Evaluation of CoBlast Coated Titanium Alloy as Proton Exchange Membrane Fuel Cell Bipolar Plates

Atinuke M Oladoye,James G Carton,Abdul G Olabi

doi:10.1155/2014/914817

Abstract

We investigated the potential of graphite based coatings deposited on titanium V alloy by a low-cost powder based process for bipolar plate application. The coatings which were deposited from a mixture of graphite and alumina powders at ambient temperature, pressure of 90 psi, and speed of 20 mm were characterised and electrochemically polarised in 0.5 M H2SO4 + 2 ppm HF bubbled with air and hydrogen gas to depict the cathode and anode PEM fuel cell environment, respectively. Surface conductivity and water contact angles were also evaluated. Corrosion current in the 1 μA/cm2 range in both cathodic and anodic environment at room temperature and showed negligible influence on the electrochemical behaviour of the bare alloy. Similar performance, which was attributed to the discontinuities in the coatings, was also observed when polarised at 0.6 V and −0.1 V with air and hydrogen bubbling at 70∘C respectively. At 140 N/cm2, the coated alloy exhibited contact resistance of 45.70 mΩ·cm2 which was lower than that of the bare alloy (66.50 mΩ·cm2) but twice that of graphite (21.29 mΩ·cm2). Similarly, the wettability test indicated that the coated layer exhibited higher contact angle of 99.63° than that of the bare alloy (66.32°). Over all, these results indicated need for improvement in the coating process to achieve a continuous layer.

Highlights

Proton exchange membrane (PEM) fuel cells as shown in Figure 1 are energy conversion devices that generate clean electrical energy from the electrochemical reaction between hydrogen and oxygen via an electrocatalyst and a solid polymer membrane at temperatures between 60∘C and 80∘C
The membrane electrode assembly (MEA), which is composed of the gas diffusion layer (GDL), the catalyst layer, and the proton exchange membrane (PEM), performs critical roles that control the transport of protons, electrons, and reactant gases from one electrode to the other
We propose a low-cost and scalable surface enhancement process based on the principle of microblasting for improving the performance of Ti in PEM fuel cell environments

Summary

Introduction

Proton exchange membrane (PEM) fuel cells as shown in Figure 1 are energy conversion devices that generate clean electrical energy from the electrochemical reaction between hydrogen and oxygen via an electrocatalyst and a solid polymer membrane at temperatures between 60∘C and 80∘C. The bipolar plates, on the other hand, electrically connect adjacent cells in the stack, facilitate uniform distribution of reactant gases over the entire active electrode area, and provide pathway for removal and management of by-products, as well as mechanically supporting the MEA [5, 6]. To effectively perform these roles, materials for bipolar plate application are required to be impermeable to gas, corrosion resistant, and chemically and mechanically stable as well as possessing high electrical and thermal conductivity

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Results

Conclusion