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습식분쇄에 의한 입자크기 변화에 따른 분쇄입자의 종횡비 거동
최진삼,Choi, Jin Sam 한국재료학회 2020 한국재료학회지 Vol.30 No.5
As a case study on aspect ratio behavior, Kaolin, zeolite, TiO<sub>2</sub>, pozzolan and diatomaceous earth minerals are investigated using wet milling with 0.3 mm media. The grinding process using small media of 0.3 pai is suitable for current work processing applications. Primary particles with average particle size distribution D<sub>50</sub>, ~6 ㎛ are shifted to submicron size, D<sub>50</sub> ~0.6 ㎛ after grinding. Grinding of particles is characterized by various size parameters such as sphericity as geometric shape, equivalent diameter, and average particle size distribution. Herein, we systematically provide an overview of factors affecting the primary particle size reduction. Energy consumption for grinding is determined using classical grinding laws, including Rittinger's and Kick's laws. Submicron size is obtained at maximum frictional shear stress. Alterations in properties of wettability, heat resistance, thermal conductivity, and adhesion increase with increasing particle surface area. In the comparison of the aspect ratio of the submicron powder, the air heat conductivity and the total heat release amount increase 68 % and 2 times, respectively.
중금속 창연산화납계 저온유리 분말을 이용한 세라믹스/금속의 접합거동
최진삼,Choi, Jin Sam 한국세라믹학회 2014 한국세라믹학회지 Vol.51 No.4
The joining behavior of forsterite ceramics to SUS304 alloy using $8PbO-78Bi_2O_3-8B_2O_3-4ZnO-2SiO_2$ (wt%) system glass frit was investigated. The contact angle was smaller than $90^{\circ}$ at a temperature of $460^{\circ}C$. Redox reaction at the interface between forsterite and SUS304 was found to appear when the electrons in the metal part moved toward the glass part and the oxygen ions in glass moved to the metal side. The decrease of the surface tension due to the PbO solubility on the forsterite side contributed to the better wetting behavior at low temperature.
최진삼,배재철,방영일,이덕동,허증수,Choi, Jin-Sam,Bae, Jae-Cheol,Bang, Yeong-Il,Lee, Deok-Dong,Huh, Jeung-Su 한국재료학회 2002 한국재료학회지 Vol.12 No.4
The NASICON solid electrolyte films, $Na_{1+x}Zr_2Si_xP_{3-x}O_{12}$(1.5< x < 2.3), was prepared from ceramic slurry by modified doctor-blade process. The NASICON solid electrolyte and fabricated sensors, Pt-electrode/NASICON/Carbonate$(Na_2CO_3-K_2CO_3CaCO_3\; system)$ electrode, were investigated to measure phase, microstructure and e.m.f variation for sensing $CO_2$ concentration. The uniform grain size of $2-4{\mu}m$ and major phase of sodium zirconium silicon phosphate phase, $Na_{1+x}Zr_2Si_xP_{3-x}O_{12}$was identified with X-ray diffraction patterns and scanning electron microscopy, respectively. The Nernst's slope of 84 mV/decade for $CO_2$ concentration from 500 to 8000 ppm was obtained at operating temperature of $400^{\circ}C$.
금속 필러가 첨가된 Pb-B-O계 유리와 Ni-Cr 합금 와이어 간의 전기 화학적 반응과 단락 거동
최진삼,다타치카 나까야마,Choi, Jin Sam,Nakayama, Tadachika 한국재료학회 2021 한국재료학회지 Vol.31 No.8
The electrochemical reaction between lead borate glass frit doped with Sn metal filler and Ni-Cr wire of a J-type resistor during a term of Joule heating is investigated. The fusing behavior in which the Ni-Cr wire is melted is not observed for the control group but measured for the Sn-doped specimen under 30 V and 500 mA. The Sn-doped lead borate glass frit shows a fusing property compared with other metal-doped specimens. Meanwhile, the redox reaction significantly contributes to the fusing behavior due to the release of free electrons of the metal toward the glass. The electrons derived from the glass, which used Joule heat to reach the melting point of Ni-Cr wire, increase with increasing corrosion rate at interface of metal/glass. Finally, the confidence interval is 95 ± 1.95<sub>9</sub> %, and the adjusted regression coefficient, R in the optimal linear graph, is 0.93, reflecting 93% of the data and providing great potential for fusible resistor applications.
MgO입자 표면에 도핑된 P<sub>2</sub>O<sub>5</sub>가 가수분해, 발수성, 그리고 절연거동에 미치는 영향
최진삼 ( Jin Sam Choi ) 한국공업화학회 2022 공업화학 Vol.33 No.6
MgO 입자 표면에 첨가된 P<sub>2</sub>O<sub>5</sub>의 가수분해, 발수성, 그리고 절연 거동에 미치는 영향을 조사하였다. MgO 표면에 첨가된 P<sub>2</sub>O<sub>5</sub>는 가수분해반응 억제와 발수성을 동시에 나타내기 때문에 독특한 절연거동을 나타내었다. 따라서 절연거동은 MgO의 표면수화반응에 의한 Mg(OH)<sub>2</sub>와 OH<sup>-</sup>전하 전달비와 친수성에 반비례하였다. 시효에 따른 MgO의 절연성은 표면수화반응, 첨가된 도펀트 종의 밴드갭, 그리고 도펀트의 친수성과 소수성에 강한 영향성과 의존성을 나타내었다. 마지막으로 친수성인 MgO의 표면수화반응을 억제하는 전기절연성을 발현하여 열전달매체 응용분야에서 큰 잠재력을 제공하는 것으로 나타났다. The effects of P<sub>2</sub>O<sub>5</sub>-doped on the surface of MgO particles on hydrolysis, water repellency, and insulation behavior were investigated. P<sub>2</sub>O<sub>5</sub>-doped MgO has exhibited a unique electrical property, which is significant insulation behavior due to both the suppression of the hydrolysis reaction by P<sub>2</sub>O<sub>5</sub> and water repellency. Therefore, the insulation behavior was inversely proportional to the hydrophilicity and the Mg(OH)<sub>2</sub> and OH<sup>-</sup>charge transfer ratio by the surface hydration reaction of MgO. The insulation of MgO according to aging was strongly influenced by the surface hydration reaction, the band gap of the added dopant species, and the hydrophilicity and hydrophobicity of the dopant. Finally, it was to show electrical insulation by inhibiting the surface hydration reaction of the hydrophilic MgO, which has a great potential for use in heat transfer medium applications.
Sb-doped SnO<sub>2</sub>를 코팅한 도전성 섬유의 제조
김홍대,최진삼,신동우,Kim, Hong-Dae,Choi, Jin-Sam,Shin, Dong-Woo 한국세라믹학회 2002 한국세라믹학회지 Vol.39 No.4
본 연구는 티탄산칼륨 섬유(K2O·$nTiO_2$)를 제조한 후, 도전율이 우수한 Sb-doped $SnO_2$(ATO: Antimony Tin Oxide)를 티탄산 칼륨 섬유에 코팅하는 기술을 개발하는데 목적이 있다. 티탄산칼륨 섬유는 서냉 소성법으로 제조하였으며 섬유의 평균 길이는 $15{\mu}m$, 평균 직경은 $0.5{\mu}m$이었다. ATO를 졸-겔법, 공침법, 균일침전법등 세가지 방법으로 티탄산칼륨 섬유에 코팅 하였으며 ATO 코팅된 티탄산칼륨 섬유는 ATO 함량(5∼70 wt%), Sb 함량(0∼20 wt%), 온도($450∼800^{\circ}C$), 수세 여부 및 회수(3∼4회) 등을 변화 시키며 비저항 변화를 관찰하였다. 공침법의 경우 ATO 함량이 30wt%에서 103${\Omega}$·cm 낮은 비저항을 나타내었으며, 그 이상의 함량에서는 거의 일정한 값($60{\Omega}{\cdot}cm∼90{\Omega}{\cdot}$cm)을 보였다. Fabricatio of the potassium-titanate fiber with K2O${\cdot}nTiO_2$ composition and coating of electrically conductive Sb-doped $SnO_2$ (ATO: Antimony Tin Oxide) layer on the fiber on the fiber were the fiber were the aims of this work. The fiber fabricated by slow-cooling technique showed the mean length of $15{\mu}m$ and mean diameter of $0.5{\mu}m$. Three different coating methods i.e, sol-gel, co-precipitation and urea technique, were attempted to coat the conductive ATO layer on the potassium-titanate fiber. The influences of coating method, concentrations of ATO(5∼70wt%) and Sb (0∼20wt%), temperature in the range of $450\;to\;800^{\circ}C$, number of washing (3∼4 times) on the resistivity of the ATO coated fiber were examined in details. The fiber coated ATO by coprecipitation exhibited lower resistivity of 103${\Omega}{\cdot}$cm at the 30 wt% of ATO, and showed nearly constant low value of $60{\Omega}{\cdot}cm\;to\;90{\Omega}{\cdot}$cm at the higher concentration of ATO.