Ex-situ evaluation of PTFE coatedmetals in a proton exchangemembrane fuel cell environment

Abdul-Ghani Olabi, Ahmad Baroutaji, J.G. Carton, Atinuke M. Oladoye, Joseph Stokes, B. Twomey

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)
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Abstract

Metallic-based bipolar plates exhibit several advantages over graphite-based plates, including higher strength, lower manufacturing cost and better electrical conductivity. However, poor corrosion resistance and high interfacial contact resistance (ICR) aremajor challenges formetallic bipolar plates used in proton exchange membrane (PEM) fuel cells.
Corrosion ofmetallic parts in PEMfuel cells not only increases the interfacial contact resistance but it can also decrease the proton conductivity of the Membrane Electrode Assembly (MEA), due to catalyst poisoning phenomena
caused by corrosive products. In this paper, a composite coating of Polytetrauoroethylene (PTFE) was deposited on stainless steel alloys (SS304, SS316L) and Titanium (G-T2) via a CoBlast™process. Corrosion resistance
of the coated and uncoatedmetals in a simulated PEM fuel cell environment of 0.5MH2SO4+2 ppmHF at 70 °C was evaluated using potentiodynamic polarisation. ICR between the selected metals and carbon paperwas
measured and used as an indicator of surface conductivity. Scanning Electron Microscopy (SEM), 3D microscopy, Energy Dispersive X-ray (EDX), X-Ray Diffraction (XRD), and contact angle measurements were used to characterise
the samples. The results showed that the PTFE coating improved the hydrophobicity and corrosion resistance but increased the ICR of the coated metals due to the unconductive nature of such coating. Thus, it was concluded that it is not fully feasible to use the PTFE alone for coating metals for fuel cell applications and a hybrid coating consisting of PTFE and a conductive material is needed to improve surface conductivity.
Original languageEnglish
Pages (from-to)10-17
JournalSurface & Coatings Technology
Volume323
Early online date1 Dec 2016
DOIs
Publication statusPublished - 25 Aug 2017

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