결정화 유리 개발 및 응용

김선욱(Sun Woog Kim),황종희(Jonghee Hwang) 한국세라믹학회 2020 세라미스트 Vol.23 No.3

Glasses have become a significant part of our daily life as they are widely used in the buildings and the mobile phone displays. Among the functional glass materials, glass-ceramics are widely used in recent times and are distinguished due to their special properties. Glass-ceramics are polycrystalline solids prepared by controlled crystallization of glass. They are used as tough glass-ceramics, biocompatible glass-ceramics, and low thermal expansion glass-ceramics. Among the glass-ceramics, low thermal expansion glassceramics has received much attention due to their excellent thermal, mechanical, and optical properties and commercially used as cook top panels and telescope mirrors. In this work, we reviewed the general theory and application of glass-ceramics.

슬래그 재활용 원료를 이용한 유리섬유 제조 및 특성

이지선,김선욱,라용호,임태영,이영진,전대우,김진호,Lee, Ji-Sun,Kim, Sun-Woog,Ra, Yong-Ho,Lim, Tae-Young,Lee, Youngjin,Jeon, Dae-Woo,Kim, Jin-Ho 한국재료학회 2018 한국재료학회지 Vol.28 No.12

In this study, glass fibers are fabricated via a continuous spinning process using manganese slag, steel slag, and silica stone. To fabricate the glass fibers, raw materials are put into an alumina crucible, melted at $1550^{\circ}C$ for 2 hrs, and then annealed at $600^{\circ}C$ for 2 hrs. We obtain a black colored glass. We identify the non-crystalline nature of the glass using an XRD(x-ray diffractometer) graph. An adaptable temperature for spinning of the bulk marble glass is characterized using a high temperature viscometer. Spinning is carried out using direct melting spinning equipment as a function of the fiberizing temperature in the range of $1109^{\circ}C$ to $1166^{\circ}C$, while the winder speed is in the range of 100rpm to 250rpm. We investigate the various properties of glass fibers. The average diameters of the glass fibers are measured by optical microscope and FE-SEM. The average diameter of the glass fibers is $73{\mu}m$ at 100rpm, $65{\mu}m$ at 150rpm, $55{\mu}m$ at 200rpm, and $45{\mu}m$ at 250rpm. The mechanical properties of the fibers are confirmed using a UTM(Universal materials testing machine). The average tensile strength of the glass fibers is 21MPa at 100rpm, 31MPa at 150rpm, 34MPa at 200rpm, and 45MPa at 250rpm.

티타늄 이소프로폭사이드를 이용한 졸-겔법에 의한 TiN 코팅 cBN 분말 합성

이윤성,김선욱,이영진,이지선,신동욱,김세훈,김진호,Lee, Youn Seong,Kim, Sun Woog,Lee, Young Jin,Lee, Ji Sun,Shin, Dongwook,Kim, Sae-Hoon,Kim, Jin Ho 한국전기전자재료학회 2020 전기전자재료학회논문지 Vol.33 No.5

In this study, TiN-coated cBN (cubic-structure boron nitride) powders were successfully synthesized by a sol-gel method using titanium (IV) isopropoxide (TTIP) and by controlling the heat treatment conditions. After the sol-gel process, amorphous nano-sized TiO_x was uniformly coated on the surface of cBN powder particles. The obtained TiO_x-coated cBN powders were heated at 1,000~1,300℃ for 1 or 6 h in a flow of 95%N₂-5%H₂ mixed gas. With increasing temperature, the chemical composition of the TiO_x coating layer changed in the order of TiO₂→Ti₆O₁₁→Ti₄O₇→TiN due to reduction of the Ti ions. The TiN coating layer was observable in the samples heated at 1,200℃ and appeared as the main phase in the sample heated at 1,300℃. The resulting thickness of the TiN coating layer of the sample heated at 1,300℃ was approximately 45~50 nm.

선탄 경석 재활용 원료를 이용한 유리 용융 특성

이지선,김선욱,라용호,이영진,임태영,황종희,전대우,김진호,Lee, Ji-Sun,Kim, Sun-Woog,Ra, Yong-Ho,Lee, Youngjin,Lim, Tae-Young,Hwang, Jonghee,Jeon, Dae-Woo,Kim, Jin-Ho 한국재료학회 2019 한국재료학회지 Vol.29 No.11

In this study, the glass melting properties are evaluated to examine the possibility of using refused coal ore as replacement for ceramic materials. To fabricate the glass, refused coal ore with calcium carbonate and sodium carbonate in it (which are added as supplementary materials) is put into an alumina crucible, melted at $1,200{\sim}1,500^{\circ}C$ for 1 hr, and then annealed at $600^{\circ}C$ for 2 hrs. We fabricate a black colored glass. The properties of the glass are measured by XRD (X-ray diffractometry) and TG-DTA (thermogravimetry-differential thermal analysis). Glass samples manufactured at more than $1,300^{\circ}C$ with more than 60 % of refused coal ore are found by XRD to be non-crystalline in nature. In the case of the glass sample with 40 % of refused coal ore, from the sample melted at $1,200^{\circ}C$, a sodium aluminum phosphate peak, a disodium calcium silicate peak, and an unknown peak are observed. On the other hand, in the sample melted at $1,300^{\circ}C$, only the sodium aluminum phosphate peak and unknown peak are observed. And, peak changes that affect crystallization of the glass according to melting temperature are found. Therefore, it is concluded that glass with refused coal ore has good melting conditions at more than $1,200^{\circ}C$ and so can be applied to the construction field for materials such as glass tile, foamed glass panels, etc.

원뿔 형태의 patterned sapphire substrate 위에 성장한 α-Ga₂O₃의 특성분석

손호기,최예지,이영진,김진호,김선욱,라용호,임태영,황종희,전대우,Son, Hoki,Choi, Ye-Ji,Lee, Young-Jin,Kim, Jin-Ho,Kim, Sun Woog,Ra, Yong-Ho,Lim, Tae-Young,Hwang, Jonghee,Jeon, Dae-Woo 한국결정성장학회 2019 韓國結晶成長學會誌 Vol.29 No.4

본 연구에서는 halide vapor phase epitaxy 성장법을 이용하여 원뿔 형태의 패턴이 주기적으로 형성된 patterned sapphire substrate(PSS) 위에 ${\alpha}-Ga_2O_3$를 성장하고 그 특성에 변화에 대해 분석하였다. PSS의 패턴의 유무에 따른 영향을 알아보기 위해 c-plane 사파이어 기판과 원뿔의 크기가 다른 두 개의 PSS 위에 ${\alpha}-Ga_2O_3$를 성장하여 비교 분석하였다. 또한 PSS 위에 성장된 ${\alpha}-Ga_2O_3$의 성장과정을 알아보기 위해 점차 성장 시간을 증가해가며 관찰하였고 성장 온도를 $470-550^{\circ}C$까지 변화해가며 성장하였다. 이를 통해 원뿔 형태의 패턴이 형성된 PSS 위에서의 최적 성장 조건과 그 성장 mechanism에 대해 분석이 가능하였고 그 결과로 성장과정에서 발생하는 수평 성장에 의해 ${\alpha}-Ga_2O_3$의 비대칭면인 (10-14) 반치폭 값을 크게 감소시킬 수 있었다. In this study, we demonstrated a characterization of ${\alpha}-Ga_2O_3$ grown on a cone-shape patterned sapphire substrate by using the halide vapor phase epitaxy. An ${\alpha}-Ga_2O_3$ was grown on different size of PSS and c-plane sapphire substrate for comparison to confirm the effect of PSS. In addition, growth time of ${\alpha}-Ga_2O_3$ was gradually increased to confirm growth mechanism of ${\alpha}-Ga_2O_3$ grown on the PSS. A growth temperature was changed to $470-550^{\circ}C$. It can be analyzed growth conditions and mechanisms on the cone-shape PSS, resulting in a significant decrease in the FWHM value of an asymmetric plane (10-14) of ${\alpha}-Ga_2O_3$, due to lateral growth that occurs during the growth process.

치과 임플란트 수술용 고출력 초음파 수술기 설계 및 제작

김나리,전대우,김진호,김선욱,황종희,이정배,최성재,임대진,이영진,Kim, Na Ri,Jeon, Dae Woo,Kim, Jin Ho,Kim, Sun Woog,Hwang, Jong Hee,Lee, Jeong Bae,Choi, Sung Jae,Im, Dae Jin,Lee, Young Jin 한국전기전자재료학회 2017 전기전자재료학회논문지 Vol.30 No.10

This paper presents the design and fabrication of a high power piezoelectric ultrasonic surgery unit for multi-purpose dental implantation. A conventional piezoelectric ultrasonic surgery units consists of a transducer and a tip. However, the drawback of this simple structure is that the output performance of the transducer considerably changes with the change of the tips. An ultrasonic surgery unit that has an additional booster between the transducer and the tip can solve this problem to some extent; for this, an optimal structural design for the transducer is required. We used the Bolted Langevin Transducer (BLT) as the basic transducer; it consists of piezoelectric ceramics and a metal body. It's structure was optimized using mathematical methods to determine the length and radius of the tail and head masses. Additionally, the booster was also subjected to the same methods. Using these mathematical methods, optimal results in terms of the resonance frequency (24.96 kHz), displacement ($14.27{\mu}m$), and pressure (2.8 MPa), could be obtained. The validity of this proposed surgery unit was confirmed experimentally, exhibiting a cutting force of around 7% higher than that of a conventional surgery unit.

HVPE 방법으로 성장된 alpha-Ga₂O₃의 특성에 대한 VI/III ratio 변화 효과

손호기,최예지,이영진,이미재,김진호,김선욱,라용호,임태영,황종희,전대우,Son, Hoki,Choi, Ye-Ji,Lee, Young-Jin,Lee, Mi-Jai,Kim, Jin-Ho,Kim, Sun Woog,Ra, Yong-Ho,Lim, Tae-Young,Hwang, Jonghee,Jeon, Dae-Woo 한국결정성장학회 2018 한국결정성장학회지 Vol.28 No.3

본 연구에서는 HVPE 성장법을 이용하여 사파이어 기판 위에 알파 갈륨옥사이드를 성장시키며 VI/III 비의 변화에 따른 효과를 확인하였다. 성장된 알파 갈륨옥사이드의 표면은 평평하고 crack 없이 성장되었다. 성장된 갈륨옥사이드의 광학적 특성을 분석하기 위해 투과율을 측정하고 광학 밴드갭을 얻었다. 광학 밴드갭은 약 5.0 eV로 나타났고 VI/III 비가 증가함에 따라 비례하여 증가하는 결과를 보여주었다. 이론적 광학 밴드갭에 가장 근접한 VI/III 비가 23인 조건에서 성장된 알파 갈륨옥사이드의 결정성을 확인하기 위해 HR-XRD를 이용하여 FWHM을 측정하였고 이를 바탕으로 전위밀도를 계산하였을 때 나선형 전위밀도는 $1.5{\times}10^7cm^{-2}$, 칼날 전위 밀도는 $5.4{\times}10^9cm^{-2}$로 계산되었다. In this study, we report the effect of VI/III ratio on ${\alpha}-Ga_2O_3$ epilayer on sapphire substrate by halide vapor phase epitaxy. The surface of ${\alpha}-Ga_2O_3$ epilayer grown with various VI/III ratios was flat and crack-free. To analyze the optical properties of the ${\alpha}-Ga_2O_3$ epilayers, the transmittance and an optical band gap were measured. The optical band gap was shown to be around 5 eV and showed a proportional increase in VI/III ratios. To determine the crystal quality of alpha gallium oxide grown with a ratio of 23, closed to the theoretical optical band gap, the FWHM was measured by HR-XRD. The calculated dislocation density of screw and edge were $1.5{\times}10^7cm^{-2}$ and $5.4{\times}10^9cm^{-2}$, respectively.

친환경 무기 형광 안료 A₃V₅O₁₄ (A = K and Rb) and Cs₂V₄O₁₁ 개발: 결정구조, 광학적 특성 및 착색 특성

정규진,김진호,이윤기,황종희,배병서,김선욱,Jeong, Gyu Jin,Kim, Jin Ho,Lee, Younki,Hwang, Jonghee,Toda, Kenji,Bae, Byoungseo,Kim, Sun Woog 한국결정성장학회 2020 한국결정성장학회지 Vol.30 No.2

본 연구에서는 밝고 화사한 적색 및 황색의 착색 특성을 가지며, 우수한 발광특을 가진 새로운 무기 형광 안료를 개발하기 위하여, A₃V₅O₁₄ (A = K and Rb) 및 Cs₂V₄O₁₁를 water assisted solid state reaction(WASSR) 방법과 고상법을 혼합하여 합성을 하였다. 합성한 A₃V₅O₁₄ (A = K and Rb ) 및 Cs₂V₄O₁₁ 샘플은 AVO₃ 및 AV₃O₈ (A = K, Rb and Cs)가 불순물로 다소 확인되었으나, trigonal 구조의 A₃V₅O₁₄ (A = K and Rb)와 orthorhombic 구조의 Cs₂V₄O₁₁가 주상으로 확인되었다. A₃V₅O₁₄ (A = K and Rb)와 Cs₂V₄O₁₁는 자외선 영역에서 강한 광흡수를 나타내었으며, 각각 적색광 및 녹색광 발광을 나타내었다. 또한, 합성된 A₃V₅O₁₄ (A = K and Rb)는 a* 값 (+ : 적색도, -: 녹색도)은 각각 + 35.5와 + 45.9를, Cs₂V₄O₁₁는 b* 값(+: 황색도, -: 청색도)는 + 50.3을 나타내었으며, 45 이상의 L* 값(명도)을 가지고 있어, 밝고 화사한 느낌을 구현하기위한 황색안료로 응용이 가능할 것으로 기대된다. To develop the bright-vivid red- and yellow-inorganic fluorescent pigments with high luminescence properties, A₃V₅O₁₄ (A = K and Rb) and Cs₂V₄O₁₁ inorganic pigments were synthesized by a water assisted solid state reaction (WASSR) method and a conventional solid state reaction method. Although impurity peaks corresponding to the AVO₃ and AV₃O₈ (A = K, Rb, and Cs) were observed in all samples prepared, the trigonal structure A₃V₅O₁₄ (A = K and Rb) and orthorhombic structure Cs₂V₄O₁₁ were successfully obtained as a main phase. These inorganic pigments showed the broad absorption band (under 550 nm) originated from CT transitions of VO₄ polyhedron, and the strong broad red- and green-emission bands due to ³T₂ → ¹A₁ and ³T₁ → ¹A₁ transitions of the [VO₄]^3- group. The A₃V₅O₁₄ (A = K and Rb) and Cs₂V₄O₁₁ pigments showed a bright-vivid red- and yellow-body color, where the a* values of the A₃V₅O₁₄ (A = K and Rb) were +35.5 and +45.9, respectively, and b* value of Cs₂V₄O₁₁ pigments was +50.3. The L* values of the A₃V₅O₁₄ (A = K and Rb) and Cs₂V₄O₁₁ inorganic pigments were over +45. These results indicate that the A₃V₅O₁₄ (A = K and Rb) and Cs₂V₄O₁₁ inorganic pigments could be an attractive candidate as a bright-vivid red- and yellow inorganic pigments.

HVPE 방법으로 성장한 Alpha-Ga₂O₃의 특성 분석

손호기,라용호,이영진,이미재,김진호,황종희,김선욱,임태영,전대우,Son, Hoki,Ra, Yong-Ho,Lee, Young-Jin,Lee, Mi-Jai,Kim, Jin-Ho,Hwang, Jonghee,Kim, Sun Woog,Lim, Tae-Young,Jeon, Dae-Woo 한국전기전자재료학회 2018 전기전자재료학회논문지 Vol.31 No.6

We demonstrated a crack-free ${\alpha}-Ga_2O_3$ on sapphire substrate by horizontal halide vapor phase epitaxy (HVPE). Oxygen-and gallium chloride-synthesized Ga metal and HCl were used as the precursors, and $N_2$ was used as the carrier gas. The HCl flow and growth temperature were controlled in the ranges of 10~30 sccm and $450{\sim}490^{\circ}C$, respectively. The surface of ${\alpha}-Ga_2O_3$ template grown at $470^{\circ}C$ was flat and the root-mean-square (RMS) roughness was ~2 nm. The full width at half maximum (FWHM) values for the symmetric-plane diffractions, were as small as 50 arcsec and those for the asymmetric-plane diffractions were as high as 1,800 arcsec. The crystal quality of ${\alpha}-Ga_2O_3$ on sapphire can be controlled by varying the HCl flow rate and growth temperature.

역 마이셀 공정에 의한 Ni, Zn, Ni-Zn 페라이트 분말의 합성 및 특성 평가

강성(Sung Kang),진정호(Jeoung-Ho Jin),김선욱(Sun-Woog Kim),손정훈(Jeong-Hun Son),배동식(Dong-Sik Bae) 한국마린엔지니어링학회 2007 한국마린엔지니어링학회 학술대회 논문집 Vol.2007 No.-

The preparation of Ni, Zn, Ni-Zn ferrite nanoparticles by the reduction of Ni nitrate, Zn nirtate and Fe nitrate in Igepal CO-520/cyclohexane reverse micelle solutions has been studied. Transmission Electron Microscope(TEM), X-ray Diffraction(XRD), and Vibration Sample Magnetometer(VSM) analyses revealed the resultant nanoparticles to be a Ni, Zn, Ni-Zn ferrite. The average size of the synthesized nanoparticles increased molar ratio of water to Igepal CO-520 and with increasing concentration of Ni nitrate, Zn nirtate and Fe nitrate.