Chromium plating

Claim 2

APPLYING TO SAID ANODE AND CATHODE A CYCLICALLY VARYING UNIDIRECTIONAL VOLTAGE,

Claim 3

IN THE METHOD OF PRODUCING A CHROMIUM PLATE OF LOW INTERNAL STRESS BY ELECTRODEPOSITING CHROMIUM ON A BASIS METAL CONSTITUTING THE CATHODE IN AN ELECTRIC CIRCUIT HAVING AN ANODE AND A CATHODE IMMERSED IN AN AQUEOUS SOLUTION MAINTAINED AT A TEMPERATURE WITHIN THE RANGE OF ABOUT 105*F., TO ABOUT 150*F., AND CONTAINING CHROMIC ACID TOGETHER WITH ANIONS AND CATIONS FOR PROMOTING THE ELECTRODEPOSITION OF CHROMIUM, THE IMPROVEMENT WHICH INCLUDES:

Claim 4

IN THE METHOD OF PRODUCING A CHROMIUM PLATE OF LOW INTERNAL STRESS BY ELECTRODEPOSITING CHROMIUM ON A BASIS METAL CONSTITUTING THE CATHODE IN AN ELECTRIC CIRCUIT HAVING AN ANODE AND A CATHODE IMMERSED IN AN AQUEOUS SOLUTION MAINTAINED AT A TEMPERATURE WITHIN THE RANGE OF ABOUT 105*F., TO ABOUT 150*F., AND CONTAINING CHROMIC ACID TOGETHER WITH ANIONS AND CATIONS FOR PROMOTING THE ELECTRODEPOSITION OF CHROMIUM, THE IMPROVEMENT WHICH INCLUDES:

Claim 5

CONTROLLING SAID VOLTAGE IN SUCH A MANNER THAT THERE IS WITHIN EACH CYCLE OF THE VOLTAGE VARIATIONS, (A) A PERIOD (T1) OF CURRENT DENSITY OF SUFFICIENT MAGNITUDE AND DURATION TO DEPOSIT CRHX. BUT LESS THAN ONE HALF THAT REQUIRED TO DEPOSIT A MONOMOLECULAR LAYER OF CRHX, AT THE CATHODE SURFACE, (B) AND A SHORTER SUCCEEDING FINIT PERIOD (T2) IN WHICH THE CURRENT COMES TO AND REMAINS AT ZERO WHEREBY DEPOSITING OF CRHX CEASES, (C) THE DURATION OF THE SUCCEEDING PERIOD (T2) BEING GREATER THAN 0.5 MILLISECOND AND SUFFICIENT TO ALLOW DECOMPOSITION OF DEPOSITED CRHX AND COINCIDENT DEPOSITION OF CHROMIUM METAL, BUT INSUFFICIENT TO ALLOW SUBSTNATIAL DIFFUSION OF THE BULK OF SAID SOLUTION INTO THE CATHODE FILM,

Claim 6

CONTROLLING SAID VOLTAGE IN SUCH A MANNER THAT THERE IS WITHIN EACH CYCLE OF THE VOLTAGE VARIATIONS, (A) A PERIOD (T1) OF CURRENT DENSITY OF SUFFICIENT MAGNITUDE AND DURATION TO DEPOSIT CRHX. BUT LESS THAN ONE HALF THAT REQUIRED TO DEPOSIT A MONOMOLECULAR LAYER OF CRHX, AT THE CATHODE SURFACE, (B) AND A SHORTER SUCCEEDING FINIT PERIOD (T2) IN WHICH THE CURRENT COMES TO AND REMAINS AT ZERO WHEREBY DEPOSITING OF CRHX CEASES, (C) THE DURATION OF THE SUCCEEDING PERIOD (T2) BEING GREATER THAN 0.5 MILLISECOND AND SUFFICIENT TO ALLOW DECOMPOSITION OF DEPOSITED CRHX AND COINCIDENT DEPOSITION OF CHROMIUM METAL, BUT INSUFFICIENT TO ALLOW SUBSTNATIAL DIFFUSION OF THE BULK OF SAID SOLUTION INTO THE CATHODE FILM,

Claim 7

AND SIMULTANEOUSLY BLOCKING THE FLOW OF CURRENT PRODUCED BY THE SYSTEM INCLUDING SAID ANODE AND CATHODE IN SAID SOLUTION DURING SAID SUCCEEDING PERIOD (T2), WHEREBY A SUBSTANTIAL PORTION OF THE CATHODE FILM IS RETAINED.

Claim 8

AND SIMULTANEOUSLY BLOCKING THE FLOW OF CURRENT PRODUCED BY THE SYSTEM INCLUDING SAID ANODE AND CATHODE IN SAID SOLUTION DURING SAID SUCCEEDING PERIOD (T2), WHEREBY A SUBSTANTIAL PORTION OF THE CATHODE FILM IS RETAINED.