Porous material, honeycomb structure, and method of producing porous material

Patent metadata

Field	Value
Publication number	US-11365665-B2
Application number	US-201715782064-A
Country	US
Kind code	B2
Filing date	Oct 12, 2017
Priority date	Oct 24, 2016
Publication date	Jun 21, 2022
Grant date	Jun 21, 2022

Abstract

A porous material includes an aggregate, and a binding material that binds the aggregate together in a state where pores are formed. The porous material contains 0.1 to 10.0 mass % of an MgO component, 0.5 to 25.0 mass % of an Al2O3 component, and 5.0 to 45.0 mass % of an SiO2 component with respect to the mass of the whole porous material, and further contains 0.01 to 5.5 mass % of an Sr component in terms of SrO.

First claim

The invention claimed is:

1. A porous material comprising:
an aggregate containing SiC particles as particle bodies; and
a binding material that binds said aggregate together in a state where pores are formed,
wherein said porous material contains 0.1 to 10.0 mass % of an MgO component, 0.5 to 25.0 mass % of an Al 2 O 3 component, and 22.6 to 45.0 mass % of an SiO 2 component with respect to a mass of said porous material as a whole,
said porous material further contains Sr which is determined as 0.01 to 5.5 mass % of SrO when measured by inductively coupled plasma emission spectroscopy and expressed in terms of SrO,
said porous material further contains Na or K as an alkali metal component,
Na is determined as 0.08 mass % or less of Na 2 O when measured by inductively coupled plasma emission spectroscopy and expressed in terms of Na 2 O, and
K is determined as less than 0.01 mass % of K 2 O when measured by inductively coupled plasma emission spectroscopy and expressed in terms of K 2 O, and
wherein an average value for an angle at which an edge of said binding material in a cross-section of said porous material rises with respect to a direction tangent to the edge at a measurement position at which curvature is locally a maximum is greater than 0 degrees and less than or equal to 25 degrees, said cross-section of said porous material being photographed at a magnification of 1500 times with a scanning electron microscope, said edge of said binding material being a boundary line between said binding material and a pore, an interface between a particle of said aggregate, said binding material and a pore being defined as a three-phase interface, said measurement position being a position which has a maximum curvature on said edge of said binding material between one three-phase interface with one particle of said aggregate and another three-phase interface with another particle of said aggregate, said average value being obtained from 10 measured values at 10 measurement positions.

2. The porous material according to claim 1 , wherein
said binding material contains 50 mass % or more of cordierite with respect to a mass of said binding material as a whole.

3. The porous material according to claim 1 , wherein
a ratio of a mass of said binding material to a mass of said porous material as a whole is in a range of 8 to 40 mass %.

4. The porous material according to claim 1 , wherein
a ratio of a mass of said alkali metal component in terms of an oxide is less than 0.1 mass % of said porous material as a whole.

5. The porous material according to claim 1 , wherein said aggregate further contains oxide films that are formed on surfaces of said particle bodies.

6. The porous material according to claim 5 , wherein
said oxide films contain cristobalite.

7. The porous material according to claim 5 , wherein said oxide films have a thickness of 0.3 to 5.0 μm.

8. The porous material according to claim 1 , wherein
at least part of Sr contained in said binding material exists as SrAl 2 Si 2 O 8 .

9. The porous material according to claim 8 , wherein
a ratio of a mass of said SrAl 2 Si 2 O 8 to a mass of said porous material as a whole is in a range of 0.1 to 10.0 mass %.

10. A honeycomb structure that is a tubular member made of the porous material according to claim 1 and having an interior partitioned into a plurality of cells by partition walls.

11. A method of producing a porous material, comprising:
a) obtaining a compact by molding a mixture of an aggregate raw material containing SiC particles as particle bodies, a raw material of binding material, and a pore forming material; and
b) obtaining a porous material by firing said compact, said porous material being a fired compact,
wherein said porous material contains 0.1 to 10.0 mass % of an MgO component, 0.5 to 25.0 mass % of an Al 2 O 3 component, and 22.6 to 45.0 mass % of an SiO 2 component with respect to a mass of said porous material as a whole,
said porous material further contains Sr which is determined as 0.01 to 5.5 mass % of SrO when measured by inductively coupled plasma emission spectroscopy and expressed in terms of SrO,
said porous material further contains Na or K as an alkali metal component,
Na is determined as 0.08 mass % or less of Na 2 O when measured by inductively coupled plasma emission spectroscopy and expressed in terms of Na 2 O, and
K is determined as less than 0.01 mass % of K 2 O when measured by inductively coupled plasma emission spectroscopy and expressed in terms of K 2 O, and
wherein an average value for an angle at which an edge of said binding material in a cross-section of said porous material rises with respect to a direction tangent to the edge at a measurement position at which curvature is locally a maximum is greater than 0 degrees and less than or equal to 25 degrees, said cross-section of said porous material being photographed at a magnification of 1500 times with a scanning electron microscope, said edge of said binding material being a boundary line between said binding material and a pore, an interface between a particle of said aggregate, said binding material and a pore being defined as a three-phase interface, said measurement position being a position which has a maximum curvature on said edge of said binding material between one three-phase interface with one particle of said aggregate and another three-phase interface with another particle of said aggregate, said average value being obtained from 10 measured values at 10 measurement positions.

Assignees

• Ngk Insulators Ltd

Inventors

• Izumi Yunie
• Tomita Takahiro

Classifications

• B01D2255/9155

  Wall flow filters · CPC title

• C04B2235/6584

  at an oxygen percentage below that of air · CPC title

• C04B2235/3481

  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 title

• F01N2330/06

  Ceramic, e.g. monoliths · CPC title

• C04B2235/656

  characterised by specific heating conditions during heat treatment · CPC title