Method of making nickel-carbon alloy sleeves

Claim 1

METHOD OF MAKING A HIGH CARBON CONTENT ALLOYNICKLE SLEEVE FOR A COATED CATHODE, COMPRISING THE STEPS OF FORMING SAID SLEEVE OF SUBSTANTIALLY PURE NICKLE SHEET METAL, HEATING SAID SLEEVE AND A STRIP OF NICKLE IN A FURNACE CONTAINING FROM 0.1% TO 1.0% OF A CARBON BEARING MEDIUM CONSISTING OF AT LEAST ONE OF PROPANE, METHANE, ETHENE, METHANOL, ETHYL ALCOHOL, PROPYL ALCOHOL, ISOPOPYL ALCOHOL, BENZOL, BENZENE AND GASOLINE, AT A TEMPERATURE BELOW 700* C. TO PREVENT EXCESSIVE SOFTINING OF SAID SLEEVE AND TO DIFFUSE CARBON INTO THE NICKLE OF SAID SLEEVE SAID STRIP AT A RATE TO PREVENT FORMATION OF A CARBON COATING ON SAID SLEEVE, MEASURING THE RESISTANCE OF SAID STRIP OF NICKLE DURING SAID HEATING STEP, AND STOPPING SAID HEATING STEP WHEN SAID RESISTANCE IS FORM 10 TO 25% HIGHER THAN PRIOR OF SAID HEATING STEP, WHEREBY SAID SLEEVE CONTAINS FROM 0.04 TO 0.10% CARBON BY WEIGHT WITHOUT AN OBJECTIONABLE OUTER COATING OF CARBON.