Plasma application of thermal barrier coatings with reduced thermal conductivity on combustor hardware

Abstract

A process for forming a thermal barrier coating comprises the steps of providing a substrate, providing a gadolinia stabilized zirconia powder, and forming a thermal barrier coating having at least one of a porosity in a range of from 5 to 20% and a dense segmented structure on said substrate by supplying the gadolinia stabilized powder to a spray gun and using an air plasma spray technique.

1 . A process for forming a thermal barrier coating comprising the steps of:
 providing a substrate;   providing a gadolinia stabilized zirconia powder; and   forming a thermal barrier coating having at least one of a porosity in a range of from 5 to 20% and a dense segmented structure on said substrate by supplying the gadolinia stabilized powder to a spray gun and using an air plasma spray technique.   
     
     
         2 . The process according to  claim 1 , wherein said substrate providing step comprises providing a combustor component. 
     
     
         3 . The process according to  claim 1 , wherein said substrate providing step comprises providing one of a combustor panel, a combustor chamber, a combustor heat shield, a combustor transition duct, and a combustor augmentor. 
     
     
         4 . The process according to  claim 1 , wherein said powder providing step comprises providing a powder consisting of optionally from 3.0 to 14 wt % of at least one of yttria and titania, from 15 to 70 wt % gadolinia, and the balance zirconia. 
     
     
         5 . The process according to  claim 1 , wherein said powder providing step comprises providing a powder consisting of from 3.0 to 14 wt % of at least one of yttria and titanium, from 15 to 70 wt % gadolinia, and the balance zirconia. 
     
     
         6 . The process according to  claim 1 , wherein said thermal barrier coating forming step comprises using an amperage range of 350 to 825 amps, a voltage of 35 to 50 volts, an argon primary gas flow of 75 to 105 SCFH, at least one of a hydrogen secondary gas flow of 1.0 to 10 SCFH and a helium secondary gas flow of 45 to 75 SCFH, a powder gas flow exiting a spray gun of 4.0 to 20 SCFH, a powder feed rate to the spray gun of 10 to 40 grams/min., and a gun distance from a surface of the substrate being coated of from 3.0 to 5.0 inches. 
     
     
         7 . The process according to  claim 1 , wherein said thermal barrier coating forming step comprises using an amperage range of from 500 to 700 amps, a voltage of 55 to 65 volts, an argon primary gas flow of 65 to 90 SCFH, a hydrogen secondary gas flow of 8 to 22 SCFH, a powder gas flow from a spray gun of 6 to 12 SCFH, a powder feed rate to the spray gun of 35 to 55 grams/min. and a gun distance from a surface of a substrate being coated of from 4.0 to 7.0 inches. 
     
     
         8 . The process according to  claim 1 , further comprising depositing a ceramic interlayer on said substrate prior to said thermal barrier coating step. 
     
     
         9 . The process according to  claim 8 , wherein said ceramic interlayer depositing step comprises depositing a layer of 7.0 wt % yttria stabilized zirconia. 
     
     
         10 . The process according to  claim 8 , further comprising depositing a bondcoat layer on said substrate prior to said ceramic interlayer depositing step. 
     
     
         11 . The process according to  claim 10 , wherein said bondcoat layer depositing step comprises depositing a metallic bondcoat layer. 
     
     
         12 . The process according to  claim 1 , wherein said thermal barrier coating forming step comprises forming a segmented coating having a thermal conductivity in the range of from 5.0 to 12.5 BTU in/hr ft 2  F. 
     
     
         13 . The process according to  claim 1 , wherein said thermal barrier coating forming step comprises forming a porous coating having a thermal conductivity in the range of from 3.0 to 10 BTU in/hr ft 2  F.