Thermal spray coating of porous nanostructured ceramic feedstock

Abstract

By engineering thermal spray parameters, such as temperature and velocity, and engineering feedstock powder size and morphology, ceramic coatings may be produced having desired mechanical and thermal properties. The ceramic thermal spray coating may have a microstructure having about 10-80% by cross-sectional area of a particulate phase based on surface area of the coating, and the particulate phase is uniformly distributed throughout the coating. The particulate phase is an unmelted portion of the thermal sprayed feedstock, which is highly porous and may be produced by agglomerating nanoparticles of the ceramic. Such coatings can be applied as TBCs or as abradable coatings.

What is claimed is: 
     
         1 . A method for producing a coating on a substrate, the method comprising:
 obtaining a ceramic powder of high porosity particles;   collecting from the ceramic powder particles within a selected size distribution; and   thermal spraying the collected particles while controlling parameters of the thermal spray to impart temperatures and velocities on the collected particles, wherein the selected size distribution, and imparted temperatures and velocities ensure that a core of the collected particles are not melted,   whereby a coating is produced having a uniform distribution of porous nanostructured inclusions.   
     
     
         2 . The method of  claim 1  wherein obtaining the ceramic powder comprises obtaining a micron scale agglomerate of ceramic nanoparticles. 
     
     
         3 . The method of  claim 2  wherein the nanoparticle agglomerate is chiefly composed of zirconium oxide. 
     
     
         4 . The method of  claim 2  wherein the nanoparticle agglomerate is chiefly composed of zirconium oxide stabilized by another metal oxide. 
     
     
         5 . The method of  claim 2  wherein the nanoparticle agglomerate is chiefly composed of zirconium oxide stabilized by yttrium oxide. 
     
     
         6 . The method of  claim 2  wherein obtaining the nanostructured agglomerate comprises agglomerating nanoscale ceramic particles of a size distribution from about 2 nm to 400 nm 
     
     
         7 . The method of  claim 2  wherein obtaining the nanostructured agglomerate comprises agglomerating nanoscale ceramic particles of a size distribution from about 30 nm to 130 nm. 
     
     
         8 . The method of  claim 2  wherein obtaining the nanostructured agglomerate comprises spray-drying nanoscale ceramic particles. 
     
     
         9 . The method of  claim 2  wherein collecting comprises separating from the nanostructured agglomerate particles having a diameter distribution ranging from 5 μm to 200 μm. 
     
     
         10 . The method of  claim 2  wherein collecting comprises separating from the nanostructured agglomerate, particles having a diameter distribution centered between 50 μm to 200 μm. 
     
     
         11 . The method of  claim 2  wherein thermal spraying the collected particles comprises mixing the collected particles with a conventional feedstock particle to form a feedstock for the thermal spraying. 
     
     
         12 . The method of  claim 2  wherein controlling parameters of the thermal spray include imparting velocities on the collected particles in a range of about 150400 m/s and heating the collected particles to a temperature within about 400° C. of the average melting point of the ceramic material. 
     
     
         13 . The method of  claim 2  wherein controlling parameters of the thermal spray include imparting velocities on the collected particles in a range of about 200-250 m/s and heating the collected particles to a temperature within about 200° C. of the average melting point of the ceramic material. 
     
     
         14 . The method of  claim 2  wherein controlling parameters of the thermal spray and the size of the collected particles produces a coating with a microstructure having about 10-80% of the porous nanostructured microzones by cross-sectional area. 
     
     
         15 . The method of  claim 2  wherein controlling parameters of the thermal spray and the size of the collected particles produces a coating with a microstructure having about 30-35% of the porous nanostructured microzones by cross-sectional area. 
     
     
         16 . A ceramic coating with a microstructure having about 10-80% by cross-sectional area of porous nanostructured microzones distributed uniformly throughout. 
     
     
         17 . The ceramic coating of  claim 16  wherein the microstructure has about 30-50% of the porous nanostructured inclusions by cross-sectional area. 
     
     
         18 . A thermal barrier coating comprising a ceramic material with a microstructure having about 10-80% by cross-sectional area of porous nanostructured inclusions distributed uniformly throughout. 
     
     
         19 . The thermal barrier coating of  claim 18  wherein the microstructure has about 30-50% by cross-sectional area of the porous nanostructured inclusions. 
     
     
         20 . An abradable ceramic coating comprising a ceramic material, the coating having a microstructure comprising about 10-50% by area, based on surface area of a cross-section of the coating, of a particulate phase comprising agglomerated ceramic nanoparticles of the ceramic material. 
     
     
         21 . The abradable ceramic coating of  claim 20  wherein the microstructure has about 30-35% by cross-sectional area of the coating, of the particulate phase comprising agglomerated ceramic nanoparticles of the ceramic material.