• 문화기술의 융합
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• 제5권4호
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• pp.367-371
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• 2019

본 연구에서는 해양성 기후조건에 있는 철도 레일의 부식으로 인한 선로장애를 최소화하고 레일의 부식을 저감시키기 위한 방식대책으로써 희생양극법을 제시하고 방식효과를 실험적으로 입증하였다. 또한 제안된 희생양극을 현장에 시험부설하여 26개월 이상 장기 레일부식모니터링 및 현장적용성을 검토하고 레일부식의 효과를 입증하였다. 셀로판테이프법을 이용한 부식상태 모니터링 결과, 현장시험부설 후 약 26개월이 경과된 현 시점에서의 희생양극의 외관상태는 양호하며, 레일복부와 희생양극의 용접부 이상 및 기타 특이사항은 발견되지 않았으나, 희생양극을 설치하지 않은 개소에서는 녹의 진전이 빠르게 진행되었다. 또한 희생양극의 적정 설치간격은 1.0~1.5m까지가 상대적으로 가장 안정적인 부식피막을 형성하는 것으로 조사되었다. 약 26개월의 모니터링 결과, 희생양극의 설치는 설치간격이 다소 넓더라도 해양성 기후조건에 있는 철도 레일의 전반적인 부식발생 수준을 안정화하는 데에 도움을 줄 수 있어 부식에 취약한 환경에 부설된 철도 레일에 적용이 가능할 것으로 분석되었다.

• Corrosion Science and Technology
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• 제19권2호
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• pp.82-88
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• 2020

This work examined the corrosion protection performance of benzoate loaded hydrotalcite/graphene oxide (HT/GO-BZ) for carbon steel. HT/GO-BZ was fabricated by the co-precipitation method and characterized by infrared spectroscopy, X-ray diffraction, and scanning electronic microscopy. The corrosion inhibition action of HT/GO-BZ on carbon steel in 0.1 M NaCl solution was evaluated by electrochemical measurements. The benzoate content in HT/GO-BZ was determined by UV-Vis spectroscopy. Subsequently, the effect of HT/GO-BZ on the corrosion resistance of the water-based epoxy coating was investigated by the salt spray test. The obtained results demonstrated the intercalation of benzoate and GO in the hydrotalcite structure. The benzoate content in HT/GO-BZ was about 16%. The polarization curves of the carbon steel electrode revealed anodic corrosion inhibition activity of HT/GO-BZ and the inhibition efficiency was about 95.2% at a concentration of 3g/L. The GO present in HT/GO-BZ enhanced the inhibition effect of HT-BZ. The presence of HT/GO-BZ improved the corrosion resistance of the waterborne epoxy coating.

• 마이크로전자및패키징학회지
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• 제24권4호
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• pp.79-84
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• 2017

태양전지와 같은 광전소자의 특성 및 신뢰성 유지하기 위해서는 수분과 산소 등으로 부터 소자 내부가 보호되어야 한다. 본 연구는 여러 연성(flexible) 플라스틱 기판위에 유 무기 복합 보호막을 스프레이코팅 방법으로 형성하여 공정조건(노즐 위치, 박막 두께, 기판 구성)에 따른 소자의 보호특성을 연구하였다. 사용된 복합 보호막 재료로서 PVA (polyvinyl alcohol)와 SA(sodium alginate) 혼합 유기 물질(P.S)에 $Al_2O_3$($P.S+Al_2O_3$)과 $SiO_2$($P.S+SiO_2$) 나노 분말을 혼합하여 유 무기 복합 보호막 용액을 합성하였다. 플라스틱 기판 위에 코팅한 보호막의 두께가 $5{\mu}m$에서 91%의 투과율을 나타내었으며 $78{\mu}m$에서 $178{\mu}m$로 두께가 증가할 경우 광 투과율은 81.6%에서 73.6%으로 감소하였다. 또한 합성한 $P.S+Al_2O_3$ 복합재료를 사용하여 PEN(polyethylene naphthalate), PC(polycarbonate) 단일 플라스틱 기판과 Acrylate film과 PC 이중막(Acrylate film/PC double layer) 구조와 $Al_2O_3$ 무기박막과 PEN 이중막($Al_2O_3$ film/PEN double layer) 구조의 기판 위에 $P.S+Al_2O_3$ 용액을 사용하여 수분투과도(water vapor transmission rate, WVTR)와 표면형상 등을 측정하여 최적의 보호막 구조를 확인하였다. 즉, $Al_2O_3$ film/PEN 이중막 기판위에 형성한 보호막의 수분투과 값은 $0.004gm/m^2-day$로 가장 우수한 내 투습 특성을 나타내었다.

• Corrosion Science and Technology
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• 제4권4호
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• pp.140-146
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• 2005

Fossil fired power plant produces the electric energy by using a thermal energy by the combustion of fossil fuels as like oil, gas and coal. The exhausted flue gas by the combustion of oil etc. contains usually many contaminated species, and especially sulfur-content has been controlled strictly and then FGD (Flue Gas Desulfurization) facility should be installed in every fossil fired power plant. To minimize the content of contaminations in final exhaust gas, high corrosive environment including sulfuric acid (it was formed during the process which $SO_2$ gas combined with $Mg(OH)_2$ solution) can be formed in cooling zone of FGD facility and severe corrosion damage is reported in this zone. These conditions are formed when duct materials are immersed in fluid that flows on the duct floors or when exhausted gas is condensed into thin layered medium and contacts with materials of the duct walls and roofs. These environments make troublesome corrosion and air pollution problems that are occurred from the leakage of those ducts. The frequent shut down and repairing works of the FGD systems also demand costs and low efficiencies of those facilities. In general, high corrosion resistant materials have been used to solve this problem. However, corrosion problems have severely occurred in a cooling zone even though high corrosion resistant materials were used. In this work, a new technology has been proposed to solve the corrosion problem in the cooling zone of FGD facility. This electrochemical protection system contains cathodic protection method and protection by coating film, and remote monitoring-control system.

• Carbon letters
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• 제26권
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• pp.51-60
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• 2018

An electroless deposition method was used to modify the surface properties of rice husk ceramic particles (RHC) by depositing nano-nickel on the surface of the RHC (Ni-RHC). The dry tribological performances of aluminum matrix composite adobes containing different contents of RHC and Ni-RHC particles have been investigated using a micro-tribometer. Results showed that the Ni-RHC particles substantially improved both the friction and wear properties of the Ni-RHC/aluminum matrix adobes. The optimal concentration was determined to be 15 wt% for both the RHC and Ni-RHC particles. The improvements in the tribological properties of aluminum adobes including the Ni-RHC were ascribed to friction-induced peeling off of Ni coating and formation of protection layer on the wear zone, both of which led to low friction and wear volume.

• Corrosion Science and Technology
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• 제9권6호
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• pp.325-330
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• 2010

Many surface protection methods have been developed to apply for constructional steels used under severe corrosive environment. Thermal spray coating has been known to be an attractive technique due to its relatively high coating speed. Furthermore high corrosion resistance of coated film with thermal spray is required to expand its application. Four types of coated films(DFT:300 um) such as pure zinc, pure aluminum and two Al-Zn alloy (Al:Zn=85:15 and Al:Zn=95:5) onto the carbon steel (SS401) were prepared with arc spray, and the corrosion behavior of their samples were evaluated by electrochemical method in this study. Pure aluminum sample showed high corrosion resistance behavior exposed to sea water solution and pure zinc and alloy (Al:Zn=95:5) samples followed pure aluminum sample. The other alloy(Al:Zn=85:15) so called galvalume coated onto the carbon steel ranks the 4th corrosion resistance in this study. The results of porosity ratio of those samples by observation are well matched with the electrochemical data.

• 대한금속재료학회지
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• 제49권8호
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• pp.601-607
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• 2011

The study investigated the influence of current density on the corrosion-protection properties of an AZ91 Mg alloy subjected to plasma electrolytic oxidation coating. The present coatings were carried out under an AC condition at three different current densities, i.e., 100, 150, and $200mA/cm^2$. From microstructural observations, the micro cracks connecting each micro pore were pronounced on the oxide surface of the samples coated at current densities higher than $150mA/cm^2$ since increasing the current density in this study led to an increment in the relative volume fraction of the MgO compound. Based on potentio dynamic polarization and immersion tests, the sample coated at a current density of $100mA/cm^2$ showed superior corrosion resistance.

• 전기화학회지
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• 제3권3호
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• pp.136-140
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• 2000

용융탄산염 연료전지의 분리판 재료로 사용되는 스테인레스 스틸은 고온 용융탄산염 분위기에서 부식이 심각하여 일반적으로 표면에 알루미늄 확산막을 코팅함으로써 내식성을 향상시켜 사용하고 있다. 본 연구에서는 기존 방법에 비해 보다 경제적인 슬러리 페인팅 및 열처리에 의한 알루미늄 확산막 형성 방법을 고안하여, 스테인레스 스틸 시편 표면에 알루미늄 확산막을 코팅하고, 산화 분위기의 용융탄산염에서 부식 실험을 수행하였다. $650\~800^{\circ}C$에서 제작된 알루미늄 확산막의 두께는 $25\~80{\mu}m$였으며, 열처리 온도가 높고 열처리 시간이 증가할 수록 알루미늄 확산막의 두께가 증가하였다. 부식 실험 결과 스테인레스 스틸 316L의 용융탄산염에 대한 내식성은 알루미늄 확산막을 표면에 형성시킴으로써 크게 향상되었음을 확인하였다. 또한 분극 실험 결과 슬러리 페인팅 및 열처리 방법에 의하여 알루미늄 확산막이 형성된 시편은 기존의 IVD 및 열처리 방법에 의해 알루미늄 확산막이 제작된 시편과 유사하게 안정한 부동태 피막을 형성함으로써 스테인레스 스틸 316L의 부식을 효과적으로 억제시킴을 알 수 있었다.

• 한국해양공학회지
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• 제27권2호
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• pp.33-38
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• 2013

In the past, a very popular method for reducing the corrosion on zinc involved the use of chemical conversion layer coatings based on $Cr^{+6}$. However, there is an important problem with using chromium salts as a result of restrictive environmental protection legislation. This study investigated the optimum condition for galvanized steel using an organic/inorganic solution with a Ti composition. In the case of a fixed heat treatment time, the corrosion resistance values of LR-0727(1) and LR-0727(2) were improved as the heat treatment temperature increased, and the optimum minimum temperature decreased with the heat treatment time. At the optimum heat treatment condition of two coating solutions, the heat treatment time of the LR-0727(1) solution was shorter than LR-0727(2) for the same heat treatment temperature. LR-0727(1) coated specimens did not show desquamation, and all of the specimens showed a good adhesive property. In contrast, in the case of the LR-0727(2) coated specimens, desquamation arose. Therefore, the adhesive property of LR-0727(1) was superior to that of LR-0727(2). The pencil hardness had a 3H average for all of the coating solutions and heat treatment conditions. In the case of a corrosion resistance test with boiling water, the coated specimens of LR-0727(1) were discolored, but LR-0727(2) was not. Finally, LR-0727(1) was more moisture proof than LR-0727(2).

• 한국재료학회지
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• 제29권5호
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• pp.328-335
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• 2019

Nb-doped $TiO_2$(NTO) coated NiCrAl alloy foam for hydrogen production is prepared using ultrasonic spray pyrolysis deposition(USPD) method. To optimize the size and distribution of NTO particles based on good physical and chemical stability, we synthesize particles by adjusting the weight ratio of the Nb precursor solution(5 wt%, 10 wt% and 15 wt%). The morphological, chemical bonding, and structural properties of the NTO coated NiCrAl alloy foam are investigated by X-ray diffraction(XRD), X-ray photo-electron spectroscopy(XPS), and Field-Emission Scanning Electron Microscopy(FESEM). As a result, the samples of controlled Nb weight ratio exhibit a common diffraction pattern at ${\sim}25.3^{\circ}$, corresponding to the(101) plane, and have chemical bonding(O-Nb=O) at 534 eV. The NTO particles with the optimum weight ratio of N (10 wt%) show a uniform distribution with a size of ~18.2-21.0 nm. In addition, they exhibit the highest corrosion resistance even in the electrochemical stability estimation. As a result, the introduction of NTO coated NiCrAl alloy foam by USPD improves the chemical stability of the NiCrAl alloy foam by protecting the direct electrochemical reaction between the foam and the electrolyte. Thus, the optimized NTO coating can be proposed for excellent protection of NiCrAl alloy foam for hydrocarbon-based steam methane reforming(SMR).