• Bulletin of the Korean Chemical Society
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• 제33권4호
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• pp.1177-1182
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• 2012

The corrosion resistance of 316L stainless steel coated with NiO-YSZ (Ni added yttria stabilized zirconia) was examined in a proton exchange membrane fuel cell (PEMFC) environment. The NiO-YSZ coating was carried out using a sol-gel dip coating method, and the corrosion resistance and interfacial contact resistance (ICR) were determined by the composition and morphology of the NiO-YSZ film. The corrosion resistance increased with increasing Ni content in the NiO-YSZ film, but rapid corrosion was observed when the YSZ film contained more than 15 wt % Ni due to surface cracks. The polarization resistance was improved by several orders of magnitude when 316L stainless steel was coated with a 15 wt % NiO-YSZ film compared to bare 316L. The ICR of the NiO-YSZ film was decreased to that of bare 316L when the YSZ film contained 25 wt % NiO, suggesting the possible application of NiO-YSZ coated stainless steel for a bipolar plate.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2009년도 춘계학술대회 논문집
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• pp.244-245
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• 2009

Sol-gel coatings of $TiO_2$ have been prepared from $TiO_2$ sol and deposited by dip-coating technique on 316L stainless steel sheets in order to study the electrochemical behaviorin corrosive solutions. The influence of the coatings on the chemical corrosion of the substrate has been evaluated by potentiodynamic polarization curves in different aqueous NaCl solution at $25^{\circ}C$.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2010년도 춘계학술발표대회
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• pp.6.2-6.2
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• 2010

Stainless steel is widely known to have superior corrosion properties. However, in some harsh conditions it still suffers various kinds of corrosions such as galvanic corrosion, pitting corrosion, intergranular corrosion, chloride stress corrosion cracking, and etc. For the corrosion protection of stainless steel, the ceramic coatings such as protective silica film can be used. The sol-gel coating technique for the silica film has been extensively studied especially because of the cost effectiveness. It has been proved that silica can improve the oxidation and the acidic corrosion resistance of metal surface in a wide range of temperatures due to its high heat and chemical resistance. However, in the sol-gel coating process there used to engage a heat treatment at an elevated temperature like $500^{\circ}C{\sim}600^{\circ}C$ where cracks in the silica film would be formed because of the thermal expansion mismatch with the metal. The cracks and pores of the film would deteriorate the corrosion resistance. When the heat treatment temperature is reduced while keeping the adhesion and the density of the film, it could possibly give the enhanced corrosion resistance. In this respect, inorganic protective silica film was tried on the surface of stainless steel using a sol-gel chemical route where silica nanoparticles, tetraethoxysilane (TEOS) and methyltriethoxysilane (MTES) were used. Silica nanoparticles with different sizes were mixed and then the film was deposited on the stainless steel substrate. It was intended by mixing the small and the large particles at the same time a sufficient consolidation of the film is possible because of the high surface activity of the small nanoparticles and a modest silica film is obtained with a low temperature heat treatment at as low as $200^{\circ}C$. The prepared film showed enhanced adhesion when compared with a silica film without nanoparticle addition. The films also showed improved protect ability against corrosion.

• Korean Chemical Engineering Research
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• 제50권1호
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• pp.118-127
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• 2012

고분자전해질 연료전지용 분리판 소재로 스텐레스 강의 내식성과 전기전도성을 향상시키기 위해 표면을 TiN(titanium nitride) 또는 Ti/TiN(titanium/titanium nitride)으로 코팅하여 연료전지 운전환경에서 표면 코팅층의 물성 변화를 조사하였다. 200시간의 연료전지 운전에서 표면 코팅층의 부식, 균열(crack), 박리, 표면 화학조성 변화 등을 분석하여 코팅된 TiN 또는 Ti/TiN 박막의 역할을 규명하고자 하였다. 스텐레스 강 분리판의 전기전도도와 부식저항성은 소재 표면에 질화층 박막을 코팅함으로써 증가하였으나 연료전지 환경하에서 운전시 코팅된 박막의 부식과 박리현상이 SUS316L-Ti/TiN을 제외하고 현저히 발생하였다. TiN 코팅층과 하부 기재 사이에 Ti 중간층을 도입함으로써 TiN 박막의 밀착성이 향상되고 또한 코팅층의 두께 증가로 부식 위험성이 감소하는 것을 관찰하였다.

• 한국표면공학회지
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• 제22권4호
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• pp.185-196
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• 1989

The surface modification of a mild and stainless steel by alumina sprayed coating were studied. The effects of surface roughness and bond coating layer on the adhesive strengthy and durability of sprayed specimens were also investiated. The adhesive strength of ceramic coating was affected by surface roughness and bond coating layer thinkness. That showed excellent undergrit blast time and bond coating layer; 60 sec and 0.15-0.33mm, respectively. The adhesive strength and densification of sprayed coating with air pressure were superior to those of without and fracture was mainly occured at alumina-bond coating interface. Under ambient atmosphere at $800^{\circ}C$, the oxides existed within bond coating layer promote diffusion of oxygen to lower durability of sprayed specimens. In this case, fracure was occured at sudstrate-bond coating interface.

• 한국재료학회지
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• 제7권1호
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• pp.76-80
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• 1997

용융탄산염 연료전지 분리판의 wet-seal부의 내식성 향상을 위한 NiAl 피복공정이 조사되었다. AlSl 316 스테인레스강위에 Ni과 Al를 순차적으로 피복한 후, $800^{\circ}C$에서 3시간 열처리하여 NiAl상이 형성됨을 확인할 수 있었다. NiAl상이 피복된 스테인레스강은 $650^{\circ}C$, 용융탄산염($62^{m}/_{o}Li_2CO_3-38^{m}/_{o}/K_{2}CO_{3}$)내에서 침지시험을 통해 내식성이 평가되었는데, AISI 316 스테인레스강에 비해 우수한 내식성을 보였다. 이는 표면에 치밀하게 형성된 AI 산화물층에 의한 것으로 판단되었다.

• KSBB Journal
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• 제18권2호
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• pp.107-110
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• 2003

스텐트 재질인 stainless steel 표면에 모델 약물인 rose bengal을 포함한 생분해성 고분자 PLGA, PHB, MCL-PHA를 코팅하여 약물방출 특성을 조사하였다. PLGA의 농도가 낮을수록, rose bengal의 농도가 높을수록, dip-coating 시간이 길수록 약물방출이 증가하였으며, PHB > PLGA > MCL-PHA의 순서로 약물이 빨리 방출되었다. 이는 생분해성 고분자의 농도 및 종류, 약물의 농도, dip-coating 시간 등을 변화시켜 약물방출을 조절할 수 있음을 나타낸다.

• 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.

• 한국표면공학회지
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• 제35권6호
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• pp.391-400
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• 2002

Corrosion characteristics of Ti, Ti/Cr coated and plasma-nitrided surface for stainless steel containing Ti have been studied. Stainless steels containing 0.09-0.92wt% Ti were fabricated by using vacuum furnace and solutionized for 1hr at 105$0^{\circ}C$. Ti and Cr coatings were done on solutionized stainless steel surface by EB-PVD. The Ti coated specimen were coated by Cr and were nitrided by plasma at $450^{\circ}C$ for 5hr. Microstructure and phase analysis were performed using SEM, OM and EDX. Corrosion behavior of the coated specimen was investigated by electrochemical test. The coated surface was of fine columnar structure. The Ti/Cr coated surface was denser than the Ti coated and the Ti coated-nitrided surfaces. The corrosion and pitting potential increased in proportion to the Ti content, coating temperature, coating thickness and formation of stable oxide film. The current density in active and passive region decreased in the case of Ti/Cr coated sample and Ti coated-nitrided samples. Especially the plasma nitrided specimen after Ti coating have a good corrosion resistance compared with the Ti coated specimen. The number and size of pits decreased as Ti content of matrix increased.

• 한국표면공학회지
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• 제36권1호
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• pp.89-98
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• 2003

Corrosion characteristics of Ti, Ti/Cr coated and plasma-nitrided surface for stainless steel containing Ti have been studied. Stainless steels containing 0.09-0.92wt% Ti were fabricated by using vacuum furnace and solutionized for 1hr at $1050^{\circ}C$. Ti and Cr coatings were done on solutionized stainless steel surface by EB-PVD. The Ti coated specimen were coated by Cr and were nitrided by plasma at $450^{\circ}C$ for 5hr Microstructure and phase analysis were performed using SEM, OM and EDX. Corrosion behavior of the coated specimen was investigated by electrochemical test. The coated surface was of fine columnar structure. The Ti/Cr coated surface was denser than the Ti coated and the Ti coated-nitrided surfaces. The corrosion and pitting potential increased in proportion to the Ti content, coating temperature, coating thickness and formation of stable oxide film. The current density in active and passive region decreased in the case of Ti/Cr coated sample and Ti coated-nitrided samples. Especially the plasma nitrided specimen after Ti coating have a good corrosion resistance compared with the Ti coated specimen. The number and size of pits decreased as Ti content of matrix increased.