Honeycomb structure

A honeycomb structure comprising:

• a pillar-shaped honeycomb structure body having porous partition walls defining a plurality of cells extending from an inflow end face to an outflow end face to become through channels for fluid;
• and
• a circumferential coating layer formed separately from the porous partition walls and disposed to surround a circumference of the honeycomb structure body, so as to form an interface between the circumferential coating layer and the circumference of the honeycomb structure body,
• wherein the cells which are formed at an outermost circumference of the honeycomb structure body and in which peripheries of the cells are defined by the partition walls without any lacks and the circumferential coating layer does not penetrate inner portions of the cells are defined as outermost circumference complete cells,
• in a cross section of the honeycomb structure body which is perpendicular to an extending direction of the cells, a smallest distance T (mm) among distances from the outermost circumference complete cells to the surface of the circumferential coating layer and a porosity P (%) of the circumferential coating layer satisfy relations of Equation (1) and Equation (2) as follows:
• 1.5≥T≥16×(100−P)−1.4;
• and Equation (1):
• 20≤P≤75, and Equation (2):
• in a cross section of the circumferential coating layer, a total area Sp (μm2) of pores formed in the circumferential coating layer and a total peripheral length Lp (μm) of the pores formed in the circumferential coating layer further satisfy a relation of Equation (4) as follows:
• 4×Sp/Lp≤45 Equation (4).