• 한국수소및신에너지학회논문집
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• 제15권1호
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• pp.39-45
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• 2004

A 12-cell PEMFC stack was fabricated using the TiN-coated 316 stainless steel bipolar plates as substitute for the expensive and brittle graphite bipolar plates. Open cirtuit voltage and the maximum power of the stack was 12.08 V and 1.197 kW (199.5 A @ 6 V), respectively. Volumetric and gravimetric power density of the stack was calculated to be 373 W/L and 168 W/kg, respectively. Performance of each cell was quite uniform initially while degraded at a singnificantly different rate. During the 1,000 hr-operation at a constant load of 48 A, stack voltage decreased from 9.0 to 7.98 V at a degradation rate of 11 %/1,000 hr. However, degradation rate of each cell was in the wide rage from 1.2 to 31 %/1,000 hr.

• 한국표면공학회지
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• 제52권4호
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• pp.194-202
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• 2019

A systematic investigation was made on the influence of processing parameters such as gas composition and treatment temperature on the surface characteristics of hardened layers of low temperature plasma nitrided 316L Austenitic Stainless Steel. Various nitriding processes were conducted by changing temperature ($370^{\circ}C$ to $430^{\circ}C$) and changing $N_2$ percentage (10% to 25%) for 15 hours in the glow discharge environment of a gas mixture of $N_2$ and $H_2$ in a plasma nitriding system. In this process a constant pressure of 4 Torr was maintained. Increasing nitriding temperature from $370^{\circ}C$ to $430^{\circ}C$, increases the thickness of S phase layer and the surface hardness, and also makes an improvement in corrosion resistance, irrespective of nitrogen percent. On the other hand, increasing nitrogen percent from 10% to 25% at $430^{\circ}C$ decreases corrosion resistance although it increases the surface hardness and the thickness of S phase layer. Therefore, optimized condition was selected as nitriding temperature of $430^{\circ}C$ with 10% nitrogen, as at this condition, the treated sample showed better corrosion resistance. Moreover to further increase the thickness of S phase layer and surface hardness without compromising the corrosion behavior, further research was conducted by fixing the $N_2$ content at 10% with introducing various amount of $CH_4$ content from 0% to 5% in the nitriding atmosphere. The best treatment condition was determined as 10% $N_2$ and 5% $CH_4$ content at $430^{\circ}C$, where the thickness of S phase layer of about $17{\mu}m$ and a surface hardness of $980HV_{0.1}$ were obtained (before treatment $250HV_{0.1}$ hardness). This specimen also showed much higher pitting potential, i.e. better corrosion resistance, than specimens treated at different process conditions and the untreated one.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.696-697
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• 2006

This paper presents the densification and microstructure evolution of bilayer components made from 316L stainless steel and M2 High speed steel during co-sintering process. The sintering was carried out at temperatures ranging from $1230-1320^{\circ}C$ in a reducing atmosphere. The addition of boron to 316L was examined in order to increase the densification rate and improve the sintering compatibility between the two layers. It was shown that the mismatch strain bettwen the two layers induces biaxial stresses during sintering, influencing the densification rate. The effect of boron addition was also found to be positive as it improves the bonding between the two layers.

• 한국표면공학회지
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• 제30권6호
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• pp.365-373
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• 1997

316L and 420 Stainless steels were deposited onto AZ9ID commercial magnesium alloy by plasma spray process with various gas flow rate of, TEX>$H_2$ secondary gas. And hardness as well as were track volume, coefficient of friction also had been measured. wear and hardness were measured by using reciprocal configuration tribometer and microghardness tester, respectively. Also, the microstructure of the coatings surface the cross sectional area of coating surface and cross sectional area of coaing/Substrate interface had been analyzed with Scanning Electron Microscope(SEM) and Optical microscope(OM). Finally, optimal process parameters for the improvement of coating efficiency such as mechanical property and wear behavior were examined.

• Corrosion Science and Technology
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• 제14권4호
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• pp.184-189
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• 2015

In this study, the combined effect of chloride and thiosulfate ions and the effect of the ratio of the two ions on passivation in 304L, 316L, and the duplex stainless steels 2101 and 2205 are investigated using potentiostatic scratch tests. Cyclic polarization and the scratch tests were used to understand the role of anions on localized corrosion in these systems. It was found that the thiosulfate pitting began at a lower potential for 2101 than 304L in 0.6 M NaCl + 0.03 M $Na_2S_2O_3$ solution. The pit morphologies for 304L, 316L, and 2101 in an 0.6 M NaCl + 0.03 M $Na_2S_2O_3$ solution were very different from each other. The results indicate that the pitting switches from predominately thiosulfate pitting to chloride pitting at approximately 0.1 V.

• 한국진공학회지
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• 제19권6호
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• pp.460-466
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• 2010

방사광 가속기 저장링 진공용기의 주요 소재로 사용되고 있는 스테인리스강 304, 316L의 투자율(Magnetic Permeability) 변화를 측정하여, 비자성 재료가 요구되는 응용 분야에서 활용가능한지 살펴보았다. 투자율은 용접, 굽힘 등 진공용기 제작 과정에서 크게 상승하였으나, 제작 후 고용화 열처리 공정을 거친다면 상대투자율 1.02 이하가 요구되는 분야에서 사용가능함을 알 수 있었다.

• Corrosion Science and Technology
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• 제18권6호
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• pp.258-266
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• 2019

The objective of this study was to evaluate corrosion resistance of additive manufactured 316L stainless steel and alloy 625 powders widely used in corrosion resistance alloys of marine industry in comparison with cast alloys. Directed Energy Deposition (DED) method was used in this work for sample production. DED parameter adjustment was also studied for optimum manufacturing and for minimizing the influence of defects on corrosion property. Additive manufactured alloys showed lower corrosion resistance in seawater compared to cast alloys. The reason for the degradation of anti-corrosion property was speculated to be due to loss of microstructural integrity intrinsic to the additive manufacturing process. Application of heat treatment with various conditions after DED was attempted. The effect of heat treatments was analyzed with a microstructure study. It was found that 316L and alloy 625 produced by the DED process could recover their expected corrosion resistance when heat treated at 1200 ℃.

• 열처리공학회지
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• 제30권6호
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• pp.271-278
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• 2017

This study was carried out to investigate the relationship between the mechanical properties and damping capacity of thermo-mechanical treated 316L stainless steel. Dislocations, ${\varepsilon}$ and ${\alpha}^{\prime}$-martensites were formed by thermo-mechanical treatment, and the grain size was changed from micrometer to sub-micrometer by 5-cycled thermo-mechanical treatment. The volume fraction of dislocations, ${\varepsilon}$ and ${\alpha}^{\prime}$-martensites was increased, and grain size of austenite increased and lengthened by the with increasing cycle number of thermo-mechanical treatment. In 5-cycled specimens, the volume fraction of ${\alpha}^{\prime}$-martensite was more than 25% and the less than 5% of volume fraction of ${\varepsilon}$-martensite was attained. With increasing number of thermo-mechanical treatment, hardness, strength and damping capacity were increased, but elongation was decreased. Damping capacity was increased with increased hardness and strength, but decreased with increased elongation, and this result was the opposite tendency for general metal.

• 소성∙가공
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• 제20권2호
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• pp.118-123
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• 2011

Manufacturing of the bipolar plate of a direct methanol fuel cell (DMFC) by direct laser melting technology (DLM) was attempted. The DLM technology is highly influenced by process parameters such as laser power, scan rate and layering height. Therefore, an analysis of the DLM technology was performed under various conditions. The bipolar plates were fabricated using the DLM process with 316L stainless steel (STS 316L) plates and powder. Powder melting trials at various energy density were performed in order to select a feasible melting range for a given laser power. The melting line height increases and eventually saturates when the energy density increases, but decreases when the laser power increases at a given energy density. For the estimation of the potential performance of the bipolar plate, the surface roughness and contact resistance of the DLM layer were also analyzed. The changes of line height and thickness are useful information to report when manufacturing bipolar plate of fuel cell through the DLM process.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2009년도 춘계학술발표대회
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• pp.55.2-55.2
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• 2009

A polymer electrolyte membrane (PEM) fuel cell has been getting large interest as a typical issue in useful applications. The PEMFC is composed of a membrane, catalyst and the bipolar plate. SnOx:F films on SUS316 stainless steel were prepared as a function of substrate with using electron cyclotron resonance-metal organic chemical vapor deposition (ECR-MOCVD) in order to achieve the corrosion-resistant and low contact resistance bipolar plates for PEM fuel cells. The SnOx:F films coated on SUS316 substrate at surface plasma treatment for excellent stability, before/after heat treatment for good crystalline structure and microwave power for were characterized by X-ray diffraction (XRD), auger electron microscopy (AES) and field emission-scanning electron microscopy (FE-SEM). The SnOx:F film coated on SUS316 substrate with various process parameters were able to observe optimum interfacial contact resistance (ICR) and corrosion resistance. It can be concluded that fluorine-doping content plays an important function in electrical property and characteristic of corrosion-protective film.