Corrosion performance of graphene oxide coated 304 SS in PEMFC environment

In this work, an electrophoretic deposition technique was used to deposit graphene oxide (GO) on 304 stainless steel. Its corrosion performance was evaluated in a simulated polymer electrolyte membrane fuel cell environment. The corrosion current density (icorr) and interfacial contact resistance (ICR) were measured at 8.9 µA/cm2 and 19.3 mΩ cm2, respectively. The icorr of GO coated 304SS is several orders lower than bare SS 304. Similarly, the ICR of GO coated 304SS is nearly half of bare 304SS at a compaction pressure of 150 N/cm2. The potentiodynamic polarization plot indicates the prevalence of multiple corrosion mechanisms. A prolonged corrosion study for 30 days immersed in the simulated PEM cell environment shows the formation of rounded pits that corroborate the activity of pitting corrosion.

Metallic Material Selection and Prospective Surface Treatments for Proton Exchange Membrane Fuel Cell Bipolar Plates—A Review

The aim of this review is to summarize the possibilities of replacing graphite bipolar plates in fuel-cells. The review is mostly focused on metallic bipolar plates, which benefit from many properties required for fuel cells, viz. good mechanical properties, thermal and electrical conductivity, availability, and others. The main disadvantage of metals is that their corrosion resistance in the fuel-cell environment originates from the formation of a passive layer, which significantly increases interfacial contact resistance. Suitable coating systems prepared by a proper deposition method are eventually able to compensate for this disadvantage and make the replacement of graphite bipolar plates possible. This review compares coatings, materials, and deposition methods based on electrochemical measurements and contact resistance properties with respect to achieving appropriate parameters established by the DOE as objectives for 2020. An extraordinary number of studies have been performed, but only a minority of them provided promising results. One of these is the nanocrystalline β-Nb2N coating on AISI 430, prepared by the disproportionation reaction of Nb(IV) in molten salt, which satisfied the DOE 2020 objectives in terms of corrosion resistance and interfacial contact resistance. From other studies, TiN, CrN, NbC, TiC, or amorphous carbon-based coatings seem to be promising. This paper is novel in extracting important aspects for future studies and methods for testing the properties of metallic materials and factors affecting monitoring characteristics and parameters.

Effects of CrN/TiN Coatings on Interfacial Contact Resistance of Stainless Steel 410 Bipolar Plates in Fuel Cells

Challenge on energy resources exists, especially when the fossil resources are limited. Fuel cells, as an alternative replacement, can be used. Fuel cells with coated bipolar plates are the interest of this paper. Current research is concerned with the effects of CrN/TiN coatings on interfacial contact resistance (ICR). Stainless steel 410 was selected as a base metal, and the coating process was performed using chromium nitride and titanium nitride by cathodic arc evaporation method. It was found that the surface roughness and ICR values of CrN-coated sample are lower than the TiN-coated sample. The concluded that the CrN layer could be replaced with the TiN layer for better performance of bipolar plates.

Bio-Based Anti-Corrosion Polymer Coating for Fuel Cells Bipolar Plates

A highly corrosion resistant and conductive polymer coating for polymer electrolyte membrane fuel cells bipolar plates have been successfully prepared from renewable plant biomass sources. The coating is based on the 5-hydroxymethylfurfural synthesis by-product resin that consists of complex furanic oligomers and polymers. The corrosion resistance and conductivity of coated titanium plates have been studied. As-prepared coated Ti samples are shown 0.083 μA/cm2 and 0.32 μA/cm2 corrosion current in the simulated PEMFCs cathode and anode environment respectively. In addition, the polymer coating are reduced the interfacial contact resistance of bare titanium up to 40 %. The Ti plates coated with by-products of 5-HMF synthesis are shown a great potential application as bipolar plates for PEMFCs.

Effect of N+ Implantation on Surface Characteristics of 316L Stainless Steels for Bipolar Plate in PEMFC

Nitrogen was implanted into 316L stainless steel by plasma immersion ion implantation (PIII) for surface modification. Due to nitrogen implantation, the corrosion resistance and interfacial contact resistance (ICR) were improved compared to the bare 316L stainless steel. The improved corrosion resistance was attributed to the formation of the expanded austenite phase (γN). The phase formation was found to be closely related to the evolution of the (111) plane texture. The formation of γN is strongly related to applied bias voltages. When bias voltages were increased to 15 kV, the γN phase was partially decomposed due to the formation of excessive nitride, including the CrN phase. For the ICR, increased crystallite size is effective in reducing contact resistance, which might arise from a reduced number of the grain boundary with electron scattering. In particular, the applied bias voltage of 10 kV was the most effective to both corrosion resistance and ICR, and its performance satisfies the demand for a bipolar plate in the Polymer Electrolyte Membrane Fuel Cells (PEMFC).