나선 운동을 이용한 랜덤 적재물의 도금특성

김덕기(Duck Gi Kim),이종항(Jong Hang Lee) 한국생산제조학회 2020 한국생산제조학회지 Vol.29 No.6

The chemical-plating quality of random-loaded small parts depends on the gap control between the parts in the bath. In this study, the plating characteristics for the screw motion of a basket in a bath were analyzed. This motion could be separated into parts for each, and the space for chemical reactions could be created, which improved its quality. The performance of the new technique was verified through experimental design and salt spray tests. The experimental results showed that the main factors that affected quality were temperature and plating solution concentration. In particular, the white rusting generated time of the screw motion method was longer than that of the conventional method.

화학물질 저장 탱크와 방류벽 사이의 공간 부족 개선을 위한 누출 방지판의 안정성 평가 기준

이은별 ( Eunbyul Lee ),곽솔림 ( Sollim Kwak ),최영보 ( Youngbo Choi ) 한국안전학회(구 한국산업안전학회) 2018 한국안전학회지 Vol.33 No.5

The Chemical Controls Act strictly regulates for the chemical companies to establish sufficient space between the liquid chemical tank and dike, but facilities already installed suffer from the space shortage between the tank and dike. Installing leakage preventing plates on the dike is considered as one of the economic solutions that can alleviate the space deficiency. However, there is no technical and reasonable criterion for the safety evaluation of the leakage preventing plate on the dike. In order to address this problem, we provide generalized and verified calculating equations that give maximum height and horizontal distance of leakage trajectories. Through the proposed equations, proper heights of the leakage preventing plates on the dike can be easily determined. In this study, new calculating methods are also developed to determine the impact force of the liquid to the leakage preventing plates. In addition, we performed the reactivity experiments between four corrosive liquid chemicals and two stainless steel materials that are candidate substances for the construction of the leakage preventing plate. The results of this study is expected to be applicable as a guideline in the design of safe dike and its leakage preventing plates.

Effects of Chemical Etching and Functionalization Times on the Properties of Cu/Polyimide Films

성기수,황수민,이창민,김원,이승묵,박근철,정승부,임준형,주진호 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.57 No.61

We fabricated flexible Cu/Polyimide (PI) films by electroless- and electro-Cu plating on surface modified PI via chemical etching and functionalization, and investigated the effects of the modification time on the contact angle, surface energy and morphology, Pd catalyst amount on PI, and resultant peel strength between Cu/PI layers. Chemical etching and successive functionalization were performed on PI surfaces for 0 - 10 min, followed by electroless- and electro-Cu plating. Chemical etching effectively modified the PI surface from a hydrophobic to a hydrophilic state. In addition, chemical functionalization significantly increased the amount of Pd absorption on PI, which consequently enhanced the peel strength between Cu/PI. The peel strength of the resulting Cu/PI film processed by both chemical etching and functionalization for 5 min increased to 5.08 N/cm, which was 4.2 and 2.8 times higher than films processed with functionalization and etching alone, respectively. The highest strength that was achieved was a result of the combined effects of the increased work of adhesion and the increased Pd amount for both treatments; however, the amount of Pd was likely to be the more critical factor for the high level of adhesion between Cu/PI, rather than the work of adhesion.

An Environment-Friendly Surface Pretreatment of ABS Plastic for Electroless Plating Using Chemical Foaming Agents

강동호,최진철,최진문,김태완 한국전기전자재료학회 2010 Transactions on Electrical and Electronic Material Vol.11 No.4

We have developed an environment-friendly etching process, an alternative to the dichromic acid etching process, as a pretreatment of acrylonitrile-butadiene-styrene (ABS) plastic for electroless plating. In order to plate ABS plastic in an electroless way, there should be fine holes on the surface of the ABS plastic to enhance mechanically the adhesion strength between the plastic surface and the plate. To make these holes, the surface was coated uniformly with dispersed chemical foaming agents in a mixture of environmentally friendly dispersant and solvent by the methods of dipping or direct application. The solvent seeps into just below the surface and distributes the chemical foaming agents uniformly beneath the surface. After drying off the surface, the surface was heated at a temperature well below the glass transition temperature of ABS plastic. By pyrolysis, the chemical foaming agents made fine holes on the surface. In order to discover optimum conditions for the formation of fine holes, the mixing ratio of the solvent, the dispersant and the chemical foaming agent were controlled. After the etching process, the surface was plated with nickel. We tested the adhesion strength between the ABS plastic and nickel plate by the cross-cutting method. The surface morphologies of the ABS plastic before and after the etching process were observed by means of a scanning electron microscope.

An Environment-Friendly Surface Pretreatment of ABS Plastic for Electroless Plating Using Chemical Foaming Agents

Kang, Dong-Ho,Choi, Jin-Chul,Choi, Jin-Moon,Kim, Tae-Wan The Korean Institute of Electrical and Electronic 2010 Transactions on Electrical and Electronic Material Vol.11 No.4

We have developed an environment-friendly etching process, an alternative to the dichromic acid etching process, as a pretreatment of acrylonitrile-butadiene-styrene (ABS) plastic for electroless plating. In order to plate ABS plastic in an electroless way, there should be fine holes on the surface of the ABS plastic to enhance mechanically the adhesion strength between the plastic surface and the plate. To make these holes, the surface was coated uniformly with dispersed chemical foaming agents in a mixture of environmentally friendly dispersant and solvent by the methods of dipping or direct application. The solvent seeps into just below the surface and distributes the chemical foaming agents uniformly beneath the surface. After drying off the surface, the surface was heated at a temperature well below the glass transition temperature of ABS plastic. By pyrolysis, the chemical foaming agents made fine holes on the surface. In order to discover optimum conditions for the formation of fine holes, the mixing ratio of the solvent, the dispersant and the chemical foaming agent were controlled. After the etching process, the surface was plated with nickel. We tested the adhesion strength between the ABS plastic and nickel plate by the cross-cutting method. The surface morphologies of the ABS plastic before and after the etching process were observed by means of a scanning electron microscope.

Durable graphene-coated bipolar plates for polymer electrolyte fuel cells

Lee, Yoon Ho,Noh, SeungTak,Lee, Ju-Hyung,Chun, Seung-Hyun,Cha, Suk Won,Chang, Ikwhang Elsevier 2017 International journal of hydrogen energy Vol.42 No.44

<P><B>Abstract</B></P> <P>In this paper, we investigate the role of a graphene layer for polymer electrolyte fuel cells (PEFCs) which require an ultrathin protective layer for copper bipolar plates. The graphene layer was deposited by chemical vapor deposition using CH<SUB>4</SUB> at 830 °C. We examined the deposited graphene layer to characterize microstructural properties using a Raman spectroscopy microscope and a secondary electron microscope. During the electrochemical tests, the current–voltage–power (I–V–P) performance of the single cell using the copper bipolar plate with the graphene layer was highly stable for 5 h, while the I–V–P performance of the single cell using the pure copper bipolar plate (without the graphene layer) was much lower. We conclude that the graphene layer acts as a very thin passivation layer on the copper bipolar plate of a PEFC.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A graphene layer on copper bipolar plate is deposited by chemical vapor deposition. </LI> <LI> The graphene layer was deposited by chemical vapor deposition using CH<SUB>4</SUB> at 830 °C. </LI> <LI> The graphene on the copper bipolar plate acts as a very thin passivation layer. </LI> </UL> </P>

Deposition of gold–titanium and gold–nickel coatings on electropolished 316L stainless steel bipolar plates for proton exchange membrane fuel cells

Elsevier 2010 International journal of hydrogen energy Vol.35 No.4

<P><B>Abstract</B></P><P>The effects of electropolishing and coating deposition on electrical resistance and chemical stability were studied for the stainless steel bipolar plates in proton exchange membrane fuel cell (PEMFC). A series of 316L stainless steel plates, selected as the substrate for a proton exchange membrane fuel cell (PEMFC) bipolar plate, were electropolished with a solution of H<SUB>2</SUB>SO<SUB>4</SUB> and H<SUB>3</SUB>PO<SUB>4</SUB> at temperatures ranging from 70 to 110 °C. The surface regions of the two electropolished stainless steel plates were coated with gold and either a titanium or nickel layer using electron beam evaporation. The electropolished stainless steel plates coated in 2-μm thick gold with a 0.1-μm titanium or nickel interlayer showed remarkably smooth and uniform surface morphologies in AFM and FE-SEM images compared to the surfaces of the plates that were coated after mechanical polishing only. The electrical resistance and water contact angle of the deposited stainless steel bipolar plates are strongly dependent on the surface modification treatments (i.e., mechanical polishing versus electropolishing). ICP-MS and XPS results indicate that after electropolishing, the coating layers show excellent chemical stability after exposure to an H<SUB>2</SUB>SO<SUB>4</SUB> solution of pH 3. Finally, it was concluded that before coating deposition, the surface modification using electropolishing was very suitable for enhancing the electrical property and chemical stability of the stainless steel bipolar plate.</P>

Durability of graphite coated carbon composite bipolar plates for vanadium redox flow batteries

Choe, Jaeheon,Lim, Jun Woo,Kim, Minkook,Kim, Jinwhan,Lee, Dai Gil Elsevier 2015 Composite structures Vol.134 No.-

<P><B>Abstract</B></P> <P>Composite bipolar plates for vanadium redox flow batteries (VRFBs) and fuel cells are coated with expanded graphite to decrease the interfacial contact resistance of the carbon composite. The bipolar plates of vanadium redox flow batteries are exposed to electro-chemical corrosion, which might degrade the graphite coating layer. From two types of graphite foil, i.e., pyrolytic graphite and expanded flake-type graphite, the former has higher durability because its graphene sheets are crystallized in a planar direction with a highly oriented structure, which has a stronger van der Waals bonding.</P> <P>In this study, the characteristics of the pyrolytic graphite and expanded flake-type graphite are investigated with respect to the porosity of graphite. The durability of the graphite coating of the carbon/epoxy composite bipolar plate during the electrochemical reaction in vanadium electrolytes, based on highly concentrated sulfuric acid, is investigated. The areal specific resistances (ASRs) of the bipolar plates coated with pyrolytic graphite are measured, from which the ASR is expressed in terms of modulus of the graphite based on the Hertzian contact model. A single cell test is performed to evaluate the performance of the developed bipolar plate.</P>

Characterization of SUS Molds for Light Guide Plates by Electro-Chemical Fabrication (ECF) Method

Min-Soo Cho,Si-Hyeong Cho,Nam-Goo Cha,Hyun-Woo Lim,Jin-Goo Park,Jae-Seung Jo 대한금속재료학회(구 대한금속학회) 2007 ELECTRONIC MATERIALS LETTERS Vol.3 No.2

A new micro fabrication method termed electro chemical fabrication (ECF) is introduced to overcome conventional problems of electrochemical machining (ECM), such as low reliability and reproducibility. This ECF process defines micro patterns using a conventional photolithography, allowing it to produce micro-scale patterns with an excellent surface profile and of excellent quality. In this paper, four-inch 304 SUS and Ni molds were fabricated by using ECF and FeCl3 wet etching processes, respectively. The etch rate of stainless steel was measured at nearly 0.27 μm/min at optimized ECF conditions and that of Ni was 0.77 μm/min with FeCl3 dipping. To ensure a uniform depth profile of 10 μm, the process time for the SUS and the Ni mold were determined to be 36 minutes and 13 minutes, respectively. After the fabrications of SUS and Ni molds, the ECF-SUS mold showed two times better surface roughness values than the FeCl3-Ni mold. To evaluate the ECF-SUS process, light guide plates (LGP) were made using an injection molding method. The LGP using the FeCl3-Ni mold showed a hazy area when tilting the plate. This haze effect is believed to have formed from poor surface roughness. An LGP made with an ECF-SUS mold showed a 25% higher brightness and a 15% higher light uniformity compared to a FeCl3-Ni mold.

Electrochemical Characteristics of Home-Made Bipolar Plate and Its Relationship with Fuel Cell Performance

권영국,이재광,지덕진,이재영,Kwon, Young-Kook,Lee, Jae-Kwang,Ji, Duk-Jin,Lee, Jae-Young The Korean Electrochemical Society 2009 한국전기화학회지 Vol.12 No.1

본 연구에서는 탄소성형 분리판의 물리화학적, 전기화학적 특성을 분석하여 수소 및 개미산연료 전지의 성능에 미치는 영향을 알아보았다. 기존 기계가공 탄소분리판과 탄소복합소재 탄소성형 분리판의 접촉저항, 부식특성, 소수성을 비교 평가하였다. 특히, 현재 연구개발 중인 탄소복합소재 성형분리판의 경우 계면접촉저항이 기계가공 분리판보다 1.5배 높게 나타났으며, 내식성 실험에서는 산에 취약하여 분리판 표면이 거칠어지고 결정성이 감소하였다. 연료전지의 성능은 분리판의 계면접촉저항에 크게 영향을 받았으며, 계면저항이 적은 기계가공 분리판이 수소 및 개미산 연료 전지에서 높은 성능을 나타냈다. The effect of physico-electrochemical properties of carbon bipolar plate(BPP) on hydrogen and formic acid fuel cell performance has been investigated. BPP made of conventional graphite and carbon fiber composite were compared with the factors of interfacial contact resistance (ICR), corrosion behaviours, and hydrophobicity. Among them, the ICR of carbon fiber composite BPP has 50% higher than conventional graphite and the surface of carbon fiber composite BPP became rougher due to weaker corrosion resistance. Fuel cell performance was strongly dependent of ICR value of carbon bipolar plate.