Phosphorus-copper base brazing alloy

Abstract

A solid phos-copper base or silver-phos-copper base brazing alloy component for forming a brazed joint with a raised shoulder, little to no black oxide, and improved corrosion resistance. The brazing alloys of the present invention are visually distinguishable from copper and copper alloy parts. The solid brazing components of the present invention may be used in forming brazed joints at low brazing temperatures and result in a joint that is strong, ductile, smooth and corrosion resistant. The solid brazing components are provided in the form of wire, strip, foil or preform, and thus are advantageously used in a wide variety of brazing applications including copper tubing. The brazing components of the present invention are made of an alloy having a liquidus temperature above 840° F. and consist essentially of about 4-9% phosphorus, about 0.1-10% tin, up to about 4% antimony, about 0.1-15% nickel, up to about 3% silicon, up to about 18% silver, up to about 3% manganese, with the balance being copper. Exemplary embodiments include about 6-15% silver and/or 5-8% nickel.

1 . A method of forming a solid brazing component having a liquidus temperature above 840° F. comprising the steps of:
 forming an alloy melt consisting essentially of, in weight percent: 
 (a) about 4-9% phosphorus; 
 (b) about 0.1-10% tin; 
 (c) about 0.1-15% nickel; 
 (d) up to about 18% silver; 
 (e) up to about 3% silicon; 
 (f) up to about 4% antimony; 
 (g) up to about 3% manganese; and the balance copper; 
 continuously casting the alloy melt into a billet; 
 fabricating the billet into a solid brazing component selected from the group consisting of wire, strip, foil and preform. 
 
     
     
         2 . The method of  claim 1  wherein the billet is fabricated into a wire by extrusion, the method further comprising drawing the wire one or more times to a final desired thickness. 
     
     
         3 . The method of  claim 2  further comprising forming the wire into a preform. 
     
     
         4 . A method of forming a brazed joint comprising the steps of:
 forming a solid brazing component by the method of  claim 1 ;   placing the solid brazing component between two metal parts;   heating the solid brazing component to melt at least a major portion of the alloy to cause the alloy to wet and flow between the two metal parts;   cooling the alloy to form a brazed joint with a raised cap between the two metal parts, wherein the brazed joint is substantially free of black metal oxide.   
     
     
         5 . The method of  claim 4  wherein the solid brazing component is placed between two copper alloy parts and the brazed joint is visually distinguishable from the parts. 
     
     
         6 . The method of  claim 4  wherein the solid brazing component is placed between two tubular shaped parts. 
     
     
         7 . The method of  claim 4  wherein the solid brazing component is heated to a temperature less than 1410° F. to melt the major portion. 
     
     
         8 . The method of  claim 4  wherein the solid brazing component is heated to a temperature less than 1300° F. to melt the major portion.