Tarnish-resistant sterling silver alloys

Abstract

Titanium sterling silver alloy compositions that exhibit enhanced tarnish resistance while maintaining an acceptable hardness. Applications and manufacturing methods thereof are disclosed.

1 . A sterling silver alloy comprising from about 92.5 wt % to about 98.1 wt % silver and from about 1.9 wt % to about 7.0% wt % titanium. 
     
     
         2 - 6 . (canceled) 
     
     
         7 . The sterling silver alloy according to  claim 1 , fluffier comprising a third metal selected from the group consisting of palladium, niobium, aluminum, germanium, boron, zinc, copper and zirconium. 
     
     
         8 . The sterling silver alloy according to  claim 1 , further comprising up to about 5% palladium, wherein the ternary alloy has improved tarnish resistance and/or hardness. 
     
     
         9 - 10 . (canceled) 
     
     
         11 . The sterling silver alloy according to  claim 1 , further comprising up to about 5 wt % niobium. 
     
     
         12 - 13 . (canceled) 
     
     
         14 . A method of making a titanium silver alloy, comprising melting a mixture of silver and titanium comprising 92.5-98.1 wt % of silver and 1.9-7.5 wt % titanium until the mixture is uniformly mixed, and transferring the melt mixture into a cast or mold. 
     
     
         15 . The method of  claim 14 , further comprising hot-working, annealing and/or solution treatment. 
     
     
         16 . The method of  claim 14 , wherein the melting container is a crucible made of refractory material selected from graphite, zirconia, calcia, and yittria. 
     
     
         17 . The method of  claim 16 , wherein the crucible is made of stabilized zirconia. 
     
     
         18 . The method of  claim 14 , wherein melting and casting the alloy are performed under an inert atmosphere to avoid reaction of titanium with materials it is in contact with. 
     
     
         19 . The method of  claim 18 , wherein said inert atmosphere comprises argon gas. 
     
     
         20 . (canceled) 
     
     
         21 . The method of  claim 18 , wherein the melting is conducted under a second argon fill after flushing with clean dry argon twice. 
     
     
         22 . The method of  claim 14 , wherein the melting is conducted at a temperature from about 100 to about 700° C. higher than melting point of silver. 
     
     
         23 . The method of  claim 14 , wherein said melting and/or casting is conducted under vacuum. 
     
     
         24 . The method of  claim 14 , wherein titanium is granular titanium to avoid titanium segregation. 
     
     
         25 - 26 . (canceled) 
     
     
         27 . The method of claim  0 , wherein the mixture contains a third metal selected from palladium, niobium, aluminum, germanium, boron, zinc, copper and zirconium. 
     
     
         28 . The method of  claim 27 , wherein the third metal is palladium, and the casting temperature is increased by an additional 10 to about 100° C., wherein the palladium content is about 0% to about 5.0% by weight. 
     
     
         29 . The method of  claim 14 , wherein the titanium is from scrap coated with a film of titanium compound, and the melting and casting temperatures are at least 700° C. above the melting and casting temperatures for silver, and melting and casting are conducted with extensive fluxing treatment to break down the film. 
     
     
         30 . The method of  claim 14 , wherein the alloy is cast and worked into a piece of jewelry, ingot, or billet. 
     
     
         31 . The method of  claim 14 , wherein the alloy is cast and worked into a fine sterling silver product selected from silverware, tubing, electrical contacts, dental implants, and body implants. 
     
     
         32 - 33 . (canceled) 
     
     
         34 . The method according to  claim 14 , wherein the mixture further comprises up to about 5% niobium. 
     
     
         35 . An article of manufacture comprising a silver alloy according to  claim 1 . 
     
     
         36 . (canceled)