Anodized Clad Copper Cookware

Abstract

An article of cookware has a copper core and is surrounded by relatively thinner outer aluminum layers. The outer aluminum layers are preferably anodized to provide a relatively inert hard and scratch resistant durable finish. This anodized finish also readily accepts non-stick finishes.

I claim: 
     
         1 . A method of forming a cookware article, the method comprising the step of:
 a) providing a sheet of metal consisting essentially of a central core layer of at least one of copper and an alloy of copper, the copper core having a thickness of at least about 1 mm thick and is clad on both opposing surfaces with layers of at least one of aluminum and an alloy of aluminum,   b) deep drawing said sheet to form a vessel capable of retaining a fluid,   c) anodizing the exposed aluminum cladding on both sides of the vessel to form a thin layer of aluminum oxide.   
     
     
         2 . A method of forming a cookware article according to  claim 1  further comprising the step of depositing a non-stick coating on the aluminum oxide on at least an inner surface of the vessel. 
     
     
         3 . A method of forming a cookware article according to  claim 2  wherein the non-stick coating comprises a low surface energy organic polymer. 
     
     
         4 . A method of forming a cookware article according to  claim 1  wherein the copper core is exposed at a rim of the vessel. 
     
     
         5 . A method of forming a cookware article according to  claim 1  wherein the copper core is covered by the aluminum cladding at a rim of the vessel. 
     
     
         6 . A method of forming a cookware article according to  claim 1  wherein the copper core has a thickness of at least about 1 mm and the aluminum cladding on each side of the copper core has a thickness of at least about 0.4 mm. 
     
     
         7 . A method of forming a cookware article according to  claim 1  wherein the combined thickness of the aluminum cladding on both sides of the copper core is at least 80% of the thickness of the copper core. 
     
     
         8 . A method of forming a cookware article according to  claim 7  wherein the copper core has a thickness of at least about 1 mm and the aluminum cladding on each side of the copper core has a thickness of at least about 0.4 mm. 
     
     
         9 . A method of forming a cookware article according to  claim 1  in which the aluminum alloys is 3003 grade aluminum. 
     
     
         10 . A method of forming a cookware article according to  claim 1  in which the aluminum alloys is 1050 grade aluminum. 
     
     
         11 . The method of forming a cookware article according to  claim 1  further comprising a step of annealing said sheet before said step of deep drawing said sheet to form a vessel capable of retaining a fluid. 
     
     
         12 . The method of forming a cookware article according to  claim 11  wherein said step of annealing is at a temperature of between about 260 to 300° C. 
     
     
         13 . The method of forming a cookware article according to  claim 12  wherein said step of annealing is for at least about 15 minutes. 
     
     
         14 . The method of forming a cookware article according to  claim 12  wherein the aluminum in said sheet is 1050 grade aluminum and the annealing is at a temperature of at least about 280° C. 
     
     
         15 . The method of forming a cookware article according to  claim 11  further comprising the step of depositing a non-stick coating on the aluminum oxide on at least an inner surface of the vessel. 
     
     
         16 . The method of forming a cookware article according to  claim 11  wherein the non-stick coating comprises a low surface energy organic polymer. 
     
     
         17 . The method of forming a cookware article according to  claim 11  wherein the copper core is exposed at a rim of the vessel. 
     
     
         18 . The method of forming a cookware article according to  claim 11  wherein the copper core is covered by the aluminum cladding at a rim of the vessel. 
     
     
         19 . The method of forming a cookware article according to  claim 11  wherein the copper core has a thickness of at least about 1 mm and the aluminum cladding on each side of the copper core has a thickness of at least about 0.4 mm. 
     
     
         20 . The method of forming a cookware article according to  claim 11  wherein the combined thickness of the aluminum cladding on both sides of the copper core is at least 80% of the thickness of the copper core.