• 대한기계학회논문집B
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• 제25권10호
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• pp.1392-1399
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• 2001

The flow fields inside a molten Zn pot of continuous hot-chip galvanizing process were investigated experimentally. With varying several parameters including the strip speed Vs, flow rate Q of induction heater. scrapper location and baffle configuration, instantaneous velocity fields were measured using a PIV velocity field measurement technique. Inside the strip region, counter-clockwise rotating flow is dominant. The general flow pattern inside the strip region is nearly not influenced by the strip speed Vs, flow rate Q and the scrapper location. In the exit region, the flow separated from the moving strip due to the existence of a stabilizing roll ascends to the free surface, for the cases of no scrapper and scrapper detached form the roll. On the other hand, the ascending flow to the free surface is decreased, as the flow rate Q of induction heater increases. By installing a baffle around the uprising strip, the flow moving up to the stabilizing roll decreases. In addition, B-type baffle is better than A-type baffle in reducing speed of flow around the stabilizing rolls. However, the flow ascended to the free surface is largely influenced by changing the flow rate Q, and the scrapper location, irrespective of the baffle type.

• 한국공간구조학회:학술대회논문집
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• 한국공간구조학회 2006년도 춘계 학술발표회 논문집 제3권1호(통권3호)
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• pp.66-72
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• 2006

최근 건축물 및 교량 건설에 있어 연성 재료를 사용함으로써 구조형식의 다양화가 적극적으로 이뤄지고 있는 실정이다. 그 중 하나인 케이블 부재는 인장력의 도입으로 인한 전체 구조물의 강성을 증대시킬 수 있으며 흥미로운 연구 대상이라 할 수 있다. 국내에서도 건축물 또는 교량에 케이블 부재를 사용하는 시공 방법이 점차 증가하고 있고 그에 따라 설계 및 시공 기술도 장족의 발전을 이루고 있다 할 수 있다. 설계에 반영된 케이블 부재가 영구적으로 성능을 유지하기 위해서는 케이블 부재의 방청성능이 가장 중요하나, 이에 대한 기술자들의 인식이 다소 부족한 점을 느껴 본 논문에서 케이블의 방청성능에 대해 고찰 하고자 한다.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2012년도 춘계학술발표회 논문집
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• pp.37-37
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• 2012

The coated steels, mainly with zinc by either hot-dip galvanizing or electroplating, are widely used for panels of automotive, electrical appliances and construction, whose size of world market have reached 130 million tons in 2008. Current issues for the coated steels can be integrated in terms of high functionality, low cost, environment-friend and available resource. The best solution can be provided if thin layer coating with higher quality is produced by an eco-friendly process, and PVD, physical vapor deposition, can be an alternative practice to existing coating processes. PVD technologies have been very common ones in electronic and semiconductor industries, but recognized as non-profitable processes for the coated steels due to low process speed and lack of continuous operation skills. Systematic researches from 1990s in Europe, even though discouraged by a shutdown of the first Japanese PVD coating plant in 1999, have realized several continuous PVD coating plants, and also enhanced launching of developments in steel industries. To be successful with PVD coating technologies over existing ones, productivity to meet economics should be created from a highly sophisticated process. Some PVD technologies fit for the high-speed process will be introduced together with experiences from industrial applications.

• 대한금속재료학회지
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• 제46권2호
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• pp.58-64
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• 2008

Surface-void defects observed on the galvannealed(GA) steel sheets in Interstitial-free high-strengthened steels containing Si and Mn have been investigated using the combination of the FIB(Focused Ion Beam) and FE-TEM(Field Emission-Transmission Electron Microscope) techniques. The scanning ion micrographs of cross-section microstructure of defects showed that these defects were identified as craters which were formed on the projecting part of the substrate surface. Also, those craters were formed on the Si or Mn-Si oxides film through the whole interface between galvannealed coating and steel substrate. Interface enrichments and oxidations of the active alloying elements such as Si and Mn during reduction annealing process for galvanizing were found to interrupt Zn and Fe interdiffusion during galvannealing process. During galvannealing, Zn and Fe interdiffusion is preferentially started on the clean substrate surface which have no oxide layer on. And then, during galvannealing, crater is developed with consumption of molten zinc on the oxide layer.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2000년도 춘계학술강연 및 발표대회 강연 및 발표논문 초록집
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• pp.9-10
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• 2000

An important business-field of world-wide steel-industry is the coating of thin metal-sheets with zinc, zinc-aluminum and aluminum based materials. These products mostly go into automotive industry. in particular for the car-body. into building and construction industry as well as household appliances. Due to mass-production, the processing is done in large continuously operating plants where the mostly cold-rolled metal-strip as the substrate is handled in coils up to 40 tons unwind before and rolled up again after passing the processing plant which includes cleaning, annealing, hot-dip galvanizing / aluminizing and chemical treatment. In the liquid Zn, Zn-AI, AI-Zn and AI-Si bathes a combined action of corrosion and wear under high temperature and high stress onto the transfer components (rolls) accounts for major economic losses. Most critical here are the bearing systems of these rolls operating in the liquid system. Rolls in liquid system can not be avoided as they are needed to transfer the steel-strip into and out of the crucible. Since several years, ceramic roller bearings are tested here [1.2], however, in particular due to uncontrollable Slag-impurities within the hot bath [3], slide bearings are still expected to be of a higher potential [4]. The today's state of the art is the application of slide bearings based on Stellite\ulcorneragainst Stellite which is in general a 50-60 wt% Co-matrix with incorporated Cr- and W-carbides and other composites. Indeed Stellite is used as the bearing-material as of it's chemical properties (does not go into solution), the physical properties in particular with poor lubricating properties are not satisfying at all. To increase the Sliding behavior in the bearing system, about 0.15-0.2 wt% of lead has been added into the hot-bath in the past. Due to environmental regulations. this had to be reduced dramatically_ This together with the heavily increasing production rates expressed by increased velocity of the substrate-steel-band up to 200 m/min and increased tractate power up to 10 tons in modern plants. leads to life times of the bearings of a few up to several days only. To improve this situation. the Mechanical Alloying (MA) TeChnique [5.6.7.8] is used to prOduce advanced Stellite-based bearing materials. A lubricating phase is introduced into Stellite-powder-material by MA, the composite-powder-particles are coated by High Energy Milling (HEM) in order to produce bearing-bushes of approximately 12 kg by Sintering, Liquid Phase Sintering (LPS) and Hot Isostatic Pressing (HIP). The chemical and physical behavior of samples as well as the bearing systems in the hot galvanizing / aluminizing plant are discussed. DependenCies like lubricant material and composite, LPS-binder and composite, particle shape and PM-route with respect to achievable density. (temperature--) shock-reSistibility and corrosive-wear behavior will be described. The materials are characterized by particle size analysis (laser diffraction), scanning electron microscopy and X-ray diffraction. corrosive-wear behavior is determined using a special cylinder-in-bush apparatus (CIBA) as well as field-test in real production condition. Part I of this work describes the initial testing phase where different sample materials are produced, characterized, consolidated and tested in the CIBA under a common AI-Zn-system. The results are discussed and the material-system for the large components to be produced for the field test in real production condition is decided. Outlook: Part II of this work will describe the field test in a hot-dip-galvanizing/aluminizing plant of the mechanically alloyed bearing bushes under aluminum-rich liquid metal. Alter testing, the bushes will be characterized and obtained results with respect to wear. expected lifetime, surface roughness and infiltration will be discussed. Part III of this project will describe a second initial testing phase where the won results of part 1+11 will be transferred to the AI-Si system. Part IV of this project will describe the field test in a hot-dip-aluminizing plant of the mechanically alloyed bearing bushes under aluminum liquid metal. After testing. the bushes will be characterized and obtained results with respect to wear. expected lifetime, surface roughness and infiltration will be discussed.

• 한국건축시공학회지
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• 제14권6호
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• pp.505-513
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• 2014

본 연구에서는 전기화학적인 시험 및 CASS Test(염수분무시험)을 실시하여 중방식도장 시험체와 용융아연도금 시험체, Zn-Al 시험체와의 비교를 통해 Zn-Sn 금속용사의 방식 성능을 평가하였다. 시험 결과, 전기화학 시험을 통하여 Zn-Sn / Zn-Al 상온금속용사 시스템 공법의 방식원리는 방식전위에 의하여 확보되는 것을 확인하였으며 강구조물의 방식 공법으로서 상온금속용사 공법은 용융아연도금 공법과 중방식 도장공법과 비교하여 매우 우수한 방식성능을 가지고 있는 것이 CASS 시험을 통하여 검증되었다. 특히 Zn-Sn 금속용사와 Zn-Al 금속용사를 비교해본 결과 그 방식성이 현저하게 차이가 있지는 않았으나 Zn-Sn(65:35) 비율의 시험체가 가장 우수하였다. 또한 중방식 도장은 손상된 부분에서 현저하게 녹이 발생하고 도막이 박리되지만, Zn-Sn / Zn-Al 상온금속용사 시스템 공법은 갈바닉 희생방식에 의하여 매우 높은 부식 방지 특성을 가지고 있음을 확인 하였다.

• 한국융합학회논문지
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• 제9권10호
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• pp.271-276
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• 2018

강의 부식을 방지하기 위해서 희생양극의 원리를 이용한 아연도금이 사용된다. 순수아연도금은 몇가지 문제점을 가지고 있어 얇으면서 내식성을 증가시키기 위한 방안의 하나로 Zn-Mn 합금도금이 연구되어지고 있다. Zn-Mn 합금도금은 도금 단가가 높음에도 불구하고 고내식성을 요구하는 자동차 부품 등에 적용이 가능하다. 본 연구에서는 산성 염화용액에서 Zn-Mn 합금도금을 전착하였다. 이때 염화욕에서 합금도금의 조성에 미치는 전해조건의 영향을 조사하였다. 전류밀도가 증가함에 따라 Zn함량이 감소하고 Mn함량은 증가하였다. 전해액의 온도가 증가함에 따라 Zn함량이 감소하고 Mn함량은 증가하였으며, 음극 분극곡선을 가지고 결과를 설명하였다.