Porous ceramic bodies and process for their preparation

Abstract

A process for producing a porous ceramic body may include: a) mixing a coated porogen with a silicate or an oxide ceramic precursor, wherein the porogen is decomposable to gaseous decomposition products and optionally solid products upon heating, and is coated with a coated agent; b) forming a green body from the mixture obtained in step (a); and c) firing the green body obtained in step (b) to obtain the ceramic body, whereby the porogen decomposes to form pores within the ceramic body, and the coating agent is deposited at the inner surface of the pores. The porogen may be coated with a coating agent which, upon firing, is deposited at the inner surface of the ceramic pores, so that porous ceramics having decreased weight and improved porosity are obtained, while maintaining good mechanical strength. A green body and porous ceramic body obtainable with the above-mentioned process are also described.

1 - 18 . (canceled) 
     
     
         19 . A porous ceramic body having total porosity of at least 10%, open porosity lower than 1.5% and closed porosity of at least 8.5%, wherein the inner surface of the pores is covered by the thermolysis product of a porogen coated with a coating agent. 
     
     
         20 . The porous ceramic body of  claim 19 , having total porosity ranging from 15 to 30%. 
     
     
         21 . The porous ceramic body of  claim 19 , having open porosity ranging from 0.01 to 1.0%. 
     
     
         22 . The porous ceramic body of  claim 19 , having closed porosity ranging from 19 to 24%. 
     
     
         23 . The porous ceramic body of  claim 19 , having an average pore diameter ranging from 10 to 500 μm. 
     
     
         24 . The porous ceramic body of  claim 19 , having bulk density lower than 2.4 g/cm 3 . 
     
     
         25 . The porous ceramic body of  claim 19 , having a bulk density reduction of at least 8%. 
     
     
         26 . The porous ceramic body of  claim 19 , having water absorption lower than 2% wt. 
     
     
         27 . The porous ceramic body of  claim 19 , wherein said pores are generally spherical in shape. 
     
     
         28 . The porous ceramic body of  claim 19 , wherein said pores are generally fiber-shaped. 
     
     
         29 . A porous ceramic body having total porosity of at least 10%, open porosity lower than 1.5%, and closed porosity of at least 8.5%, wherein the porous ceramic body has pores, and the inner surface of the pores is covered by a coating agent different than the ceramic comprising the ceramic body. 
     
     
         30 . The porous ceramic body of  claim 29 , having total porosity ranging from 15 to 30%. 
     
     
         31 . The porous ceramic body of  claim 29 , having open porosity ranging from 0.01 to 1.0%. 
     
     
         32 . The porous ceramic body of  claim 29 , having closed porosity ranging from 19 to 24%. 
     
     
         33 . The porous ceramic body of  claim 29 , having an average pore diameter ranging from 10 to 500 μm. 
     
     
         34 . The porous ceramic body of  claim 29 , having a bulk density lower than 2.4 g/cm 3 . 
     
     
         35 . The porous ceramic body of  claim 29 , having a bulk density reduction of at least 8%. 
     
     
         36 . The porous ceramic body of  claim 29 , having water absorption lower than 2% wt. 
     
     
         37 . The porous ceramic body of  claim 29 , wherein said pores are generally spherical in shape. 
     
     
         38 . The porous ceramic body of  claim 29 , wherein said pores are generally fiber-shaped. 
     
     
         39 . The porous ceramic body of  claim 29 , wherein said ceramic comprises an oxide ceramic. 
     
     
         40 . The porous ceramic body of  claim 29 , wherein said ceramic comprises alumina.