전해도금에 의한 Ni-C 복합층의 내식성 및 표면 전기저항

박제식,이성형,정구진,이철경,Park, Je-Sik,Lee, Sung-Hyung,Jeong, Goo-Jin,Lee, Churl-Kyoung 한국재료학회 2011 한국재료학회지 Vol.21 No.5

Simultaneous Ni and C codeposition by electrolysis was investigated with the aim of obtaining better corrosion resistivity and surface conductivity of a metallic bipolar plate for application in fuel cells and redox flow batteries. The carbon content in the Ni-C composite plate fell in a range of 9.2~26.2 at.% as the amount of carbon in the Ni Watt bath and the roughness of the composite were increased. The Ni-C composite with more than 21.6 at.% C content did not show uniformly dispersed carbon. It also displayed micro-sized defects such as cracks and crevices, which result in pitting or crevice corrosion. The corrosion resistance of the Ni-C composite in sulfuric acid is similar with that of pure Ni. Electrochemical test results such as passivation were not satisfactory; however, the Ni-C composite still displayed less than $10^{-4}$ $A/cm^2$ passivation current density. Passivation by an anodizing technique could yield better corrosion resistance in the Ni-C composite, approaching that of pure Ni plating. Surface resistivity of pure Ni after passivation was increased by about 8% compared to pure Ni. On the other hand, the surface resistivity of the Ni-C composite with 13 at.% C content was increased by only 1%. It can be confirmed that the metal plate electrodeposited Ni-C composite can be applied as a bipolar plate for fuel cells and redox flow batteries.

상온제련을 위한 네오디뮴의 비수계 전해 기초연구

박제식,이철경,Park, Jesik,Lee, Churl Kyoung 한국자원리싸이클링학회 2018 資源 리싸이클링 Vol.27 No.4

In this study, the electrochemical redox behavior of neodymium in non-aqueous electrolytes was investigated to confirm the possibility of neodymium metallurgy at room temperature. The non-aqueous electrolytes include ionic liquids such as $[C_4mim]PF_6$, $[C_4mim]Cl$, and $[P_{66614}]PF_6$, ethanol which are highly soluble in neodymium salts, and mixed electrolytes based on carbonate with highly electrochemical stability. The electrochemical redox properties of neodymium were better than those of other electrolytes in the case of the mixed electrolyte based on ethylene carbonate (EC)/di-ethylene carbonate (DEC). Ethanol was added to improve the physical properties of the mixed electrolyte. Thorough the analysis about ionic conductivity of EC/DEC ratio, ethanol content and $NdCl_3$ concentration, the best electrolyte composition was 50 vol% content of ethanol and 0.5 M of $NdCl_3$. Using cyclic voltametry and linear sweep voltametry, a current peak estimated at -3.8 V (vs. Pt-QRE) was observed as a limiting current of neodymium reduction. Potentiostatic electrolysis for 18 hours at room temperature at -6 V (vs. Pt-QRE) confirmed that metallic neodymium was electrodeposited.

Preparation of Magnesium Thin Film by Non-Aqueous Electrolysis at Room Temperature

박제식,이철경 한국정밀공학회 2014 International Journal of Precision Engineering and Vol. No.

The synthesis of a magnesium thin film by simple electrolysis was investigated in three non-aqueous electrolytes. Linear sweep voltammograms of magnesium on the copper electrode showed the possibility of electrodepositing metallic magnesium at room-temperature. Morphology of the magnesium thin film could be controlled by controlling the applied current. The metallic magnesium thin film could be easily and uniformly deposited on a copper electrode under galvanostatic conditions in THF solution of EtMgBr. The magnesium film formation was confirmed by X-ray diffractometry and scanning electron microscopy with energy-dispersive spectroscopy.

실리콘 슬러지로부터 실리콘의 전해회수(電解回收)

박제식,장희동,이철경,Park, Jesik,Jang, Hee Dong,Lee, Churl Kyoung 한국자원리싸이클링학회 2012 資源 리싸이클링 Vol.21 No.5

실리콘 웨이퍼공정에서 발생하는 실리콘 슬러지로부터 실리콘 및 탄화규소를 분리한 다음, 전해법으로 원소형태의 실리콘을 회수하는 연구를 수행하였다. 실리콘 슬러지의 주요 불순물은 절삭유, 금속불순물, 실리콘 및 실리콘 카바이드를 들 수 있다. 기계적 선별법으로 분리한 실리콘, 탄화실리콘 복합물을 $1000^{\circ}C$에 1시간동안 염화 배소하여 응축하고 회수한 사염화실리콘을 이온성액체인 $[Bmpy]Tf_2N$에 용해하여 전해액으로 사용하였다. 순환전위법으로부터 $[Bmpy]Tf_2N$의 안정한 전압구간과 사염화실리콘을 용해한 $[Bmpy]Tf_2N$ 전해액에서 실리콘의 환원으로 추정되는 환원피크를 얻을 수 있었다. 정전위법(-1.9 V vs. Pt-QRE)에서 1시간동안 금 전극 상에 전해한 다음, 전극표면을 XRD, SEM-EDS 및 XPS 분석을 통하여 실리콘이 원소형태로 전착되었음을 확인하였으며, 미량의 산소가 검출되는 것은 분석과정에서 시편이 공기 중에 노출되었기 때문으로 판단된다. As a recovery of elemental silicon from the sludge of Si wafer process, a process of mechanical separation-chlorine roasting-electrolysis has been suggested. The silicon sludge consisted of Si, SiC, machine oil, and metallic impurities. The oil and metal impurities was removed by mechanical separation. The Si-SiC mixture was converted to silicon chloride by chlorine roasting at $1000^{\circ}C$ for 1 hr and the silicon chloride was dissolved into an ionic liquid of $[Bmpy]Tf_2N$ as an electrolyte. Cyclic voltammetry results showed an wide voltage window of pure $[Bmpy]Tf_2N$ and a reduction peak of elemental Si from $[Bmpy]Tf_2N$ dissolved $SiCl_4$ on Au electrode, respectively. The silicon deposits could be prepared on the Au electrode by the potentiostatic electrolysis of -1.9 V vs. Pt-QRE. The elemental silicon uniformly electrodeposited was confirmed by various analytical techniques including XRD, FE-SEM with EDS, and XPS. Any impurity was not detected except trace oxygen contaminated during handling for analysis.

전해도금에 의한 Ni-W 합금의 내식성 및 표면 전도도 특성 연구

박제식(Jesik Park),정구진(Goojin Jeong),김영준(Youngjun Kim),김기재(Kijae Kim),이철경(Churl Kyoung Lee) 한국표면공학회 2011 한국표면공학회지 Vol.44 No.2

A Ni-W thin-film was synthesized by electrodeposition, and its corrosion resistance and electrical surface conductivity were investigated. Amount of tungsten in the Ni-W thin-film increased linearly with current density during the electrodeposition, and crack-free and low-crystalline Ni-21 at.%W coating layer was obtained. Corrosion resistances of the Ni-W thin-films were examined with an anodic polarization method and a storage test in a strong sulfuric acid solution. As a result, the Ni-21 at.%W thin-film exhibited the greatest corrosion resistance, and maintained the electrical surface conductivity even after the severe corrosion test, which could be applicable as a surface treatment for advanced metallic bipolar plates in fuel cell or redox flow battery systems.

[박막의 부식, 방식 및 마모 거동] Ni-Px/C 다층 도금층의 내식성과 표면 전기저항 평가

박제식(Jesik Park),정은경(Eun-Kyung Jung),이철경(Churl Kyoung Lee) 한국표면공학회 2012 한국표면공학회지 Vol.45 No.4

Ni-P/C multi-layer was synthesized by electroless plating and paste coating for better corrosion and surface conductance as a metallic bipolar plate. The Ni-P layer could be synthesized with the range of 2.6~22.4 at.% P contents and it"s surface morphology and corrosion resistance depend on content of P. Corrosion resistance of the Ni-P layer in sulfuric acid by electrochemical test is similar with pure Ni. Surface resistance of pure Ni after corrosion was increased about 8% compared to pure Ni. On the other hand, that of the Ni-P/C composite with 20% carbon content was increased only 1%.

상온(常溫) 전해법(電解法)에 의한 리튬 금속(金屬)의 회수(回收): I. 전극물질(電極物質)의 영향(影響)

이재오,박제식,이철경,Lee, Jae-O,Park, Jesik,Lee, Churl Kyoung 한국자원리싸이클링학회 2012 資源 리싸이클링 Vol.21 No.6

리튬 리싸이클링의 일환으로 상온 전해법으로 금속형태의 리튬을 회수하는 연구를 수행하였다. 리튬 전해액으로 이온성액체인 PP13TFSI에 리튬염으로 LiTFSI를 용해시켜 사용하였으며, 작동전극으로 금, 백금 및 구리를 각각 적용하였다. 작동전극 상에서 조사한 순환전위주사 실험 결과로부터 리튬의 상온 전해환원에 대한 가능성을 확인하였으며, 백금이나 구리의 경우 보다 금 전극에서 리튬 환원전류가 더 크게 나타났다. 정전위법(-2.4 V vs. Pt-QRE)으로 1시간동안 금 전극 상에 전착한 다음, 전극표면을 SEM-EDS 및 XRD 분석을 하였다. 전착된 리튬은 금속 리튬 혹은 금과의 합금 형태이었으며, 침상형으로 균일하게 전착되었음을 확인하였다. 또한 전착물에 미량의 산소가 검출되는 것은 분석과정에서 시편이 공기 중에 노출되었기 때문으로 판단된다. The room-temperature electrodeposition of metallic lithium was investigated from ionic liquid, 1-methyl-1-propylpiperidinium bis(trifluoromethanesulfonyl)imide (PP13TFSI) with lithium bis (trifluoromethanesulfonyl)imide (LiTFSI) as a lithium source. Cyclic voltammograms on gold working electrode showed the possibility of the electrodeposition of metallic lithium, and the reduction current on a gold electrode was higher than the value on platinum and copper. The metallic lithium could be electrodeposited on the gold electrode under potentiostatic condition at -2.4 V (vs. Pt-QRE) and was confirmed by analytical techniques including XRD and SEM-EDS. The dendrite-typed electrodeposits were composed of a metallic lithium and a alloy with gold substrate. And any impurity could be detected except for trace oxygen introduced during handling for the analyses.

이온성액체 기반 비수계 용액에서 용매추출과 전해에 의한 백금족 금속의 분리회수

박광원,박제식,이철경,Park, Gwang-won,Park, Jesik,Lee, Churl Kyoung 한국자원리싸이클링학회 2019 資源 리싸이클링 Vol.28 No.2

In this study, the extraction and reduction behavior of platinum group metals in a non-aqueous solvent based on ionic liquids was investigated in order to confirm a new extraction technology of platinum group metals. Platinum was selectively extracted using an ionic liquid $[C_4mim]PF_6$ from a mixed solution of $PdCl_2$, $PtCl_4$ and $RhCl_3$ dissolved with concentration ratio of 10:1:0.5 M. After stripping of the metals by 1 M $HNO_3$ solution, the platinum was preferentially reduced by aqueous electrolysis on gold electrode at -0.8 V (vs. Pt-QRE). The residual palladium and rhodium were transferred to ionic liquid of $[C_4mim]Cl$. The metallic palladium and rhodium could be sequentially reduced on gold and STS304 as working electrodes by non-aqueous electrolysis, respectively.

Corrosion Behavior of Stainless Steel 304, Titanium, Nickel and Aluminium in Non-Aqueous Electrolytes

Bonita Dilasari,박제식,Priyandi Kusumah,권경중,이철경 한국전기화학회 2014 한국전기화학회지 Vol.17 No.1

The corrosion behavior of stainless steel 304 (SS 304), titanium, nickel and aluminiumis studied by immersion and anodic polarization tests in non-aqueous electrolytes. Tetraethylammonium tetrafluoroborate is used as a supporting electrolyte in the three kinds ofsolvents. The immersion test shows that chemical corrosion rate in propylene carbonate-basedelectrolyte is lower than those in acetonitrile- or γ-butyrolactone-based electrolytes. Surfaceanalyses do not reveal any corrosion product formed after the immersion test. In the anodicpolarization tests, a higher concentration of supporting electrolyte gives a higher current density. In addition, a higher temperature increases the current density in the active region and reducesthe potential range in the passive region. SS 304 shows the highest corrosion potential whileAl shows the lowest corrosion potential and the highest current density in all studied conditions. Based on the conducted corrosion tests, the corrosion resistance of metal substrates in theorganic solvents can be sorted in descending order as follows: SS 304 - Ti - Ni - Al.

Study of Electrochemical Redox of Gold for Refining in Non-aqueous Electrolyte

이재오,박광원,박제식,조영주,이철경 한국정밀공학회 2015 International Journal of Precision Engineering and Vol. No.

The electrorefining of gold by simple electrolysis was investigated in the ionic liquid, 1-ethyl-3-methyl-imidazolium bis (trifluoromethanesulfonyl)imide (EMIMTFSI) with titanium tetrachloride (TiCl4) used as a supporting electrolyte at room temperature. From the cyclic voltammetry results, optimal electrorefining conditions were found for selective dissolution of gold from an anode and for selective reduction on a cathode under potentiostatic conditions, in which is able to obtain pure gold on a cathode surface. The composition, crystal structure, and morphology of pure gold were confirmed by X-ray diffraction and scanning electron microscopy with energy-dispersive spectroscopy. The electrodeposited gold was uniformly distributed on the platinum electrode surface without any impurities by non-aqueous electrolysis at room temperature.