Spray deposition apparatus and methods for metal matrix composites

Abstract

A spray deposition apparatus comprises a source of aqueous fiber slurry that includes a mixture of milled graphite fibers in suspension. A slurry input of the spray deposition apparatus is coupled to the source of aqueous fiber slurry. The slurry input receives the mixture of aqueous fiber slurry. A gas pressure input receives pressurized gas. A nozzle aspirates the mixture of aqueous fiber slurry with the pressurized gas to produce a stream of fiber cluster droplets.

1 . A spray deposition apparatus comprising: 
 a source of aqueous fiber slurry that includes a mixture of milled graphite fibers in suspension;    a slurry input that is coupled to the source of aqueous fiber slurry, the slurry input receiving the mixture of aqueous fiber slurry;    a gas pressure input that receives pressurized gas; and    a nozzle that aspirates the mixture of aqueous fiber slurry with the pressurized gas to produce a stream of fiber cluster droplets.    
   
   
       2 . The spray deposition apparatus of  claim 1  wherein the source of aqueous fiber slurry comprises a continuously recirculating source of aqueous fiber slurry.  
   
   
       3 . The spray deposition apparatus of  claim 1  wherein the source of aqueous fiber slurry comprises a binder that is dissolved in the aqueous fiber slurry.  
   
   
       4 . The spray deposition apparatus of  claim 1  wherein the gas pressure input is positioned in the apparatus so as to promote forming the stream of fiber cluster droplets with a uniform spray pattern.  
   
   
       5 . The spray deposition apparatus of  claim 1  wherein the nozzle comprises a plurality of nozzles.  
   
   
       6 . The spray deposition apparatus of  claim 1  further comprising a reciprocal scanning mechanism that is attached to the nozzle, the reciprocal scanning mechanism providing a reciprocal scanning motion to the spray nozzle.  
   
   
       7 . The spray deposition apparatus of  claim 1  wherein the stream of fiber cluster droplets produced by the nozzle is essentially a random stream.  
   
   
       8 . A system for forming a composite preform, the system comprising: 
 a source of aqueous fiber slurry that includes a mixture of milled graphite fibers in suspension;    a slurry input that is coupled to the source of aqueous fiber slurry, the slurry input receiving the mixture of aqueous fiber slurry;    a gas pressure input that receives pressurized gas;    a nozzle that aspirates the mixture of aqueous fiber slurry with the pressurized gas to produce a stream of fiber cluster droplets;    a translating fiber belt that translates a fiber preform adjacent to the nozzle so that the stream of fiber cluster droplets deposits on the preform mat; and    a vacuum plenum that is positioned under the preform mat, the vacuum plenum removing excess carrier fluid from the fiber cluster droplets deposited on the preform mat.    
   
   
       9 . The system of  claim 8  wherein the preform mat is translated at a constant rate of speed.  
   
   
       10 . The system of  claim 8  wherein the vacuum plenum is positioned directly under the nozzle.  
   
   
       11 . The system of  claim 8  wherein the vacuum plenum is positioned a distance away from the nozzle.  
   
   
       12 . A method of forming a fiber preform mat, the method comprising: 
 forming an aqueous fiber slurry comprising milled graphite fibers in suspension;    aspirating the aqueous fiber slurry to produce a spray of fiber cluster droplets;    translating a fiber preform mat in a path of the fiber cluster droplets so that a randomized distribution of fibers is deposited on the fiber preform mat; and    extracting excess carrier fluid from the fiber cluster droplets, thereby setting the binder in the fiber preform mat.    
   
   
       13 . The method of  claim 12  wherein the aqueous fiber slurry further comprises a binder.  
   
   
       14 . The method of  claim 12  wherein the translating the fiber preform mat comprises translating the fiber preform mat at a constant rate.  
   
   
       15 . The method of  claim 12  further comprising spraying binder onto the fiber preform mat.  
   
   
       16 . The method of  claim 12  wherein the extracting excess the carrier fluid comprises reducing a pressure proximate to the preform mat.  
   
   
       17 . The method of  claim 12  wherein the extracting the excess carrier fluid comprises increasing a temperature of the fiber preform mat to remove moisture from the fiber preform mat.  
   
   
       18 . The method of  claim 12  wherein the extracting the excess carrier fluid comprises dehumidifying the fiber preform mat to remove moisture from the fiber preform mat.  
   
   
       19 . The method of  claim 12  wherein the extracting the excess carrier fluid is performed simultaneously with the deposition of the randomized distribution of fibers on the fiber preform mat.  
   
   
       20 . The method of  claim 12  wherein the extracting the excess carrier fluid is performed at a predetermined time after the deposition of the randomized distribution of fibers on the fiber preform mat.  
   
   
       21 . A method of forming a fiber preform mat, the method comprising: 
 forming an aqueous fiber slurry comprising milled graphite fibers in suspension;    aspirating the aqueous fiber slurry to produce a spray of fiber cluster droplets;    translating a fiber preform mat in a path of the fiber cluster droplets so that a randomized distribution of fibers is deposited on the fiber preform mat;    extracting excess carrier fluid from the fiber cluster droplets, thereby setting the binder in the fiber preform mat; and    controlling at least one of a rate of extracting the excess carrier fluid from the fiber cluster droplets and a time at which the excess carrier fluid is extracted from the fiber cluster droplets to adjust an average fiber angular inclination above a basal plan.    
   
   
       22 . The method of  claim 21  wherein the controlling the at least one of the rate of extracting the excess carrier fluid and the time at which the excess carrier fluid is extracted adjusts the average fiber angular inclination above the basal plan in the range of about 10%-30%.  
   
   
       23 . The method of  claim 21  wherein the controlling the at least one of the rate of extracting the excess carrier fluid and the time at which the excess carrier fluid is extracted adjusts the average fiber angular inclination above the basal plan in the range of about 10%-30%.  
   
   
       24 . The method of  claim 21  wherein the controlling the at least one of the rate of extracting the excess carrier fluid and the time at which the excess carrier fluid is extracted adjusts the average fiber angular inclination above the basal plan in the range of about 20%-30%.  
   
   
       25 . A method for manufacturing metal matrix composites, the method comprising: 
 forming an aqueous fiber slurry comprising milled graphite fibers in suspension;    aspirating the aqueous fiber slurry to produce fiber cluster droplets;    translating a fiber preform mat in a path of the fiber cluster droplets so that a randomized distribution of fibers is deposited on the fiber preform mat;    extracting excess carrier fluid from the fiber cluster droplets, thereby setting the binder in the fiber preform mat;    stripping filter material from the fiber preform mat to create a fiber preform;    pressing the fiber preform to a desired volume fraction; and    pressure infiltrating a metal matrix to form a composite preform.    
   
   
       26 . The method of  claim 25  wherein the extracting the excess carrier fluid comprises reducing a pressure proximate to the preform mat.  
   
   
       27 . The method of  claim 25  wherein the extracting the excess carrier fluid comprises increasing a temperature of the fiber preform mat to a temperature that removes moisture from the fiber preform mat.  
   
   
       28 . The method of  claim 25  wherein the extracting the excess carrier fluid comprises dehumidifying the fiber preform mat to remove moisture from the fiber preform mat.  
   
   
       29 . The method of  claim 25  wherein the extracting the excess carrier fluid is performed simultaneously with the deposition of the randomized distribution of fibers on the fiber preform mat.  
   
   
       30 . The method of  claim 25  wherein the extracting the excess carrier fluid is performed at a predetermined time after the deposition of the randomized distribution of fibers on the fiber preform mat.  
   
   
       31 . The method of  claim 25  wherein the pressing the fiber preform further comprises controlling a temperature of the fiber preform.  
   
   
       32 . The method of claims  25  further comprising cutting and stacking the fiber preform to form a fiber preform with the desired dimensions prior to pressing.  
   
   
       33 . The method of  claim 25  wherein the pressure infiltrating the metal matrix comprises pressure infiltrating at least one of Al, Mg, and Cu alloy matrix.  
   
   
       34 . The method of  claim 25  wherein the aqueous fiber slurry further comprises a binder.  
   
   
       35 . The method of  claim 25  further comprising spraying binder onto the fiber preform mat.