Method of making a sintered fuel cell electrode structure

Claim 1

A METHOD OF PRODUCING A SINTERED BODY CAPABLE OF FORMING A GAS-IMPERMEABLE CATHODE STRUCTURE FOR A FUEL CELL, COMPRISING THE STEPS OF FORMING, SUPERPOSED UPON EACH OTHER, A FIRST PULVERULETN LAYER CONSISTING ESSENTIALLY OF A FIRST MIXTURE OF NICKEL POWDER AND OF A PULVERULENT NICKEL SALT WHICH UPON HEATING IN A REDUCING ATMOSPHERE TO THE SINTERING TEMPERATURE IF NICKEL WILL BE DECOMPOSED UNDER FORMATION OF METALLIC NICKEL AND GASEOUS DECOMPOSITION PRODUCTS, AND A SECOND PULVERULENT LAYER CONSISTING ESSENTIALLY OF A MIXTURE OF SAID FIRST MIXTURE AND OF A PULVERULENT PORE-FORMING MATERIAL WHICH CAN BE REMOVED UNDER CONDITIONS WHICH WILL NOT CAUSE REMOVAL OF NICKEL; JOINTLY COMPRESSING SAID SUPERPOSED LAYERS, THEREBY FORMING THEREOF A COMPRESSED COMPOSITE LAYER; HEATING SAID COMPRESSED COMPOSITE LAYER IN A REDUCING ATMOSPHERE AT A TEMPERATURE BETWEEN ABOUT 650*C. AND 750*C. THEREBY REDUCING SAID PULVERULENT NICKEL SALT OF SAID LAYERS TO METALLIC NICKEL AND ALSO FORMING GASEOUS DECOMPOSITION PRODUCTS, THEREBY FORMING A POROUS, COHERENT SINTERED NICKEL BODY OF THE ORIGINALLY PRESENT PULVERULENT NICKEL AND THE NICKEL FORMED BY REDUCTION OF SAID REDUCIBLE NICKEL SALT OF SAID TWO LAYERS; AND REMOVING SAID PULVERULENT PORE-FORMING MATERIAL FROM THE PORTION OF SAID COHERENT SINTERED NICEL BODY FORMED OF SAID SECOND LAYER WITHOUT CAUSING REMOVAL OF NICKEL THEREBY INCREASING THE POROSITY OF THE LATTER, WHEREBY A COHERENT SINTERED NICKEL BODY IS FORMED CONSISTING OF TWO LAYERS OF DIFFERENT POROSITY INTEGRAL WITH EACH OTHER.

Claim 2

A METHOD OF PRODUCING A SINTERED BODY CAPABLE OF FORMING A GAS-IMPERMEABLE CATHODE STRUCTURE FOR A FUEL CELL, COMPRISING THE STEPS OF FORMING, SUPERPOSED UPON EACH OTHER, A FIRST PULVERULETN LAYER CONSISTING ESSENTIALLY OF A FIRST MIXTURE OF NICKEL POWDER AND OF A PULVERULENT NICKEL SALT WHICH UPON HEATING IN A REDUCING ATMOSPHERE TO THE SINTERING TEMPERATURE IF NICKEL WILL BE DECOMPOSED UNDER FORMATION OF METALLIC NICKEL AND GASEOUS DECOMPOSITION PRODUCTS, AND A SECOND PULVERULENT LAYER CONSISTING ESSENTIALLY OF A MIXTURE OF SAID FIRST MIXTURE AND OF A PULVERULENT PORE-FORMING MATERIAL WHICH CAN BE REMOVED UNDER CONDITIONS WHICH WILL NOT CAUSE REMOVAL OF NICKEL; JOINTLY COMPRESSING SAID SUPERPOSED LAYERS, THEREBY FORMING THEREOF A COMPRESSED COMPOSITE LAYER; HEATING SAID COMPRESSED COMPOSITE LAYER IN A REDUCING ATMOSPHERE AT A TEMPERATURE BETWEEN ABOUT 650*C. AND 750*C. THEREBY REDUCING SAID PULVERULENT NICKEL SALT OF SAID LAYERS TO METALLIC NICKEL AND ALSO FORMING GASEOUS DECOMPOSITION PRODUCTS, THEREBY FORMING A POROUS, COHERENT SINTERED NICKEL BODY OF THE ORIGINALLY PRESENT PULVERULENT NICKEL AND THE NICKEL FORMED BY REDUCTION OF SAID REDUCIBLE NICKEL SALT OF SAID TWO LAYERS; AND REMOVING SAID PULVERULENT PORE-FORMING MATERIAL FROM THE PORTION OF SAID COHERENT SINTERED NICEL BODY FORMED OF SAID SECOND LAYER WITHOUT CAUSING REMOVAL OF NICKEL THEREBY INCREASING THE POROSITY OF THE LATTER, WHEREBY A COHERENT SINTERED NICKEL BODY IS FORMED CONSISTING OF TWO LAYERS OF DIFFERENT POROSITY INTEGRAL WITH EACH OTHER.