High temperature metallic seal

Abstract

A metallic seal includes a cold formed substrate layer and one or more additional layers. At least one of the layers offers improved resistance to high temperature stress relaxation.

1 . A process for manufacturing a seal for sealing between interior and exterior volumes when held under compression, comprising: 
 cold forming an annular first seal layer; and    applying a second layer to a first surface of the first layer via a process selected from the group consisting of: 
 thermal spray of molten alloy droplets and powder;  
 thermal spray of creep resistant alloys with ceramic particles;  
 vapor deposition;  
 slurry coating of ceramics and curing at elevated temperatures;  
 electroforming of high temperature alloys; and  
 combinations thereof.  
   
   
   
       2 . The process of  claim 1  wherein: 
 the first layer is formed having a bellows-like section prior to the application of the second layer; and    after the application of the second layer, there is no machining step which removes a portion of the applied second layer material.    
   
   
       3 . The process of  claim 2  wherein the step of cold forming comprises one of: 
 cutting an annulus from a tube and deforming the annulus to provide a radial section of enhanced compressibility;    forming and welding a strip into an annulus and deforming the annulus to provide a radial section of enhanced compressibility; and    deforming a flat strip to provide a section of enhanced compressibility and further deforming and welding the strip to provide an annulus having a radial section of enhanced compressibility.    
   
   
       4 . A process for manufacturing a seal having a central longitudinal axis and forming a seal between interior and exterior volumes when held under compression between opposed first and second parallel faces of respective first and second flanges, comprising: 
 cold forming an annular first seal layer from a refractory material; and    applying an oxidation resistant coating to the first layer.    
   
   
       5 . The process of  claim 4  wherein the coating entirely covers the first seal layer.  
   
   
       6 . The process of  claim 4  wherein the coating comprises at least one of molybdenum disilicide and nickel aluminide and is formed by a process including the acts of slurry coating of at least one component of the coating and baking.  
   
   
       7 . The process of  claim 4  wherein the coating comprises at least a silicide is formed by a process including the acts of slurry coating of at least one component of the coating and baking.  
   
   
       8 . The process of  claim 4  wherein the coating comprises at least one of gold, platinum, and iridium is formed by a process including at least one of electroplating, vapor deposition or thermal spray.  
   
   
       9 . The process of  claim 4  wherein the coating comprises one or more oxides of yttrium, zirconium, hafnium, and boron.  
   
   
       10 . A process for manufacturing an article, comprising: 
 cold forming a substrate from a first nickel- or cobalt-based superalloy; and    applying a coating of a γ′ hardened second nickel-based superalloy to the substrate.    
   
   
       11 . The process of  claim 10  wherein the application is via thermal spray process and provides the coating having a thickness of at least 10% of a thickness of the substrate.  
   
   
       12 . The process of  claim 10  wherein the article has a creep resistance at 982° C. greater than a cold formed article of like dimensions consisting essentially of the first superalloy.  
   
   
       13 . The process of  claim 10  wherein said substrate is formed from said first nickel-based superalloy.