Article for high temperature service

Abstract

Articles for high temperature service, especially where enhanced strain tolerance coupled with resistance to ingested dust and debris (CMAS) is desirable, are provided herein. The article comprises a substrate and a multi-layered coating system disposed over the substrate. The coating system comprises a first layer comprising a first material and a second layer comprising a second material, with the first layer disposed between the second layer and the substrate. The second material is more resistant to infiltration by a nominal CMAS composition relative to 8 weight percent yttria-stabilized zirconia at a temperature of 1300 degrees Celsius. The second layer comprises a plurality of through-thickness cracks, wherein at least 90 percent of the cracks have a mean crack opening displacement, measured in a distal surface region, of up to about 5 micrometers.

1 . An article comprising:
 A substrate; and a coating system disposed over the substrate,   wherein the coating system comprises a first layer comprising a first material and a second layer comprising a second material, the first layer disposed between the second layer and the substrate, the second layer comprising proximal and distal surfaces relative to the substrate and having a thickness defined between the proximal and distal surfaces, and the second layer having a distal surface region extending from the distal surface to a depth below the distal surface of 20% of the thickness of the second layer;   wherein the first material has a higher fracture toughness than the second material;   wherein the second material is more resistant to infiltration by nominal CMAS relative to 8 weight percent yttria-stabilized zirconia at a temperature of 1300 degrees Celsius; and   wherein the second layer comprises a plurality of through-thickness cracks, wherein at least 90 percent of the cracks have a mean crack opening displacement, measured in the distal surface region, of up to about 5 micrometers.   
     
     
         2 . The article of  claim 1 , wherein the first material comprises yttria-stabilized zirconia. 
     
     
         3 . The article of  claim 2 , wherein the yttria-stabilized zirconia has a yttria content in a range from about 7 weight percent to about 9 weight percent. 
     
     
         4 . The article of  claim 1 , wherein the first material comprises stabilized hafnia, stabilized titania, or combinations thereof. 
     
     
         5 . The article of  claim 1 , wherein the first layer comprises a silicate. 
     
     
         6 . The article of  claim 1 , wherein the second material comprises yttria-stabilized zirconia, with a yttria content greater than 38 weight percent. 
     
     
         7 . The article of  claim 6 , wherein the yttria content is at least about 55 weight percent. 
     
     
         8 . The article of  claim 1 , wherein the second material comprises an oxide. 
     
     
         9 . The article of  claim 8 , wherein the oxide comprises at least one transition metal element, at least one rare-earth element, silicon, indium, or combinations thereof. 
     
     
         10 . The article of  claim 8 , wherein the oxide comprises zirconium, hafnium, titanium, or combinations thereof. 
     
     
         11 . The article of  claim 8 , wherein the oxide comprises an oxyapatite, a garnet, or a pyrochlore. 
     
     
         12 . The article of  claim 8 , wherein the oxide comprises gadolinium-stabilized zirconia. 
     
     
         13 . The article of  claim 1 , wherein the second material comprises a carbide, a nitride, or a silicide. 
     
     
         14 . The article of  claim 1 , wherein the first layer has a porosity in a range from about 2% to about 30%. 
     
     
         15 . The article of  claim 1 , wherein the first layer has a porosity in a range from about 2% to about 10%. 
     
     
         16 . The article of  claim 1 , wherein the first layer has a porosity in a range from about 10% to about 30%. 
     
     
         17 . The article of  claim 1 , wherein the second layer has a porosity in the range from about 2% to about 30%. 
     
     
         18 . The article of  claim 1 , wherein the plurality of through-thickness cracks has a linear crack frequency of at least about 5 cracks per inch. 
     
     
         19 . The article of  claim 1 , wherein the plurality of through-thickness cracks has a linear crack frequency of at least about 25 cracks per inch. 
     
     
         20 . The article of  claim 1 , wherein the substrate comprises a metal. 
     
     
         21 . The article of  claim 20 , wherein the substrate comprises a superalloy. 
     
     
         22 . The article of  claim 1 , wherein the substrate comprises a ceramic. 
     
     
         23 . The article of  claim 22 , wherein the substrate comprises silicon nitride or silicon carbide. 
     
     
         24 . The article of  claim 1 , wherein the coating system further comprises a bondcoat disposed between the first layer and the substrate. 
     
     
         25 . The article of  claim 24 , wherein the bondcoat comprises an aluminide or an MCrAlY material. 
     
     
         26 . The article of  claim 24 , wherein the bondcoat comprises a silicide or elemental silicon. 
     
     
         27 . The article of  claim 1 , wherein the second layer is at least 10% of the combined thickness of the first layer and second layer. 
     
     
         28 . The article of  claim 1 , wherein the second layer is at least 50% of the combined thickness of the first layer and second layer. 
     
     
         29 . The article of  claim 1 , wherein the article is a component of a gas turbine assembly. 
     
     
         30 . The article of  claim 1 , wherein at least 50 percent of the cracks have a mean crack opening displacement, measured in the distal surface region, of up to about 1.5 micrometers. 
     
     
         31 . The article of  claim 1 , wherein the second layer comprises a plurality of through-thickness cracks, wherein at least 95 percent of the cracks have a mean crack opening displacement, measured in the distal surface region, of up to about 5 micrometers. 
     
     
         32 . An article comprising
 a substrate comprising a superalloy; and a coating system disposed over the substrate, wherein the coating system comprises   a bondcoat comprising an aluminide or an MCrAlY material and disposed over the substrate;   a first layer, comprising yttria-stabilized zirconia, disposed over the bondcoat; and   a second layer, comprising yttria-stabilized zirconia having at least about 55 weight percent yttria, disposed over the first layer, the second layer comprising proximal and distal surfaces relative to the substrate, and the second layer having a distal surface region extending from the distal surface to a depth below the distal surface of 20% of the thickness of the second layer;   wherein the second layer comprises a plurality of through-thickness cracks, wherein at least 90 percent of the cracks have a mean crack opening displacement, measured in the distal surface region, of up to about 5 micrometers.   
     
     
         33 . An article comprising
 a substrate comprising a ceramic-matrix composite; and a coating system disposed over the substrate, wherein the coating system comprises   a bondcoat comprising a silicide or elemental silicon and disposed over the substrate;   a first layer, comprising a silicate, disposed over the bondcoat; and   a second layer, comprising a rare earth silicate disposed over the first layer, the second layer comprising proximal and distal surfaces relative to the substrate, and the second layer having a distal surface region extending from the distal surface to a depth below the distal surface of 20% of the thickness of the second layer;   wherein the second layer comprises a plurality of through-thickness cracks, wherein at least 80 percent of the cracks have a mean crack opening displacement, measured in the distal surface region, of up to about 5 micrometers.