Ceramic double layer based on zirconium oxide

Abstract

At least two ply layers of ceramic on a substrate which is applied to protect a surface in a heated hot environment. Each of the outer and bottom layers including zirconium oxide and stabilizers of yttrium oxide in different respective proportions of the yttrium oxide; the outer layer has fully stabilized zirconium oxide and the bottom layer has partially stabilized zirconium oxide.

1 . A layer system for application to a surface which is heated to a high temperature, the layer system comprising at least:
 a substrate on which ceramic layers are applied;   at least two ceramic layers on the substrate comprising a bottom layer above the substrate and an outer layer outward of the bottom layer, each layer of the at least two layers is based on zirconium oxide, and each of the at least two layers has respective different properties of the layers;   optionally a metallic bonding layer between the substrate and the ceramic layer;   the outer layer comprises fully stabilized zirconium oxide; and   the bottom layer above the substrate comprises partially stabilized zirconium oxide.   
     
     
         2 - 3 . (canceled) 
     
     
         4 . The layer system as claimed in  claim 1 , further comprising yttrium oxide as a stabilizer of zirconium oxide in each layer used. 
     
     
         5 . The layer system as claimed in  claim 1 , further comprising the metallic bonding layer which comprises an MCrAlX alloy, in which X is optionally, at least one of the elements yttrium (Y) or rhenium (Re). 
     
     
         6 . The layer system as claimed in  claim 1 , wherein each of the outer and bottom ceramic layers has a porosity of at least 16%. 
     
     
         7 . The layer system as claimed in  claim 1 , wherein the ceramic layers have identical porosities. 
     
     
         8 . The layer system as claimed in  claim 1 , wherein the outer ceramic layer is at least 20%, thicker than the bottom ceramic layer. 
     
     
         9 . The layer system as claimed in  claim 1 , wherein the yttrium oxide proportion of the bottom zirconium oxide layer is between 4% by weight and 12% by weight. 
     
     
         10 . The layer system as claimed in  claim 1 , wherein the yttrium oxide proportion of the outer zirconium oxide layer is between 20% by weight and 50% by weight. 
     
     
         11 . The layer system as claimed in  claim 1 , wherein the ceramic layers each comprise only zirconium oxide and at least one stabilizer. 
     
     
         12 . The layer system as claimed in  claim 1 , further comprising only yttrium oxide as a stabilizer of zirconium oxide in each layer. 
     
     
         13 . The layer system as claimed in  claim 1 , wherein the porosity of each of the outer and bottom ceramic layers is between 16% and 24%. 
     
     
         14 . The layer system as claimed in  claim 1 , wherein the outer ceramic layer is at least 30% thicker than the bottom ceramic layer. 
     
     
         15 . The layer system as claimed in  claim 1 , wherein the yttrium oxide proportion of the outer zirconium oxide layer is between 30% by weight and 40% by weight. 
     
     
         16 . The layer system as claimed in  claim 1 , wherein the bottom layer is a bottommost layer above the substrate; and
 the outer layer is an outermost layer outward of the bottom layer.