Claims
- 1. An integral monolithic porous graphite electrode having a differential porosity by volume increasing from the perimeter inward to the center of said electrode, wherein the base raw material is a cellulosic filter paper with a nominal thickness of from 0.5 to 5 mm. impregnated with the residue of a low coke yield impregnant, and wherein the edge of the electrode is impregnated with the residue of a medium to high coke yield impregnant in an amount effective to reduce the porosity by volume at the perimeter of the electrode to less than about 30%.
- 2. The electrode of claim 1 wherein the edge is approximately 1 cm wide.
- 3. A porous monolithic graphite electrode for a fuel cell having a porosity by volume of less than 30% in a narrow band along the edges and a porosity of over 70% by volume in the balance of the area the edge of the electrode having pores impregnated with a medium to high coke yield impregnant.
- 4. A porous monolithic graphite electrode for a fuel cell having a differential porosity by volume increasing from about 20% at the perimeter to about 77% at the center, the porosity at the perimeter having been reduced by multiple impregnation steps, the perimeter being approximately 1 cm wide, the base raw material being a cellulosic filter paper with a nominal thickness of from 0.5 to 5 mm impregnated with creosote, cured for approximately 2 to 24 hours in air at 225.degree. C., baked for approximately 4 hours to 10 days in a reducing atmosphere on a cycle rising to 500.degree.-1100.degree. C., impregnated on the perimeter with coal tar, recured and rebaked as before, re-impregnated one or more times with coal tar on the perimeter, recured and rebaked as before, and graphitized in 4 hours to 8 days on a cycle rising to about 270.degree. C. in an inert atmosphere.
- 5. An integral porous monolithic graphic electrode for a fuel cell having a differential porosity from the perimeter to the center, the porosity in a band of approximately 1 cm width being from approximately 15% to 30% by volume and to the porosity in the center of the electrode being from approximately 67 to 81% by volume, the band of approximately 1 cm width having pores impregnated with a medium to high coke yield impregnant.
Parent Case Info
This application is a continuation of application Ser. No. 878,905, filed June 26, 1986 now abandoned which is a division of application Ser. No. 723,419, filed Apr. 15, 1985 now U.S. Pat. No. 4,611,396.
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Divisions (1)
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Number |
Date |
Country |
Parent |
723419 |
Apr 1985 |
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Continuations (1)
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Number |
Date |
Country |
Parent |
878905 |
Jun 1986 |
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