Foundry media formed from slurry droplets and methods of use

Abstract

A foundry media pellet includes a sintered ceramic material having a size from about 10 AFS GFN to about 110 AFS GFN, and a surface roughness of less than about 4 microns.

What is claimed is: 
     
         1 . A casting mold, comprising:
 a plurality of pellets, each pellet of the plurality comprising:
 a sintered ceramic material having:
 a size from about 10 AFS GFN to about 110 AFS GFN, and 
 a surface roughness of less than about 4 microns; and 
 
 a resin coated onto the surface of the sintered ceramic material, the resin present in an amount of from 0.8% to about 1.35% based on the weight of each pellet. 
   
     
     
         2 . The casting mold of  claim 1 , wherein the sintered ceramic material has an average largest pore size of less than about 10 microns. 
     
     
         3 . The casting mold of  claim 1 , wherein the size is from about 30 AFS GFN to about 80 AFS GFN. 
     
     
         4 . The casting mold of  claim 1 , wherein the sintered ceramic material has a thermal expansion of less than 0.002 in/in at 1200° C. 
     
     
         5 . The casting mold of  claim 1 , wherein the resin comprises a phenolic resin, the resin having a transverse strength from about 160 psi to about 190 psi. 
     
     
         6 . The casting mold of  claim 1 , wherein a surface viscosity of the sintered ceramic material has a first peak that is greater than 4.01×10 10  Pa*s at a temperature of less than 1200° C. and a second peak that is greater than 4.01×10 10  Pa*s at a temperature of from about 1250° C. to about 1350° C., as calculated by thermal expansion determined by Dilatometry tests. 
     
     
         7 . The casting mold of  claim 1 , wherein the sintered ceramic material has a specific heat capacity of greater than 1.6 J/g ° C. at 1310° C. 
     
     
         8 . A green sand mold, comprising:
 a plurality of pellets, each pellet comprising:
 a sintered ceramic material having:
 a size from about 10 AFS GFN to about 110 AFS GFN, and 
 a surface roughness of less than about 4 microns; and 
 
   a clay; and   water,   the green sand mold having a green compression strength that is greater than 30 psi when the green sand mold has a clay content of 9 wt %.   
     
     
         9 . The green sand mold of  claim 1 , wherein the green sand mold has a dry compression strength that is greater than 50 psi. 
     
     
         10 . The green sand mold of  claim 1 , wherein the green sand mold has a shear strength of greater than 7.3 psi. 
     
     
         11 . The green sand mold of  claim 1 , wherein the green sand mold has a muller efficiency of greater than 84%. 
     
     
         12 . The green sand mold of  claim 1 , wherein the green sand mold has an AFS permeability of greater than 500. 
     
     
         13 . The green sand mold of  claim 1 , wherein the green sand mold has a mold hardness of greater than 93 on the B scale. 
     
     
         14 . The green sand mold of  claim 1 , wherein the green sand mold has a sinter temperature of greater than 2500° F. 
     
     
         15 . A method for forming a casting mold, comprising:
 providing a plurality of pellets, each pellet comprising:
 a sintered ceramic material formed from a blend of kaolin and bauxite and having:
 a thermal expansion of less than 0.002 in/in at 1200° C.; 
 a size from about 10 AFS GFN to about 110 AFS GFN, and 
 a surface roughness of less than about 4 microns; and 
 
   forming the pellets into a mold.   
     
     
         16 . The method of  claim 15 , further comprising coating each pellet with a resin to provide a plurality of foundry media pellets having a resin coating content of 0.8% to about 1.35% based on the weight of each foundry media pellet, prior to forming the pellets into the mold. 
     
     
         17 . The method of  claim 16 , wherein the resin comprises a phenolic resin. 
     
     
         18 . The method of  claim 15 , further comprising blending the pellets with a clay and water prior to forming the pellets into the mold, wherein the mold is a green sand mold. 
     
     
         19 . The method of  claim 18 , wherein the green sand mold has a green compression strength that is greater than 30 psi, as determined when the green sand mold has a clay content of 9 wt %. 
     
     
         20 . The method of  claim 19 , wherein the green sand mold comprises a dry compression strength that is greater than 50 psi, a green shear strength of greater than 7.3 psi, a muller efficiency of greater than 84%, and an AFS permeability of greater than 500.