Honeycomb ceramic substrates, honeycomb extrusion dies, and methods of making honeycomb ceramic substrates

Abstract

A honeycomb ceramic substrate, a method of making thereof, and a honeycomb extrusion die configured to extrude a honeycomb ceramic substrate from a batch of ceramic or ceramic-forming material is provided. The substrate may include a lattice of intersecting walls defining a honeycomb network of flow channels extending between an inlet end and an outlet end of the honeycomb substrate. Each flow channel may be defined by a plurality of channel walls of the intersecting walls with at least two of the plurality of channel walls including concave inner surfaces facing a center of the corresponding flow channel from central portions of the concave inner surfaces to concave corner portions facing the center of the corresponding flow channel.

What is claimed is: 
     
         1 . A honeycomb extrusion die configured to extrude a honeycomb ceramic substrate from a batch of ceramic or ceramic-forming material, the honeycomb extrusion die comprising:
 a plurality of die pins arranged in a matrix and spaced from one another to define a lattice of intersecting slots defined between the die pins at an outer face of the die pins, wherein an outer periphery at the outer face of at least one of the die pins includes a plurality of sides joined by corresponding corner portions with at least two convex sides facing away from a center of the corresponding die pin, and wherein at least one corner portion is convex facing away from the center of the corresponding die pin.   
     
     
         2 . The honeycomb extrusion die of  claim 1 , wherein (i) two adjacent die pins of the plurality of die pins comprise facing sides that at least partially define a wall slot and (ii) each facing side is convex facing away from a center of the corresponding adjacent die pin. 
     
     
         3 . The honeycomb extrusion die of  claim 1 , wherein (i) at least one wall slot is defined between facing sides of two adjacent die pins of the plurality of die pins, (ii) each of the facing sides are convex facing each other from central portions thereof to corresponding corner portions of the facing sides, and (iii) the at least one wall slot is concave toward central portions of the two adjacent die pins. 
     
     
         4 . The honeycomb extrusion die of  claim 1 , wherein a shape of the outer periphery of the outer face of the at least one of the die pins is substantially defined by the equation: 
       
         
           
             
               
                 
                   
                     
                        
                       
                         x 
                         a 
                       
                        
                     
                     n 
                   
                   + 
                   
                     
                        
                       
                         y 
                         b 
                       
                        
                     
                     m 
                   
                 
                 = 
                 1 
               
               , 
             
           
         
         wherein a and b are rectangular-fitted half-lengths along an x direction and a y direction, respectively, of the sides of the die pins on either side of a y axis and an x axis, respectively, 
         wherein x and y represent coordinates (x, y) of the sides of the die pins in the x direction and the y direction, respectively, 
         wherein −a≦x≦a, 
         wherein −b≦y≦b, and 
         wherein n and m are exponents defining a degree of curvature of the sides of the die pins. 
       
     
     
         5 . The honeycomb extrusion die of  claim 4 , wherein at least one of n and m is in a range of from about 2.5 to about 10. 
     
     
         6 . The honeycomb extrusion die of  claim 4 , wherein a and b are independently in a range of from about 330 microns to about 1.829 mm. 
     
     
         7 . The honeycomb extrusion die of  claim 4 , wherein n and m are varied across the plurality of the die pins. 
     
     
         8 . The honeycomb extrusion die of  claim 1 , wherein the sides of each of the die pins are symmetric to each other. 
     
     
         9 . The honeycomb extrusion die of  claim 1 , wherein the sides of each of the die pins are continuously curved around the center of the corresponding die pin. 
     
     
         10 . A honeycomb extrusion die configured to extrude a honeycomb ceramic substrate from a batch of ceramic or ceramic-forming material, the honeycomb extrusion die comprising:
 a plurality of die pins arranged in a matrix and spaced from one another to define a lattice of intersecting slots defined between the die pins at an outer face of the die pins, wherein (i) an outer periphery at the outer face of each of the plurality of die pins includes a plurality of sides joined by corresponding corner portions, (ii) two adjacent die pins of the plurality of die pins comprise facing sides that at least partially define a wall slot, and (iii) each facing side is convex facing away from a center of the corresponding adjacent die pin.   
     
     
         11 . The honeycomb extrusion die of  claim 10 , wherein each of the adjacent die pins comprises a plurality of sides joined by corresponding corner portions with at least two convex sides facing away from a center of the corresponding adjacent die pin, and wherein at least one corner portion is convex facing away from the center of the corresponding adjacent die pin. 
     
     
         12 . The honeycomb extrusion die of  claim 11 , wherein each of the adjacent die pins comprises a plurality of four convex sides joined by four corresponding convex corner portions with the four convex sides and the four corresponding corner portions each facing away from the center of the corresponding adjacent die pin. 
     
     
         13 . The honeycomb extrusion die of  claim 10 , wherein a shape of the outer periphery of the outer face of the adjacent die pins is substantially defined by the equation: 
       
         
           
             
               
                 
                   
                     
                        
                       
                         x 
                         a 
                       
                        
                     
                     n 
                   
                   + 
                   
                     
                        
                       
                         y 
                         b 
                       
                        
                     
                     m 
                   
                 
                 = 
                 1 
               
               , 
             
           
         
         wherein a and b are rectangular-fitted half-lengths along an x direction and a y direction, respectively, of the sides of the adjacent die pins on either side of a y axis and an x axis, respectively, 
         wherein x and y represent coordinates (x, y) of the sides of the adjacent die pins in the x direction and the y direction, respectively, 
         wherein −a≦x≦a, 
         wherein −b≦y≦b, and 
         wherein n and m are exponents defining a degree of curvature of the sides of the adjacent die pins. 
       
     
     
         14 . The honeycomb extrusion die of  claim 13 , wherein at least one of n and m is in a range of from about 2.5 to about 10. 
     
     
         15 . The honeycomb extrusion die of  claim 13 , wherein a and b are independently in a range of from about 330 microns to about 1.829 mm. 
     
     
         16 . The honeycomb extrusion die of  claim 13 , wherein n and m are varied across the plurality of the adjacent die pins. 
     
     
         17 . The honeycomb extrusion die of  claim 9 , wherein the sides of each of the adjacent die pins are symmetric. 
     
     
         18 . The honeycomb extrusion die of  claim 9 , wherein the sides of each of the adjacent die pins are continuously curved around the center of the corresponding adjacent die pin.