Hematite系 微粉鑛石을 사용한 $CO-H_2$ 混合 Gas에 의한 高炭化鐵의 合成

정우창,Chung, Uoo-Chang 한국자원리싸이클링학회 2004 資源 리싸이클링 Vol.13 No.5

탄화철을 합성하는 공정을 수소($H_2$) 환원과 $CO-H_2$ 혼합가스에 의한 탄화의 2단계 과정으로 나누어서 수행했다. 환원종료 후 미량의 암모니아 가스를 첨가하여 환원철의 표면을 개질한 후, 탄화시간 경과별 탄화상태를 C/S 분석기(Low C/S determinator), 뫼스바우어 분광 분석기(Mossbauer spectroscopy), XRD(X-ray diffraction patterns), SEM(Scanning electron microscopy), TEM(Transmission electron microscopy), XPS(Photoelectron spectroscopy), 및 라만분광기 (Raman spectroscopy)를 사용하여 조사하였다. 연구결과, 미량의 암모니아가스로 환원철 표면을 개질함으로써 탄화철의 분해 및 유리탄소의 석출을 방지할 수 있을 뿐만아니라 6.68wt% 이상 10wt% 까지 탄소가 과고용된 상태에서도 분해되거나 유리탄소를 석출하지 않고 안정상태를 유지하였다. 이러한 결과로부터 철(Fe)과 세멘타이트(cementite, $Fe_3C$)가 혼합되지 않고 고탄화철(SIC, super iron carbide)인 Fe5C2 상태의 안정한 단일상을 얻는데 성공하였다. To investigate the characteristics of phases formed in iron carbides, super iron carbide was synthesized from hematite fines with $CO-H_2$ gas mixture after reduction under $H_2$ gas at $600^{\circ}C$. Before carburization, the surface of iron powder reduced was pre-treated in the atmosphere of 0.05 vol% $NH_3$-Ar. The synthesized iron carbides were comprehensively explored by C/S analyzer(Low C/S determinator), M$\"{o}$ssbauer spectroscopy, X-ray diffraction patterns(XRD), scanning electron microscopy(SEM), transmission electron microscopy(TEM), and Raman spectroscopy at various reaction time of 5, 10, 15, 20, 25, 30, and 35 min, respectively. By adding a small amount of $NH_3$ gas, the super iron carbides containing 10 wt% carbon were synthesized, and its addition stabilized iron carbides. It was found that the $NH_3$ treatment played a major role in the formation of iron carbide without decomposition($Fe_3C{\to}$3Fe+C) of iron carbides and precipitation of free carbon. It also succeed to synthesize super iron carbide, $Fe_5C_2$, as a stable single phase without involving Fe and $Fe_3C$ phases.

전기로 분진과 압연 Scale의 환원 및 탄화거동

황호순,정우창,정원섭,정원배,Hwang Ho-Sun,Chung Uoo-Chang,Chung Won-Sub,Chung Won-Bae 한국자원리싸이클링학회 2003 資源 리싸이클링 Vol.12 No.5

전기로에서 발생하는 분진과 압연스케일의 재활용을 위하여 전기로의 철원과 열원을 동시에 사용할 수 있는 탄화철 제조가 필요하다. 이를 위한 기초 자료를 확보하기 위하여 전기로 분진과 압연스케일의 환원거동과 탄화 거동을 조사하였다. $650^{\circ}C$ 이하의 온도에서 일산화탄소 100%로 탄화를 시키면 유리탄소는 생성되지 않으면서 세멘타이트보다 탄소함량이 더 높은 탄화철(약 9wt% C)을 생성할 수 있었다. 전기로 분진의 환원에 필요한 탄재의 양은 이론 탄재양의 약 1.2배, 그리고 환원온도는 $900^{\circ}C$가 가장 적당하였다. 압연 스케일의 환원온도는 $1000^{\circ}C$가 가장 적당하였다. 전기로 분진 및 압연 스케일의 탄화속도는 압연 스케일의 경우가 모두 빠르게 나타났다. 그리고 슈퍼탄화철의 성분은 대부분 $Fe_2$C이었다. To be recycled iron and heat source in EAF, EAF dust and mill scale generated from steelmaking plant should be made to iron carbide. Behavior of reduction and carburization in EAF dust and mill scale is studied to get fundamental data. EAF dust and mill scale are carburized at $650^{\circ}C$ by 100% CO gas. The carbon content of iron carbide(about 9 wt,% C) is higher than that of cementite without free carbon. The 1.2 times of calculated carbon content is suitable for reduction of EAF dust. The reduction temperature is appropriate to $900^{\circ}C$ in EAF dust and $1000^{\circ}C$ in mill scale. The carburization rate of mill scale are faster than those of EAF dust. The composition of super iron carbide is almost $Fe_2$C.

입도분포가 넓은 분철광석의 유동층 환원에 있어서 분화와 비산특성

김용하,정우창,김행구 ( Yong Ha Kim,Uoo Chang Chung,Hang Goo Kim ) 한국공업화학회 1997 응용화학 Vol.1 No.1

The minimum fluidization velocity for coarse ores, of which fluidization behavior is governed by the force of inertia, increases with temperature while that of fine ores smaller than about 1500 ㎛ decreases. As the gas velocity increases, the abrasion and degradation in coarse ores are more severe but the elutriation rate and the concentration of fine ores entrained in gas also increase and it finally results in a high elutriation loss.

입도분포가 넓은 분철광석의 탄화특성

황호순,정우창,정원섭,정원배,Hwang Ho-Sun,Chung Uoo-Chang,Chung Won-Sub,Chung Won-Bae 한국자원리싸이클링학회 2003 資源 리싸이클링 Vol.12 No.5

넓은 입도분포를 가지는 헤마타이트 철광석을 사용하여 $H_2$ 및 $H_2$-CO 혼합가스 분위기에서 환원 및 탄회특성에 대하여 고찰하였다. 환원에 의한 활성화에너지 값은 약 20kJ/mol 였다. 환원 및 탄화단계에서 무게변화는 환원단계에서는 약 28% 감소하였고, 탄화단계에서는 약 5%증가하였다. 이는 이론 계산식에 의한 값과 거의 일치하였다. 온도, 입도 및 가스비($_H2$/CO=1~5 범위)에 따른 탄화속도는 온도가 낮을수록 입자가 작을수록 그리고 가스비가 작을수록 탄화속도가 증가하였다. 또한 $H_2$의 가스비($H_2$/CO=1)가 낮을 때는 유리카본(C, free carbon)이 발생하였다. 수소가스를 혼합하였을 경우가 탄화속도는 증가하였으나, 수소분율에 비례하여 증가하지는 않았다. 혼합가스 중 수소분율($X_{H2}$ )이 0.5일 때 ($H_2$/CO=1) 탄화속도가 최대였다. 이때 수소가 탄화철 생성과정에 있어서 촉매역할을 한 것으로 추정된다. Characteristics of reduction and carbidization for hematite ore with a wide size range have been investigated at high temperature(590∼64$0^{\circ}C$) under $H_2$ and $H_2$-CO gas mixtures. The apparent activation energy for reduction of hematite ore with H2 gas was found to be 20 kJ/mol. The weight loss by reduction was about 28% md the weight gain by carbidization was about 5%. The measured values of weight change were compared with those calculated from equation (3) & (5) and fairly good agreement was obtained. The rate of carbidization was increased with an decrease in temperature, particle diameter and gas ratio($H_2$/ CO). The free carbon was increased with decrease in gas ratio($H_2$/ CO). The rate of carbidization was increased with mixing of $H_2$ gas but this effect was not proportional to fraction of $H_2$ gas. It was also found that the rate of carbidization was the maximum in the $H_2$ gas fraction of 0.5. It is considered that $H_2$ plays a part as a catalyst for formation of iron carbide($Fe_3$C).

리튬 2차 전지용 LiCo_1-XMg_xO₂(x=0.03)의 결정구조, 전기전도도 및 전기화학적 특성

김호진,정우창,정연욱,이준형,김정주,Kim, Ho-Jin,Chung, Uoo-Chang,Jeong, Yeon-Uk,Lee, Joon-Hyung,Kim, Jeong-Joo 한국세라믹학회 2005 한국세라믹학회지 Vol.42 No.9

[ $LiCoO_{2}$ ] is the most common cathode electrode materials in Lithium-ion batteries. $LiCo_{0.97}Mg_{0.03}O_2$ was synthesized by the solid-state reaction method. We investigated crystal structures, electrical conductivities and electrochemical properties. The crystal structure of $LiCo_{0.97}Mg_{0.03}O_2$ was analyzed by X-ray powder diffraction and Rietveld refinement. The material showed a single phase of a layered structure with the space group R-3m. The lattice parameter(a, c) of $LiCo_{0.97}Mg_{0.03}O_2$ was larger than that of $LiCoO_2$. The electrical conductivity of sintered samples was measured by the Van der Pauw method. The electrical conductivities of $LiCoO_2$ and $LiCo_{0.97}Mg_{0.03}O_2$ were $2.11{\times}10^{-4}\;S/cm$ and $2.41{\times}10^{-1}\;S/cm$ at room temperature, respectively. On the basis of the Hall effect analysis, the increase in electrical conductivities of $LiCo_{0.97}Mg_{0.03}O_2$ is believed due to the increased carrier concentrations, while the carrier mobility was almost invariant. The electrochemical performance was investigated by coin cell test. $LiCo_{0.97}Mg_{0.03}O_2$ showed improved cycling performance as compared with $LiCoO_2$.

Al 6061 합금 양극산화피막의 성장과 부식특성에 미치는 혼합 전해용액의 영향

류한웅,김용환,정우창,정원섭,Ryu, Han-Woong,Kim, Yong-Hwan,Chung, Uoo-Chang,Chung, Won-Sub 한국재료학회 2007 한국재료학회지 Vol.17 No.5

The properties of anodized films on aluminum 6061 alloy in single electrolyte of sulfuric acid and mixed electrolyte of sulfuric-boric acid and sulfuric-boric-nitric acid have been studied. Polarization tests in NaC solution were used to investigate the corrosion performance. Characteristics of film formation and surface morphology were examined by optical microscopy, FE-SEM and EDS. The results obtained have indicated that oxide films growth have been promoted by nitric acid and anodized films in mixed electrolyte have superior corrosion resistance. In case of anodic films formed in mixed electrolyte, some grooves and numerous crazings were also observed at the surface.

복사에너지를 이용한 TIM소재의 방열 특성 향상을 위한 연구

황명원,김도형,정우창,정원섭,Hwang, Myungwon,Kim, Dohyung,Jung, Uoo-Chang,Chung, Wonsub 한국표면공학회 2019 한국표면공학회지 Vol.52 No.2

The aim of this study is to quantitatively demonstrate the possibility of heat transfer by thermal radiation by comparing heat transfer by conventional heat transfer and radiation by radiation. 1) The heat transfer was measured by using filler of TIM material with low thermal conductivity (CuS). As a result, heat transfer was easier than ceramic with high thermal conductivity ($Al_2O_3$ and $Si_3N_4$). 2) The reason for this is thought to be that the infrared wave due to radiation of the air diaphragm has moved easily. 3) From the above results, the heat dissipation of the TIM material indicates the possibility of heat transfer by thermal radiation.

Linear Ion Source를 이용한 Anode Voltage 변화에 따른 DLC 박막특성

김왕렬(Wang Ryeol Kim),정우창(Uoo Chang Jung),조형호(Hyung Ho Jo),박민석(Min Suk Park),정원섭(Won Sub Chung) 한국표면공학회 2009 한국표면공학회지 Vol.42 No.4

Diamond-like carbon(DLC) films were deposited by linear ion source(LIS)-physical vapor deposition method changing the anode voltages from 800V to 1800V , and characteristics of the films were investigated using residual stress tester, nano-indentation, micro raman spectroscopy, scratch tester and Field Emission Scanning Electron Microscope(FE-SEM). The results showed that the residual stress and hardness increased with increasing the ion energy up to anode voltage of 1400 V. It was also found that the content of SP³ carbon increased with increasing the anode voltage SP³/SP² ratio through investigation of SP³/SP² ratio by the micro-raman analysis. From these results, it can be concluded that the physical properties of DLC films such as residual stress and hardness are increased with increasing the anode voltage. These results can be explained that 3- dimensional cross-links between carbon atoms and Dangling bond are enhanced and the internal compressive stress also increased with increasing the anode voltage. The optimal anode voltage is considered to be around 1400 V in these experimental conditions.

학술발표회 초록 : ( 유동층 ) ; Bench - Scale 상온 순환유동층 환원로내 Multi - size 철광석의 유동특성

김용하(Yong Ha Kim),정우창(Uoo Chang Chung),박문덕(Moon Duck Park),이일옥(Il - Ock Lee) 한국화학공학회 1992 추계학술발표회 Vol.- No.-

논문 : 건식제련 ; 철광석의 가스환원반응에 있어서 원주형광석을 위한 모델 개발

강흥원 ( Heung Won Kang ),정우창 ( Uoo Chang Chung ),정원배 ( Won Bae Chung ),정원섭 ( Won Sub Chung ) 대한금속재료학회 ( 구 대한금속학회 ) 1998 대한금속·재료학회지 Vol.36 No.7

Two cylindrical models for the reduction of iron ores are proposed. One model is for the long cylindrical particle and the other for disc-shape particle. The determination method of the rate parameters included in these models are illustrated. The models are applied to the reduction data for a long-cylindrical pellet of which the height is 2.3 times longer than the diameter and a disc-shaped pellet of which thickness is as 0.34 time thick as the diameter. According to the application results, the fractional reductions calculated by the proposed models are on the good agreement of the observed ones and the reasonable values of the rate parameters are obtained.