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1.
A physical vapor deposition (PVD) TiN coating has been used to increase the corrosion resistance of two stainless steel materials for bipolar plate application in proton exchange membrane fuel cells (PEMFCs). Our earlier studies had shown that a TiN coating on SS410 and SS316L increased the corrosion resistance of SS410 and SS316L significantly. In this study, we examine how the substrate affects the corrosion of TiN-coated stainless steel in the simulated anode and cathode environments. Potentiodynamic and contact resistance test results show that the polarization resistance and contact resistance of TiN-coated SS410 and TiN-coated SS316L are almost the same. However, in the simulated anode condition, the corrosion current density of TiN-coated SS410 is positive and the corrosion current density of TiN-coated SS316L is negative. Inductively coupled plasma optical emission spectrometry (ICP-OES) test results also show that the metal ion concentration is much higher for TiN-coated SS410 at the anode side. At the cathode side, the potentiostatic and ICP-OES tests show that the corrosion of TiN-coated SS410 and TiN-coated SS316L are in the same range. Therefore, the substrate has an effect on corrosion in the simulated anode working conditions of PEMFCs. In order to be the suitable bipolar plate materials, both the coating and substrate need to have a higher corrosion resistance.  相似文献   

2.
A conducting and anticorrosive coating is crucial for the application of metal bipolar plates (BP) in proton exchange membrane fuel cell (PEMFC). In this work, a Ti3C2Tx (T)-carbon black (C)-acrylic epoxy (AE) coating is prepared on 304 stainless steel (SS) with enhanced corrosion resistance and conductivity. The corrosion resistance of the T-C-AE coating is investigated in a 0.5 M H2SO4 solution as compared to the AE, T, and T-AE coatings. The T-C-AE coated 304SS exhibits the strongest corrosion resistance with the most positive corrosion potential and the lowest corrosion current density of 0.00673 μA cm?2 in all the samples, while retaining intact and compact surface morphology with the lowest metal ion dissolution even after immersed for 720 h. The addition of Ti3C2Tx and carbon black into the AE matrix greatly decreases interfacial contact resistance (ICR), and the T-C-AE coating achieves a low ICR of 15.5 mΩ cm?2 under 140 N cm?2 compaction force. The excellent anticorrosion performance is mainly attributed to the physical barrier and the cathodic protection provided by the stacked Ti3C2Tx (MXene) nanosheets in the T-C-AE coating. This eco-friendly, conducting, and anticorrosive T-C-AE coating has a good application prospect on SS BP of PEMFC.  相似文献   

3.
In the present study, a multilayer composing of Cr3Ni2/Cr2N/CrN is sputtered onto stainless steel. The potential of using the coated stainless steel as the bipolar plate for polymer electrolyte membrane fuel cell (PEMFC) is evaluated. The coated stainless steel exhibits improved corrosion resistance and higher electrical conductivity. The coated surface also demonstrates a hydrophobic characteristic. By using single cell test, the multilayer-coated SS304 plate exhibits an improved performance in terms of I-V properties.  相似文献   

4.
A molybdenum nitride diffusion coating has been prepared on the surface of AISI 304 stainless steel (304 SS) by plasma surface diffusion alloying method as bipolar plate for proton exchange membrane fuel cell (PEMFC). X-ray diffraction data shows that the molybdenum nitride is face-centered-cubic Mo2N phase. The results of scanning electron microscopy in combination with energy-dispersive X-ray analysis spectrometer indicate that the as-prepared molybdenum nitride diffusion coating consists of a ∼3.5 μm surface layer (molybdenum nitride) and a ∼0.5 μm subsurface layer (Mo and N solid solution). In addition, the average contact angle with water for modified 304 SS is 91°, demonstrating the better hydrophobic property of the surface modified 304 SS as compared to the untreated ones with average contact angle of 68°. Potentiodynamic and potentiostatic testing in simulated PEFMC operating conditions (0.05 M H2SO4 + 2 ppm F solution at 70 °C purged with either hydrogen or air) as well as interfacial contact resistance (ICR) measurement imply that the molybdenum nitride modified 304 SS exhibits improved corrosion resistance and promising ICR.  相似文献   

5.
In the present study, an economic feasible coating technique, multi-arc ion plating (MIP) technique, is adopted to prepare a titanium nitride (TiN) coating onto titanium (Ti) substrate. The use of the TiN-coated Ti as the bipolar plate for proton exchange membrane fuel cell (PEMFC) is then evaluated. Contrast to Ti substrate, the corrosion resistance and interfacial contact resistance are improved after applying the TiN coating. The single fuel cell with Ti/TiN bipolar plate shows higher performance and has been operated for more than 1000 h without decrease in output.  相似文献   

6.
In order to reduce the cost, weight and volume of the bipolar plates, considerable attention is being paid to developing metallic bipolar plates to replace the non-porous graphite bipolar plates that are in current use. However, metals are prone to corrosion in the proton exchange membrane (PEM) fuel cell environments, which decreases the ionic conductivity of the membrane and lowers the overall performance of the fuel cells. In this study, TiN was coated on SS316L using a physical vapor deposition (PVD) technology (plasma enhanced reactive evaporation) to increase the corrosion resistance of the base SS316L. X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical methods were used to characterize the TiN-coated SS316L. XRD showed that the TiN coating had a face-centered-cubic (fcc) structure. Potentiodynamic tests and electrochemical impedance tests showed that the corrosion resistance of SS316L was significantly increased in 0.5 M H2SO4 at 70 °C by coating with TiN. In order to investigate the suitability of these coated materials as cathodes and anodes in a PEMFC, potentiostatic tests were conducted under both simulated cathode and anode conditions. The simulated anode environment was −0.1 V versus SCE purged with H2 and the simulated cathode environment was 0.6 V versus SCE purged with O2. In the simulated anode conditions, the corrosion current of TiN-coated SS316L is −4 × 10−5 A cm−2, which is lower than that of the uncoated SS316L (about −1 × 10−6 A cm−2). In the simulated cathode conditions, the corrosion current of TiN-coated SS316L is increased to 2.5 × 10−5 A cm−2, which is higher than that of the uncoated SS316L (about 5 × 10−6 A cm−2). This is because pitting corrosion had taken place on the TiN-coated specimen.  相似文献   

7.
Graphite/polymer composites have high corrosion resistance, low contact resistance and low fabrication cost but low cell efficiency and mechanical strength. This study examined the electrical and mechanical properties of graphite/polypropylene composite bipolar plates. Carbon nanotubes (CNTs) were used to improve the electrical properties of the graphite/PP composites. Although the electrical properties increased when excess conducting filler was added to the composite, the mechanical strength decreased significantly. 304 stainless steel (304 SS) plates with different thicknesses were used as the support material of a graphite/PP composite bipolar plate. The 304 SS-supported graphite/PP composite bipolar plate had an optimum CNTs/graphite/PP composite composition of 1.2, 83 and 17 wt.%, respectively. The flexural strength of the 304 SS-supported graphite/PP composites increased from 35 to 58 MPa with increasing 304 SS thickness from 0.5 to 1 mm. The power density of the graphite bipolar plate and 304 SS-supported graphite/PP composite bipolar plate were 968 and 877 mW cm−2, respectively. The 304 SS complemented the mechanical strength of the graphite/PP composite bipolar plate as well as the cell efficiency.  相似文献   

8.
Stainless steel is quite attractive as bipolar plate material for polymer electrolyte fuel cells (PEFCs). Passive film on stainless steel protects the bulk of it from corrosion. However, passive film is composed of mixed metal oxides and causes a decrease in the interfacial contact resistance (ICR) between the bipolar plate and gas diffusion layer. Low ICR and high corrosion resistance are both required. In order to impart low ICR to stainless steel (SUS304), carbon-coating was prepared by using plasma-assisted chemical vapor deposition. Carbon-coated SUS304 was characterized by Raman spectroscopy and atomic force microscopy. Anodic polarization behavior under PEFC operating conditions (H2SO4 solution bubbled with H2 (anode)/O2 (cathode) containing 2 ppm HF at 80 °C) was examined. Based on the results of the ICR evaluated before and after anodic polarization, the potential for using carbon-coated SUS304 as bipolar plate material for PEFC was discussed.  相似文献   

9.
An austenitic stainless steel with a niobium diffusion protective layer is evaluated for bipolar plate of direct methanol fuel cell (DMFC). Corrosion resistance of niobium diffusion modified AISI 304 stainless steel (niobized 304 SS) is investigated in simulated DMFC cathodic environment (0.5 M H2SO4 + 2 ppm HF + 0.1 M methanol solution at 50 °C) and anodic environment (0.5 M H2SO4 + 2 ppm HF + (1 M, 10 M and 20 M) methanol solution at 50 °C), respectively. Potentiodynamic, potentiostatic as well as electrochemical impedance spectroscopy tests show that, comparing with a bare 304 SS, the corrosion current density of niobized 304 SS is reduced greatly while the polarization resistance is raised in the simulated DMFC cathodic environment. Corrosion tests in the simulated anodic environment are applied to examine the effect of methanol on the corrosion behaviour of niobized 304 SS. It is interesting to find that the niobized 304 SS shows better corrosion resistance in the higher methanol concentration solutions.  相似文献   

10.
The corrosion of metallic bipolar plates in the proton exchange membrane fuel cells (PEMFCs) anode environment would degrade the performance and shorten the lifespan of the fuel cell. Hence, it is essential to develop a conductive coating with good corrosion resistance. Herein we demonstrate a dense, defect-free, and well-adhered nanocrystalline β-Nb2N coating prepared on 430 ferritic stainless steel (430 FSS) via disproportionation of Nb(Ⅳ) species in molten salts. The corrosion mechanism of bare and β-Nb2N coated 430 FSS in the simulated PEMFC anode environment is also studied by electrochemical techniques including potentiodynamic polarization, potentiostatic polarization, and electrochemical impedance spectroscopy. Results show that β-Nb2N coating can significantly improve the corrosion resistance of the steel alloy with acceptable contact resistance. In addition, no obvious degradation is observed for the β-Nb2N coating after potentiostatic polarization measurement for 500 h. This work offers a promising strategy to develop the corrosion protective coating on metallic bipolar plates for PEMFCs.  相似文献   

11.
In this paper, two types of chromium PVD coatings (100 nm) have been elaborated on 316L stainless steel (SS) by adjusting the nitrogen flow rate. The first coating is a mixture of Cr2N and Cr, the second one is a single phase CrN. It is shown that the performances of the material are strongly dependant of the nature of the passive film formed on the chromium nitride layers due to the galvanic coupling between the coating and the substrate. The CrN coated SS shows very good corrosion resistance in simulated PEMFC media. The surface conductivity of the SS is also greatly improved and the CrN coated SS shows an interfacial contact resistance of 10 mΩ cm2 at 140 N cm−2. Five single cells of stainless steel bipolar plates coated with the CrN film were assembled for performance test. This 5 cell stack does not show any mean voltage degradation over 200 h dynamic cycling. Moreover, the performances of the CrN coated SS bipolar plates are very close to the Au-coated SS bipolar plates.  相似文献   

12.
Carbon film has been deposited on 304 stainless steel (SS304) using close field unbalanced magnetron sputter ion plating (CFUBMSIP) to improve the corrosion resistance and electrical conductivity of SS304 acting as bipolar plates for proton exchange membrane fuel cells (PEMFCs). The corrosion resistance, interfacial contact resistance (ICR), surface morphology and contact angle with water of the bare and carbon-coated SS304 are investigated. The carbon-coated SS304 shows good corrosion resistance in the simulated cathode and anode PEMFC environment. The ICR between the carbon-coated SS304 and the carbon paper is 8.28-2.59 mΩ cm2 under compaction forces between 75 and 360 N cm−2. The contact angle of the carbon-coated SS304 with water is 88.6°, which is beneficial to water management in the fuel cell stack. These results indicate that the carbon-coated SS304 exhibits high corrosion resistance, low ICR and hydrophobicity and is a promising candidate for bipolar plates.  相似文献   

13.
The main purpose of this study is to understand the interfacial contact resistance (ICR) characteristics of coated metallic bipolar plates (BPP) manufactured through stamping and hydroforming. To this goal, 51 μm thick SS316L stainless steel sheet blanks were formed into BPPs using two forming techniques (stamping and hydroforming); then these formed plates were coated with three different PVD coatings (CrN, TiN, ZrN) at three different coating thicknesses (0.1, 0.5 and 1 μm). Contact resistance of the formed and coated BPP samples were measured before and after they were exposed to the proton exchange membrane fuel cells (PEMFC) operating conditions (i.e., corrosive environment). ICR tests indicated that CrN coating increased the contact resistance of the samples, unexpectedly. TiN samples showed the best performance in terms of low ICR; however, their ICR dramatically increased after short-term exposure to corrosion. ZrN coating, as well, improved conductivity of the SS316L BPP samples and demonstrated similar ICR performance before and after exposure to corrosion.  相似文献   

14.
Thermal (gas) nitridation of stainless steel alloys can yield low interfacial contact resistance (ICR), electrically conductive and corrosion-resistant nitride containing surface layers (Cr2N, CrN, TiN, V2N, VN, etc.) of interest for fuel cells, batteries, and sensors. This paper presents results of scale-up studies to determine the feasibility of extending the nitridation approach to thin 0.1 mm stainless steel alloy foils for proton exchange membrane fuel cell (PEMFC) bipolar plates. Developmental Fe-20Cr-4V alloy and type 2205 stainless steel foils were treated by pre-oxidation and nitridation to form low-ICR, corrosion-resistant surfaces. As-treated Fe-20Cr-4V foil exhibited target (low) ICR values, whereas 2205 foil suffered from run-to-run variation in ICR values, ranging up to 2× the target value. Pre-oxidized and nitrided surface structure examination revealed surface-through-layer-thickness V-nitride particles for the treated Fe-20Cr-4V, but near continuous chromia for treated 2205 stainless steel, which was linked to the variation in ICR values. Promising corrosion resistance was observed under simulated aggressive PEMFC anode- and cathode-side bipolar plate conditions for both materials, although ICR values were observed to increase. The implications of these findings for stamped bipolar plate foils are discussed.  相似文献   

15.
Dynamic potentials of polymer electrolyte membrane fuel cells (PEMFCs) lead to the corrosion of metal bipolar plates and significantly increase their interfacial contact resistance (ICR). Herein, two nano-thin C/Ti coatings with different thicknesses are prepared on SS316L (C/Ti/SS) and examined under three types of polarization potential modes. The C100Ti60 coating has improved corrosion resistance than C20Ti140 coating. The C100Ti60 coating exhibits a low ICR of 2.67 mΩ cm2 and a small corrosion rate of 1.47 μA/cm2, highlighting the high electrical conductivity and corrosion resistance. Moreover, C100Ti60/SS achieves a slight degradation of ICR after polarization at 0.67 V and cyclic polarization between 0.43 and 0.73 V. However, the high potential of 1.43 V induces severe delamination of C layer, resulting in a remarkable increase of ICR. Analysis suggests that the Ti layer improves the oxidation resistance and the C layer could provide effective protection when the potential is below 1.13 V.  相似文献   

16.
Metallic bipolar plates are one of the promising alternatives to the graphite bipolar plates in proton exchange membrane fuel cell (PEMFC) systems. In this study, stainless steel (SS304, SS316L, and SS430), nickel (Ni 270), and titanium (Grade 2 Ti) plates with an initial thickness of 51 μm were experimented as bipolar plate substrate materials in corrosion resistance tests. In addition to unformed blanks, SS316L plates were formed with stamping and hydroforming processes to obtain bipolar plates under different process conditions (stamping force, hydroforming pressure, stamping speed, hydroforming pressure rate). These bipolar plates, then, were subjected to corrosion tests, and the results were presented and discussed in detail. Potentiodynamic polarizations were performed to observe corrosion resistance of metallic bipolar plates by simulating the anodic and cathodic environments in the PEMFC. In order to determine the statistical significance of the corrosion resistance differences between different manufacturing conditions, analysis of variance (ANOVA) technique was used on the corrosion current density (Icorr, μA cm−2) values obtained from experiments. ANOVA for the unformed substrate materials indicated that SS430 and Ni have less corrosion resistance than the other substrate materials tested. There was a significant difference between blank (unformed) and stamped SS316L plates only in the anodic environment. Although there was no noteworthy difference between unformed and hydroformed specimens for SS316L material, neither of these materials meet the Department of Energy‘s (DOE) target corrosion rate of ≤1 μA cm−2 by 2015 without coating. Finally, stamping parameters (i.e. speed and force levels) and hydroforming parameters (i.e. the pressure and pressure rate) significantly affected the corrosion behavior of bipolar plates.  相似文献   

17.
The lower temperature chromizing treatment is developed to modify 316L stainless steel (SS 316L) for the application of bipolar plate in proton exchange membrane fuel cell (PEMFC). The treatment is performed to produce a coating, containing mainly Cr-carbide and Cr-nitride, on the substrate to improve the anticorrosion properties and electrical conductivity between the bipolar plate and carbon paper. Shot peening is used as the pretreatment to produce an activated surface on stainless steel to reduce chromizing temperature. Anticorrosion properties and interfacial contact resistance (ICR) are investigated in this study. Results show that the chromized SS 316L exhibits better corrosion resistance and lower ICR value than those of bare SS 316L. The chromized SS 316L shows the passive current density about 3E−7 A cm−2 that is about four orders of magnitude lower than that of bare SS 316L. ICR value of the chromized SS 316L is 13 mΩ cm2 that is about one-third of bare SS 316L at 200 N cm−2 compaction forces. Therefore, this study clearly states the performance advantages of using chromized SS 316L by lower temperature chromizing treatment as bipolar plate for PEMFC.  相似文献   

18.
Low temperature plasma nitriding is developed to meet the requirements for corrosion resistance and interfacial contact resistance (ICR) of stainless steel 304L as the bipolar plate for PEMFC. A dense and supersaturated‐nitrogen nitrided layer has formed on the surface of the stainless steel 304L. Electrochemical behavior for the untreated and plasma‐nitrided 304L was measured in H2SO4 (pH=1–5)+2 ppm F? simulating PEMFC environment, and the ICR was evaluated before and after corrosion tests. The experimental results have shown that the ICR for the plasma nitrided 304L is lower than the requirement of U.S. DOE (<10 mΩ cm2 to 2010). Corrosion resistance and the ICR at the compaction force of 150–200 N cm?2 increase with increasing pH value for the untreated and plasma‐nitrided 304L. The passive current densities for the untreated and plasma‐nitrided 304L are all lower than 16 µA cm?2. The ICR between passive film and carbon paper are increased markedly because of passive film formed on the surface of both studied 304L. However, the passive current density and the ICR are lower for the plasma nitrided 304L than those for the untreated one at the given pH value, which results from the different composition of the stable passive film formed on the surface. The low temperature plasma nitriding provides a promising method for 304L using as bipolar plate for PEMFC. Further research is needed to evaluate the long‐term stability of passive film and the performance of single fuel cell. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

19.
Proton exchange membrane water electrolysis (PEMWE) is a promising technology to be incorporated in the production of green hydrogen, but one of its limitation to market penetration is the cost of bipolar plates (BPP).Aiming to reduce the cost of PEMWE stack, different surface engineered coating systems based on CrN/TiN, Ti/TiN, Ti and TiN deposited by physical vapor deposition on SS 316L, SS 904L and SS 321 were tested, as potential cost effective solutions to be implemented on bipolar plates. A corrosion evaluation has been carried out in anodic PEMWE conditions in order to determine the best substrate/coating combination for bipolar plates. Ti/TiN multi-layered coating on SS 321 shown the best performance with ?0.02% weight loss, current at 2 VSHE to 436 μA cm?2 and ICR after corrosion test to 9.9 mΩ cm2.  相似文献   

20.
Carbon film-coated stainless steel (CFCSS) has been evaluated as a low-cost and small-volume substitute for graphite bipolar plate in polymer electrolyte membrane fuel cell (PEMFC). In the present work, AISI 304 stainless steel (304SS) plate was coated with nickel layer to catalyze carbon deposits at 680°C under C2H2/H2 mixed gas atmosphere. Surface morphologies of carbon deposits exhibited strong dependence on the concentration of carbonaceous gas and a continuous carbon film with compact structure was obtained at 680 °C under C2H2/H2 mixed gas ratio of 0.45. Systematic analyses indicated that the carbon film was composed of a highly ordered graphite layer and a surface layer with disarranged graphite structure. Both corrosion endurance tests and PEMFC operations showed that the carbon film revealed excellent chemical stability similar to high-purity graphite plate, which successfully protected 304SS substrate against the corrosive environment in PEMFC. We therefore predict CFCSS plates may practically replace commercial graphite plates in the application of PEMFC.  相似文献   

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