• 한국재료학회지
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• 제31권12호
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• pp.704-709
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• 2021

In the flux used in the batch galvanizing process, the effect of the component ratio of NH₄Cl to ZnCl₂ on the microstructure, coating adhesion, and corrosion resistance of Zn-Mg-Al ternary alloy-coated steel is evaluated. Many defects such as cracks and bare spots are formed inside the Zn-Mg-Al coating layer during treatment with the flux composition generally used for Zn coating. Deterioration of the coating property is due to the formation of AlCl_x mixture generated by the reaction of Al element and chloride in the flux. The coatability of the Zn-Mg-Al alloy coating is improved by increasing the content of ZnCl₂ in the flux to reduce the amount of chlorine reacting with Al while maintaining the flux effect and the coating adhesion is improved as the component ratio of NH₄Cl to ZnCl₂ decreases. Zn-Mg-Al alloy-coated steel products treated with the optimized flux composition of NH₄Cl·3ZnCl₂ show superior corrosion resistance compared to Zn-coated steel products, even with a coating weight of 60 %.

• 한국구조물진단유지관리공학회 논문집
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• 제27권5호
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• pp.16-22
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• 2023

이 연구는 원전 콘크리트 배합설계를 모사한 콘크리트 시험체에 대하여 염수침지 실험을 수행하였으며, 시험체 깊이에 따른 염화물량과 XRF 성분의 상관관계를 분석하였다. 원전 콘크리트의 표면부의 염화물량은 염수 침지기간이 증가함에 따라 소폭 증가하였으나, 깊이 5.5 mm 이상의 콘크리트 시험체 내부 염화물량은 염수 침지기간이 증가함에 증가하는 경향이 뚜렷하게 나타났다. 콘크리트의 염화물량과 XRF 성분의 상관관계 분석결과, OPC 배합과 비교하여 FA가 20% 치환된 배합은 XRF 성분분석을 통한 Cl 이온의 구성비율과 염해저항성 평가결과의 상관관계가 매우 높게 나타났다. 이에 따라 FA가 20% 치환된 원전 콘크리트 배합에서는 반복적인 데이터 누적을 통해 XRF 성분분석을 통하여 염소이온분석 및 염해저항성능 평가가 가능함을 확인하였다.

• 한국안전학회지
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• 제14권4호
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• pp.114-119
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• 1999

When NaOCl was generated and put into sea-water cooling machine in order to overcome the biological hindrances against sea-water cooling machine, it was converted into metallic ion, particularly Ca and Mg, as a hydrate in sea-water and is to stick to electrolyte as a side reaction. This phenomena make the distance between the electrolytes narrow to decrease the flow rate, which induces the local vortex flow which erodes the pole plate. Moreover, this increases the resistance of the electrolyte as well as voltage to decrease the electrolytic efficiency, which has curtailed a chlorine yield and caused a pole plate cut. We are able to overcome these problems by chemical cleaning and intend to extend the life-time of electrolyte and to increase output of the sea-water electrolysis facilities by studying optimal policy regarding chemical cleaning of electrolytic cell. Cleaning time of electrolytic facilities is determined when both increase in electrolytic efficiency and decrease in pole-plate voltage are 10%. At this time as operating current of electrolytic facilities is high, operating time is diminished. Whereas, parameter of end point determination according to cleaning is Mg ionic concentration in solution. When we use Cleaner as a 7wt% HCl, cleaning time is about 80min proper. We are able to maintain pole plate performance by protecting against pole plate cut by means of electrolytic by-product, improve operating rate of facilities, and cut down on maintenance expenditure after acidic cleaning.

• Corrosion Science and Technology
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• 제7권1호
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• pp.27-34
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• 2008

In industrial and fluid handling systems, frequently the protective film forming materials suffer from severe corrosion due to microbial effects. As an example, various micro-organisms, including bacteria, exist in seawater normally fed to power and desalination plants. Unless seawater intakes are properly disinfected to control these microbial organisms, biological fouling and microbial induced corrosion (MIC) will be developed. This problem could destroy metallic alloys used for plant construction. Seawater intakes of cogeneration plants are usually disinfected by chlorine gas or sodium hypochlorite solution. The dose of disinfectant is designed according to the level of contamination of the open seawater in the vicinity of the plant intake. Higher temperature levels, lower pH, reduced flow velocity and oxidation potential play an important role in the enhancement of microbial induced corrosion and bio-fouling. This paper describes, in brief, the different types of bacteria, mechanisms of microbiological induced corrosion, susceptibility of different metal alloys to MIC and possible solutions for mitigating this problem in industry. A case study is presented for the power plant steam condenser at Al-Taweelah B-station in Abu Dhabi. The study demonstrates resistance of Titanium tubes to MIC.

• 한국재료학회지
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• 제3권5호
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• pp.451-458
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• 1993

베아링강(AISI S2100) 위에 TiCi/sub 4/, N/sub 2/,H/sub 2/,그리고 Ar의 기체혼합계를 이용하여 플라즈마화학증착법으로 내마모 TiN증착층을 얻었다. 증착된 TiN층 내의 잔류 CI에 의한 결정성, 미소경도, 접착력, 그리고 마모특성에 대해 연구하였다. TiN 중착층은 좋은 내마모성을 가지고 있었으며, TiN의 기계적 특성은 잔류CI함량이 증가할때 나빠졌다. 마모측정결과 마모면의 trailing edge에 인장응력이 걸려 많은 crack이 관찰되엇다.

• 멤브레인
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• 제17권4호
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• pp.381-386
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• 2007

니켈입자와 고분자를 함유한 니켈슬러리를 상전환법을 이용하여 중공사 형태로 성형한 후, 소결법을 이용하여 $1,150^{\circ}C$ 환원조건에서 소결하여 금속 필터를 제조하였고 니켈 입자를 표면에 함침한 후, $800^{\circ}C$ 환원조건에서 소결하여 금속 정밀여과막을 제조하였다. 소결조건에 따른 금속 중공사 필터와 정밀여과막의 기공크기, 강도를 살펴보았다. 금속 중공사 정밀여과막은 산, 염기 및 염소에 대한 저항성이 뛰어났으며 역세척에 의한 투수량 회복률이 우수하였다.

• Corrosion Science and Technology
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• 제10권2호
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• pp.60-64
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• 2011

Lean duplex stainless steels have been developed in Korea for the purpose of being used in the seawater systems of industry. There are also many important seawater systems in nuclear power plants. These systems supply seawater to cooling water condenser tubes, heat exchanger tubes, related pipes and chlorine injection systems. The flow velocity of some part of seawater systems in nuclear power plants is high and damages of components from corrosion are severe. The considered lean duplex stainless steels are STS329LD (20.3Cr-2.2Ni-1.4Mo) and STS329J3L (22.4Cr-5.7Ni-3Mo) and PRENs of them are 29.4 and 37.3 respectively. Physical, mechanical and micro-structural properties of them are evaluated, and electrochemical corrosion resistance is measured quantitatively in NaCl solution. Critical Pitting Temperatures (CPT)s are measured on these alloys and pit depths are evaluated using laser microscope. Long period field tests on these alloys are now being performed, and some results are going to be presented in the following study.

• 한국세라믹학회지
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• 제44권7호
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• pp.375-380
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• 2007

Tribological properties of carbon layers produced by high temperature chlorination of SiC ceramic and DLC (diamond-like carbon) coatings produced by ion plating method were investigated and compared. Carbon coatings were produced by exposure of ball and disc type SiC in chlorine and hydrogen gas mixtures at $1200^{\circ}C$. After treatment for 10 h, dense carbon films up to $180{\mu}m$ in thickness were formed. Tribological behavior of newly developed carbon films were compared with that of DLC films. Wear resistance and frictional coefficient of the surface modified ball and disc type SiC were significantly improved compared to an untreated SiC specimen, and also the modified carbon layer had better performance than DLC coatings. Therefore, in this study, the newly developed carbon films have several advantages over existing carbon coatings such as DLC coatings and showed superior tribological performances.

• 멤브레인
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• 제19권4호
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• pp.324-332
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• 2009

본 연구는 정밀여과용 Chlorinated Polyvinyl Chloride (CPVC) 평막의 화학약품 수용액 내에서 경과시간에 따른 내화학성을 측정하기 위하여 실시하였다. 화학약품으로는 막 세정에 주로 사용되는 유효염소 0.5 wt% NaClO 수용액과 산성인 HCl 1 wt%, pH 4 수용액 그리고 알카리인 NaOH 4 wt%, pH 10 수용액을 사용하였다. 이상의 수용액중에 CPVC 분리막을 1일, 3, 5, 10일 동안 5, 25, $50^{\circ}C$에서 침지시킨 후, 각각의 인장강도와 파단시 신장율을 측정하여 내구성을 평가하였다. 막 세정시 주로 사용되는 유효염소 0.5 wt% NaClO 수용액의 경우 $5^{\circ}C$ 조건에서는 인장강도 변화는 5% 이내이지만 25, $50^{\circ}C$에서는 17%까지 감소하였다. CPVC 분리막의 내화학성은 산성인 HCl 1 wt%와 pH 4 수용액에서 우수하였으나 NaOH 4 wt% 수용액에 대해서 가장 취약한 것으로 나타났다.

• 한국건설순환자원학회논문집
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• 제9권4호
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• pp.545-552
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• 2021

본 연구에서는 산업부산물인 탈황석고 및 페로니켈슬래그 미분말을 혼합한 진동전압방식 모르타르의 강도 및 내구성의 평가를 실시한다. VR관 제작시 사용되는 석회석미분말 25% 치환을 기준으로 탈황석고 및 페로니켈슬래그 미분말을 복합치환하고, 진동전압방식을 사용하여 시편을 제작하였다. 강도발현 특성을 평가하기 위해 휨 및 압축강도를 실시하였으며, 내구성을 평가하기 위해 염소이온침투저항성 및 내황산저항성 시험을 실시하였다. 휨 및 압축강도에서 혼화재 중 탈황석고의 비율이 20~60% 범위에서 강도가 향상되었으며, 탈황석고의 비율이 20~80% 범위에서 염소이온침투저항성 시험에서 통과 전하량이 감소하는 경향을 보였다. 내황산저항성은 탈황석고의 비율이 40%인 경우 침지기간에 따른 강도 및 질량 감소율이 줄어들었다. 강도 및 내구성 실험결과를 기초로 탈황석고 및 페로니켈슬래그 미분말을 적절하게 혼합해서 사용한다면 강도 및 내구성에서 성능 개선 효과를 기대할 수 있다고 판단된다.