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Dur E.,Virginia Commonwealth University | Dur E.,Istanbul Gas Distribution Company IGDAS | Cora O.N.,Virginia Commonwealth University | Ko M.,Virginia Commonwealth University | Ko M.,Istanbul Sehir University
International Journal of Hydrogen Energy | Year: 2011

Bipolar plates (BPPs) made of stainless steels preferred in PEM Fuel Cell (PEMFC) applications due to their high electrical conductivity, low material and production costs, low weight and mechanical strength. However, their corrosion resistances are not at desired levels for real PEMFC working conditions. To overcome this issue, different coating types are suggested. In this study, corrosion resistance behavior of 51 μm-thick SS316L metallic bipolar plates that were coated with the three different PVD coatings (TiN, CrN, and ZrN) at three thicknesses (0.1 μm, 0.5 μm, and 1 μm), and then were formed with two different manufacturing processes (stamping and hydroforming) investigated. Potentiodynamic and potentiostatic corrosion experiments were performed on the coated-formed SS316L plates, and coated-unformed blanks. Corrosion test results indicate that 1 μm ZrN coating demonstrated the highest corrosion resistance among the tested cases regardless of the manufacturing process employed. Moreover, hydroformed bipolar plates exhibited higher corrosion resistance than the stamped BPPs, but lower than the blank samples. Hardness measurements were also performed on the coated samples and resulted in higher corrosion resistance for harder surfaces. © 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Murad S Seralioglu S.,Istanbul Gas Distribution Company IGDAS | Turkel V.,IGDAS | Atalay K.,IGDAS
International Gas Union World Gas Conference Papers | Year: 2012

As in most countries of the world, in Turkey; oil and natural gas constitute the major share in energy consumption. Domestic sources are far from meeting the growing energy demand; Turkey is importing significant amounts of oil and natural gas. High economic growth and increasing prosperity are causing a change in consumption habits. As a result, primary energy consumption is increasing at annual rate of %6. The legal framework for the natural gas market in Turkey formed for the first time with Law No 6326 Petroleum Act. In 1987 BOTAS was the only player in natural gas market, responsible for transmission and trading activities. Natural Gas Market Law No. 4646 which came into force in 2002, officially ended in this position and EMRA became the regulatory authority responsible for regulation of the market. Parallel with the success in forming the legal and regulatory frameworks, there has been significant success on the part of the private sector which invested in natural gas distribution. Several natural gas distribution tenders were finalized in quite a short time with very low distribution charges. However, a look at the wholesale market reveals that there are still problems. In this study, the development of the natural gas market in Turkey is examined. Also the structures before and after the Law No 4646 are analyzed.

Turan C.,National Science Foundation | Turan C.,Istanbul Gas Distribution Company IGDAS | Cora O.N.,National Science Foundation | Cora O.N.,Karadeniz Technical University | And 2 more authors.
Journal of Power Sources | Year: 2013

In this study, results of an investigation on the effects of manufacturing and coating process sequence on the contact resistance (ICR) of metallic bipolar plates (BPP) for polymer electrolyte membrane fuel cells (PEMFCs) are presented. Firstly, uncoated stainless steel 316L blanks were formed into BPP through hydroforming and stamping processes. Then, these formed BPP samples were coated with three different PVD coatings (CrN, TiN and ZrN) at three different thicknesses (0.1, 0.5 and 1 μm). Secondly, blanks of the same alloy were coated first with the same coatings, thickness and technique; then, they were formed into BPPs of the same shape and dimensions using the manufacturing methods as in the first group. Finally, these two groups of BPP samples were tested for their ICR to reveal the effect of process sequence. ICR tests were also conducted on the BPP plates both before and after exposure to corrosion to disclose the effect of corrosion on ICR. Coated-then-formed BPP samples exhibited similar or even better ICR performance than formed-then-coated BPP samples. Thus, manufacturing of coated blanks can be concluded to be more favorable and worth further investigation in quest of making cost effective BPPs for mass production of PEMFC. © 2013 Elsevier B.V. All rights reserved.

Dur E.,National Science Foundation | Dur E.,Istanbul Gas Distribution Company IGDAS | Cora O.N.,National Science Foundation | Cora O.N.,Karadeniz Technical University | And 2 more authors.
Journal of Power Sources | Year: 2014

Metallic bipolar plate (BPP) with high corrosion and low contact resistance, durability, strength, low cost, volume, and weight requirements is one of the critical parts of the PEMFC. This study is dedicated to understand the effect of the process sequence (manufacturing then coating vs. coating then manufacturing) on the corrosion resistance of coated metallic bipolar plates. To this goal, three different PVD coatings (titanium nitride (TiN), chromium nitride (CrN), zirconium nitride (ZrN)), with three thicknesses, (0.1, 0.5, 1 μm) were applied on BPPs made of 316L stainless steel alloy before and after two types of manufacturing (i.e., stamping or hydroforming). Corrosion test results indicated that ZrN coating exhibited the best corrosion protection while the performance of TiN coating was the lowest among the tested coatings and thicknesses. For most of the cases tested, in which coating was applied before manufacturing, occurrence of corrosion was found to be more profound than the case where coating was applied after manufacturing. Increasing the coating thickness was found to improve the corrosion resistance. It was also revealed that hydroformed BPPs performed slightly better than stamped BPPs in terms of the corrosion behavior. © 2013 Elsevier B.V. All rights reserved.

Turan C.,Virginia Commonwealth University | Turan C.,Istanbul Gas Distribution Company IGDAS | Cora O.N.,Virginia Commonwealth University | Cora O.N.,Karadeniz Technical University | And 2 more authors.
International Journal of Hydrogen Energy | Year: 2011

In this study, metallic bipolar plate (BPP) samples manufactured with stamping and hydroforming under different process conditions were tested for their electrical contact resistance characteristics to reveal the effect of manufacturing type and conditions. Punch speed and force in stamping, and pressure and pressure rate in hydroforming were selected as variable process parameters. In addition, two different channel sizes were tested to expose the effect of BPP micro-channel geometry and its consequences on the contact resistance. As a general conclusion, stamped BPPs showed higher contact conductivity than the hydroformed BPPs. Moreover, pressure in hydroforming and geometry had significant effects on the contact resistance behavior of BPPs. Short term corrosion exposure was found to decrease the contact resistance of bipolar plates. Results also indicated that contact resistance values of uncoated stainless steel BPPs are significantly higher than the respective target set by U.S. Department of Energy. Conforming to literature, proper coating or surface treatments are necessary to satisfy the requirements. © 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

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