Metallic compositions useful for brazing, and related processes and devices

Abstract

A braze alloy composition is disclosed, containing nickel, about 5% to about 40% of at least one refractory metal selected from niobium, tantalum, or molybdenum; about 2% to about 32% chromium; and about 0.5% to about 10% of at least one active metal element. An electrochemical cell that includes two components joined to each other by such a braze composition is also described. A method for joining components such as those within an electrochemical cell is also described. The method includes the step of introducing a braze alloy composition between a first component and a second component to be joined, to form a brazing structure. In many instances, one component is formed of a ceramic, while the other is formed of a metal or metal alloy.

What is claimed: 
     
         1 . A high-temperature thermal battery based on sodium metal halide or sodium sulfur, comprising a sealing region that includes at least one metal component and at least one ceramic component that are joined together by an active braze seal, wherein the seal is formed of a braze alloy composition that comprises
 a) about 45% to about 70% nickel;   b) about 5% to about 40% of at least one refractory metal selected from niobium, tantalum, or molybdenum.   c) about 2% to about 32% chromium; and   d) about 0.5% to about 10% (total) of at least one active metal element selected from titanium, zirconium, hafnium, and vanadium;   based on the weight of the composition.   
     
     
         2 . The high-temperature thermal battery of  claim 1 , wherein the metal component is a ring, and the ceramic component is a collar, brazed to the ring. 
     
     
         3 . The high-temperature thermal battery of  claim 2 , further comprising a second ring in the sealing region, brazed to another portion of the collar. 
     
     
         4 . The high-temperature thermal battery of  claim 2 , wherein the metal ring comprises nickel; and the collar comprises alpha-alumina. 
     
     
         5 . The high-temperature thermal battery of  claim 1 , wherein the sealing region includes a reaction layer at the interface of the braze alloy and the ceramic component. 
     
     
         6 . The high-temperature thermal battery of  claim 5 , wherein the reaction layer has a thickness of less than about 10 microns. 
     
     
         7 . The high-temperature thermal battery of  claim 1 , wherein at least about 50%, by weight, of the refractory metal composition of component (b) is niobium. 
     
     
         8 . The high-temperature thermal battery of  claim 7 , wherein all of the refractory metal composition of component (b) is niobium. 
     
     
         9 . The high-temperature thermal battery of  claim 1 , wherein the refractory metal is niobium, present in the braze alloy composition at a level of about 10% to about 40%, by weight. 
     
     
         10 . The high-temperature thermal battery of  claim 1 , wherein the braze alloy composition comprises about 50% to about 70% nickel. 
     
     
         11 . The high-temperature thermal battery of  claim 1 , wherein the braze alloy composition has a liquidus temperature of less than about 1250° C. 
     
     
         12 . The high-temperature thermal battery of  claim 1 , wherein the braze alloy composition is substantially free of iron. 
     
     
         13 . The high-temperature thermal battery of  claim 1 , wherein the braze alloy composition further comprises aluminum, at a level less than about 5% by weight. 
     
     
         14 . The high-temperature thermal battery of  claim 1 , wherein the active metal element is present at a level in the range of about 0.5% by weight to about 5% by weight. 
     
     
         15 . The high-temperature thermal battery of  claim 1 , wherein the active metal element is present at a level in the range of about 1% by weight to about 5% by weight.