Porous ceramic coating system

Abstract

A coating system having two layers of porous coatings is provided. The layers include a tightly controlled and matched porosity. The layer system also includes a substrate with a bonding layer. The inner ceramic layer and the outer ceramic layer are formed on the bonding layer. The bonding layer may comprise a MCrAlX alloy.

1 - 8 . (canceled) 
     
     
         9 . A layer system, comprising:
 a substrate;   a metallic bonding layer on the substrate;   an oxide layer on the bonding layer or on the substrate;   an inner ceramic layer having a porosity of 11% to 12%; and   an outermost ceramic layer, having a porosity of 16% to 18%, on the inner ceramic layer.   
     
     
         10 . The layer system as claimed in  claim 9 , wherein the metallic bonding layer comprises an MCrAl or MCrAlX alloy. 
     
     
         11 . The layer system as claimed in  claim 9 , wherein the metallic bonding layer consists of an MCrAl or MCrAlX alloy. 
     
     
         12 . The layer system as claimed in  claim 9 , wherein the material of the inner ceramic layer comprises zirconium oxide. 
     
     
         13 . The layer system as claimed in  claim 9 , wherein the material of the inner ceramic layer comprises partially stabilized zirconium oxide. 
     
     
         14 . The layer system as claimed in  claim 9 , wherein the material of the inner ceramic layer comprises zirconium oxide partially stabilized by yttrium. 
     
     
         15 . The layer system as claimed in  claim 9 , wherein the material of the inner ceramic layer consists of zirconium oxide partially stabilized by yttrium. 
     
     
         16 . The layer system as claimed in  claim 9 , wherein the outer layer comprises zirconium oxide. 
     
     
         17 . The layer system as claimed in  claim 9 , wherein the outer layer comprises partially stabilized zirconium oxide. 
     
     
         18 . The layer system as claimed in  claim 9 , wherein the outer layer comprises zirconium oxide partially stabilized by yttrium. 
     
     
         19 . The layer system as claimed in  claim 9 , wherein the outer layer consists of zirconium oxide partially stabilized by yttrium. 
     
     
         20 . The layer system as claimed in  claim 9 , wherein the substrate comprises a nickel-based or cobalt-based superalloy. 
     
     
         21 . The layer system as claimed in  claim 9 , wherein the substrate consists of a nickel-based or cobalt-based superalloy. 
     
     
         22 . The layer system as claimed in  claim 9 , wherein the material of the inner ceramic layer and the material of the outer ceramic layer are different. 
     
     
         23 . The layer system as claimed in  claim 22 , wherein the outer ceramic layer comprises a pyrochlore structure. 
     
     
         24 . The layer system as claimed in  claim 9 , wherein the inner ceramic layer is at least 10% thinner than the outermost ceramic layer. 
     
     
         25 . A layer system, consisting of:
 a substrate;   a metallic bonding layer;   an oxide layer on the bonding layer;   an inner ceramic layer; and   an outermost ceramic layer.