Preparation of carbonaceous porous materials from carbon fibers and evaluation of their corrosion resistance in hot phosphoric acid

A study was conducted to evaluate corrosion resistance of carbonaceous porous materials made from various fibers and binder as an electrode substrate of phosphoric acid fuel cells. A great improvement in corrosion resistance was achieved by using a high performance carbon fiber as a filler material and by treating at higher temperatures to increase the graphitizability of final products. The corrosion of the product occured mainly at the surface of fibers because the graphitizability of binder carbon was higher than that of fibers due to the great thermal stress applied during volume shrinkage of binder at carbonization process. Also it became clear that a high corrosion resistance was ensured by good adhesion between fibers and binders. For a product in which fibers separated from binder carbon, its corrosion resistance was low. By using a high performance carbon fiber and by achieving good adhesion of carbon fibers and binder carbon, other properties; e.g. thermal conductivity, electrical conductivity and mechanical strength were also improved greatly.