Ceramic honeycomb structure with grooves and outer coating, process of producing the same, and coating material used in the honeycomb structure

A ceramic honeycomb structure comprising:

• a ceramic honeycomb body having a matrix of partition walls forming a multiplicity of cells extending in an axial direction of the honeycomb body, a radially outermost array of said multiplicity of cells being open to an outside of the honeycomb body in radial directions thereof, to provide a plurality of grooves formed in an outer periphery of the honeycomb body so as to extend in said axial direction;
• and
• an outer coating which fills at least said grooves to cover said outer periphery of said ceramic honeycomb body, so as to provide an outer surface of the honeycomb structure, said outer coating consisting essentially of cordierite particles and a matrix of an amorphous oxide for bonding the cordierite particles together, said cordierite particles having an average particle size not larger than 50 .mu.m, wherein said matrix of an amorphous oxide is formed from one of colloidal silica and colloidal alumina, and wherein said coating contains 3-35 parts by weight of said matrix of an amorphous oxide per 100 parts by weight of said cordierite particles.

A ceramic honeycomb structure comprising:

• a ceramic honeycomb body having a matrix of partition walls forming a multiplicity of cells extending in an axial direction of the honeycomb body, a radially outermost array of said multiplicity of cells being open to an outside of the honeycomb body in radial directions thereof, to provide a plurality of grooves formed in an outer periphery of the honeycomb body so as to extend in said axial direction;
• and
• an outer coating which fills at least said grooves to cover said outer periphery of said ceramic honeycomb body, so as to provide an outer surface of the honeycomb structure, said outer coating consisting essentially of ceramic fibers and a matrix of an amorphous oxide for bonding the ceramic fibers together, said ceramic fibers having a fiber length of 10-15 .mu.m and a fiber diameter of 2-3 .mu.m, said matrix of an amorphous oxide being formed from one of colloidal silica and colloidal alumina, and said outer coating containing 3-35 parts by weight of said matrix of an amorphous oxide per 100 parts by weight of said ceramic fibers.