Bubbles silicon carbide

Similar to a MCFC, in the PAFC, the electrolyte is stored between the electrodes within a thin 50% porosity, 50-200-pm-thick porous matrix. The purpose for the silicon carbide (SiC) porous matrix used in PAFCs is to retain the acid electrolyte by capillary forces. If there were no matrix, the acid could simply drain into the flow channels or bulge according to gravimetric forces. It is critical that the bubble pressure of the matrix exceed 35 kPa, or electrolyte blow-through and excessive crossover from internal pressure differentials would occur. The maximum pressure differential between the anode and cathode is hmited to around 20 kPa to avoid this problem. 

Gangireddy, S., Karlsdottir, S. N., Norton, S. J., Tucker, J. C., Halloran, J. W. (2010). In situ microscopy observation of liquid flow, zirconia growth, and CO bubble formation during high temperature oxidation of zirconium diboride-silicon carbide. Journal of the European Ceramic Society, 30(11), 2365. doi 10.1016/j. jeurceramsoc.2010.01.034. 

Narushima T, Goto T, Yokoyama Y, Takeuchi Y, IguchiY, Hirai T, Active-to-passive transition and bubble formation for high-temperature oxidation of chemically vapor-deposited silicon carbide in CO-CO2 atmosphere , J Am Ceram Soc, 1994 77(4) 1079-1082. 

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