ partial pressures. The influences of $O_2$ partial pressures of the morphology, deposition rate, microstructure, and the dielectric constant of $ZrO_2$ have been discussed. The results show that deposition rate of $ZrO_2$ films decreases, the roughness, and the thickness of the native $SiO_2$ interlayer increases with the increase of $O_2$ partial pressure. $ZrO_2$ films synthesized at low $O_2$ partial pressure are amorphous and monoclinic polycrystalline in nanometer scale at low $O_2$ partial pressure. The relative dielectrics of $ZrO_2$ films are in the range of 12 to 25.

• 한국전기전자재료학회논문지
• /
• 제16권9호
• /
• pp.775-782
• /
• 2003

In the study, the total conductivies in [(Ce $O_2$)$_{1-x}$ (Zr $O_2$)$_{x}$]$_{0.8}$(Sm $O_{1.5}$)$_{0.2}$ (x- 0, 0.05, 0.1, 0.2) solid solution were measured as a function of temperature and oxygen partial pressure between 80$0^{\circ}C$ and 1,00$0^{\circ}C$ using 4-probe d.c method. Under pure oxygen atmospere, the oxygen ionic conductivity of [(Ce $O_2$)$_{1-x}$ (Zr $O_2$)$_{x}$]$_{0.8}$(Sm $O_{1.5}$)$_{0.2}$ decreased with the concentration of Zr $O_2$At high oxygen partial pressure, the electrical conductivity is almost independent of oxygen partial pressure and decreased with the increase in Zr content. However, the electrical conductivity increase with decreasing oxygen partial pressure and is almost independent of Zr content at low oxygen partial pressure. Empirically, Total conductivity( $\sigma$ ) was expressed by the p$o_{2}$ -independent conductivity as $\sigma$$_{i}$, and the $p_{-1/4}$ $o_{2}$sup -dependent part as $\sigma$$_{e}$. Total, ionic and electronic conductivities fitted by data enabled to determine the transference number. The ionic transference number( $t_{i}$ ) decreased while the electronic transference( $t_{e}$ ) increase with the increase in Zr content and p$o_{2}$.

• 한국세라믹학회지
• /
• 제41권4호
• /
• pp.334-339
• /
• 2004

SPS법에 의해 제조된 단상의 HAp, HAp-Ag 및 HAp-ZrO$_2$복합 소결체의 미세조직과 기계적 특성을 XRD, SEM, TEM에 의해 조사되었다. 나노크기의 HAp 분말은 Ca(No$_3$)$_2$$.$4$H_2O$과(NH$_4$)HPO$_4$용액을 하여 침전법에 의해 성공적으로 합성되었다. HAp-Ag 복합체에 존재하는 마이크론 크기의 Ag 입자와 HAp 계면에서는 두 상의 열평창계수의 차이로 인하여 수축공의 결함이 관찰되었다. 그러나 나노크기의 Ag의 경우 계면에서의 결함은 관찰되지 않았다. HAp-ZrO$_2$ 복합체의 경우 나노크기의 ZrO$_2$입자들은 HAp 상의 결정립계에 대부분 분산되었다. HAp-Ag 및 HAp-ZrO$_2$ 복합체의 상대밀도와 파괴인성은 각각 HAp 기지에 분산된 미분의 Ag 및 ZrO$_2$상의 소성변형 및 상변태 인성기구에 의해 증가하였다.

• 한국세라믹학회지
• /
• 제22권5호
• /
• pp.3-8
• /
• 1985

$ZrO_2$ single crystals were grown by slow cooling flux method using Borax $(Na_2B_4O_7)$ and KF as flux agent. The morphology of grown crystals was observed under a petrographic microscope. And the results obtained from grow crystals were as follows : 1. $ZrO_2$ crystals grown in the present work are morphologically divided into two shapes ; tabular and den-dritic crystals. 2. The maximum size of the crystals grown reaches to $4{\times}15{\times}2mm$ on edge into length at $ZrO_2$ 15mole% Borax 50mole% and KF 35mole% 3. $ZrO_2$ single crystals grown by flux method have monoclinc structure. 4. The content of KF as flux agents was limited by 60mole% KF. Since alumina crucible was heavily damaged by increasing KF content.

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

• 한국응용과학기술학회지
• /
• 제24권4호
• /
• pp.427-435
• /
• 2007

에너지원으로서 수소를 생산하기 위하여 하니컴 구조를 갖는 모노리스에 10 wt% $Ni/CeO_2-ZrO_2$ 촉매를 담지한 후 메탄의 수증기 개질 실험을 수행하였다. 다른 $CeO_2/ZrO_2$ 몰비를 갖는 촉매들 중에서, $Ni/CeO_2-ZrO_2(CeO_2/ZrO_2=4/1)$촉매가 $700-800^{\circ}C$에서 높은 메탄의 전환율을 보여 주었다. 10wt% $Ni/CeO_2-ZrO_2$ 촉매가 담지된 금속 모노리스 촉매체는 높은 열전도도와 비표면적들로 인하여 좋은 촉매 특성을 보여줌을 확인할 수 있었다. 또한, 금속모노리스 촉매체는 반응물에서 과다의 수증기에 의한 수소 수율에서 크게 영향을 받지 않음을 알 수 있었다. $GHSV=30,000h^{-1}$, 반응물 비$(H_2O/CH_4=3.0)$ 반응온도 $800^{\circ}C$에서 금속모노리스 촉매체는 98%이상의 메탄의 전환율을 보여주었다. 생성물 가스에서 $CO_2/CO$의 비는 수증기/메탄의 반응물비가 증가할수록 수성가스화 반응에 의하여 증가됨을 알 수 있었다.