Tetsuo Mitani

Durability of Graphite Composite Bipolar Plates

Highly graphite filled polymer composites were developed for use as bipolar plates in polymer electrolyte fuel cells (PEFCs). For use in PEFCs, composites should possess excellent durability in a hot and humid environment in addition to high electrical conductivity and good mechanical properties. Therefore, the stability of different composites in hot water was estimated by comparison with the initial properties and target values. On the basis of this comprehensive estimation, we obtained thermosetting composites for compression molding and thermoplastic composites for injection molding that enabled the production of precise bipolar plates. A PEFC stack assembly using the composite bipolar plates showed good, stable performance comparable to that of conventional machined graphite plates.

Simulation of Injection Molding Process for a Box-Shaped Part

The filling and the post-filling (packing and cooling) stages of the injection molding for a simple box shaped part were simulated. The simulation provides the shrinkage and the warpage generated after the post-filling stage. The shrinkage and the warpage can be calculated by the volumetric strain under non-uniform shrinkage. The results of the simulation were qualitatively in agreement with those of the actual molded part.