Coating material, outer periphery-coated silicon carbide-based honeycomb structure, and method for coating outer periphery of silicon carbide-based honeycomb structure

An outer periphery-coated silicon carbide-based honeycomb structure, comprising:

• a silicon carbide-based honeycomb structure including a plurality of cells forming a flow path for a fluid;
• and an outer periphery-coated layer covering an outer periphery of the silicon carbide-based honeycomb structure,
• wherein the outer periphery-coated layer comprises from 20 to 75% by mass of ceramic powder (A), the ceramic powder (A) comprising from 55 to 95% by mass of silicon carbide and from 5 to 30% by mass of silicon dioxide as chemical components, and
• wherein the ceramic powder (A) has a D10 on a volume basis of from 1 to 4 μm, a D50 on a volume basis of from 8 to 30 μm, and a D90 of from 20 to 75 μm (D90>D50), based on a particle size distribution measurement by a laser diffraction/scattering method, and
• wherein a ratio of a thermal expansion coefficient of the outer periphery-coated layer to a thermal expansion coefficient of the silicon carbide-based honeycomb structure is from 0.8 to 1.1, and
• wherein the thermal expansion coefficients of the outer periphery-coated layer and the silicon carbide-based honeycomb structure are determined by measuring average linear thermal expansion coefficient at a temperature of from 40 to 800° C. in a direction parallel to the flow path of the silicon carbide-based honeycomb structure.