Silver solder or brazing alloys, and their use

Abstract

The present invention relates to silver solder or brazing alloys and to their use in making soldered joints in various grades of silver, particularly silversmithing grades. They alloys are of the Ag—Cu—Zn family containing at least 55 wt % Ag and from 0.5 to 3 wt % Ge. Additional alloys are silver solders or brazing alloys of the Ag—Cu—Zn family containing more than 70 wt % Ag and from 0.5 to 3 wt % Ge. They can exhibit an advantageous combination of colour, flowability and corrosion resistance. A method is also provided of making a joint in Sterling silver which includes using a silver solder or brazing alloy of the Ag—Cu—Zn family containing 10-30 wt % Cu, 8-15 wt % Zn, from 0.5-3 wt % Ge, optionally 0.05-0.4 wt % Si, optionally 1-3 wt % Sn, optionally 1 ppm-0.3 wt % B, the balance being 55-77 wt %, Ag, said solder being a colour match for said Sterling silver.

1 . A silver solder or brazing alloy of the Ag—Cu—Zn family containing at least 55 wt % Ag and from 0.5 to 3 wt % Ge.  
   
   
       2 . The alloy of  claim 1 , containing 1.5-2.5 wt % Ge.  
   
   
       3 . The alloy of  claim 1 , containing about 2 wt % Ge.  
   
   
       4 . The alloy of any preceding claim, containing 55-77 wt % Ag, 10-30 wt % Cu and 8-15 wt % Zn.  
   
   
       5 . The alloy of any preceding claim, furter comprising 0.05-0.4 wt % Si.  
   
   
       6 . The alloy of  claim 5 , comprising about 0.1 wt % Si.  
   
   
       7 . The alloy of any preceding claim, further comprising 1-3 wt % Sn.  
   
   
       8 . The alloy of  claim 7 , comprising about 2 wt % Sn.  
   
   
       9 . The alloy of any preceding claim, containing 55-77 wt % Ag, 10-30 wt % Cu and 8-15 wt % Zn, 2-2.5 wt % Ge and 0.05-0.4 wt % Si.  
   
   
       10 . The alloy of any preceding claim, containing 55-77 wt % Ag, 10-30 wt % Cu and 8-15 wt % Zn, 2-2.5 wt % Ge and 1-3 wt % Sn.  
   
   
       11 . The alloy of any preceding claim, containing 55-77 wt % Ag, 10-30 wt % Cu and 8-15 wt % Zn, 2-2.5 wt % Ge, 0.05-0.4 wt % Si and 1-3 wt % Sn.  
   
   
       12 . The alloy of any preceding claim, further comprising 0.1-0.3 wt % boron.  
   
   
       13 . The alloy of any preceding claim having a solidus temperature of about 705° C. and a liquidus temperature of about 725° C.  
   
   
       14 . The alloy of any of claims  1 - 12 , having a solidus temperature of about 720° C. and a liquidus temperature of about 765° C.  
   
   
       15 . The alloy of any of claims  1 - 12 , having a solidus temperature of about 745° C. and a liquidus temperature of about 778° C.  
   
   
       16 . Use of the alloy of any preceding claim to solder or braze ajoint in silver.  
   
   
       17 . Use of the alloy of any of claims  1 - 15  to solder or braze a joint in Sterling silver.  
   
   
       18 . Use of the alloy of any of claims  1 - 15  to solder or braze ajoint in silver of content about Ag 92.5 wt %, Cu 6.3 wt %, Ge 1.2 wt %.  
   
   
       19 . An alloy according to any of claims  1 - 15 , which is in the form of rod, strip or wire.  
   
   
       20 . An alloy according to any of claims  1 - 15 , which is in the form of paste.