Compositions and methods for making ceramic plates

Abstract

Compositions and methods of making ceramic plates are described. The compositions are water-based slurries that include filler material, one or more clay components, one or more strength or processing additives, and/or a carbon source. The filler material can include a first grade of boron carbide having a relatively large average particle size, a second grade of boron carbide having an intermediate average particle size, a third grade of boron carbide having a fine average particle size, and/or a silicon carbide having a fine average particle size. The methods of the invention involve casting and drying the slurry to make a substantially dry preform, providing a silicon loaf having a solid form for supporting one or more preforms, placing the substantially dry preform on top of the silicon loaf inside of an infiltration furnace and heating the substantially dry preform and loaf to melt silicon within the loaf and infiltrate the perform to create a ceramic plate.

1 - 20 . (canceled) 
     
     
         21 . A silicon loaf for use in infiltrating of reaction bonded or siliconized products, the loaf comprising:
 a major proportion of silicon;   a minor proportion of a first bonding agent;   a minor proportion of a first boron carbide;   a minor proportion of a second boron carbide; and   water.   
     
     
         22 . The loaf of  claim 21  wherein the silicon comprises silicon metal fragments and silicon powder. 
     
     
         23 . The loaf of  claim 21  wherein the silicon comprises, by weight, less than 0.07% calcium, less than 0.5% iron, and less than 0.20% aluminum. 
     
     
         24 . The loaf of  claim 21  wherein the first bonding agent comprises a high temperature bonding agent. 
     
     
         25 . The loaf of  claim 24  wherein the first bonding agent comprises carbon black. 
     
     
         26 . The loaf of  claim 21  wherein the first boron carbide consists of, by weight, at least 50% particles that are between about 5 microns and about 20 microns. 
     
     
         27 . The loaf of  claim 26  wherein the second boron carbide consists of, by weight, at least 50% particles that are larger than about 40 microns. 
     
     
         28 . The loaf of  claim 26  further comprising a minor proportion of a second bonding agent. 
     
     
         29 . The loaf of  claim 28  wherein the second bonding agent comprises a low temperature bonding agent. 
     
     
         30 . The loaf of  claim 29  wherein the second bonding agent comprises potato starch.