Honeycomb structure and manufacturing method thereof

Abstract

A honeycomb structure is made of cordierite and has a plurality of cells separated from each other by porous partition walls and functioning as fluid passages. The honeycomb structure has a thermal expansion coefficient of 0.25×10 −6 /° C. or less, an average pore diameter is 3 to 8 μm, and a porosity of 25% or more. The honeycomb structure is made of cordierite excellent in thermal shock resistance even with large pore diameters and high porosity.

1 . A honeycomb structure made of cordierite and having a plurality of cells separated from each other by porous partition walls and functioning as fluid passages, 
 wherein the honeycomb structure has a thermal expansion coefficient of 0.25×10 −6 /° C. or less, an average pore diameter is 3 to 8 μm, and a porosity of 25% or more.    
   
   
       2 . A honeycomb structure according to  claim 1 , wherein a thermal shock resistance temperature measured in a thermal shock resistance test is 800° C. or more.  
   
   
       3 . A honeycomb structure according to  claim 1 , wherein a thermal expansion coefficient is 0.2×10 −6 /° C. or less.  
   
   
       4 . A method for manufacturing a honeycomb structure, comprising the steps of: 
 forming clay containing cordierite-forming raw material satisfying the following conditions 1 and 2 in a honeycomb shape to obtain a formed body, and    drying and firing the formed body to obtain the honeycomb structure having a plurality of cells separated from each other by porous partition walls and functioning as fluid passages and a thermal expansion coefficient of 0.25×10 −6 /° C. or less, an average pore diameter is 3 to 8 μm, and a porosity of 25% or more:    Condition 1: An alumina source having a BET specific surface area of 10 m 2 /g or more is contained in an amount of 13 to 28% by mass.    Condition 2: Boehmite (Al 2 O 3 .H 2 O) having an average particle size of 1 μm or less is contained in at least a part of the alumina source at a ratio of 0.45 to 15.8% by mass with respect to the cordierite-forming raw material.    
   
   
       5 . A method for manufacturing a honeycomb structure according to  claim 4 , wherein the boehmite (Al 2 O 3 .H 2 O) has a BET specific surface area of 80 m 2 /g or more.  
   
   
       6 . A method for manufacturing a honeycomb structure according to  claim 4 , wherein the cordierite-forming raw material further contains 8% by mass or less of silica.  
   
   
       7 . A method for manufacturing a honeycomb structure according to  claim 4 , wherein the alumina source further contains alumina and/or aluminum hydroxide.  
   
   
       8 . A method for manufacturing a honeycomb structure according to  claim 4 , wherein the alumina source has a BET specific surface area of 20 m 2 /g or more.