• 한국표면공학회지
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• 제31권1호
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• pp.3-11
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• 1998

Molten Carbonate Fuel cell is a promising new type electric power generation system which can achieve high efficiency, lower matrrial cost and high operating temperature Making internal reforming possible. Although the development of the MCEC is progressing rapidly toward commercialization, two important tchological problems such as dissolution of NiO cathode and not corrosion of metallic separator plate must be resolved. Because MCFC is operated at $650^{\circ}C$ and the electrolyte is very corrosive, corrosion-resistance of separator plated against oxidation abd molten carbonate is required. Al-coating on separator material for corrosion-resistance was carried out by painting, thermal spraying. hot dipping and vacuum vapour deposition. The corrosion of Al-coated STS 316S and 316L in molten carbonate at $700^{\circ}C$was studied. Vacuum vapour deposition and thermal spraing for Al-coating on STS 310S and 316L were the most effective methods for protecting thestainless steel corrosion in molten carbonate.

• 한국표면공학회지
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• 제35권1호
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• pp.53-63
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• 2002

Ni coating was carried out by pulse plating at room temperature. So, experimental conditions for Ni-coating were based on Watt's bath, and new additives(propionic acid) were introduced in the Watt's bath electrolyte as $H_3$$BO_3$ alternatives. By adding propionic acid, coating layer demonstrated a good adhesion and uniformity without special pre-treatment of the 316L stainless steel at room temperature. With a decrease of amount of propionic acid and applied average current density, cathode current efficiency increased. Also, edge effect was decreased with decreasing a peak current and increasing a pulse frequency in the same bath condition. It was found that the optimum condition for Ni coating was a current density of 10~20mA/$\textrm{cm}^2$ at below 500 mA peak current in the $5m\ell/\ell$ propionic acid solution.

• 한국재료학회지
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• 제13권9호
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• pp.587-592
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• 2003

The thin films of 316L stainless steel were made on glass and S45C substrate by Ion beam assisted deposition with reactive atmosphere of argon and nitrogen. The films were deposited at the various conditions of ion beam power and the ratios of Ar/$N_2$gas. Properties of these films were analyzed by glancing x-ray diffraction method(GXRD), AES, potentiodynamic test, and salt spray test. The results of GXRD showed that austenite phase could be appeared by $N_2$ion beam treatment and the amount of austenite phase increased with the amount of nitrogen gas. The films without plasma ion source treatment had the weak diffraction peak of ferrite phase. But under the Ar plasma ion beam treatment, the strong diffraction peaks of ferrite phase were appeared and the grain size was increased from 12 to 16 nm. Potentiodynamic polarization test and salt spray test indicated that the corrosion properties of the STS 316L films with nitrogen ion source treatment were better than bulk STS 316L steel and STS 316L films with Ar ion source treatment.

• 동력기계공학회지
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• 제19권6호
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• pp.12-18
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• 2015

Austenitic stainless steels generally experience the occurrence of chromium-depleted zones at the boundaries, known as sensitization, caused by the carbide precipitation that takes place due to a welding process or heat treatment. Normally, the depleted zones become the focus of the intense corrosion. In this study, the Cr-free organic/inorganic hybrid solution was developed, and the artificially degraded STS316S and STS347H with the solution-coating investigated the corrosion resistance by salt spray test. Both the OIBD-1 and OIBD-2 solutions improved the corrosion resistance of STS310S and STS347H. The corrosion resistance with the OIBD-1 solution was better than that of OIBD-2 solution. Additionally, Both solutions have been proven excellence in adhesion ability, boiling water resistance and flexibility. However, a problem of rubbing after the boiling was found out to be overcome.

• 대한기계학회논문집A
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• 제31권12호
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• pp.1188-1193
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• 2007

This study focuses on the corrosion problems of STS316(stainless steel 316) tube for the cooling system of PEMFC (Proton Exchange Membrane Fuel Cell) operation. Deionized water which is highly corrosive is used especially for cooling agent of PEMFC to eliminate electrical conductivity, The tensile stress analysis was performed to check the change of mechanical strength of cooling line and pH of the water was monitored for the observation of extent of corrosion at simulated PEMFC operating condition. When STS316 tube was exposed to deionized water for 500 hours, substantial cracks were found on the surface and the pH of water was decreased from 6.8 to 5.8. For prevention of corrosion problems, the STS316 was coated by three kinds of fluororesin such as PTFE, FEP and ETFE. Among the coating materials, PTFE was the most protective in corrosive environment and was maintained the mechanical strength. To lower the cost, the same experimental analyses were carried out for iron tubes and the result will be discussed in detail.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.137.2-137.2
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• 2010

본 연구는 스테인리스 스틸(STS)을 직접메탄올 연료전지(DMFC)용 바이폴라 플레이트에 적용하기 위한 것이다. 약산성의 연료전지 환경에서 부식저항성을 향상시키고자 오스테나이트계 STS 316L과 페라이트계 STS 430에 UBM(unbalanced magnetron) DC sputter로 CrN 코팅막을 제작하였다. CrN이 코팅된 스테인리스 스틸은 부식특성, 접촉 저항 및 접촉각 등을 측정하여 무 코팅의 스테인리스 스틸과 특성을 비교하였다. 그리고 이들 재료의 연료전지(DMFC) 적용 가능성을 알아보기 위하여 단위전지로 제작하여 연료전지 성능 등을 측정하고 평가하였다. 무 코팅 스테인리스 스틸(STS 316L, STS 430)과 CrN 코팅 스테인리스 스틸의 부식저항 특성은 동전위와 정전위 실험으로 조사하였다. 동전위 부식 실험은 -0.4~1.0 V로 0.001 M의 황산용액 또는 메탄올을 첨가하여 질소 또는 공기의 환경에서 실험을 실시하였으며, 정전위 부식 실험은 0.4 V 또는 0.6 V에서 진행하였다. 연료전지의 단전지 측정은 실제 DMFC의 운전조건에서 실시하였다. 부식실험과 단전지 실험 전/후 메탈 바이폴라 플레이트의 조직 변화는 SEM을 통해 관찰하였고, 부식산화물의 화학적 조성과 메탈 바이폴라의 표면은 EDS를 이용하여 측정하였다.

• 한국압력기기공학회 논문집
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• 제19권2호
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• pp.102-108
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• 2023

A Chloride-induced stress corrosion cracking (CISCC) of austenite stainless steel in dry cask storage system (DCSS) can occur with extending service time than originally designed. Cold spray coating (CSC) not only form a very dense microstructure that can protect from corrosive environments, but also can generate compressive stress on the surface. This characteristic of CSC process is very helpful to increase the resistance for CISCC. CSC with several powders, such as 304L, 316L and Ni can be optimized to form very dense coating layer. In addition, the impact energy generated as the CSC powder collides with the surface of base metal at a speed of Mach 2 or more can remove the residual tensile stress of welding area and serve the compress stress. CSC layers include no oxidation and no contamination with under 0.2% porosity, which is enough to protect from the penetration of corrosive chloride. Therefore, the CSC coating layer can be accompanied by a function that can be disconnected from the corrosive environment and an effect of improving the residual stress that causes CISCC, so the canister's CISCC resistance can be increased.

• Journal of Welding and Joining
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• 제18권3호
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• pp.51-59
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• 2000

Sink roll has been used in molten 55%Al-Zn alloy bath of continuous galvanizing line for sinking and stabilizing working steel strip in molten metal bath. In the process, the sink roll body inevitably build up dross compounds and pitting on the sink roll surface during 55%Al-Zn alloy coated strip production, and the life time of the sink roll is shorten by build up dross compounds and pitting. The present study examined the application of thermally sprayed ceramic coatings method on sink roll body for improving erosion resistance at molten 55% Al-Zn pool. In this experiment, the stainless steels such as STS 316L and STS 430F were used as the substrate materials. The CoNiCr and WE-Co powder were selected as bond coating materials. Moreover $Al_2O_3-ZrO_2-SiO_2 and ZrO_2-SiO_2$ powders selected as the top coating materials. Appearances of the specimens before and after dipping to molten 55%Al-Zn pool were compared and analyzed. As a result of this study, STS430F of substrate, WC-Co of bond spray coatings, $ZrO_2-SiO_2$ power of top spray coatings is the best quality in erosion resistance test at molten 55%Al-Zn pool

• 한국표면공학회지
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• 제44권5호
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• pp.226-231
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• 2011

Graphene was coated on STS 316L by electro spray coating method to improve its properties of corrosion resistance and contact resistance. Exfoliated graphite (graphene) was made of the graphite by chemical treatment. Graphene is distributed using dispersing agent, and STS 316L was coated with diffuse graphene solution by electro spray coating method. The structure of the exfoliated graphite was analyzed using XRD and the coating layer of surface was analyzed by using SEM. Analysis showed that multi-layered graphite structure was destroyed and it was transformed into fine layers graphene structure. And the result of SEM analysis on the surface and the cross section, graphene layer was uniformly formed with 3~5 ${\mu}m$ thickness on the surface of substrate. Corrosion resistance test was applied in the corrosive solution which is similar to the PEM fuel cell stack inside. And interfacial contact resistance test was measured to simulate the internal operating conditions of PEM fuel cell stack. The results of measurements show that stainless steel coated with graphene was improved in corrosion resistance and surface contact resistance than stainless steel without graphene coating layer.

• 한국지열·수열에너지학회논문집
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• 제14권1호
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• pp.22-29
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• 2018

The purpose of this study is to investigate the preliminary thermal performance of a plastic coated aluminum material(PCAM) plate heat exchanger. Plastic coating which has high corrosion resistivity and thermal conductivity can overcome corrosive weakness of aluminum material. The heat exchangers are modeled for STS316, Titanium and PCAM materials, and analyzed numerically using HTRI and ANSYS Fluent CFD softwares. The results show that PCAM heat exchanger is superior in heat transfer performance compared to existing materials. For chevron angle of $60^{\circ}$, thermal performances of Titanium and PCAM are higher by 12.2% and 48.9% when compared to STS316, respectively.