Curable slurry for forming ceramic microstructures on a substrate using a mold

Abstract

A curable slurry for forming ceramic microstructures on a substrate using a mold. The slurry is a mixture of a ceramic powder, a fugitive binder, and a diluent. The ceramic powder has a low softening temperature in a range of about 400° C. to 600° C. and a coefficient of thermal expansion closely matched to that of the substrate. The fugitive binder is capable of radiation curing, electron beam curing, or thermal curing. The diluent promotes release properties with the mold after curing the binder or quick and complete burn out of the binder during debinding.

1. A curable paste for patterning microstructures on a substrate using a mold, the paste comprising a mixture of:
 a ceramic powder;  
 a crosslinkable binder comprising an acrylic resin; and  
 a diluent comprising butane diol, the diluent to resin ration  being about 1:3 or greater.  
 
     
     
       2. The curable paste of  claim 1 , further comprising a silane coupling agent. 
     
     
       3. The curable paste of  claim 1 , further comprising TiO 2  particles mixed therein. 
     
     
       4. The curable paste of  claim 1 , wherein the binder includes a cure initiator capable of being activated by exposure to blue light. 
     
     
       5. The curable paste of  claim 1 , wherein the ceramic powder is substantially free of alkali metals. 
     
     
       6. The curable paste of  claim 1 , wherein the ceramic powder is substantially free of lead. 
     
     
       7. The curable paste of  claim 1 , wherein the binder is crosslinkable by exposure to visible light. 
     
     
       8. A method of forming ceramic microstructures comprising:
   providing a mold with a microstructured surface;        placing a slurry between the microstructured surface of the mold and a surface of a substrate so that the slurry substantially fills the microstructured surface of the mold;        hardening the slurry by radiation curing, electron beam curing, thermal curing, or cooling from a melted state to produce green state material adhered to the substrate, wherein the slurry comprises a ceramic powder, a binder, and a diluent that phase separates from the binder when the binder is hardened; and        removing the mold.     
     
     
       9. The method of  claim 8  wherein the diluent is present at greater than about  1 : 3  diluent to binder ratio. 
     
     
       10. The method of  claim 8  wherein the binder is selected from the group of materials consisting of acrylates and epoxies. 
     
     
       11. The method of  claim 10  wherein the binder is an acrylate. 
     
     
       12. The method of  claim 8  wherein the slurry is hardened by curing and the diluent is soluble in the binder prior to curing and remains liquid after curing. 
     
     
       13. The method of  claim 8  wherein the slurry is hardened by radiation curing. 
     
     
       14. The method of  claim 13  wherein the ceramic powder comprises titania. 
     
     
       15. The method of  claim 14  wherein the slurry comprises a cure initiator which is activated by radiation and can simultaneously propagate through the substrate and the titania particles. 
     
     
       16. The method of  claim 13  wherein the slurry comprises a cure initiator that is active in the blue region. 
     
     
       17. The method of  claim 13  wherein the ceramic powder is present in an amount ranging from about  40  to  96 %  by weight, the binder is present in an about of about  2  to  50   %  by weight, and the diluent is present in an amount of about  2  to  50   %  by weight.   
     
     
       18. A curable paste for patterning microstructures on a substrate using a mold, the paste comprising a mixture of:
   a ceramic powder;        a fugitive binder capable of being hardened by radiation curing, electron beam curing, thermal curing, or cooling from a melted state; and        a diluent that phase separates from the binder when the binder is hardened.     
     
     
       19. The curable paste of  claim 18  wherein the diluent is present at greater than about  1 : 3  diluent to binder ratio. 
     
     
       20. The curable paste of  claim 18  wherein the diluent is soluble in the binder prior to curing and remains liquid after curing.