US3539339A - Brazing alloy - Google Patents

Description

United States Patent US. Cl. 75-134 2 Claims ABSTRACT OF THE DISCLOSURE A cadmium, copper and zinc containing silver alloy with less than 40% but at least 30% by weight of silver wherein said copper and zinc contents of the resultant reduced silver alloy are determined by the following formulae:

Resultant Cu by wt. percent=l9+.8 (40Ag content by wt. percent) Resultant Zn by wt. percent=22+.2 (40Ag content by wt. percent) and wherein the copper content of the resultant alloy varies i-l.5% by weight and wherein the zinc content of the resultant alloy varies i.5% by weight, wherein the balance of said alloy is cadmium.

3,539,339 Patented Nov. 10, 1970 ice position while maintaining essential properties only where the silver content of the reference alloy is reduced between 29 and 39% silver by weight.

In addition, experimentation revealed that the desirable properties are maintained in this class of alloys and this concept is applicable where the copper content of the resultant alloys, as indicated by the outlined mathematical formula, ranges plus and minus 1.5% by weight in the broad range and plus and minus 1% by weight in the preferred range and where the zinc content indicated by the formula ranges plus and minus .5% by Weight in the broad range and plus and minus .3% by weight for the preferred range.

A sampling of the numerous alloy compositions that were tested is as follows:

Composition by weight percent Ag Cu Cd Zn The foregoing alloy samples when tested revealed the following results:

This invention relates generally to silver alloys and more particularly to silver alloys with reduced silver con tent but which have the same essential basic properties as alloys with higher silver contents.

Heretofore it has been known that silver alloys containing silver and with additions of copper, zinc and cadmium of approximately 20% each by weight have solidus and liquidus temperatures, tensile strength, shear strength, plasticity and surface Wetting characteristics that are most desirable in various welding processes such as brazing. For some time experiments have been conducted to develop silver alloys of this general type with reduced silver content but which would retain the foregoing outlined characteristics so essential in the application of these alloys.

After lengthy experimentation with various alloy systems it was discovered that within a particular zone range of the silver, copper, cadmium and zinc alloy system, Where cadmium is maintained at a range of approximately 18 to 21% by weight, the essential properties of the alloy system with 40% by weight silver, are maintained in alloys of the same system where silver is reduced provided the copper and zinc contents of these alloys are increased in accordance with the following formulae:

Resultant Cu by wt. percent=l9+.8 (40Ag content by wt. percent) Resultant Zn by wt. percent=22+.2 (40Ag content by wt. percent) Experimentation further revealed that the above outlined concept is valid in determining changes in alloy com- It will now be understood by those skilled in the art that the objects of this invention have been achieved by providing a formula for the reduction of silver in silver alloys while maintaining at reasonable constancy the essential properties of the high silver content silver base alloys.

What is claimed is:

1. A cadmium, copper and zinc containing silver alloy consisting essentially of 37.5% silver, 21% copper, 22.5% zinc, balance cadmium.

2. A cadmium, copper and zinc containing silver alloy consisting essentially of 35% silver, 23% copper, 23% zinc, balance cadmium.

References Cited L. DEWAYNE RUTLEDGE, Primary Examiner G. K. WHITE, Assistant Examiner US. Cl. X.R. -173