Claims
- 1. A process for the production of a porous monolithic graphite plate useful as an electrode in a fuel cell and having a zone of low porosity in a band at the perimeter approximately 1 cm in width of less than 30% porosity by volume and a center zone of over 70% porosity by volume, said process consisting of impregnating a porous sheet selected from the group consisting of cellulosic filter paper, synthetic fiber paper and felts with an impregnant selected from the group consisting of creosote and coal tar derivatives and resins giving a coke yield of less than 50% by weight, curing the impregnated sheet in air for a period of 2 to 24 hours at a temperature of from 150.degree. to 300.degree. C., carbonizing by baking the sheet for a period of 4 hours to 4 days at a temperature cycle rising at 500.degree. to 1100.degree. C. in an inert atmosphere, sealing the perimeter with an impregnant selected from the group consisting of liquid coal tar, phenolic resins, and polymers having a coke yield of 40 to 70%, curing and baking the impregnant as before, and final heat treating the sheet at a temperature over 1800.degree. C.
- 2. A process for the production of a porous monolithic graphite electrode for a fuel cell having an integral edge seal comprising impregnating the perimeter or edge of a sheet having a thickness of from 0.5 to 5 mm and selected from the group consisting of cellulosic filter paper, synthetic fiber paper and felts with an impregnant selected from the group consisting of coal tar, phenolformaldehyde resins, thermosetting resins and polymers having a coke yield of from 40 to 70%, curing the impregnant in air at a temperature of 150.degree. to 300.degree. C. for a period of 2 to 24 hours, baking the sheet to carbonize the impregnant in an inert atmosphere at a temperature of 500.degree. to 1100.degree. C. for a period of 4 hours to 4 days, repeating the impregnation cure and bake cycles until a desired porosity is reached, impregnating the center with an impregnant having a low coke yield of less than 30% when cured and baked as above, curing and baking the sheet as above, and final heat treating the sheet at a temperature over 1800.degree. C.
- 3. A process for the production of a porous monolithic graphite electrode for a fuel cell comprising impregnating the edge of a cellulosic filter sheet to a distance of 1 cm from the edge with a high coke yield impregnant selected from the group consisting of coal tar and phenolic resins, impregnating the remaining area with a low coke yield impregnant, curing the impregnated sheet in air for a period of 2 to 24 hours at 150.degree. to 300.degree., baking the sheet in an inert atmosphere for 4 hours to 4 days at 500.degree. to 1100.degree. C., and final heat treating the sheet to 1800.degree. C. to 3000 C. on a cycle of 4 hours to 4 days.
- 4. The process of claim 3 wherein the impregnants are applied by spraying.
- 5. The process of claim 3 wherein the impregnants are applied by roller coating.
- 6. The process of claim 3 wherein the edge is impregnated with a fusible resin powder coating.
- 7. The process of claim 2 wherein said impregnant having a low coke yield of less than 30% when cured and baked is creosote.
- 8. The process of claim 3 wherein the low coke yield impregnant is creosote.
Parent Case Info
This application is a continuation of application Ser. No. 878,904 filed June 26, 1986, now abandoned, which in turn is a continuation of application Ser. No. 723,419, filed Apr. 15, 1985, now U.S. Pat. No. 4,611,396.
US Referenced Citations (4)
Number |
Name |
Date |
Kind |
4115528 |
Christner et al. |
Sep 1978 |
|
4165349 |
Sandelli |
Aug 1979 |
|
4233369 |
Breault et al. |
Nov 1980 |
|
4365008 |
De Casperis et al. |
Dec 1982 |
|
Continuations (2)
|
Number |
Date |
Country |
Parent |
878904 |
Jun 1986 |
|
Parent |
723419 |
Apr 1985 |
|