Claims
- 1. A solid electrolyte cell comprising a solid electrolyte body having a first side and a second side, a first electrode on the first side of the body, the first side of the body having a porous surface of greater porosity than an underlying matrix of the body, the porous surface comprising a plurality of recesses, the first electrode substantially covering the first side of the body, the first electrode comprising a thin layer of conductive catalytic material extending into the recesses to mechanically lock the layer to the porous surface, and a second electrode on the second side of the body.
- 2. The cell of claim 1 wherein the porous surface of the body comprises a plurality of substantially spherical recesses and further comprises a small ball of solid electrolyte at the bottom of each of the substantially spherical recesses.
- 3. The cell of claim 1 wherein the cell is a part of a lambda oxygen sensor installed in the exhaust system of an internal combustion engine.
- 4. The cell of claim 1 wherein the cell is a part of an oxygen generator.
- 5. The cell of claim 1 wherein the cell is formed as a thimble, the porous surface being the outside of the thimble.
- 6. The cell of claim 5 wherein the layer is plated on the porous surface at a substantially uniform thickness from a closed axial end of the thimble to near an open axial end of the thimble.
- 7. The cell of claim 1 wherein the solid electrolyte is a yttria-stabilized zirconia.
- 8. The cell of claim 1 wherein the first and second electrodes are formed of a material selected from the group consisting of platinum, rhodium and palladium.
- 9. The cell of claim 8 wherein the first and second electrodes are formed of platinum.
- 10. A method of forming a solid electrolyte cell comprising forming a solid electrolyte body, forming a porous layer on a first surface of the body, activating the porous layer on the first surface of the body to form a plurality of growth points for a conductive layer on the first surface, growing a first electrode by electroless plating of a conductive layer on the activated porous layer on the first surface of the body, and forming a second electrode on a second surface of the body.
- 11. The method of claim 10 wherein the step of forming a solid electrolyte body comprises forming a body which is impervious to air.
- 12. The method of claim 10 wherein activating the porous layer on the first surface comprises wicking a metal salt carried by a liquid into the porous layer.
- 13. The method of claim 10 wherein the body is formed as a thimble with an outer surface and an inner surface, the first electrode being formed on the outer surface.
- 14. The method of claim 10 wherein growing a first electrode comprises immersion of the porous layer on the first surface in an unstable solution of a salt of a metal.
- 15. The method of claim 14 wherein the unstable solution further comprises a reducing agent
- 16. The method of claim 15 wherein the reducing agent comprises hydrazine.
- 17. A method of forming a coating of a precious metal on a ceramic substrate, the method comprising a step of forming a ceramic substrate having pores at a surface of the substrate; a step of forming a solution of a salt of a first metal in an organic solvent which wets the ceramic; a step of forming nucleation sites on the surface of the substrate, said step of forming nucleation sites including wicking the solution into the pores at the surface of the substrate; and thereafter an electroless plating step of plating the precious metal onto the surface from an aqueous plating bath.
- 18. The method of claim 15 wherein the organic solvent is acetone.
- 19. The method of claim 15 wherein the first metal and the precious metal are the same.
- 20. The method of claim 15 including a step, after wicking the solution into the pores at the surface of the substrate, of heating the substrate to drive off the solvent and reduce the salt to a 0.01 to 0.5 micron layer of the first metal with numerous unplated areas.
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This is a division of copending application Ser. No. 08/953,864, filed Oct. 16, 1997, including continued prosecution application filed May 10, 2000, now U.S. Pat. No. 6,315,880.
Divisions (1)
|
Number |
Date |
Country |
Parent |
08953864 |
Oct 1997 |
US |
Child |
10044704 |
Nov 2001 |
US |