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염화동 폐액으로부터 양이온격막 전해 채취된 구리 분말을 이용한 황산동의 제조방법 연구
강용호,현승균,Kang, Yong-Ho,Hyun, Soong-Keun 한국자원리싸이클링학회 2019 資源 리싸이클링 Vol.28 No.1
일반적으로, 황산동을 제조하기 위한 원료는 $H_2SO_4$ 및 Cu 금속이 사용된다. 본 연구는 폐산, 폐염화동 폐기물부터 전해 채취법을 이용하여 황산동을 제조하는 방법에 관한 것이다. 황산구리의 용도는 공업용, 도금용, 사료용, 농업용, 전자급 PCB 동도금에 사용된다. 종래의 황산동 제조법은 다량의 폐수 및 에너지 비용이 높은 문제점이 있다. 구리(Cu) 화합물 중에서 가장 사용이 많이 되는 황산동($CuSO_4$)의 제조 방법에 관한 연구로서, 공정 운전비가 적고, 폐수 발생이 적으며, 제조 공정이 간단하다. 양이온 맴브레인을 이용하여 Na, Ca, Mg, Al을 불순물로서 제거하기 쉽다. 또한 동시에 전해 채취 방법으로 고 순도 구리 분말을 회수 할 수 있었다. 회수 된 구리 분말을 사용하여 고 순도 황산동을 제조 할 수 있었다.
양현민(Hyun-Min Yang),유회수(Hoi-Soo Ryoo),현승균(Soong-Keun Hyun) 대한용접·접합학회 2016 대한용접·접합학회지 Vol.34 No.3
The digital controlled SMA welding power source having the hot start current and short circuit waveform control was developed. The inverter power controller was used an analog circuit and the short circuit waveform controller was developed using a 8-bit MCU. For the evaluation of the developed SMA welding power source it were compared with a domestic welding power sources. Using the high titanium oxide type and low hydrogen type electrodes, the characteristics of hot start and short circuit was evaluated. Developed SMA welding power source shows good start performance. Also, arc stability and low current weldability were improved by the short circuit waveform control.
APT(S) 제조 시 전기투석법을 이용한 H<sub>2</sub>WO<sub>4</sub>(Aq)내의 Na 제거 방법에 관한 연구
강용호,현승균,Kang, Yong-Ho,Hyun, Soong-Keun 한국자원리싸이클링학회 2017 資源 리싸이클링 Vol.26 No.6
APT (Ammonium paratungstate)는 금속절단 공구, 드릴의 날, 광산공구, 군사무기 재료 등 산업 전반에 다양한 용도로 사용되며, 고순도의 APT(S)를 제조하기 위해서는 $Na_2WO_4$ 수용액으로부터 전환된 $H_2WO_4$ 내의 불순물 정제 공정이 필요하다. 이미 널리 알려진 기존의 습식방법인 $Na_2WO_4$ 수용액에 HCl(Aq)을 첨가하여 $H_2WO_4(S)$을 제조하는 경우에는 불순물인 Na를 200 ppm 이하로 제거하는데 어려움이 있다. 이러한 점을 개선하기 위하여 본 연구에서는 양이온 격막을 이용한 전기투석 공정을 통해 Na를 제거하는 보다 경제적이고 효율적인 방법을 연구하였다. 폐 텅스텐 초경드릴 및 스크랩을 용해하기 위해 첨가되었던 $Na_2CO_3(S)$로 인한 $H_2WO_4$ 수용액 내의 다량의 Na를 전기투석 공정을 통해 20 ppm 이내로 제거함으로써 전기투석법 이용 시 Na 제거 효과가 큼을 확인하였다. APT (Ammonium paratungstate) is widely used in various industries such as metal cutting tools, drill bits, mining tools, and military inorganic materials. In order to produce high purity APT(S), an impurity purification step in an aqueous $Na_2WO_4$ convert $H_2WO_4$ solution is required. It is difficult to remove impurity Na of 200 ppm or less when $H_2WO_4(S)$ is prepared by adding HCl(Aq) to an aqueous solution of $Na_2WO_4$, which is a well-known conventional wet method. However, in this study, a more economical and efficient method of removing Na through electrodialysis using a cationic membrane was studied. A large amount of Na in aqueous solution of $H_2WO_4$ due to $Na_2CO_3(S)$ which was added to dissolve waste tungsten carbide drill and scrap was removed to 20ppm or less through electrodialysis process, and it was confirmed that the effect of Na removal was great when using electrodialysis.
니켈 MHP로부터 제조된 염화니켈을 이용한 탄산니켈 제조연구
강용호,신기웅,현승균,Kang, Yong-Ho,Shin, Gi-Wung,Hyun, Soong-Keun 한국자원리싸이클링학회 2018 資源 리싸이클링 Vol.27 No.5
Generally $NiSO_4$ and $NiCl_2$ were used as raw materials for producing nickel carbonate. In the case of the produced nickel carbonate, $Na_2SO_4$ and NaCl are generated on the surface and inside of the nickel carbonate to decrease the purity of the nickel carbonate. High purity nickel carbonate can be produced according to the degree of removal of such impurities. In this study, $NiCl_2$ produced by nickel MHP solvent extraction process was used to study the production of nickel carbonate. High purity nickel carbonate was prepared by the conditions according to the nickel salt and carbonate equivalence ratio, the reduction of Na and Cl in nickel carbonate according to the washing of nickel carbonate, and the reduction of Na and Cl according to the washing water temperature.
주조 상태 및 용체화처리한 AZ91-4%RE 마그네슘 합금의 부식 거동
한진구 ( Jin-gu Han ),현승균 ( Soong-keun Hyun ),전중환 ( Joong-hwan Jun ) 한국열처리공학회 2018 熱處理工學會誌 Vol.31 No.5
The objective of this study is to investigate the effect of solution treatment on the microstructure and corrosion behavior of cast AZ91-4%RE magnesium alloy. In the as-cast state, microstructure of the AZ91-4%RE alloy was characterized by intermetallic β(Mg<sub>17</sub>Al<sub>12</sub>), Al<sub>11</sub>RE<sub>3</sub> and Al2RE phase particles distributed in α-(Mg) matrix. After solution treatment, the β particles with low melting point dissolved into the matrix, but Al-RE phases still remained due to their high thermal stabilities. It was found from the immersion and potentiodynamic polarization tests that corrosion rate of the AZ91-4%RE alloy increased after the solution treatment. On the contrary, EIS tests and EDS compositional analyses on the surface corrosion products indicated that the stability of the corrosion product was improved after the solution treatment. Examinations on the corroded microstructures for the ascast and solution-treated samples revealed that dissolution of the β particles which play a beneficial role in suppressing corrosion propagation, would be responsible for the deterioration of corrosion resistance after the solution treatment. This result implies that the microstructural features such as amount, size and distribution of secondary phases that determine corrosion mechanism, are more influential on the corrosion rate in comparison with the stability of surface corrosion product. (Received August 7, 2018; Revised August 31, 2018; Accepted September 6, 2018)
Al2Ca를 함유한 A356 합금에서의 다양한 열처리 조건에 따른 공정 Si 개량화 거동
김세준 ( Se Jun Kim ),현승균 ( Soong Keun Hyun ),김세광 ( Shae K. Kim ),윤영옥 ( Young Ok Yoon ) 한국주조공학회 2014 한국주조공학회지 Vol.34 No.5
This study is focused on the effect of Al2Ca as a modifier on eutectic Si modification of A356 alloy. Microstructural observation was carried out for as-cast, as-solution treated and as-aged samples. Solution treatment and aging were performed for 2, 4, 6 and 10 hrs at 540oC and 170oC, respectively. Although A356 alloy, which Al2Ca was added, has no significant difference in as-cast phases with normal A356 alloys, it shows much more modified eutectic Si, grain refinement and improved tensile property both in as-cast and as-heat treated conditions. TGA result shows that Al2Ca added A356 alloy has a certain improvement in oxidation resistance.
방전플라즈마 소결법으로 제조된 Ta-Cu의 미세조직 및 전기접점 특성
주원,김영도,심재진,최상훈,현승균,임경묵,박경태,Ju, Won,Kim, Young Do,Sim, Jae Jin,Choi, Sang-Hoon,Hyun, Soong Keun,Lim, Kyoung Mook,Park, Kyoung-Tae 한국분말야금학회 2017 한국분말재료학회지 (KPMI) Vol.24 No.5
Microstructure, electric, and thermal properties of the Ta-Cu composite is evaluated for the application in electric contact materials. This material has the potential to be used in a medium for a high current range of current conditions, replacing Ag-MO, W, and WC containing materials. The optimized SPS process conditions are a temperature of $900^{\circ}C$ for a 5 min holding time under a 30 MPa mechanical pressure. Comparative research is carried out for the calculated and actual values of the thermal and electric properties. The range of actual thermal and electric properties of the Ta-Cu composite are 50~300 W/mk and 10~90 %IACS, respectively, according to the compositional change of the 90 to 10 wt% Ta-Cu system. The results related to the electric contact properties, suggest that less than 50 wt% of Ta compositions are possible in applications of electric contact materials.