Protection of thermal barrier coating by impermeable barrier coating

Abstract

According to an embodiment of the invention, disclosed is a composite comprising a porous thermal barrier coating on a metallic part and an impermeable barrier coating adjacent to the outer surface of the thermal barrier coating. The impermeable barrier coating is dense and non-porous and comprises a rare earth silicate, the impermeable barrier coating thereby preventing infiltration of the contaminant composition into the thermal barrier coating.

1 - 23 . (canceled)  
   
   
       24 . A method for protecting a thermal barrier coating on a superalloy part, comprising: 
 depositing a dense, non-porous impermeable barrier coating comprising a rare earth silicate on the thermal barrier coating, which is located on the superalloy part, thereby preventing infiltration of a contaminant composition into the thermal barrier coating.    
   
   
       25 . The method of  claim 24 , wherein the contaminant composition adheres on an outer surface of the thermal barrier coated part, and is prevented from infiltrating into the thermal barrier coating.  
   
   
       26 . The method of  claim 24 , wherein the rare earth silicate is selected from the group consisting of a silicate of lanthanum, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium, yttrium, and mixtures thereof.  
   
   
       27 . The method of  claim 24 , wherein the impermeable barrier coating is deposited by a process selected from the group consisting of sol-gel, sputtering, air plasma spray, organo-metallic chemical vapor deposition, physical vapor deposition, hot pressing, and chemical vapor deposition.