1. In a process for producing a high temperature stable fiber composite ceramic by chemical vapor infiltration (CVI) with a methyltrichlorosilane (MTS) in hydrogen (H2) on fiber scrims of carbon fiber preforms or silicon carbide fiber preforms, wherein the partial pressure ratio of hydrogen to methyltrichlorosilane is adjusted between 4 and 8, the process further comprising:
adjusting the process pressure to \u22670.6 bar absolute;
adjusting the process temperature to \u22671100\xb0 C.; and
arranging a heat-resistant material with a large surface between a gas feed in the reaction space and the fiber scrims of carbon fiber preforms or silicon carbide fiber preforms to be infiltrated for pre-reacting the methyltrichlorosilane on contact with the large surface of the heat-resistant material, and wherein the carbon fiber preforms or silicon carbide fiber preforms are generated in that fiber layers are first constructed, the fiber layers are fixed one above the other at a distance from one another by binders and then simultaneously molding and stabilizing the preform approximating a desired end product.
2. The process according to claim 1, wherein the binder is selected from organic andor silicon-organic polymer resins.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
We claim:
1. A fuel cell, comprising:
an anode support plate and a cathode support plate and a membrane electrode assembly disposed between said anode and cathode support plates, said membrane electrode assembly comprising a polymer electrolyte membrane, at least one of said support plates comprising a hydrophilic substrate layer having pores therein;
a water transport plate adjacent to each said hydrophilic substrate layer, each said water transport plate having a passageway for a water stream and another passageway for a reactant gas stream; and
a partially hydrophobic porous carbon fluoropolymer particulate composite diffusion layer disposed between at least one said hydrophilic substrate layer and said membrane electrode assembly, each said diffusion layer comprising about 10% fluoropolymer by weight.
2. A fuel cell according to claim 1 wherein:
said diffusion layer comprises a fluoropolymer selected from the group consisting of polytetrafluoroethylene, fluorinated ethylene propylene, polytetrafluoroethylene-co-perfluoromethyl vinylether, copolymers of ethylene and tetrafluoroethylene, copolymers of ethylene and chlorotrifluoroethylene, polyvinylidene fluoride, polyvinyl fluoride and amorphous fluoropolymers.
3. A fuel cell, comprising:
an anode support plate and a cathode support plate and a membrane electrode assembly disposed between said anode and cathode support plates, said membrane electrode assembly comprising a polymer electrolyte membrane, at least one of said support plates comprising a hydrophilic substrate layer having pores therein;
a water transport plate adjacent to each said hydrophilic substrate layer, each said water transport plate having a passageway for a water stream and another passageway for a reactant gas stream; and
a diffusion layer disposed between at least one said hydrophilic substrate layer and said membrane electrode assembly, the thickness of each said diffusion layer being more than about 5.0 microns and less than 25.0 microns.
4. A fuel cell, comprising:
an anode support plate and a cathode support plate and a membrane electrode assembly disposed between said anode and cathode support plates, said membrane electrode assembly comprising a polymer electrolyte membrane, at least one of said support plates comprising a hydrophilic substrate layer having pores therein;
a water transport plate adjacent to each said hydrophilic substrate layer, each said water transport plate having a passageway for a water stream and another passageway for a reactant gas stream;
a diffusion layer disposed between at least one said hydrophilic substrate layer and said membrane electrode assembly; and
means for creating pressure differential between said reactant gas streams and said coolant stream such that the pressure of each said reactant gas stream is greater than the pressure of said coolant stream, said pressure differential being more than 0.2 psi and less than 1.7 psi.
5. A fuel cell, comprising:
an anode support plate and a cathode support plate and a membrane electrode assembly disposed between said anode and cathode support plates, said membrane electrode assembly comprising a polymer electrolyte membrane, at least one of said support plates comprising a hydrophilic substrate layer having pores therein;
a water transport plate adjacent to each said hydrophilic substrate layer, each said water transport plate having a passageway for a water stream and another passageway for a reactant gas stream; and
means for creating pressure differential between said reactant gas streams and said coolant stream such that the pressure of each said reactant gas stream is greater than the pressure of said coolant stream, said pressure differential being more than 0.2 psi and less than 1.7 psi.