Variable-Density Preforms

Abstract

Provided are novel devices and methods for making a variable density preform, the methods comprising obtaining a slurry comprising a reinforcement particle component and a liquid component; obtaining a die cavity having at least one inlet opening and at least one exit opening defining at least one die cavity flow path therebetween directed toward the exit opening, the at least one exit opening suitably sized or configured to provide for exit of the at least one liquid component while impeding or blocking exit of the at least one reinforcement particle component; and introducing the slurry under pressure, and for a sufficient time period, through the inlet orifice into the die cavity flow path to provide for a decreasing pressure gradient along the flow path direction, to provide for a variable density of the at least one particle component, the particle density increasing in the at least one flow path direction.

1 . A preform comprising:
 at least one reinforcement particle component, wherein the density of the at least one reinforcement particle component increases in a gradient in at least one flowed direction through the preform; and wherein   the preform is made using a method comprising:   providing a slurry comprising the at least one reinforcement particle component, and at least one liquid component;   providing a die cavity having at least one inlet opening or orifice and at least one exit opening or orifice defining at least one die cavity flow path therebetween directed toward the exit opening or orifice, the at least one exit opening or orifice suitably sized or configured to provide for exit of the at least one liquid component while impeding or blocking exit of the at least one reinforcement particle component; and   introducing the slurry under pressure, and for a sufficient time period, through the inlet orifice into the flow path of the die cavity to provide for a decreasing pressure gradient along the flow path direction, wherein during said introducing the at least one liquid component exits through the at least one exit orifice while the at least one reinforcement particle component is impeded or blocked from exiting through the at least one exit orifice, to provide a variable density of the at least one particle component with the particle density increasing in the gradient in the at least one flow path direction.   
     
     
         2 . An infiltration casting, comprising a preform according to  claim 1 . 
     
     
         3 . A brake rotor or drum comprising a preform according to  claim 1 . 
     
     
         4 . A preform comprising:
 at least one reinforcement particle component, wherein the density of the at least one reinforcement particle component increases in a gradient in at least one flowed direction through the preform;   wherein the preform is porous; and wherein   the preform is made using a method comprising:   providing a slurry comprising the at least one reinforcement particle component, and at least one liquid component;   providing a die cavity having at least one inlet opening or orifice and at least one exit opening or orifice defining at least one die cavity flow path therebetween directed toward the exit opening or orifice, the at least one exit opening or orifice suitably sized or configured to provide for exit of the at least one liquid component while impeding or blocking exit of the at least one reinforcement particle component;   introducing the slurry under pressure, and for a sufficient time period, through the inlet orifice into the flow path of the die cavity to provide for a decreasing pressure gradient along the flow path direction, wherein during said introducing the at least one liquid component exits through the at least one exit orifice while the at least one reinforcement particle component is impeded or blocked from exiting through the at least one exit orifice, to provide a variable density of the at least one particle component with the particle density increasing in the gradient in the at least one flow path direction;   drying the preform to remove residual amounts of the at least one liquid component; and   firing or sintering the dried preform by heating it to or at a temperature higher than the drying temperature; wherein   the slurry additionally comprises at least one fugitive or organic binder component, and firing comprises heating the dried preform to or at a temperature sufficient to effectively remove any residual amounts of the at least one fugitive or organic binder component.   
     
     
         5 . An infiltration casting, comprising a preform according to  claim 4 . 
     
     
         6 . A brake rotor or drum comprising a preform according to  claim 4 . 
     
     
         7 . A die casting apparatus for casting a preform from a slurry having at least one reinforcement particle component and at least one liquid component, comprising:
 a die cavity having at least one inlet opening or orifice and at least one exit opening or orifice defining at least one die cavity flow path therebetween directed toward the exit opening or orifice, the at least one exit opening or orifice suitably sized or configured to provide for exit of at least one liquid component of a slurry while impeding or blocking exit of at least one reinforcement particle component of the slurry.   
     
     
         8 . The apparatus of  claim 7 , wherein the die cavity comprises at least one centrally-positioned inlet orifice and at least one circumferentially or perimetrically-positioned exit orifice defining at least one radial flow path and direction. 
     
     
         9 . The apparatus of  claim 8 , wherein the circumference or perimeter of the die cavity comprises one or more exit openings or orifices that individually or collectively extend continuously or discontinuously around the circumference or perimeter of the die cavity to provide for a concentric radial flow path extending 360 degrees around the at least one centrally positioned inlet orifice, to provide for production of a variable-density preform with increasing particle density in the radial direction. 
     
     
         10 . The apparatus of  claim 7 , wherein the at least one exit opening or orifice is configured to comprise or be in fluid communication with a filtering element suitably sized or configured to provide for exit of at least one liquid component of a slurry while impeding or blocking exit of at least one reinforcement particle component of the slurry. 
     
     
         11 . The apparatus of  claim 8 , wherein the filtering element comprises a plurality of effluent flow channels in open or fluid communication with the filter to provide for variable effluent flow/psi. 
     
     
         12 . The apparatus of  claim 9 , wherein a plurality of the effluent flow channels can be individually configured to be in open or fluid communication with the filer element, and with the slurry flow path within the die cavity.