Characterization of Bipolar Plates

However, the main drawback with metals is the lack of ability to combat corrosion in the harsh acidic and humid enviroiunent inside the PEM fuel cell without forming oxidants, passive layers, and metal ions that cause considerable power degradation. Various coatings are applied to improve the corrosion resistance of the metals used without sacrificing surface contact resistance and maintaining cost-effectiveness. Thus, key parameters for 

To measure the gas permeability of fhe graphite bipolar plate samples, a nitrogen gas is passed through the specimen to produce a differential pressure across the specimen DP and measure the rate of nifrogen flow, Q. The permeability is calculated using the formula 

The electrical resistivity of fhe graphite bipolar plates can be measured either by passing DC current and measuring the voltage drop across the plate sample or by direct resistance measurement using a milliohmmeter. Using the measured electrical resistance R, the electrical resistivity is calculated as 

The high porosity in the electrode and diffusion layer structure is required for efficient transport of species between electrolyte membrane and gas flow fields. The porosity of the material is defined as the fraction of the void space in the volume of the material. Thus, porosity 

It can also be expressed in terms of the density of the porous sample (pp) and the bulk density (p,) of the material used to make the porous sample. 

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