Ex-situ evaluation of PTFE coated metals in a proton exchange membrane fuel cell environment

A. Baroutaji; J. G. Carton; A. M. Oladoye; J. Stokes; B. Twomey; A. G. Olabi

doi:10.1016/j.surfcoat.2016.11.105

Ex-situ evaluation of PTFE coated metals in a proton exchange membrane fuel cell environment

A. Baroutaji^*, J. G. Carton, A. M. Oladoye, J. Stokes, B. Twomey, A. G. Olabi

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

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) are major challenges for metallic bipolar plates used in proton exchange membrane (PEM) fuel cells. Corrosion of metallic parts in PEM fuel 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 polytetrafluoroethylene (PTFE) was deposited on stainless steel alloys (SS304, SS316L) and Titanium (G-T2) via a CoBlast™ process. Corrosion resistance of the coated and uncoated metals in a simulated PEM fuel cell environment of 0.5 M H₂SO₄ + 2 ppm HF at 70 °C was evaluated using potentiodynamic polarisation. ICR between the selected metals and carbon paper was 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 language	English
Pages (from-to)	10-17
Number of pages	8
Journal	Surface and coatings technology
Volume	323
Early online date	1 Dec 2016
DOIs	https://doi.org/10.1016/j.surfcoat.2016.11.105
Publication status	Published - 25 Aug 2017

Bibliographical note

Funding Information:
The authors would like to thank Enterprise Ireland for funding this work under grant CF20133023.

Keywords

CoBlast™
Corrosion
Flow plates
Interfacial contact resistance
PEM fuel cell
PTFE coatings

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10.1016/j.surfcoat.2016.11.105

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@article{b8251026d53d4d09b891115643ae2bdf,

title = "Ex-situ evaluation of PTFE coated metals in a proton exchange membrane fuel cell environment",

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) are major challenges for metallic bipolar plates used in proton exchange membrane (PEM) fuel cells. Corrosion of metallic parts in PEM fuel 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 polytetrafluoroethylene (PTFE) was deposited on stainless steel alloys (SS304, SS316L) and Titanium (G-T2) via a CoBlast{\texttrademark} process. Corrosion resistance of the coated and uncoated metals in a simulated PEM fuel cell environment of 0.5 M H2SO4 + 2 ppm HF at 70 °C was evaluated using potentiodynamic polarisation. ICR between the selected metals and carbon paper was 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.",

keywords = "CoBlast{\texttrademark}, Corrosion, Flow plates, Interfacial contact resistance, PEM fuel cell, PTFE coatings",

author = "A. Baroutaji and Carton, {J. G.} and Oladoye, {A. M.} and J. Stokes and B. Twomey and Olabi, {A. G.}",

note = "Funding Information: The authors would like to thank Enterprise Ireland for funding this work under grant CF20133023. ",

year = "2017",

month = aug,

day = "25",

doi = "10.1016/j.surfcoat.2016.11.105",

language = "English",

volume = "323",

pages = "10--17",

journal = "Surface and coatings technology",

issn = "0257-8972",

publisher = "Elsevier",

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TY - JOUR

T1 - Ex-situ evaluation of PTFE coated metals in a proton exchange membrane fuel cell environment

AU - Baroutaji, A.

AU - Carton, J. G.

AU - Oladoye, A. M.

AU - Stokes, J.

AU - Twomey, B.

AU - Olabi, A. G.

N1 - Funding Information: The authors would like to thank Enterprise Ireland for funding this work under grant CF20133023.

PY - 2017/8/25

Y1 - 2017/8/25

N2 - 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) are major challenges for metallic bipolar plates used in proton exchange membrane (PEM) fuel cells. Corrosion of metallic parts in PEM fuel 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 polytetrafluoroethylene (PTFE) was deposited on stainless steel alloys (SS304, SS316L) and Titanium (G-T2) via a CoBlast™ process. Corrosion resistance of the coated and uncoated metals in a simulated PEM fuel cell environment of 0.5 M H2SO4 + 2 ppm HF at 70 °C was evaluated using potentiodynamic polarisation. ICR between the selected metals and carbon paper was 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.

AB - 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) are major challenges for metallic bipolar plates used in proton exchange membrane (PEM) fuel cells. Corrosion of metallic parts in PEM fuel 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 polytetrafluoroethylene (PTFE) was deposited on stainless steel alloys (SS304, SS316L) and Titanium (G-T2) via a CoBlast™ process. Corrosion resistance of the coated and uncoated metals in a simulated PEM fuel cell environment of 0.5 M H2SO4 + 2 ppm HF at 70 °C was evaluated using potentiodynamic polarisation. ICR between the selected metals and carbon paper was 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.

KW - CoBlast™

KW - Corrosion

KW - Flow plates

KW - Interfacial contact resistance

KW - PEM fuel cell

KW - PTFE coatings

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UR - https://www.sciencedirect.com/science/article/pii/S0257897216312816?via%3Dihub

U2 - 10.1016/j.surfcoat.2016.11.105

DO - 10.1016/j.surfcoat.2016.11.105

M3 - Article

AN - SCOPUS:85007429421

SN - 0257-8972

VL - 323

SP - 10

EP - 17

JO - Surface and coatings technology

JF - Surface and coatings technology

ER -

Ex-situ evaluation of PTFE coated metals in a proton exchange membrane fuel cell environment

Abstract

Bibliographical note

Keywords

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