HONEYCOMB STRUCTURE AND METHOD FOR PRODUCING A HONEYCOMB STRUCTURE

Abstract

A honeycomb structure (1) comprising: one end face (21); the other end face (22); a plurality of partition walls (23) extending in the axial direction (20) from one end face (21) to the other end face (22); and a plurality of cell closures provided at one end face (21) and the other end face (22). The plurality of partition walls (23) forms a plurality of cells (24), each of which is a space extending in the axial direction (20) and arranged two-dimensionally as viewed in the axial direction (20). The plurality of cell closures close openings of some of the plurality of cells (24) in the one end face (21) and openings of the remaining cells (24) of the plurality of cells (24) in the other end face (22). The plurality of partition walls (23) is formed of a porous material consisting predominantly of cordierite.each partition (23) between adjacent cells (24) contains surface layer sections (32) with a porosity of 50% or more and an inner section (33) with a porosity of 50% or more, wherein the surface layer sections (32) are sections each extending from opposite surfaces to a depth corresponding to 25% of a thickness of the partition (23), and the inner section (33) is the other section, the surface layer sections (32) contain pores with axial pore widths of less than 30 µm and pores with axial pore widths of 30 µm or more, wherein the axial pore widths are the widths of the pores in the axial direction (20) in a binary image of a section parallel to the axial direction (20), wherein the inner section (33) contains pores with an axial pore width of less than 30 µm and pores with an axial pore width of 30 µm or more,a mean axial pore width in the surface layer sections (32) is smaller than a mean axial pore width in the inner section, wherein the mean axial pore widths are the mean pore widths in the axial direction (20) in the binary image, the mean axial pore widths gradually decrease from the center of the partition wall (23) towards the surfaces.,

Claims

[1] Honeycomb structure (1), comprising: an end face (21); the other end face (22); a plurality of partition walls (23) extending in the axial direction (20) from one end face (21) to the other end face (22); and a plurality of cell closures provided on one end face (21) and the other end face (22), wherein the plurality of partition walls (23) forms a plurality of cells (24), each of which is a space extending in the axial direction (20) and arranged two-dimensionally as seen in the axial direction (20), the plurality of cell closures closes openings of some of the plurality of cells (24) in one end face (21) and openings of the remaining cells (24) of the plurality of cells (24) in the other end face (22), the plurality of partition walls (23) are formed from a porous material consisting predominantly of cordierite, each partition wall (23) between adjacent cells (24) contains surface layer sections (32) with a porosity of 50% or more and an inner section (33) with a porosity of 50% or more, wherein the surface layer sections (32) are sections each extending from opposite surfaces to a depth corresponding to 25% of a thickness of the partition wall (23), and the inner section (33) is the other section, the surface layer sections (32) contain pores with axial pore widths of less than 30 µm and pores with axial pore widths of 30 µm or more, wherein the axial pore widths are the widths of the pores in the axial direction (20) in a binary image of a section parallel to the axial direction (20), wherein the inner portion (33) contains pores having an axial pore width of less than 30 µm and pores having an axial pore width of 30 µm or more, a mean axial pore width in the surface layer sections (32) is smaller than a mean axial pore width in the inner section, the mean axial pore widths being the mean pore widths in the axial direction (20) in the binary image, the mean axial pore widths gradually decrease from the center of the partition wall (23) towards the surfaces. [2] Honeycomb structure (1) according to claim 1, wherein Nsp10 > Nip10 and Nsp50 < Nip50 are met, where Nsp10 is a percentage of the number of pore widths of less than 10 µm in a distribution of axial pore widths in the surface layer sections (32), Nsp50 is a percentage of the number of pore widths of 50 µm or more in the distribution in the surface layer sections (32), Nip10 is a percentage of the number of pore widths of less than 10 µm in a distribution of axial pore widths in the inner section (33), and Nip50 is a percentage of the number of pore widths of 50 µm or more in the distribution in the inner section (33). [3] The honeycomb structure (1) according to claim 2, wherein Nsp10 - Nip10 ≥ 5 and Nsp50 - Nip50 ≤ -4 are further satisfied. [4] The honeycomb structure (1) according to claim 2 or 3, wherein -30 ≤ Nsp50 - Nip50 ≤ -4 are further satisfied. [5] Honeycomb structure (1) according to any one of claims 2 to 4, wherein Nsp10 ≥ 45 and Nip50 ≥ 5 are further satisfied. [6] The honeycomb structure (1) according to any one of claims 1 to 5, wherein the average axial pore width of pores having an axial pore width of 1 µm or more and 250 µm or less in the inner portion (33) is larger than the average axial pore width of pores having an axial pore width of 1 µm or more and 250 µm or less in the surface layer portions (32). [7] Honeycomb structure (1) according to one of claims 1 to 6, wherein the average axial pore width in the inner portion (33) is 17 µm or more. [8] The honeycomb structure (1) according to claim 7, wherein the average axial pore width in the inner portion (33) is 20 µm or more. [9] Honeycomb structure (1) according to one of claims 1 to 8, wherein the axial pore widths in the surface layer sections (32) are 100 µm or less, and the axial pore widths in the inner portion (33) are 250 µm or less. [10] The honeycomb structure (1) according to any one of claims 1 to 9, wherein the average axial pore width of pores having an axial pore width of 50 µm or more in the inner portion (33) is larger than another average pore width in a direction perpendicular to the axial direction (20), the another average pore width being an average pore width of pores having a pore width of 50 µm or more in the direction perpendicular to the axial direction (20) in the inner portion (33). [11] Method for producing a honeycomb structure (1), wherein the honeycomb structure (1) comprises: an end face (21); the other end face (22); a plurality of partition walls (23) extending in the axial direction (20) from one end face (21) to the other end face (22); and a plurality of cell closures provided on one end face (21) and the other end face (22), wherein the plurality of partition walls (23) forms a plurality of cells (24), each of which is a space extending in the axial direction (20) and arranged two-dimensionally as seen in the axial direction (20), the plurality of cell closures closes openings of some of the plurality of cells (24) in one end face (21) and openings of the remaining cells (24) of the plurality of cells (24) in the other end face (22), and the plurality of partition walls (23) are formed of porous cordierite, the method for producing the honeycomb structure (1), comprising: Kneading a cordierite raw material containing a small pore-forming material and a large pore-forming material to produce a kneaded material while maintaining a state in which the small pore-forming material flocculates; Forming a honeycomb body from the kneaded material by extrusion; Drying the honeycomb molded body; Providing a plurality of cell closures on the honeycomb molded body; and Firing the honeycomb molded body.

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