Ultrahard stishovite nanoparticles and methods of manufacture

Abstract

Compositions comprising nanoparticles (e.g., nanocrystals) of stishovite silica are described. Such nanoparticles may be made by (1) subjecting a mesoporous silica starting material (e.g., SBA-16 or KIT-6) to a pressure of less than about 20 GPa (e.g., about 12 GPa); (2) heating the mesoporous silica starting material while under pressure to an elevated temperature of less than about 1000° C. (e.g., a temperature of between about 300° C. and about 400° C.); and thereafter isolating the nanoparticles. The nanoparticles may be used in a work tool that is configured and adapted for cutting, drilling, abrading, polishing, machining, or grinding, among other uses.

1 . A composition comprising nanoparticles of stishovite silica. 
   
   
       2 . The composition according to  claim 1 , wherein said nanoparticles are nanocrystals. 
   
   
       3 . The composition according to  claim 1 , wherein said nanoparticles have an average particle size of between about 2 nm and about 1000 nm. 
   
   
       4 . The composition according to  claim 3 , wherein said nanoparticles have an average particle size of between about 200 nm and about 800 nm. 
   
   
       5 . The composition according to  claim 1 , wherein said nanoparticles are essentially free of any polymorph phase of silica other than the stishovite polymorph of silica. 
   
   
       6 . The composition according to  claim 1 , wherein said composition further comprises a colloidal matrix, said nanoparticles being suspended in said matrix. 
   
   
       7 . A method of manufacturing nanoparticles of stishovite silica comprising
 subjecting a mesoporous silica starting material to a pressure of less than about 20 GPa;   heating said mesoporous silica starting material while under said pressure to an elevated temperature of not greater than about 1000° C.; and thereafter   isolating nanoparticles of stishovite silica.   
   
   
       8 . The method according to  claim 7 , wherein said mesoporous silica starting material is a cubic mesoporous silica. 
   
   
       9 . The method according to  claim 8 , wherein said cubic mesoporous silica is KIT-6 or SBA-16. 
   
   
       10 . The method according to  claim 7 , wherein said nanoparticles comprise nanocrystals of stishovite silica having an average particles size of between about 200 nm and about 400 nm. 
   
   
       11 . The method according to  claim 7 , wherein said nanoparticles comprise nanocrystals of stishovite silica having an average particles size of between about 400 nm and about 800 nm. 
   
   
       12 . The method according to  claim 7 , wherein said pressure is at least about 10 GPa. 
   
   
       13 . The method according to  claim 7 , wherein said elevated temperature is at least about 300° C. 
   
   
       14 . The method according to  claim 7 , wherein said heating is carried out for between about 2 minutes and about 20 minutes. 
   
   
       15 . The method according to  claim 7 , further comprising, after said heating and prior to said isolating, reducing said elevated temperature to about room temperature. 
   
   
       16 . The method according to  claim 7 , wherein said nanoparticles comprise nanocrystals of stishovite silica. 
   
   
       17 . A work tool comprising nanoparticles of stishovite silica. 
   
   
       18 . The work tool according to  claim 17 , wherein said work tool is configured and adapted for cutting, drilling, abrading, polishing, machining, or grinding. 
   
   
       19 . The work tool according to  claim 17 , wherein said work tool has a surface that is at least partially impregnated with or coated with said nanoparticles of stishovite silica. 
   
   
       20 . The work tool according to  claim 17 , wherein said nanoparticles are nanocrystals.