Pressure controlled droplet spraying (pcds) method for forming particles of compound materials from melts

Abstract

A method and apparatus of forming compositionally homogeneous particles is provided. The method includes forming a homogenous melt from a plurality of constituent materials under a first pressure sufficient to prevent substantial vaporization of the constituent materials. Droplets are generated from the homogenous melt. The droplets are cooled under a second pressure sufficient to prevent substantial vaporization of the constituent materials at least until the homogeneous particles formed therefrom have stabilized.

1 . A method of forming compositionally homogeneous particles, comprising:
 (i) forming a homogenous melt from a plurality of constituent materials under a first pressure sufficient to prevent substantial vaporization of the constituent materials;   (ii) generating droplets from the homogenous melt; and   (iii) cooling droplets under a second pressure sufficient to prevent substantial vaporization of the constituent materials at least until the homogeneous particles formed therefrom have stabilized.   
   
   
       2 . The method of  claim 1  wherein the homogenous particles comprise nanoparticles. 
   
   
       3 . The method of  claim 1  wherein the homogenous melt is formed above its liquidus temperature. 
   
   
       4 . The method of  claim 1  wherein the first pressure arises from an inert gas. 
   
   
       5 . The method of  claim 1  wherein the second pressure arises from an inert gas. 
   
   
       6 . The method of  claim 1  wherein the second pressure arises from a reactive gas. 
   
   
       7 . The method of  claim 1  wherein generating the droplets further comprises mixing the homogenous melt with a high pressure inert gas stream while maintaining the homogeneous melt at an elevated temperature at least until the droplets are formed. 
   
   
       8 . The method of  claim 1  wherein generating the droplets is performed using a spray nozzle. 
   
   
       9 . The method of  claim 1  wherein steps (i), (ii) and (iii) are performed in a melting vessel, droplet generation vehicle and particle generation vehicle, respectively. 
   
   
       10 . The method of  claim 9  further comprising controlling and monitoring temperature in the melting vessel, droplet generation vehicle, or the particle generation vehicle. 
   
   
       11 . The method of  claim 9  further comprising controlling and monitoring temperature in the melting vessel, droplet generation vehicle and the particle generation vehicle. 
   
   
       12 . The method of  claim 9  further comprising controlling and monitoring pressure in the melting vessel, droplet generation vehicle, or the particle generation vehicle. 
   
   
       13 . The method of  claim 9  further comprising controlling and monitoring pressure in the melting vessel, droplet generation vehicle and the particle generation vehicle. 
   
   
       14 . The method of  claim 9  further comprising controlling and monitoring gas composition in the melting vessel, droplet generation vehicle, or the particle generation vehicle. 
   
   
       15 . The method of  claim 9  further comprising controlling and monitoring gas composition in the melting vessel, droplet generation vehicle and the particle generation vehicle. 
   
   
       16 . The method of  claim 1  wherein the homogeneous melt is formed from a solid body that is melted in a droplet generation vehicle that generates the droplets. 
   
   
       17 . The method of  claim 9  further comprising siphoning the homogenous melt from the melting vessel to the droplet generation vehicle. 
   
   
       18 . The method of  claim 9  further comprising transporting the homogenous melt from the melting vessel to the droplet generation vehicle by a gravitational feed extending from the melting vessel. 
   
   
       19 . The method of  claim 9  further comprising transporting the homogenous melt from the melting vessel to the droplet generation vehicle by a pressurized feed extending from the melting vessel. 
   
   
       20 . A method of forming compositionally homogeneous layers, comprising:
 forming a homogenous melt from a plurality of constituent materials under a first pressure sufficient to prevent substantial vaporization of the constituent materials;   generating droplets from the homogenous melt; and   applying the droplets to a substrate under a second pressure sufficient to prevent substantial vaporization of the constituent materials so that a homogenous layer is formed upon cooling.   
   
   
       21 . The method of  claim 20  further comprising applying the droplets to the substrate under the second pressure so that a plurality of homogenous layers is formed. 
   
   
       22 . The method of  claim 21  wherein the plurality of homogenous layers forms a preform structure.