Coating system with alkaline earth oxides

Abstract

A coating system, along with its methods of formation, are provided. The coating system may be disposed on a surface of a substrate. The coating system may include: a bondcoat on the surface of the substrate; a thermal barrier coating on the bondcoat defining a plurality of elongated surface-connected voids; and a protective composition disposed within at least some of the plurality of elongated surface-connected voids of the thermal barrier coating. The protective composition may include an oxide or a mixture of oxides, with the oxide or the mixture of oxides including an alkaline earth element and at least one of aluminum, gallium, or a combination of aluminum and gallium.

1 . A coating system disposed on a surface of a substrate, the coating system comprising:
 a bondcoat on the surface of the substrate;   a thermal barrier coating on the bondcoat, wherein the thermal barrier coating defines a plurality of elongated surface-connected voids; and   a protective composition disposed within at least some of the plurality of elongated surface-connected voids of the thermal barrier coating, wherein the protective composition comprises an oxide or a mixture of oxides, wherein the oxide or the mixture of oxides comprises an alkaline earth element and at least one of aluminum, gallium, or a combination of aluminum and gallium.   
     
     
         2 . The coating system as in  claim 1 , wherein the protective composition is substantially free from a rare earth element. 
     
     
         3 . The coating system as in  claim 1 , wherein the protective composition is substantially free from silica. 
     
     
         4 . The coating system as in  claim 1 , wherein the alkaline earth element comprises magnesium, calcium, strontium, or a mixture thereof. 
     
     
         5 . The coating system as in  claim 1 , wherein the protective composition comprises the mixture of oxides, wherein the mixture of oxides comprises an alkaline earth oxide and Al 2-x Ga x O 3  where x is 0 to 2. 
     
     
         6 . The coating system as in  claim 5 , wherein the protective composition comprises 5 wt % to 85 wt % of the Al 2-x Ga x O 3  where x is 0 to 2. 
     
     
         7 . The coating system as in  claim 5 , wherein the protective composition comprises 10 wt % to 75 wt % of the Al 2-x Ga x O 3  where x is 0 to 2. 
     
     
         8 . The coating system as in  claim 5 , wherein the protective composition comprises the alkaline earth oxide in a molar ratio to Al 2-x Ga x O 3  that is 1:2 to 2:1. 
     
     
         9 . The coating system as in  claim 5 , wherein x is 0 to 1. 
     
     
         10 . The coating system as in  claim 9 , wherein x is less than 1. 
     
     
         11 . The coating system as in  claim 10 , wherein x is 0. 
     
     
         12 . The coating system as in  claim 9 , wherein x is greater than 0 to 1. 
     
     
         13 . The coating system as in  claim 5 , wherein the alkaline earth oxide comprises MgO, CaO, or a mixture thereof. 
     
     
         14 . The coating system as in  claim 5 , wherein the protective composition comprises at least two alkaline earth oxides and Al 2-x Ga x O 3  where x is 0 to 2, wherein the at least two alkaline earth oxides are different from each other. 
     
     
         15 . The coating system as in  claim 1 , wherein the protective composition comprises an oxide compound comprising the alkaline earth element and at least one of aluminum, gallium, or a combination of aluminum and gallium. 
     
     
         16 . The coating system as in  claim 1 , wherein each of the elongated surface-connected voids are defined by column walls of the thermal barrier coating, and wherein the protective composition forms a coating on at least 50% of a surface area of the column walls defining each of the plurality of elongated surface-connected voids. 
     
     
         17 . The coating system as in  claim 16 , further comprising:
 a barrier layer disposed on the column walls of each of the plurality of elongated surface-connected voids of the thermal barrier coating, wherein the barrier layer is positioned between the thermal barrier coating and the protective composition.   
     
     
         18 . The coating system as in  claim 17 , wherein the barrier layer comprises alumina. 
     
     
         19 . A method of forming a coating system, the method comprising:
 forming a thermal barrier coating on a bondcoat on a surface of a substrate, wherein the thermal barrier coating defines a plurality of elongated surface-connected voids; and   infiltrating a protective composition into at least some of the plurality of elongated surface-connected voids of the thermal barrier coating, wherein the protective composition comprises an oxide or mixture of oxides, wherein the oxide or mixture of oxides comprises an alkaline earth element and at least one of aluminum, gallium, or a combination of aluminum and gallium.   
     
     
         20 . The method of  claim 19 , further comprising:
 prior to infiltrating the protective composition into at least some of the plurality of elongated surface-connected voids of the thermal barrier coating, infiltrating a barrier material into at least some of the plurality of elongated surface-connected voids of the thermal barrier coating to form a barrier layer positioned between the thermal barrier coating and the protective composition.