Methods of forming a porous thermal barrier coating

Abstract

A method for controlling the porosity parameter of porous thermal barrier coatings is presented. The method includes disposing a feedstock material on a substrate to form a porous thermal barrier coating. The feedstock material includes a gas-forming additive and a thermal barrier coating material. The disposing step further includes controlling the porosity parameter of the porous thermal barrier coating by controlling a feedstock material feed rate, an amount of the gas-forming additive in the feedstock material, a temperature of the disposed feedstock material on the substrate, or combinations thereof.

1 . A method of forming a porous thermal barrier coating, comprising:
 disposing a feedstock material on a substrate to form the porous thermal barrier coating, wherein the feedstock material comprises a gas-forming additive and a thermal barrier coating material, and wherein the disposing comprises controlling a porosity parameter of the porous thermal barrier coating by controlling a feedstock material feed rate, an amount of the gas-forming additive in the feedstock material, a temperature of the disposed feedstock material on the substrate, or combinations thereof.   
     
     
         2 . The method according to  claim 1 , wherein the controlling the porosity parameter of the porous thermal barrier coating comprises controlling the temperature of the disposed feedstock material on the substrate using an auxiliary heat source. 
     
     
         3 . The method according to  claim 1 , wherein the disposed feedstock material on the substrate is heated to a temperature greater than a temperature that the substrate can withstand. Amend to  claim 1  and include. 
     
     
         4 . The method according to  claim 3 , wherein the disposed feedstock material on the substrate is heated to a temperature in a range from about 1000° C. to about 1500° C. 
     
     
         5 . The method according to  claim 1 , wherein the controlling the porosity parameter of the porous thermal barrier coating comprises controlling the amount of the gas-forming additive in the feedstock material in a range from about 0.1 wt % to about 10 wt %. 
     
     
         6 . The method according to  claim 1 , wherein the controlling the porosity parameter of the porous thermal barrier coating comprises controlling the feedstock material feed rate in a range from about 2.5 gm/min to about 100 gm/min. 
     
     
         7 . The method according to  claim 1 , wherein the gas-forming additive comprises graphite, carbides, oxycarbides, nitrides, or combinations thereof. 
     
     
         8 . The method according to  claim 1 , wherein the gas-forming additive comprises elemental carbon. 
     
     
         9 . The method according to  claim 1 , wherein the thermal barrier coating material comprises yttria-stabilized zirconia. 
     
     
         10 . The method according to  claim 1 , wherein the feedstock material is disposed on the substrate using an air plasma spray process. 
     
     
         11 . The method according to  claim 1 , wherein the porosity parameter comprises an average pore size, an average pore volume, a pore size distribution, a pore microstructure, or combinations thereof. 
     
     
         12 . The method according to  claim 1 , wherein the porous thermal barrier coating comprises a plurality of pores such that at least some pores of the plurality of pores are intragranular. 
     
     
         13 . The method according to  claim 1 , wherein the controlling the porosity parameter of the porous thermal barrier coating comprises controlling an average pore size of a plurality of pores in the porous thermal barrier coating in a range from about 0.1 microns to about 25 microns. 
     
     
         14 . The method according to  claim 1 , wherein the controlling the porosity parameter of the porous thermal barrier coating comprises controlling an average pore volume of a plurality of pores in the porous thermal barrier coating in a range from about 5 volume % to about 10 volume %. 
     
     
         15 . The method according to  claim 1 , wherein the controlling the porosity parameter of the thermal barrier coating further comprises forming a graded porosity across a thickness of the thermal barrier coating. 
     
     
         16 . A method of forming a porous thermal barrier coating, comprising:
 disposing a feedstock material using an air plasma spray process on a substrate to form the porous thermal barrier coating, wherein the feedstock material comprises a gas-forming additive and a thermal barrier coating material, and wherein the disposing comprises controlling a porosity parameter of the porous thermal barrier coating by controlling a temperature of the disposed feedstock material on the substrate using an auxiliary heat source.   
     
     
         17 . The method according to  claim 16 , wherein the disposed feedstock material on the substrate is heated to a temperature in a range from about 1000° C. to about 1500° C. 
     
     
         18 . The method according to  claim 16 , wherein the gas-forming additive comprises elemental carbon. 
     
     
         19 . The method according to  claim 16 , wherein the thermal barrier coating material comprises yttria-stabilized zirconia. 
     
     
         20 . A method of forming a porous thermal barrier coating comprising a graded porosity, the method comprising:
 disposing a feedstock material on a substrate to form the porous thermal barrier coating, wherein the feedstock material comprises a gas-forming additive and a thermal barrier coating material, and wherein the disposing comprises forming the graded porosity in the thermal barrier coating by controlling: an amount of the gas-forming additive in the feedstock material, a temperature of the disposed feedstock material on the substrate using an auxiliary heat source, or a combination thereof.