Porous carbon fuel cell substrates and method of manufacture
AssigneeUnited Technologies Corporation
InventorsGeorge K. Layden, Roscoe A. Pike, Michael A. DeCrescente
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Abstract
Porous carbon sheets suitable for use as fuel cell electrode support plates are produced by stabilizing acrylic filament precursors through the controlled addition of oxygen thereto. The stabilized filaments are thereafter chopped into short lengths, felted and pressed into sheets with the pressing step being performed at a temperature determined by the oxygen content of the stabilized filaments. The sheets are thereafter pyrolyzed to produce the desired porous substrate material.
Claims13
A process for the manufacture of substrate material having a porosity in the range of 50% to 70% comprising the steps of:
- stabilizing a plurality of acrylic polymer filaments, said filaments containing at least 50% acrylonitrile, by heating in an oxidizing atmosphere until 3 to 10% by weight oxygen is introduced into the polymer;
- reducing the length of the stabilized filaments to form fibers having an average length commensurate with the desired substrate porosity;
- felting the fibers of reduced length to provide a layer of uniform thickness with random fiber orientation;
- subjecting the layer of fibers to heat and pressure in the range of 50-1000 psi to cause self-bonding of contiguous fibers whereby a sheet is formed without the aid of a binder for the felted fibers;
- and
- carbonizing the sheet by heating in a non-oxidizing atmosphere to produce a porous substrate material.
Dependencies are inferred from the claim text.