Duplex coatings and bulk materials, and methods of manufacture thereof

Abstract

A contiguous duplex microstructured material comprises a nanostructured material having two structural states, for example, a duplex microstructured coating. One state comprises substantially nanostructured features, while the second state substantially comprises microstructured features. A duplex nanostructured coating can be made by thermal spraying a reconstituted nanostructured material onto a substrate under conditions effective to form a coating comprising more than one structural state.

1 . A method of forming a duplex microstructured material, comprising thermally processing a nanostructured material to fully melt one portion of the nanostructured material and partially melt another portion of the nanostructured material to provide a duplex microstructure upon solidification.  
     
     
         2 . The method of  claim 1  wherein the nanostructured material is fully nanostructured.  
     
     
         3 . The method of  claim 1 , wherein the thermal processing is thermal spraying.  
     
     
         4 . The method of  claim 1  wherein thermal spraying comprises plasma spraying.  
     
     
         5 . The method of  claim 1  wherein the nanostructured material comprises alumina and titania.  
     
     
         6 . The method of  claim 4  wherein plasma spraying is performed with a CPSP of about 340 to about 390.  
     
     
         7 . The method of  claim 1  wherein the nanostructured material comprises chromia and titania.  
     
     
         8 . The method of  claim 1 , wherein the nanostructured material is in the form of a reconstituted nanostructured material, wherein the reconstituted nanostructured material is formed by hot spraying a slurry comprising a particulate nanostructured material, a carrier, and an optional binder.  
     
     
         9 . The method of  claim 8 , wherein the reconstituted nanostructured material is in the form of hollow spheres.  
     
     
         10 . The method of  claim 8 , wherein the sprayed slurry is further heat treated to remove the carrier and the binder.  
     
     
         11 . The method of  claim 1 , further comprising consolidating and sintering the solidified material to form a bulk material.  
     
     
         12 . A coating formed by the method of  claim 1 .  
     
     
         13 . An article formed by the method of  claim 1 .  
     
     
         14 . A method of forming a coating comprising a contiguous duplex microstructure, the method comprising: 
 thermally spraying a reconstituted nanostructured powder onto a substrate, wherein the reconstituted nanostructured powder is in the form of particles having average diameters about 0.5 to about 100 micrometers, and further wherein thermally spraying is at a temperature effective to form a fully-melted state and a partially melted state.    
     
     
         15 . The method of  claim 14 , wherein spraying is under a predetermined critical plasma spray parameter.  
     
     
         16 . The method of  claim 14  wherein the powder comprises alumina-titania.  
     
     
         17 . The method of  claim 15  wherein the critical plasma spray parameter is about 340 to about 390.