Method of joining tantalum clade steel structures

Abstract

The present invention is directed to a process for joining tantalum clad steel structures. The process broadly comprises: a) providing a first tantalum clad section, said first tantalum clad section comprising a tantalum layer over a steel layer, with a bonding layer optionally therebetween, with a portion of said steel layer in an edge region not being covered by said tantalum layer or said bonding layer, b) providing a second tantalum clad section, said second tantalum clad section comprising a tantalum layer over a steel layer, with a bonding layer optionally therebetween, with a portion of said steel layer in an edge region not being covered by said tantalum layer or said bonding layer, c) locating said steel edge regions adjacent each other, d) welding the steel edge regions together, e) cold spraying a tantalum powder onto the welded edge regions and over the tantalum layers adjacent said edge regions thereby joining the tantalum clad steel sections. The invention is also directed to tantalum welds or joints formed by cold spraying tantalum powder.

1 . A process for joining tantalum clad steel structures comprising:
 a) providing a first tantalum clad section, said first tantalum clad section comprising a tantalum layer over a steel layer, with a bonding layer optionally therebetween, with a portion of said steel layer in an edge region not being covered by said tantalum layer or said bonding layer,   b) providing a second tantalum clad section, said second tantalum clad section comprising a tantalum layer over a steel layer, with a bonding layer optionally therebetween, with a portion of said steel layer in an edge region not being covered by said tantalum layer or said bonding layer,   c) locating said edge regions adjacent each other,   d) welding the edge regions together, and   e) cold spraying a tantalum powder onto the welded edge regions and over the tantalum layers adjacent said edge regions thereby joining the tantalum clad steel sections.   
     
     
         2 . The process of  claim 1  wherein said first tantalum clad section and said second tantalum clad section are produced by cold spraying tantalum powder onto the respective steel layer in a pattern such that a portion of each steel layer in an edge region thereof is not sprayed with said powder. 
     
     
         3 . The process of  claim 1 , wherein said tantalum layers have thicknesses of from about 0.005 inches to about 0.040 inches. 
     
     
         4 . The process of  claim 3 , wherein said tantalum layers have thicknesses of from about 0.005 inches to about 0.020 inches. 
     
     
         5 . The process of  claim 4 , wherein said tantalum layers have thicknesses of from about 0.005 inches to about 0.010 inches 
     
     
         6 . A tantalum weld or joint, wherein the weld or joint is formed by cold spraying tantalum powder and consists of elongated tantalum powder particles, elongated normal to the direction of the spray, and wherein the powdered particles have a random crystallographic orientation. 
     
     
         7 . The weld or joint of  claim 6 , wherein the powder particles have an aspect ratio of from 2 to 6. 
     
     
         8 . The weld or joint of  claim 7 , wherein said aspect ratio is from 2 to 3. 
     
     
         9 . A tantalum weld or joint, wherein the weld or joint is formed by cold spraying tantalum powder and consists of equiaxed grains of approximately the same size as or less than the sprayed powder and wherein the grains have a random crystallographic orientation.