Thermal barrier coating formation method, thermal barrier coating, and high-temperature member

Abstract

A thermal barrier coating is provided that includes a ceramic layer ( 120 ) formed on a heat-resistant alloy substrate and containing a ceramic. The ceramic layer ( 120 ) has: a first dense layer ( 121 ); an intermediate porous layer ( 122 ) which is laminated on the first dense layer ( 121 ), which has a higher density than the first dense layer ( 121 ), and in which numerous pores are formed; and a second dense layer ( 123 ) that is laminated on the intermediate porous layer ( 122 ) and has a lower density than the intermediate porous layer ( 122 ).

1 . A thermal barrier coating, comprising
 a ceramic layer formed on a heat-resistant alloy substrate and configured to contain a ceramic,   wherein the ceramic layer has   a first dense layer;   an intermediate porous layer which is laminated on the first dense layer, which has a higher density than the first dense layer, and in which numerous pores are formed; and   a second dense layer which is laminated on the intermediate porous layer and has a lower density than the intermediate porous layer, wherein:   the first dense layer has first vertical cracks that extend in a thickness direction and are distributed in a surface direction,   the second dense layer has second vertical cracks that extend in a thickness direction and are distributed in a surface direction, and   the first vertical cracks and the second vertical cracks extend to be inclined with respect to a surface of the ceramic layer.   
     
     
         2 . The thermal barrier coating according to  claim 1 , wherein a porosity continuously varies at a first boundary part that is a boundary part between the intermediate porous layer and the first dense layer and a second boundary part that is a boundary part between the intermediate porous layer and the second dense layer. 
     
     
         3 . The thermal barrier coating according to  claim 1 , wherein a porosity of the intermediate porous layer is 10% or more and 20% or less. 
     
     
         4 . The thermal barrier coating according to  claim 1 , wherein a porosity of the first dense layer and a porosity of the second dense layer are 10% or less and 5% or more. 
     
     
         5 . (canceled) 
     
     
         6 . (canceled) 
     
     
         7 . The thermal barrier coating according to  claim 1 , wherein angles of inclination of the first vertical cracks with respect to the surface of the ceramic layer are different from those of the second vertical cracks with respect to the surface of the ceramic layer. 
     
     
         8 . A thermal barrier coating formation method, comprising
 a ceramic layer formation step of forming a ceramic layer containing a ceramic on a surface of a heat-resistant alloy substrate,   wherein the ceramic layer formation step includes:   a first dense layer formation step of forming a first dense layer;   a porous layer formation step, performed after the first dense layer formation step, of forming an intermediate porous layer, which has a higher density than the first dense layer and in which numerous pores are formed, on the first dense layer; and   a second dense layer formation step, performed after the porous layer formation step, of forming a second dense layer, which has a lower density than the intermediate porous layer, on the intermediate porous layer, wherein:   a thermal spraying gun is inclined with respect to the surface of the heat-resistant alloy substrate by a predetermined angle of inclination, and performs thermal spraying using a suspension in which thermal spraying particles are dispersed, and the ceramic layer which contains a ceramic and in which vertical cracks, which extend in a thickness direction and extend to be inclined by the angle of inclination, are distributed in a surface direction is formed on the heat-resistant alloy substrate.   
     
     
         9 . The thermal barrier coating formation method according to  claim 8 , wherein:
 a thermal spraying method is used in the ceramic layer formation step; and   a distance between a spraying hole of a thermal spraying gun and a surface of a thermal spraying target is shorter in the first and second dense layer formation steps than in the porous layer formation step.   
     
     
         10 . The thermal barrier coating formation method according to  claim 8 , wherein:
 the first dense layer formation step includes forming the first dense layer such that first vertical cracks extending in a thickness direction are distributed in a surface direction; and   the second dense layer formation step includes forming the second dense layer such that second vertical cracks extending in a thickness direction are distributed in a surface direction.   
     
     
         11 . The thermal barrier coating formation method according to  claim 8 , wherein the thermal spraying particles have a particle size of 0.1 μm or more and 1.0 μm or less. 
     
     
         12 . The thermal barrier coating formation method according to  claim 8 , wherein at least a part of the ceramic layer formation step uses suspension plasma spraying. 
     
     
         13 . (canceled) 
     
     
         14 . A thermal barrier coating, comprising
 a ceramic layer formed on a heat-resistant alloy substrate and configured to contain a ceramic,   wherein the ceramic layer has:   a first dense layer;   an intermediate porous layer which is laminated on the first dense layer, which has a higher density than the first dense layer, and in which numerous pores are formed; and   a second dense layer which is laminated on the intermediate porous layer and has a lower density than the intermediate porous layer, wherein:   the ceramic layer has vertical cracks that extend in a thickness direction and are distributed in a surface direction; and   the vertical cracks extend to be inclined with respect to a surface of the ceramic layer.   
     
     
         15 . The thermal barrier coating according to  claim 14 , wherein angles of inclination of the vertical cracks are different between a side close to the surface of the ceramic layer and a side close to the heat-resistant alloy substrate. 
     
     
         16 . The thermal barrier coating according to  claim 14 , wherein the vertical cracks have a distribution rate per 1 mm of 6 cracks/mm or more and 12 cracks/mm or less. 
     
     
         17 . The thermal barrier coating according to  claim 14 , wherein the vertical cracks extend intermittently. 
     
     
         18 . The thermal barrier coating according to  claim 14 , wherein all the plurality of vertical cracks are inclined toward one side in the surface direction as those vertical cracks go to the surface of the ceramic layer. 
     
     
         19 . The thermal barrier coating according to  claim 14 , wherein angles of inclination of the vertical cracks are angles of 45° or more and 80° or less with respect to the surface of the ceramic layer. 
     
     
         20 . (canceled) 
     
     
         21 . The thermal barrier coating formation method according to  claim 8 , wherein the thermal spraying is suspension plasma spraying. 
     
     
         22 . The thermal barrier coating formation method according to  claim 8 , wherein the thermal spraying particles have a particle size of 0.1 μm or more and 1.0 μm or less. 
     
     
         23 . The high-temperature member, comprising:
 a heat-resistant alloy substrate; and   the thermal barrier coating according to  claim 14  formed on the heat-resistant alloy substrate.