Ceramic honeycomb structure and its production method

• US 9,981,255 B2
• Filed: 03/31/2014
• Issued: 05/29/2018
• Est. Priority Date: 04/02/2013
• Status: Active Grant

• Current Assignee: Hitachi Metals (Thailand) Ltd.
• Original Assignee: Hitachi Metals (Thailand) Ltd.
• Inventors: Okazaki, Shunji
• Primary Examiner(s): Jordan, Nicholas W.
• Application Number:
  US14/765,871
• Publication Number:
  US 20150367335A1
• Time in Patent Office: 1,520 Days
• Field of Search: None
• CPC Class Codes: B01J 23/63 with rare earths or actinides
• CPC Class Codes: B01J 29/70 of types characterised by their specific structure not provided for in groups B01J29/08 - B01J29/65
• CPC Class Codes: B01J 35/56 Foraminous structures having flow-through passages or channels, e.g. grids or three-dimensional monoliths
• CPC Class Codes: B01J 35/60 characterised by their surface properties or porosity
• CPC Class Codes: B01J 37/0018 Addition of a binding agent or of material, later completely removed among others as result of heat treatment, leaching or washing,(e.g. forming of pores; protective layer, desintegrating by heat)
• CPC Class Codes: B01J 37/04 Mixing B01J37/0009, B01J37/0018 take precedence
• CPC Class Codes: B01J 37/082 Decomposition and pyrolysis
• CPC Class Codes: C04B 2235/3206 Magnesium oxides or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3217 Aluminum oxide or oxide forming salts thereof, e.g. bauxite, alpha-alumina
• CPC Class Codes: C04B 2235/3222 Aluminates other than alumino-silicates, e.g. spinel (MgAl2O4)
• CPC Class Codes: C04B 2235/3418 Silicon oxide, silicic acids or oxide forming salts thereof, e.g. silica sol, fused silica, silica fume, cristobalite, quartz or flint
• CPC Class Codes: C04B 2235/3463 Alumino-silicates other than clay, e.g. mullite
• CPC Class Codes: C04B 2235/3481 Alkaline earth metal alumino-silicates other than clay, e.g. cordierite, beryl, micas such as margarite, plagioclase feldspars such as anorthite, zeolites such as chabazite
• CPC Class Codes: C04B 2235/349 Clays, e.g. bentonites, smectites such as montmorillonite, vermiculites or kaolines, e.g. illite, talc or sepiolite
• CPC Class Codes: C04B 2235/5436 micrometer sized, i.e. from 1 to 100 micron
• CPC Class Codes: C04B 2235/5463 Particle size distributions
• CPC Class Codes: C04B 2235/6021 Extrusion moulding
• CPC Class Codes: C04B 2235/6562 Heating rate
• CPC Class Codes: C04B 2235/6565 Cooling rate
• CPC Class Codes: C04B 2235/80 Phases present in the sintered or melt-cast ceramic products other than the main phase
• CPC Class Codes: C04B 2235/96 : Properties of ceramic products, e.g. mechanical properties such as strength, toughness, wear resistance
• CPC Class Codes: C04B 2235/9607 : Thermal properties, e.g. thermal expansion coefficient
• CPC Class Codes: C04B 35/195 : Alkaline earth aluminosilicates, e.g. cordierite or anorthite
• CPC Class Codes: C04B 38/0006 : Honeycomb structures from one or more corrugated sheets by winding or stacking C04B38/0083
• CPC Class Codes: C04B 38/0054 : the pores being microsized or nanosized
• CPC Class Codes: C04B 38/0074 : expressed as porosity percentage
• CPC Class Codes: Y10T 428/24149 : Honeycomb-like

Abstract

A ceramic honeycomb structure comprising large numbers of cells partitioned by porous cell walls, the cell walls having (a) porosity of 50-80%, and when measured by mercury porosimetry, (b) a median pore diameter being 25-50 μm, (c) (i) a cumulative pore volume in a pore diameter range of 20 μm or less being 25% or less of the total pore volume, (ii) a cumulative pore volume in a pore diameter range of more than 20 μm and 50 μm or less being 50% or more of the total pore volume, and (iii) a cumulative pore volume in a pore diameter range of more than 50 μm being 12% or more of the total pore volume.

Claims

1. A ceramic honeycomb structure comprising a plurality of cells partitioned by porous cell walls, said cell walls having

(a) porosity of 50-80%;

and

when measured by mercury porosimetry,

(b) a median pore diameter being 25-50 μ

m;

(c) (i) a cumulative pore volume in a pore diameter range of 20 μ

m or less being 25% or less of the total pore volume;

(ii) a cumulative pore volume in a pore diameter range of more than 20 μ

m and 50 μ

m or less being 50% or more of the total pore volume; and

(iii) a cumulative pore volume in a pore diameter range of more than 50 μ

m being 12% or more of the total pore volume;

wherein an opening area ratio of pores open on said cell wall surfaces (a total opening area of pores per a unit cell wall surface area) is 30% or more; and

wherein said ceramic honeycomb structure has an A-axis compression strength of 1.0 MPa or more.

2. The ceramic honeycomb structure according to claim 1, wherein pores open on said cell wall surfaces have a median opening diameter (expressed by an equivalent circle diameter) of 60 μ

m or more.

3. The ceramic honeycomb structure according to claim 1, wherein a cumulative opening area of pores open on said cell wall surfaces, which have opening diameters (each expressed by an equivalent circle diameter) of 30 μ

m or less, is 20% or less of the total opening area.

4. The ceramic honeycomb structure according to claim 1, wherein a cumulative opening area of pores open on said cell wall surfaces, which have opening diameters (each expressed by an equivalent circle diameter) of 100 μ

m or more, is 30-70% of the total opening area.

5. The ceramic honeycomb structure according to claim 1, wherein said cell walls have permeability of 10×

10<sup>−

12</sup> m² to 30×

10<sup>−

12</sup> m².