Ceramic layer constituted of partially and fully stabilized zirconium oxide

Abstract

The use of a physical mixture of partially stabilized and fully stabilized zirconium oxide powder for producing a thermal barrier coating results in good thermal barrier properties and good mechanical properties is provided.

1 . A ceramic thermal barrier coating system which comprises at least:
 a substrate,   wherein the substrate is   either a metallic substrate,   based on a nickel or cobalt superalloy,   or   a substrate composed of CMC;   having a bonding layer,   which is either   in the case of a metallic substrate metallic,   wherein said metallic substrate is an MCrAlY alloy,   wherein M is at least one of nickel and cobalt,   or   in the case of a substrate composed of CMC a ceramic bonding layer;   and also an outer ceramic thermal barrier coating,   which coating comprises grains both of partially stabilized zirconium oxide and of fully stabilized zirconium oxide.   
     
     
         2 . The ceramic thermal barrier coating system as claimed in  claim 1 , wherein the stabilization of the zirconium oxide is effected by means of yttrium oxide, in particular 8% for partial stabilization and/or from 22% to 48% for full stabilization. 
     
     
         3 . The ceramic thermal barrier coating system as claimed in  claim 1 , wherein the concentration of the fully stabilized zirconium oxide increases in the direction of the outermost surface of the ceramic thermal barrier coating. 
     
     
         4 . The ceramic thermal barrier coating system as claimed in  claim 1 , wherein the mixing ratio of PSZ and FSZ is constant over the entire thickness of the ceramic layer. 
     
     
         5 . The ceramic thermal barrier coating system as claimed in  claim 1 , wherein depressions or elongated vertical cracks which have been introduced by means of a laser or produced during the coating process or by means of an after-treatment method are present extending from the outermost surface of the ceramic layer. 
     
     
         6 . The ceramic thermal barrier coating system as claimed in  claim 1 , wherein the surface of the substrate or of the bonding layer on the substrate to which the ceramic layer or the bonding layer has been applied has been machined. 
     
     
         7 . The ceramic thermal barrier coating system as claimed in  claim 1 , wherein the proportion of FSZ is at least 10% by weight and not more than 90% by weight.