Method of facilitating visual detection of a crack in a component of a gas turbine engine

Abstract

A component of a gas turbine engine comprises a substrate, a corrosion resistant top layer, and an intermediate corrodible layer disposed between the corrosion resistant top layer and the substrate. When corroding, the intermediate layer has a color contrasting with a color of the top layer. A method of detecting a crack when it penetrated the top layer in a component of a gas turbine engine having a corrosion resistant top layer and an intermediate corrodible layer comprises, in sequence, observing that at least one area of the component has a color contrasting with that of the top layer; determining that the color of the at least one area is a result of corrosion of the intermediate corrodible layer; and determining that the top layer has a crack as a result of determining corrosion of the intermediate layer. A method of facilitating crack detection in a component is also presented.

1 . A component of a gas turbine engine, the component comprising:
 a substrate;   a corrosion resistant top layer; and   an intermediate corrodible layer disposed between the corrosion resistant top layer and the substrate, when corroding, the corroded intermediate layer having a color contrasting with a color of the top layer.   
     
     
         2 . The component as defined in  claim 1 , wherein the top layer is metal. 
     
     
         3 . The component as defined in  claim 2 , wherein the top layer is cobalt. 
     
     
         4 . The component as defined in  claim 1 , wherein the intermediate layer is a ferrous alloy. 
     
     
         5 . The component as defined in  claim 1 , wherein when corroding, the corroded intermediate layer expands on corrosion. 
     
     
         6 . The component as defined in  claim 1 , wherein the substrate is an aluminum alloy. 
     
     
         7 . The component as defined in  claim 1 , wherein the intermediate layer stiffens and strengthens the component. 
     
     
         8 . The component as defined in  claim 1 , wherein the top layer is not galvanic compatible with the substrate. 
     
     
         9 . The component as defined in  claim 1 , wherein the top layer is generally gray in color and when corroding, the corroded intermediate layer is generally red in color. 
     
     
         10 . The component as defined in  claim 1 , wherein the top layer is plated. 
     
     
         11 . The component as defined in  claim 1 , wherein the top layer includes a crack therethrough and the intermediate layer has a corroded portion expanding through the crack. 
     
     
         12 . A method of detecting a crack in a component of a gas turbine engine having a corrosion resistant top layer and an intermediate corrodible layer, the method comprising, in sequence:
 observing that at least one area of the component has a color contrasting with that of the top layer;   determining that the color of the at least one area is a result of corrosion of the intermediate corrodible layer; and   determining that the top layer has a crack therethrough as a result of determining corrosion of the intermediate corrodible layer.   
     
     
         13 . The method as defined in  claim 12 , wherein observing that at least one area of the component has a color contrasting with that of the top layer comprises observing red color stains over a gray color background.