Production method of ceramic honeycomb structure, and ceramic honeycomb structure

A ceramic honeycomb structure comprising a ceramic honeycomb body having a plurality of longitudinal cells partitioned by porous cell walls, and a peripheral wall formed on a peripheral surface of said ceramic honeycomb body, wherein said ceramic honeycomb body has longitudinal grooves coated with a colloidal metal oxide on the peripheral surface;

• wherein said peripheral wall fills said longitudinal grooves coated with the colloidal metal oxide, so that not only cell walls constituting said grooves, but also cell walls radially inward of the cell walls constituting said grooves, have a smaller porosity than that of cell walls in an inner portion of said ceramic honeycomb body, and wherein the porosity of the cell walls radially inward of the cell walls constituting said grooves becomes gradually larger or stepwisely larger radially inward from the peripheral surface.

A ceramic honeycomb structure comprising a ceramic honeycomb body having a plurality of longitudinal cells partitioned by porous cell walls, and a peripheral wall formed on a peripheral surface of said ceramic honeycomb body, wherein said ceramic honeycomb body has longitudinal grooves on the peripheral surface;

• wherein said peripheral wall fills said longitudinal grooves, so that cell walls constituting said grooves on the peripheral surface have a smaller porosity than that of cell walls in an inner portion of said ceramic honeycomb body;
• wherein the peripheral wall comprises (i) a colloidal metal oxide layer consisting of a colloidal metal oxide having a particle size of 5-100 nm on the grooves on the peripheral surface and (ii) a coating comprising ceramic particles having an average particle size of 1 μm or more on the colloidal metal oxide layers;
• and wherein the ceramic honeycomb structure does not have crack-like voids open on an outer surface of the peripheral wall or gaps between the ceramic honeycomb body and the peripheral wall.