[go: up one dir, main page]

WO2025197973A1 - Corps poreux d'alumine, filtre céramique et procédé de production d'un corps poreux d'alumine - Google Patents

Corps poreux d'alumine, filtre céramique et procédé de production d'un corps poreux d'alumine

Info

Publication number
WO2025197973A1
WO2025197973A1 PCT/JP2025/010767 JP2025010767W WO2025197973A1 WO 2025197973 A1 WO2025197973 A1 WO 2025197973A1 JP 2025010767 W JP2025010767 W JP 2025010767W WO 2025197973 A1 WO2025197973 A1 WO 2025197973A1
Authority
WO
WIPO (PCT)
Prior art keywords
porous body
alumina porous
mass
particles
alumina
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
PCT/JP2025/010767
Other languages
English (en)
Japanese (ja)
Inventor
佳奈 井畑
憲一 日高
明日美 永井
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
NGK Insulators Ltd
Original Assignee
NGK Insulators Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by NGK Insulators Ltd filed Critical NGK Insulators Ltd
Publication of WO2025197973A1 publication Critical patent/WO2025197973A1/fr
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D39/00—Filtering material for liquid or gaseous fluids
    • B01D39/14—Other self-supporting filtering material ; Other filtering material
    • B01D39/20—Other self-supporting filtering material ; Other filtering material of inorganic material, e.g. asbestos paper, metallic filtering material of non-woven wires
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
    • C04B35/10—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on aluminium oxide
    • C04B35/111—Fine ceramics
    • C04B35/117—Composites
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B38/00—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof

Definitions

  • the present invention relates to an alumina porous body, a ceramic filter, and a method for producing an alumina porous body.
  • a typical ceramic filter comprises a substrate (i.e., support), which is a porous body in which aggregate particles made of ceramic particles such as alumina are bonded together by a binder phase, and a porous membrane (i.e., filtration membrane) laminated on the surface of the substrate and having an average pore diameter smaller than that of the substrate.
  • Chemical washing is a cleaning process that uses a chemical solution suitable for dissolving suspended solids, etc., and is usually carried out to dissolve and remove suspended solids that have accumulated over a long period of time.
  • chemical solutions include alkaline solutions such as aqueous sodium hydroxide solutions, or acidic solutions such as aqueous citric acid solutions.
  • Backwashing is a cleaning process that, contrary to normal filtration processes, applies pressure to the fluid flow from the fluid permeation side of the ceramic filter to the supply side of the fluid being treated, removing suspended solids that have clogged the pores and discharging them outside the system. Backwashing is usually carried out to remove suspended solids that have accumulated over a short period of time. Backwashing is carried out between filtration processes, for example, every few minutes to several hours.
  • the strength of the substrate decreases due to the repeated chemical washing and backwashing described above. Specifically, the chemicals used during chemical washing chemically erode the binder phase of the substrate, reducing the bonding strength between the aggregate particles. In addition, backwashing is performed at a higher pressure than during normal filtration processes, which also causes physical erosion of the binder phase. As a result, the strength of the entire substrate and the entire ceramic filter decreases.
  • Japanese Patent Laid-Open No. 2010-228946 proposes that alumina, which has high corrosion resistance against chemical solutions, be used as the main component of the binder phase in an alumina-based porous body used in a ceramic filter.
  • Japanese Patent Laid-Open No. 2010-228948 proposes that titania, which has high corrosion resistance against chemical solutions, be used as the main component of the binder phase in an alumina-based porous body used in a ceramic filter.
  • the alumina porous bodies described in References 1 and 2 use relatively expensive materials such as copper (Cu) and manganese (Mn) as sintering aids, which increases the manufacturing costs of the alumina porous bodies. There is also a risk that the copper and other materials may contaminate the firing furnace.
  • Cu copper
  • Mn manganese
  • the strength of the alumina porous body may be reduced. Furthermore, if the amount of raw material for the binder phase is increased or the particle size of the raw material for the aggregate particles is reduced in an attempt to prevent a decrease in the strength of the alumina porous body, the porosity and average pore diameter of the alumina porous body may become excessively small, and the alumina porous body may not meet the performance requirements for use as a substrate for a ceramic filter, etc.
  • the present invention is directed to an alumina porous body, and aims to increase the strength of an alumina porous body having a desired porosity and average pore diameter.
  • a first aspect of the invention is an alumina porous body comprising Al2O3 and TiO2 .
  • the TiO2 content is 10% by mass or more and 40% by mass or less.
  • the porosity is 10% by mass or more and 45% by mass or less.
  • the average pore diameter is 2 ⁇ m or more and 12 ⁇ m or less.
  • the bonding ratio between the Al2O3 particles and the TiO2 domains is 5% or more.
  • the strength of alumina porous bodies can be increased.
  • Aspect 2 of the invention is an alumina porous body according to aspect 1, in which the porosity is 20% or more and the average pore diameter is 5 ⁇ m or more.
  • a third aspect of the present invention is the alumina porous body of the first aspect, wherein the total content of Al 2 O 3 and TiO 2 is 100 mass %.
  • Aspect 4 of the invention is the alumina porous body of aspect 1, further containing Ca.
  • the Ca content in the alumina porous body is 0.1 mass% or more and 1.5 mass% or less, calculated as oxide.
  • Aspect 5 of the invention is an alumina porous body according to aspect 1 (or any one of aspects 1 to 3), having a bending strength of 15 MPa or more.
  • Aspect 6 of the invention is an alumina porous body according to aspect 5, in which the body is immersed in an alkaline chemical solution, which is a sodium hydroxide aqueous solution with a pH of 13, at 80°C for 60 hours, followed by washing to remove the alkaline chemical solution and drying.
  • the post-treatment strength which is the bending strength after the alkaline immersion treatment
  • the initial strength which is the bending strength before the alkaline immersion treatment
  • have a strength reduction rate which is the rate at which the post-treatment strength is reduced from the initial strength, of 20% or less.
  • Aspect 7 of the invention is an alumina porous body according to any one of aspects 1 to 6, which is used as a ceramic filter.
  • Aspect 8 of the invention is a ceramic filter comprising an alumina porous body according to any one of aspects 1 to 6, and a porous ceramic membrane provided on the surface of the alumina porous body and having an average pore diameter smaller than that of the alumina porous body.
  • a ninth aspect of the invention is a method for producing an alumina-based porous body, comprising: a) a step of forming a raw material mixture containing Al 2 O 3 particles and TiO 2 particles to obtain a molded body; and b) a step of firing the molded body to obtain an alumina-based porous body.
  • a tenth aspect of the present invention is the method for producing an alumina porous body according to the ninth aspect, wherein the TiO2 particles contained in the raw material mixture are coated with aluminum hydroxide.
  • An eleventh aspect of the invention is the method for producing an alumina-based porous body according to the ninth or tenth aspect, wherein the total content of the Al 2 O 3 particles and the TiO 2 particles in the material constituting the alumina-based porous body in the raw material mixture is 100 mass %.
  • a twelfth aspect of the invention is the method for producing an alumina porous body according to aspect 9 or 10, wherein the raw material mixture further contains a sintering aid containing Ca.
  • the content of the sintering aid in the material constituting the alumina porous body in the raw material mixture is 0.1% by mass or more and 1.5% by mass or less.
  • Aspect 13 of the invention is a method for producing an alumina porous body according to aspect 9 or 10, wherein the firing temperature in step b) is 1200°C or higher and 1450°C or lower.
  • FIG. 1 is a perspective view of an alumina porous body according to one embodiment. 1 is a SEM image showing the microstructure of an alumina porous body. FIG. 2 is a diagram showing the flow of manufacturing an alumina porous body.
  • FIG. 1 is a perspective view showing an alumina porous body 1 according to one embodiment of the present invention.
  • the alumina porous body 1 shown in FIG. 1 has a substantially cylindrical outer shape.
  • the alumina porous body 1 has a monolithic shape with a plurality of cells 2 (i.e., through holes) penetrating in the longitudinal direction.
  • the cross section perpendicular to the longitudinal direction of each cell 2 is substantially circular.
  • the alumina porous body 1 is used, for example, as a ceramic filter for solid-liquid separation used in water treatment.
  • the alumina porous body 1 is used as the substrate for such a ceramic filter.
  • the shape of the alumina porous body 1 is not limited to a monolithic shape and may be variously modified, such as a substantially cylindrical shape or a substantially flat plate shape. Furthermore, the use of the alumina porous body 1 is not limited to ceramic filters and ceramic filter substrates and may be variously modified.
  • the alumina porous body 1 contains alumina (Al 2 O 3 ) and titania (TiO 2 ).
  • the alumina porous body 1 is a porous body whose main component is Al 2 O 3 (aluminum oxide).
  • Al 2 O 3 constitutes aggregate particles
  • TiO 2 titanium oxide
  • the term "porous body whose main component is Al 2 O 3 " refers to a porous body in which the proportion of Al 2 O 3 in the entire porous body is 50 mass % or more.
  • the Al 2 O 3 content in the alumina porous body 1 is 50 mass% or more and 90 mass% or less.
  • the Al 2 O 3 content is preferably 60 mass% or more, and more preferably 70 mass% or more.
  • the Al 2 O 3 content is preferably 85 mass% or less, and more preferably 80 mass% or less.
  • the TiO2 content in the alumina porous body 1 is 10% by mass or more and 40% by mass or less.
  • the TiO2 content is preferably 15% by mass or more, and more preferably 20% by mass or more.
  • the TiO2 content is preferably 35% by mass or less, and more preferably 30% by mass or less.
  • the TiO2 content By setting the TiO2 content to 10% by mass or more, strong bonding between aggregate particles (i.e., Al2O3 particles ) is achieved, thereby increasing the strength of the alumina porous body 1. Furthermore, by setting the TiO2 content to 40% by mass or less, it is possible to increase the porosity and average pore diameter (also referred to as average pore diameter) of the alumina porous body 1. As a result, when the alumina porous body 1 is used, for example, in a ceramic filter for solid-liquid separation or as a substrate for the ceramic filter, a sufficient amount of liquid permeation can be obtained.
  • the binder phase that bonds the aggregate particles is not a glass phase, which has low corrosion resistance to alkaline and acidic solutions, but a phase mainly composed of TiO2 , which has high corrosion resistance. Therefore, the alumina porous body 1 exhibits excellent corrosion resistance to alkaline and acidic solutions, and strength degradation is suppressed even in harsh environments where it is frequently exposed to these solutions.
  • a binder phase mainly composed of TiO2 means a binder phase in which the proportion of TiO2 in the entire binder phase is 50 mass% or more.
  • the alumina porous body 1 may contain substances other than Al 2 O 3 and TiO 2. However, the alumina porous body 1 does not contain copper (Cu) or Cu compounds, or manganese (Mn) or Mn compounds. In other words, the Cu content and Mn content in the alumina porous body 1 are each 0.00 mass%.
  • the alumina porous body 1 is formed substantially only of Al2O3 and TiO2 .
  • the total content of Al2O3 and TiO2 in the alumina porous body 1 is preferably substantially 100 mass%.
  • the aggregate particles are formed substantially only of Al2O3
  • the binder phase is formed only of TiO2 .
  • the total content of Al2O3 and TiO2 is 100% by mass means that the content of substances other than Al2O3 and TiO2 in the alumina porous body 1 is less than 0.05% by mass in terms of oxides.
  • the alumina porous body 1 may contain calcium (Ca) derived from the raw material for Al2O3 as an impurity in an amount of about 0.02% by mass in terms of oxides (i.e., assuming that all of the Ca in the alumina porous body 1 is calcium oxide (CaO)).
  • the alumina porous body 1 does not substantially contain any substances other than Ca as an impurity, or if the total content of impurities including Ca is less than 0.05% by mass in terms of oxides, the total content of Al2O3 and TiO2 in the alumina porous body 1 is considered to be 100% by mass.
  • the alumina porous body 1 does not contain Cu or Mn as impurities.
  • the contents of Al 2 O 3 and TiO 2 are measured by the method for chemical analysis of ceramic raw materials (in accordance with JIS M 8853).
  • the content of Ca in terms of oxide is also measured by the method for chemical analysis of ceramic raw materials (in accordance with JIS M 8853).
  • Fig. 2 is a scanning electron microscope (SEM) image showing an example of the microstructure of an alumina porous body 1.
  • SEM scanning electron microscope
  • the black parts in Fig. 2 are pores 91
  • the dark gray parts are aggregate particles (i.e., Al2O3 particles ) 92 formed by Al2O3
  • the white or light gray parts are binder phases 93 formed by TiO2 .
  • the binder phases 93 are also referred to as " TiO2 domains 93.”
  • the portion of the outer periphery of an Al 2 O 3 particle 92 that is in contact with a TiO 2 domain 93 is the bonding portion with the TiO 2 domain 93 in the Al 2 O 3 particle 92. Furthermore, the portion of the outer periphery of an Al 2 O 3 particle 92 that is not in contact with the TiO 2 domain 93 is the portion facing the pore in the Al 2 O 3 particle 92 (i.e., forming the inner wall of the pore), or the portion in contact with an adjacent Al 2 O 3 particle 92.
  • the bonding ratio is determined as follows. First, an SEM image such as that shown in FIG. 2 is binarized. Next, the entire peripheral edge length (hereinafter also referred to as "particle perimeter") of each Al2O3 particle 92 is measured in the binarized SEM image. Next, the TiO2 domains 93 are expanded in the binarized SEM image, and then, for each Al2O3 particle 92 , the portion of the peripheral edge of the Al2O3 particle 92 that is in contact with the TiO2 domain 93 is extracted, and the length of that portion (hereinafter also referred to as "contact length”) is measured. In FIG.
  • the peripheral edge of one Al2O3 particle 92 located slightly to the right of the center of the figure is indicated by a thick black solid line
  • the portion of the peripheral edge that is in contact with the TiO2 domain 93 is indicated by a thick white dashed line that aligns with the thick black solid line.
  • the bonding ratio of the Al 2 O 3 particles 92 to the TiO 2 domains 93 is preferably 50% or less, and more preferably 40% or less. By setting the bonding ratio to 40% or less, it is possible to increase the porosity and average pore diameter of the alumina porous body 1. As a result, when the alumina porous body 1 is used, for example, in a ceramic filter for solid-liquid separation or as a substrate for the ceramic filter, a sufficient liquid permeation rate can be obtained.
  • the porosity of the alumina porous body 1 is 10% or more and 45% or less.
  • the porosity is preferably 20% or more, more preferably 25% or more, and even more preferably 30% or more.
  • the porosity is preferably 60% or less, and even more preferably 50% or less.
  • the average pore diameter of the alumina porous body 1 is 2 ⁇ m or more and 12 ⁇ m or less.
  • the average pore diameter is preferably 5 ⁇ m or more, more preferably 5.5 ⁇ m or more, and even more preferably 6 ⁇ m or more.
  • the average pore diameter is preferably 20 ⁇ m or less, and even more preferably 15 ⁇ m or less.
  • the average particle size of the Al2O3 particles is preferably 10 ⁇ m or more, and more preferably 20 ⁇ m or more.
  • the average particle size of the Al2O3 particles is preferably 80 ⁇ m or less, and more preferably 70 ⁇ m or less.
  • the average particle size of Al2O3 particles is determined as follows. First, image processing is performed on an SEM image such as that shown in Figure 2 to extract only Al2O3 particles 92. Next, the area of each Al2O3 particle 92 is calculated in the processed image, and the diameter (hereinafter also referred to as "particle diameter") of each Al2O3 particle 92 , assuming that it is circular , is calculated from the area. Then, the arithmetic average of the particle diameters of a predetermined number of Al2O3 particles 92 is determined as the average particle size of the Al2O3 particles . The predetermined number is, for example, 50 to 200.
  • the bending strength of the alumina porous body 1 (corresponding to the initial strength described below) is preferably 15 MPa or more, and more preferably 20 MPa or more. By ensuring that the bending strength is 15 MPa or more, breakage of the alumina porous body 1 can be suitably suppressed. Note that in this specification, the bending strength is measured by a bending strength test in accordance with JIS R 1601.
  • the strength reduction rate is preferably 20% or less, and more preferably 19% or less.
  • the alkali immersion treatment involves immersing the alumina porous body 1 in an alkaline solution (hereinafter also referred to as the "alkaline chemical solution"), which is an aqueous sodium hydroxide (NaOH) solution with a pH of 13, at 80°C for 60 hours, washing the alumina porous body 1 to remove the alkaline chemical solution from the alumina porous body 1, and then drying the alumina porous body 1.
  • an alkaline solution hereinafter also referred to as the "alkaline chemical solution”
  • the strength reduction rate is the reduction rate of the bending strength of the alumina porous body 1 after one alkali immersion treatment (hereinafter also referred to as the "post-treatment strength") relative to the bending strength of the alumina porous body 1 before the alkali immersion treatment (hereinafter also referred to as the "initial strength").
  • the strength reduction rate can be calculated using the following formula 1.
  • Strength reduction rate (initial strength ⁇ strength after treatment)/initial strength (Equation 1)
  • a manufacturing flow of the alumina porous body 1 will be described with reference to Fig. 3.
  • a manufacturing method of the above-mentioned alumina porous body 1 in which the total content of Al2O3 and TiO2 is substantially 100 mass% will be described.
  • a puddle obtained by kneading the raw material mixture is formed into a predetermined shape (for example, a monolith shape) to obtain a molded body (step S11).
  • the shape of the molded body is not limited to a monolith shape, and various shapes may be used depending on the application.
  • the average particle size of the Al 2 O 3 particles contained in the raw material mixture is, for example, 1 ⁇ m to 120 ⁇ m.
  • the average particle size of the Al 2 O 3 particles is preferably 5 ⁇ m or more, and more preferably 10 ⁇ m or more.
  • the average particle size of the Al 2 O 3 particles is preferably 100 ⁇ m or less, and more preferably 90 ⁇ m or less.
  • the Al 2 O 3 particles contained in the raw material mixture may be a combination (i.e., a mixture) of multiple types of Al 2 O 3 particles with different average particle sizes.
  • the average particle size of the Al 2 O 3 particles after mixing is 1 ⁇ m to 120 ⁇ m as described above.
  • the average particle size of at least one type of Al 2 O 3 particles among the multiple types of Al 2 O 3 particles described above is 1 ⁇ m to 100 ⁇ m.
  • the average particle diameters of the Al 2 O 3 particles and TiO 2 particles contained in the raw material mixture are volume-based average particle diameters determined from particle size distributions measured by a laser diffraction scattering method in accordance with JIS R 1629.
  • the raw material mixture contains, in addition to the materials (i.e., Al2O3 particles and TiO2 particles) that constitute the alumina porous body 1, an organic binder, a dispersant, a surfactant, water, etc.
  • an organic binder for example, one or more of methyl cellulose, hydroxypropoxyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, polyvinyl alcohol, etc. can be used.
  • dispersants and surfactants for example, one or more of the following can be used: fatty acid salts, alkyl sulfate ester salts, polyoxyethylene alkyl ether sulfate ester salts, alkylbenzene sulfonates, alkylnaphthalene sulfonates, alkyl sulfosuccinates, alkyldiphenyl ether disulfonates, alkyl phosphates, polycarboxylates, polyacrylates, aliphatic quaternary ammonium salts, aliphatic amine salts, polyoxyethylene alkyl ethers, polyoxyethylene alcohol ethers, polyoxyethylene glycerin fatty acid esters, polyoxyethylene sorbitan (or sorbitol) fatty acid esters, polyethylene glycol fatty acid esters, alkyl betaines, amine oxides, cationic cellulose derivatives, etc.
  • step S11 as described above, the raw material mixture is kneaded to form a plastic clay, which is then molded into a predetermined shape (e.g., a monolithic shape) to obtain a molded body.
  • the clay is produced, for example, by adding Al2O3 particles , an organic binder, a surfactant, and an appropriate amount of water to a slurry obtained by mixing TiO2 particles, a dispersant, and water, and then kneading the resulting mixture.
  • the molded body is formed, for example, by extrusion molding.
  • step S11 the compact is dried and then fired to produce the alumina porous body 1 (step S12).
  • step S12 the compact is dried using a drying method that uses, for example, microwaves or hot air.
  • the firing temperature for the molded body is preferably 1200°C or higher and 1450°C or lower.
  • the firing temperature is more preferably 1250°C or higher, and even more preferably 1280°C or higher.
  • the firing temperature is more preferably 1330°C or lower, and even more preferably 1300°C or lower.
  • the firing time for the molded body is not particularly limited, but is, for example, 0.5 to 10 hours.
  • the firing atmosphere is not particularly limited, but is, for example, air or nitrogen.
  • the compact may be pre-fired to burn and remove organic matter (e.g., organic binders) in the compact.
  • This pre-fire is also called degreasing or de-bindering.
  • the combustion temperature of organic binders is generally around 100°C to 300°C, so the pre-fire temperature is, for example, 200°C to 600°C.
  • the pre-fire time is not particularly limited, but may be, for example, 1 to 10 hours.
  • the pre-fire atmosphere is not particularly limited, but may be, for example, air or nitrogen.
  • heat treatment may be performed after the sintering treatment of the molded body.
  • the heat treatment temperature is preferably 1200°C or higher and 1350°C or lower. It is desirable that the heat treatment temperature does not significantly exceed the sintering treatment temperature of the molded body. By setting the heat treatment temperature to 1200°C or higher, the sinterability of the alumina porous body is improved. Furthermore, by setting the heat treatment temperature to 1350°C or lower, an increase in the amount of shrinkage of the alumina porous body can be suppressed.
  • the heat treatment time is not particularly limited, but is, for example, 5 to 80 hours.
  • the heat treatment atmosphere is not particularly limited, but is, for example, an air atmosphere or a nitrogen atmosphere.
  • the alumina porous body 1 shown in Figure 1 is used as a ceramic filter.
  • the alumina porous body 1 When the alumina porous body 1 is used alone as a ceramic filter (i.e., without a membrane such as a separation membrane provided on the surface of the alumina porous body 1), the alumina porous body 1 performs the filtering function of the ceramic filter.
  • the alumina porous body 1 has high initial strength and also high corrosion resistance against alkaline solutions. Therefore, when the alumina porous body 1 is used alone as a ceramic filter, the ceramic filter can maintain sufficient strength for a long period of time even when used in applications where cleaning conditions are more severe than those used for ordinary ceramic filters (for example, removal of solid matter in the pharmaceutical or food industries, etc.).
  • the alumina porous body 1 may be used as a ceramic filter by providing a porous ceramic membrane on its surface.
  • This ceramic filter comprises the above-mentioned alumina porous body 1 and a porous ceramic membrane provided on the surface of the alumina porous body 1.
  • the average pore diameter of the porous ceramic membrane is smaller than the average pore diameter of the alumina porous body 1.
  • the average pore diameter of the porous ceramic membrane is measured by mercury intrusion porosimetry (in accordance with JIS R 1655).
  • the alumina porous body 1 and the porous ceramic membrane perform the filtering function.
  • the alumina porous body 1 used as the substrate (i.e., support) for the porous ceramic membrane in a ceramic filter has high initial strength and also high corrosion resistance to alkaline solutions. Therefore, the ceramic filter can maintain sufficient strength over long periods of time, even when used in applications where cleaning conditions are more severe than those used for ordinary ceramic filters (for example, removal of solid matter in the pharmaceutical or food industries).
  • the porous ceramic membrane described above is a filtration membrane that performs the filtration function of the ceramic filter.
  • an intermediate membrane having an average pore diameter smaller than that of the alumina porous body 1 and larger than that of the filtration membrane may be provided between the alumina porous body 1 serving as the substrate and the filtration membrane.
  • the ends of the alumina porous body 1, intermediate membrane, and filtration membrane are preferably sealed by sealing portions formed to encase the ends. This prevents the fluid to be treated from directly penetrating the alumina porous body 1 and intermediate membrane from the end faces into the interior of the alumina porous body 1 and intermediate membrane without passing through the filtration membrane.
  • a method for manufacturing the ceramic filter When manufacturing a ceramic filter, first, approximately 70% by mass of ceramic particles, a dispersant, an organic binder, a surfactant, and water are mixed in a pot mill or the like, and the ceramic particles are crushed to an average particle size of approximately 0.1 ⁇ m to 3 ⁇ m to prepare a slurry for forming a porous ceramic membrane (hereinafter also referred to as "membrane-forming slurry").
  • the ceramic particles are, for example, primarily composed of Al 2 O 3 particles and TiO 2 particles.
  • O-rings are attached to the outer peripheral surface of the monolithic porous alumina body 1 at both longitudinal ends of the alumina porous body 1.
  • the alumina porous body 1 with the O-rings attached is fixed inside a substantially cylindrical flange. This separates the outer peripheral surface of the alumina porous body 1 from the interior of the cell 2.
  • the outer peripheral surface of the alumina porous body 1 is depressurized using a vacuum pump, creating a pressure difference between the outer peripheral surface and the inside of the cell 2.
  • the membrane-forming slurry flowing inside the cell 2 is sucked from the outer peripheral surface of the alumina porous body 1 and adheres to the inner peripheral surface of the cell 2, forming a film of ceramic particles on the inner peripheral surface.
  • the alumina porous body 1 is then dried and then fired, for example, at 950°C to 1250°C, to form the above-mentioned ceramic filter.
  • the total content of Al2O3 particles and TiO2 particles in the materials constituting the alumina porous body 1 in the raw material mixture is substantially 100% by mass.
  • the materials constituting the alumina porous body 1 do not contain a sintering aid, but may contain a sintering aid.
  • the sintering aid may include, for example, calcium (Ca).
  • the sintering aid may be, for example, calcium carbonate ( CaCO3 ) particles.
  • the sintering aid may contain elements other than Ca, but does not include Cu or Mn.
  • the content of the sintering aid in the materials constituting the alumina porous body 1 is 0.1% by mass or more and 1.5% by mass or more.
  • the manufacturing method of the alumina porous body 1 when using a sintering aid is substantially the same as steps S11 and S12 described above.
  • step S11 for example, when preparing the above-mentioned slurry, the sintering aid is mixed with TiO2 particles, dispersant, and water.
  • step S12 the inclusion of the sintering aid in the compact improves the sinterability of TiO2 , achieving stronger bonding between aggregate particles and further increasing the strength of the alumina porous body 1.
  • the alumina porous body 1 can be sintered at a relatively low temperature.
  • the Ca in the sintering aid exists in the form of an oxide produced by oxidation during firing, or a complex compound with Ti, etc.
  • the Ca content in the alumina porous body 1 is preferably 0.1 mass% or more and 1.5 mass% or less, calculated as an oxide.
  • the Ca content in terms of oxide is more preferably 0.5 mass% or more, and even more preferably 1.0 mass% or more.
  • the Ca content in terms of oxide is more preferably 5 mass% or less, and even more preferably 3 mass% or less.
  • the alumina porous body 1 can effectively function as a sintering agent during sintering. Furthermore, by setting the Ca content in terms of oxide to 1.5% by mass or less, the proportion of the TiO2 component in the binder phase described above is maintained relatively high, and the binder phase maintains relatively high corrosion resistance to alkaline solutions.
  • Table 1 shows the conditions for producing the alumina porous bodies 1 of Examples 1 to 26 and the alumina porous bodies of Comparative Examples 1 to 7, and Table 2 shows the properties of the alumina porous bodies 1 of Examples 1 to 26 and the alumina porous bodies of Comparative Examples 1 to 7. Note that the present invention is not limited to the following examples.
  • a slurry was first prepared by mixing TiO2 particles, a dispersant, and water in a pot mill.
  • CaCO3 particles, a sintering aid were also added when preparing the slurry.
  • the slurry was then mixed with Al2O3 particles , an organic binder, a surfactant, and water to obtain a raw material mixture, which was then kneaded to obtain a plastic clay.
  • the clay was then extruded and dried to obtain a square plate-shaped compact measuring approximately 25 mm x 50 mm x 5 mm.
  • the organic binder, dispersant, surfactant, and water contents in the raw material mixture were 6 mass%, 0.09 mass%, 1 mass%, and 17 mass%, respectively.
  • the total amount of Al 2 O 3 particles and TiO 2 particles was 100 mass parts, and CaCO 3 particles were added in the amounts (parts by mass) shown in Table 1.
  • the compact was then calcined (i.e., degreased) at 450°C and then fired under the firing conditions shown in Table 1 to obtain an alumina porous body 1.
  • heat treatment was performed under the heat treatment conditions shown in Table 1.
  • the initial strength i.e., bending strength before alkali immersion treatment
  • post-treatment strength i.e., bending strength after alkali immersion treatment
  • strength reduction rate porosity, average pore diameter, bonding ratio with TiO2 domains in Al2O3 particles, TiO2 content, and Ca content in terms of oxide, etc., shown in Table 2
  • the initial strength i.e., bending strength before alkali immersion treatment
  • post-treatment strength i.e., bending strength after alkali immersion treatment
  • strength reduction rate porosity
  • average pore diameter i.e., bonding ratio with TiO2 domains in Al2O3 particles, TiO2 content, and Ca content in terms of oxide, etc.
  • the post-treatment strength was measured in the same manner as for the initial strength after the above-mentioned alkaline immersion treatment was performed once on the alumina porous body 1.
  • an alkaline solution which was a sodium hydroxide aqueous solution with a pH of 13
  • Teflon registered trademark
  • the alumina porous body 1 was immersed in the alkaline solution.
  • the pressure vessel was sealed and kept at 80°C for 60 hours.
  • the alumina porous body 1 was removed from the alkaline solution and washed, and the alkaline solution was removed from the alumina porous body 1, after which the alumina porous body 1 was dried.
  • the strength reduction rate was calculated using the above-mentioned formula 1 from the initial strength and post-treatment strength measured as described above.
  • the porosity was measured by cutting a measurement sample of approximately 25 mm x 10 mm x 5 mm from the alumina porous body 1 using the Archimedes method (in accordance with JIS R 1634).
  • the average pore diameter was measured by cutting a measurement sample of approximately 8 mm x 10 mm x 5 mm from the alumina porous body 1 and using the mercury intrusion method (in accordance with JIS R 1655).
  • the bonding ratio between the Al 2 O 3 particles and the TiO 2 domains was determined by the above-mentioned method using an SEM image such as that shown in Figure 2. Specifically, the particle perimeter and contact length of each Al 2 O 3 particle 92 in the SEM image were measured, and the bonding ratio was determined by dividing the total contact length of all Al 2 O 3 particles 92 in the SEM image by the total particle perimeter of all Al 2 O 3 particles 92.
  • the TiO 2 content and the Ca content calculated as oxide were measured by the method for chemical analysis of ceramic raw materials (in accordance with JIS M 8853).
  • the total content of Al2O3 particles and TiO2 particles in the raw material mixture was 100 parts by mass, as described above.
  • the content of Al2O3 particles in the raw material mixture was 70 parts by mass, and the content of TiO2 particles was 30 parts by mass.
  • the Al2O3 particles in the raw material mixture were a mixture of multiple types of Al2O3 particles with different average particle sizes. Specifically, the Al2O3 particles in the raw material mixture were a mixture of 30 parts by mass of Al2O3 particles with an average particle size of 27 ⁇ m, 30 parts by mass of Al2O3 particles with an average particle size of 15 ⁇ m, and 10 parts by mass of Al2O3 particles with an average particle size of 4.6 ⁇ m.
  • the average particle size of the TiO2 particles in the raw material mixture was 0.8 ⁇ m.
  • the TiO2 particles with an average particle size of 0.8 ⁇ m contained in the raw material mixture were not coated with aluminum hydroxide (the same applies to other Examples and Comparative Examples).
  • the firing temperature and firing time of the compact are 1300° C. and 2 hours, respectively, and the heat treatment temperature and heat treatment time are 1250° C. and 72 hours, respectively.
  • the alumina porous body of Comparative Example 1 had an initial strength of 55 MPa, a post-treatment strength of 53 MPa, and a strength reduction rate of 3.6%.
  • the porosity was 8%, and the average pore diameter was 1.8 ⁇ m.
  • the bonding ratio was 33.8%.
  • the TiO 2 content was 30 mass%, and the Ca content was 0.0 mass% in oxide equivalent.
  • the alumina porous body of Comparative Example 1 contained approximately 0.02 mass% Ca in oxide equivalent as an impurity derived from the raw material Al 2 O 3 particles. The same applies to the other comparative examples and examples.
  • the alumina porous body of Comparative Example 1 had a small porosity of less than 10%, and an average pore diameter of less than 2 ⁇ m.
  • Comparative Example 2 the conditions for producing an alumina porous body were the same as in Comparative Example 1, except that the contents of Al2O3 particles and TiO2 particles in the raw material mixture were different.
  • the contents of Al2O3 particles in the raw material mixture were 65 parts by mass, and the content of TiO2 particles was 35 parts by mass.
  • the Al2O3 particles in the raw material mixture were a mixture of 27.5 parts by mass of Al2O3 particles with an average particle size of 27 ⁇ m, 27.5 parts by mass of Al2O3 particles with an average particle size of 15 ⁇ m, and 10 parts by mass of Al2O3 particles with an average particle size of 4.6 ⁇ m.
  • the alumina porous body of Comparative Example 2 had an initial strength of 62 MPa, a post-treatment strength of 59 MPa, and a strength reduction rate of 4.8%.
  • the porosity was 6%, and the average pore diameter was 1.4 ⁇ m.
  • the bonding ratio was 37.3%.
  • the TiO2 content was 35% by mass, and the Ca content, calculated as oxide, was 0.0% by mass.
  • the alumina porous body of Comparative Example 2 had a small porosity of less than 10%, and an average pore diameter of less than 2 ⁇ m.
  • Example 1 the conditions for producing the alumina porous body 1 were the same as in Comparative Example 1, except that the content and average particle size of Al2O3 particles in the raw material mixture and the content of TiO2 particles were different.
  • the content of Al2O3 particles in the raw material mixture was 80 parts by mass, and the content of TiO2 particles was 20 parts by mass.
  • the Al2O3 particles in the raw material mixture were a mixture of 25 parts by mass of Al2O3 particles with an average particle size of 18 ⁇ m, 30 parts by mass of Al2O3 particles with an average particle size of 53 ⁇ m, 15 parts by mass of Al2O3 particles with an average particle size of 27 ⁇ m, and 10 parts by mass of Al2O3 particles with an average particle size of 3.9 ⁇ m .
  • the alumina porous body 1 of Example 1 had an initial strength of 27 MPa, a post-treatment strength of 23 MPa, and a strength reduction rate of 14.8%.
  • the porosity was 33%, and the average pore diameter was 5.9 ⁇ m.
  • the bonding ratio was 20.5%.
  • the TiO2 content was 20% by mass, and the Ca content was 0.0% by mass in terms of oxide.
  • the alumina porous body 1 of Example 1 had an initial strength of 15 MPa or more, a strength reduction rate of 20% or less, a porosity in the range of 20% to 45%, an average pore diameter in the range of 5 ⁇ m to 12 ⁇ m, a bonding ratio of 5% or more, and a TiO2 content in the range of 10% to 40% by mass. The same applies to the other examples.
  • Example 2 the conditions for producing the alumina porous body 1 were the same as in Example 1, except that the average particle size of the TiO2 particles in the raw material mixture was different.
  • the average particle size of the TiO2 particles in the raw material mixture was 0.6 ⁇ m.
  • the TiO2 particles with an average particle size of 0.6 ⁇ m contained in the raw material mixture were not coated with aluminum hydroxide (this was also the case in other Examples and Comparative Examples).
  • the alumina porous body 1 of Example 2 had an initial strength of 18 MPa, a post-treatment strength of 15 MPa, and a strength reduction rate of 16.7%.
  • the porosity was 33%, and the average pore diameter was 5.3 ⁇ m.
  • the bonding ratio was 12.3%.
  • the TiO2 content was 20% by mass, and the Ca content, calculated as oxide, was 0.0% by mass.
  • Example 3 the conditions for producing the alumina porous body 1 were the same as in Example 1, except that the average particle size of the TiO2 particles in the raw material mixture was different.
  • the average particle size of the TiO2 particles in the raw material mixture was 1.4 ⁇ m.
  • the TiO2 particles with an average particle size of 1.4 ⁇ m contained in the raw material mixture were coated with aluminum hydroxide (the same applies to other Examples and Comparative Examples).
  • the alumina porous body 1 of Example 3 had an initial strength of 21 MPa, a post-treatment strength of 17 MPa, and a strength reduction rate of 19.0%.
  • the porosity was 32%, and the average pore diameter was 6.7 ⁇ m.
  • the bonding ratio was 31.6%.
  • the TiO2 content was 20% by mass, and the Ca content, calculated as oxide, was 0.0% by mass.
  • Example 4 the conditions for producing the alumina porous body 1 were the same as in Example 1, except that the average particle size of the TiO2 particles in the raw material mixture was different.
  • the average particle size of the TiO2 particles in the raw material mixture was 0.95 ⁇ m.
  • the TiO2 particles with an average particle size of 0.95 ⁇ m contained in the raw material mixture were not coated with aluminum hydroxide (this was also the case in other Examples and Comparative Examples).
  • the alumina porous body 1 of Example 4 had an initial strength of 20 MPa, a post-treatment strength of 18 MPa, and a strength reduction rate of 10.0%.
  • the porosity was 33%, and the average pore diameter was 5.3 ⁇ m.
  • the bonding ratio was 13.2%.
  • the TiO2 content was 20% by mass, and the Ca content, calculated as oxide, was 0.0% by mass.
  • Example 5 the conditions for producing the alumina porous body 1 were the same as in Example 3, except that the content and average particle size of Al2O3 particles and the content of TiO2 particles in the raw material mixture were different.
  • the content of Al2O3 particles in the raw material mixture was 60 parts by mass, and the content of TiO2 particles was 40 parts by mass.
  • the Al2O3 particles in the raw material mixture were a mixture of 30 parts by mass of Al2O3 particles with an average particle size of 18 ⁇ m and 30 parts by mass of Al2O3 particles with an average particle size of 27 ⁇ m.
  • the average particle size of the TiO2 particles in the raw material mixture was 1.4 ⁇ m.
  • the alumina porous body 1 of Example 5 had an initial strength of 35 MPa, a post-treatment strength of 32 MPa, and a strength reduction rate of 8.6%.
  • the porosity was 20%, and the average pore diameter was 5.0 ⁇ m.
  • the bonding ratio was 35.0%.
  • the TiO2 content was 40% by mass, and the Ca content, calculated as oxide, was 0.0% by mass.
  • Example 6 the conditions for producing the alumina porous body 1 were the same as in Example 3, except for the content and average particle size of the Al 2 O 3 particles in the raw material mixture, as well as the firing and heat treatment conditions.
  • the content of Al 2 O 3 particles in the raw material mixture was 80 parts by mass, and the content of TiO 2 particles was 20 parts by mass.
  • the Al 2 O 3 particles in the raw material mixture were a mixture of 51.8 parts by mass of Al 2 O 3 particles with an average particle size of 18 ⁇ m, 18.2 parts by mass of Al 2 O 3 particles with an average particle size of 53 ⁇ m, and 10 parts by mass of Al 2 O 3 particles with an average particle size of 4.6 ⁇ m.
  • the average particle size of the TiO 2 particles in the raw material mixture was 1.4 ⁇ m.
  • the firing temperature and firing time for the compact were 1250°C and 5 hours, respectively. Furthermore, no heat treatment was performed after firing.
  • the alumina porous body 1 of Example 6 had an initial strength of 15 MPa, a post-treatment strength of 13 MPa, and a strength reduction rate of 13.3%.
  • the porosity was 41%, the average pore diameter was 12.0 ⁇ m, and the bonding ratio was 12.0%.
  • the TiO2 content was 20% by mass, and the Ca content, calculated as oxide, was 0.0% by mass.
  • Example 8 the conditions for producing the alumina porous body 1 were the same as in Example 7, except for the content of CaCO3 particles in the raw material mixture.
  • the content of CaCO3 particles in the raw material mixture was 1.5 parts by mass.
  • the average particle size of the CaCO3 raw material particles was 1 ⁇ m.
  • the alumina porous body 1 of Example 8 had an initial strength of 22 MPa, a post-treatment strength of 20 MPa, and a strength reduction rate of 9.1%.
  • the porosity was 38%, and the average pore diameter was 10.8 ⁇ m.
  • the bonding ratio was 18.8%.
  • the TiO2 content was 20% by mass, and the Ca content was 1.5% by mass in terms of oxide. Note that no CaCO3 particles were observed in the SEM image after firing.
  • Comparative Example 3 the conditions for producing the alumina porous body were the same as in Example 6, except for the content and average particle size of Al 2 O 3 particles in the raw material mixture, the content of TiO 2 particles, and the firing conditions.
  • the content of Al 2 O 3 particles in the raw material mixture was 75 parts by mass, and the content of TiO 2 particles was 25 parts by mass.
  • the Al 2 O 3 particles in the raw material mixture were a mixture of 25 parts by mass of Al 2 O 3 particles with an average particle size of 18 ⁇ m, 25 parts by mass of Al 2 O 3 particles with an average particle size of 53 ⁇ m, 15 parts by mass of Al 2 O 3 particles with an average particle size of 27 ⁇ m, and 10 parts by mass of Al 2 O 3 particles with an average particle size of 3.9 ⁇ m.
  • the average particle size of the TiO 2 particles in the raw material mixture was 1.4 ⁇ m.
  • the firing temperature and firing time for the compact were 1250°C and 2 hours, respectively. No heat treatment was performed after firing.
  • the alumina porous body of Comparative Example 3 had an initial strength of 13 MPa, a post-treatment strength of 11 MPa, and a strength reduction rate of 15.4%.
  • the porosity was 29%, and the average pore diameter was 6.1 ⁇ m.
  • the bonding ratio was 25.0%.
  • the TiO2 content was 25% by mass, and the Ca content, calculated as oxide, was 0.0% by mass.
  • the alumina porous body of Comparative Example 3 had a low initial strength of less than 15 MPa.
  • Example 9 the conditions for producing the alumina porous body 1 were the same as those in Comparative Example 3, except for the firing conditions.
  • the firing temperature and firing time for the compact were 1250°C and 5 hours, respectively.
  • the alumina porous body 1 of Example 9 had an initial strength of 19 MPa, a post-treatment strength of 16 MPa, and a strength reduction rate of 15.8%.
  • the porosity was 27%, and the average pore diameter was 5.4 ⁇ m.
  • the bonding ratio was 27.5%.
  • the TiO2 content was 25% by mass, and the Ca content, calculated as oxide, was 0.0% by mass.
  • Example 10 the conditions for producing the alumina porous body 1 were the same as those in Comparative Example 3, except for the firing conditions.
  • the firing temperature and firing time for the compact were 1280°C and 2 hours, respectively.
  • the alumina porous body 1 of Example 10 had an initial strength of 23 MPa, a post-treatment strength of 20 MPa, and a strength reduction rate of 13.0%.
  • the porosity was 26%, and the average pore diameter was 5.5 ⁇ m.
  • the bonding ratio was 28.9%.
  • the TiO2 content was 25% by mass, and the Ca content, calculated as oxide, was 0.0% by mass.
  • Example 11 the conditions for producing the alumina porous body 1 were the same as those in Example 10, except for the content and average particle size of Al 2 O 3 particles, the content and average particle size of TiO 2 particles in the raw material mixture, and the firing conditions.
  • the content of Al 2 O 3 particles in the raw material mixture was 82.2 parts by mass, and the content of TiO 2 particles was 17.8 parts by mass.
  • the Al 2 O 3 particles in the raw material mixture were a mixture of 41.1 parts by mass of Al 2 O 3 particles with an average particle size of 18 ⁇ m and 41.1 parts by mass of Al 2 O 3 particles with an average particle size of 27 ⁇ m.
  • the average particle size of the TiO 2 particles in the raw material mixture was 0.8 ⁇ m.
  • the firing temperature and firing time for the compact were 1300°C and 2 hours, respectively.
  • the alumina porous body 1 of Example 11 had an initial strength of 15 MPa, a post-treatment strength of 12 MPa, and a strength reduction rate of 20%.
  • the porosity was 38%, and the average pore diameter was 5.1 ⁇ m.
  • the bonding ratio was 12.6%.
  • the TiO2 content was 17.8% by mass, and the Ca content, calculated as oxide, was 0.0% by mass.
  • Comparative Example 4 the conditions for producing the alumina porous body were the same as in Example 11, except for the different firing conditions. In Comparative Example 4, the firing temperature and firing time for the compact were 1,350°C and 2 hours, respectively.
  • the initial strength was low at 6.0 MPa, so the post-treatment strength was not measured and the strength reduction rate was not calculated.
  • the porosity was 41%, and the average pore diameter was 8.0 ⁇ m.
  • the bonding ratio was not measured due to the low initial strength as described above.
  • the TiO2 content was 17.8% by mass, and the Ca content, calculated as oxide, was 0.0% by mass.
  • Comparative Example 5 the conditions for producing the alumina porous body were the same as in Example 11, except for the different firing conditions.
  • the firing temperature and firing time for the compact were 1400°C and 2 hours, respectively.
  • the initial strength was low at 4.3 MPa, so the post-treatment strength was not measured and the strength reduction rate was not calculated.
  • the porosity was 42% and the average pore diameter was 7.8 ⁇ m.
  • the bonding ratio was not measured due to the low initial strength as described above.
  • the TiO2 content was 17.8% by mass, and the Ca content was 0.0% by mass in terms of oxide.
  • Comparative Example 6 the conditions for producing the alumina porous body were the same as in Example 11, except for the different firing conditions.
  • the firing temperature and firing time for the compact were 1,450°C and 2 hours, respectively.
  • the initial strength was low at 1.8 MPa, so the post-treatment strength was not measured and the strength reduction rate was not calculated.
  • the porosity was 41% and the average pore diameter was 8.3 ⁇ m.
  • the bonding ratio was not measured due to the low initial strength as described above.
  • the TiO2 content was 17.8% by mass, and the Ca content, calculated as oxide, was 0.0% by mass.
  • Example 12 the conditions for producing the alumina porous body 1 were the same as in Example 3, except for the firing conditions and heat treatment conditions.
  • the firing temperature and firing time of the compact were 1250°C and 2 hours, respectively.
  • the heat treatment temperature and heat treatment time were also 1250°C and 5 hours, respectively.
  • the alumina porous body 1 of Example 12 had an initial strength of 16 MPa, a post-treatment strength of 13 MPa, and a strength reduction rate of 18.8%.
  • the porosity was 36%, and the average pore diameter was 7.2 ⁇ m.
  • the bonding ratio was 13.2%.
  • the TiO2 content was 20% by mass, and the Ca content, calculated as oxide, was 0.0% by mass.
  • Example 13 the conditions for producing the alumina porous body 1 were the same as those in Example 12, except for the heat treatment conditions.
  • the heat treatment temperature and heat treatment time were 1250°C and 10 hours, respectively.
  • the alumina porous body 1 of Example 13 had an initial strength of 17 MPa, a post-treatment strength of 14 MPa, and a strength reduction rate of 17.6%.
  • the porosity was 34%, and the average pore diameter was 7.0 ⁇ m.
  • the bonding ratio was 14.3%.
  • the TiO2 content was 20% by mass, and the Ca content, calculated as oxide, was 0.0% by mass.
  • Example 14 the conditions for producing the alumina porous body 1 were the same as in Example 12, except for the heat treatment conditions.
  • the heat treatment temperature and heat treatment time were 1250°C and 20 hours, respectively.
  • the alumina porous body 1 of Example 14 had an initial strength of 18 MPa, a post-treatment strength of 15 MPa, and a strength reduction rate of 16.7%.
  • the porosity was 30%, and the average pore diameter was 6.8 ⁇ m.
  • the bonding ratio was 16.5%.
  • the TiO2 content was 20% by mass, and the Ca content, calculated as oxide, was 0.0% by mass.
  • Example 15 the preparation conditions for the alumina porous body 1 were the same as those in Example 12, except for the firing conditions and heat treatment conditions.
  • the firing temperature and firing time for the compact were 1250°C and 5 hours, respectively. Furthermore, no heat treatment was performed after firing.
  • the alumina porous body 1 of Example 15 had an initial strength of 15 MPa, a post-treatment strength of 13 MPa, and a strength reduction rate of 13.3%. Furthermore, the porosity was 37%, and the average pore diameter was 7.5 ⁇ m. The bonding ratio was 17.5%.
  • the TiO2 content was 20% by mass, and the Ca content, calculated as oxide, was 0.0% by mass.
  • Example 16 the conditions for producing the alumina porous body 1 were the same as those in Example 15, except for the heat treatment conditions.
  • the heat treatment temperature and time were 1250°C and 5 hours, respectively.
  • the alumina porous body 1 of Example 16 had an initial strength of 17 MPa, a post-treatment strength of 15 MPa, and a strength reduction rate of 11.8%.
  • the porosity was 35%, and the average pore diameter was 7.3 ⁇ m.
  • the bonding ratio was 20.4%.
  • the TiO2 content was 20% by mass, and the Ca content, calculated as oxide, was 0.0% by mass.
  • Example 17 the preparation conditions for the alumina porous body 1 were the same as those in Example 16, except for the firing conditions.
  • the firing temperature and firing time for the compact were 1280°C and 2 hours, respectively.
  • the alumina porous body 1 of Example 17 had an initial strength of 19 MPa, a post-treatment strength of 16 MPa, and a strength reduction rate of 15.8%.
  • the porosity was 30%, and the average pore diameter was 6.9 ⁇ m.
  • the bonding ratio was 23.1%.
  • the TiO2 content was 20% by mass, and the Ca content, calculated as oxide, was 0.0% by mass.
  • Example 18 the conditions for producing the alumina porous body 1 were the same as those in Example 16, except for the firing conditions.
  • the firing temperature and firing time for the compact were 1300°C and 2 hours, respectively.
  • the alumina porous body 1 of Example 18 had an initial strength of 20 MPa, a post-treatment strength of 18 MPa, and a strength reduction rate of 10.0%.
  • the porosity was 29%, and the average pore diameter was 6.8 ⁇ m.
  • the bonding ratio was 25.3%.
  • the TiO2 content was 20% by mass, and the Ca content, calculated as oxide, was 0.0% by mass.
  • Example 19 the conditions for producing the alumina porous body 1 were the same as in Example 18, except for the heat treatment conditions.
  • the heat treatment temperature and heat treatment time were 1,300°C and 5 hours, respectively.
  • the alumina porous body 1 of Example 19 had an initial strength of 23 MPa, a post-treatment strength of 20 MPa, and a strength reduction rate of 13.0%.
  • the porosity was 30%, and the average pore diameter was 6.7 ⁇ m.
  • the bonding ratio was 28.7%.
  • the TiO2 content was 20% by mass, and the Ca content, calculated as oxide, was 0.0% by mass.
  • Example 20 the conditions for producing the alumina porous body 1 were the same as in Example 19, except for the heat treatment conditions.
  • the heat treatment temperature and heat treatment time were 1300°C and 10 hours, respectively.
  • the alumina porous body 1 of Example 20 had an initial strength of 25 MPa, a post-treatment strength of 23 MPa, and a strength reduction rate of 8.0%.
  • the porosity was 29%, and the average pore diameter was 6.6 ⁇ m.
  • the bonding ratio was 31.8%.
  • the TiO2 content was 20% by mass, and the Ca content, calculated as oxide, was 0.0% by mass.
  • Example 21 the conditions for producing the alumina porous body 1 were the same as in Example 19, except for the heat treatment conditions.
  • the heat treatment temperature and heat treatment time were 1300°C and 20 hours, respectively.
  • the alumina porous body 1 of Example 21 had an initial strength of 29 MPa, a post-treatment strength of 27 MPa, and a strength reduction rate of 6.9%.
  • the porosity was 27%, and the average pore diameter was 6.5 ⁇ m.
  • the bonding ratio was 33.5%.
  • the TiO2 content was 20% by mass, and the Ca content, calculated as oxide, was 0.0% by mass.
  • Example 22 the preparation conditions for the alumina porous body 1 were the same as those in Example 11, except for the different firing conditions.
  • the compact was fired at 1450°C for 2 hours, and then at 1280°C for 10 hours. No heat treatment was performed after firing.
  • the alumina porous body 1 of Example 22 had an initial strength of 22 MPa, a post-treatment strength of 20 MPa, and a strength reduction rate of 9.1%.
  • the porosity was 45%, and the average pore diameter was 9.0 ⁇ m.
  • the bonding ratio was 35.0%.
  • the TiO2 content was 17.8% by mass, and the Ca content, calculated as oxide, was 0.0% by mass.
  • Comparative Example 7 the conditions for producing the alumina porous body were the same as in Example 22, except for the different firing conditions.
  • the compact was fired at 1,450°C for 2 hours, and then at 1,250°C for 10 hours. No heat treatment was performed after firing. Since the initial strength of the alumina porous body of Comparative Example 7 was low at 8.0 MPa, the post-treatment strength was not measured, and the strength reduction rate was not calculated.
  • the porosity was 42%, and the average pore diameter was 8.6 ⁇ m.
  • the bonding ratio was not measured due to the low initial strength as described above.
  • the TiO2 content was 17.8% by mass, and the Ca content was 0.0% by mass in terms of oxide.
  • Example 23 the conditions for producing the alumina porous body 1 were the same as in Example 1, except that the content and average particle size of the Al 2 O 3 particles in the raw material mixture and the content of the TiO 2 particles in the raw material mixture were different.
  • the content of the Al 2 O 3 particles in the raw material mixture was 85 parts by mass, and the content of the TiO 2 particles in the raw material mixture was 15 parts by mass.
  • the Al 2 O 3 particles in the raw material mixture were a mixture of 18.75 parts by mass of Al 2 O 3 particles with an average particle size of 47 ⁇ m, 37.5 parts by mass of Al 2 O 3 particles with an average particle size of 27 ⁇ m, 18.75 parts by mass of Al 2 O 3 particles with an average particle size of 12 ⁇ m, and 10 parts by mass of Al 2 O 3 particles with an average particle size of 4.6 ⁇ m.
  • the average particle size of the TiO 2 particles in the raw material mixture was 0.8 ⁇ m.
  • the alumina porous body 1 of Example 23 had an initial strength of 22 MPa, a post-treatment strength of 20 MPa, and a strength reduction rate of 9.1%.
  • the porosity was 33%, and the average pore diameter was 3.8 ⁇ m.
  • the bonding ratio was 13.5%.
  • the TiO2 content was 15% by mass, and the Ca content, calculated as oxide, was 0.0% by mass.
  • Example 24 the conditions for producing the alumina porous body 1 were the same as in Example 23, except that the content and average particle size of the Al 2 O 3 particles in the raw material mixture were different.
  • the content of Al 2 O 3 particles in the raw material mixture was 85 parts by mass, and the content of TiO 2 particles was 15 parts by mass.
  • the Al 2 O 3 particles in the raw material mixture were a mixture of 18.75 parts by mass of Al 2 O 3 particles with an average particle size of 53 ⁇ m, 37.5 parts by mass of Al 2 O 3 particles with an average particle size of 27 ⁇ m, 18.75 parts by mass of Al 2 O 3 particles with an average particle size of 12 ⁇ m, and 10 parts by mass of Al 2 O 3 particles with an average particle size of 4.6 ⁇ m.
  • the average particle size of the TiO 2 particles in the raw material mixture was 0.8 ⁇ m.
  • the alumina porous body 1 of Example 24 had an initial strength of 27 MPa, a post-treatment strength of 24 MPa, and a strength reduction rate of 11.1%.
  • the porosity was 23%, and the average pore diameter was 3.0 ⁇ m.
  • the bonding ratio was 12.8%.
  • the TiO2 content was 15% by mass, and the Ca content, calculated as oxide, was 0.0% by mass.
  • Example 25 the conditions for producing the alumina porous body 1 were the same as in Example 23, except that the content and average particle size of the Al 2 O 3 particles in the raw material mixture and the content of the TiO 2 particles in the raw material mixture were different.
  • the content of the Al 2 O 3 particles in the raw material mixture was 90 parts by mass, and the content of the TiO 2 particles in the raw material mixture was 10 parts by mass.
  • the Al 2 O 3 particles in the raw material mixture were a mixture of 40 parts by mass of Al 2 O 3 particles with an average particle size of 27 ⁇ m, 40 parts by mass of Al 2 O 3 particles with an average particle size of 15 ⁇ m, and 10 parts by mass of Al 2 O 3 particles with an average particle size of 4.6 ⁇ m.
  • the average particle size of the TiO 2 particles in the raw material mixture was 0.8 ⁇ m.
  • the alumina porous body 1 of Example 25 had an initial strength of 29 MPa, a post-treatment strength of 26 MPa, and a strength reduction rate of 10.3%.
  • the porosity was 37%, and the average pore diameter was 3.6 ⁇ m.
  • the bonding ratio was 5.8%.
  • the TiO2 content was 10% by mass, and the Ca content, calculated as oxide, was 0.0% by mass.
  • Example 26 the conditions for producing the alumina porous body 1 were the same as in Example 23, except that the content and average particle size of the Al 2 O 3 particles in the raw material mixture and the content of the TiO 2 particles in the raw material mixture were different.
  • the content of the Al 2 O 3 particles in the raw material mixture was 75 parts by mass, and the content of the TiO 2 particles in the raw material mixture was 25 parts by mass.
  • the Al 2 O 3 particles in the raw material mixture were a mixture of 32.5 parts by mass of Al 2 O 3 particles with an average particle size of 27 ⁇ m, 32.5 parts by mass of Al 2 O 3 particles with an average particle size of 15 ⁇ m, and 10 parts by mass of Al 2 O 3 particles with an average particle size of 4.6 ⁇ m.
  • the average particle size of the TiO 2 particles in the raw material mixture was 0.8 ⁇ m.
  • the alumina porous body 1 of Example 26 had an initial strength of 48 MPa, a post-treatment strength of 45 MPa, and a strength reduction rate of 6.3%.
  • the porosity was 15%, and the average pore diameter was 2.0 ⁇ m.
  • the bonding ratio was 21.2%.
  • the TiO2 content was 25% by mass, and the Ca content, calculated as oxide, was 0.0% by mass.
  • the porosity, average pore diameter, TiO 2 content, bonding ratio, initial strength, and strength reduction rate were each within the above-mentioned preferred ranges.
  • the alumina porous body 1 contains Al2O3 and TiO2 .
  • the TiO2 content in the alumina porous body 1 is 10% by mass or more and 40% by mass or less.
  • the porosity of the alumina porous body 1 is 10% by mass or more and 45% by mass or less.
  • the average pore diameter of the alumina porous body 1 is 2 ⁇ m or more and 12 ⁇ m or less.
  • the bonding ratio of the Al2O3 particles to the TiO2 domains is 5% or more.
  • the porosity of the alumina porous body 1 be 20% or more, and that the average pore diameter of the alumina porous body 1 be 5 ⁇ m or more. This makes it possible to effectively prevent the porosity and average pore diameter of the alumina porous body 1 from becoming excessively small.
  • the total content of Al 2 O 3 and TiO 2 in the alumina porous body 1 is preferably 100 mass %.
  • a sintering aid i.e., a material other than Al 2 O 3 and TiO 2
  • a sintering aid containing Cu and Mn it is possible to prevent the firing furnace from being contaminated by Cu and Mn.
  • the alumina porous body 1 further contains Ca.
  • the Ca content in the alumina porous body 1 is preferably 0.1 mass % or more and 1.5 mass % or less in terms of oxide.
  • a sintering aid containing Ca when producing the alumina porous body 1, it is possible to increase the bonding ratio between the Al 2 O 3 particles constituting the alumina porous body 1 and the TiO 2 domains, and as a result, it is possible to increase the initial strength and post-treatment strength of the alumina porous body 1.
  • the bending strength (i.e., initial strength) of the alumina porous body 1 is preferably 15 MPa or more. This makes it possible to provide an alumina porous body 1 with high bending strength.
  • the strength reduction rate which is the rate at which the strength of the alumina porous body 1 after treatment is reduced relative to its initial strength, is preferably 20% or less. This makes it possible to suitably suppress reduction in the strength of the alumina porous body 1 due to chemical washing (i.e., cleaning using a chemical solution).
  • the strength after treatment refers to the bending strength of the alumina porous body 1 after undergoing an alkali immersion treatment, which involves immersing the body in an alkaline chemical solution, which is an aqueous sodium hydroxide solution with a pH of 13, at 80°C for 60 hours, followed by washing to remove the alkaline chemical solution and drying.
  • the initial strength refers to the bending strength of the alumina porous body 1 before the alkali immersion treatment.
  • the alumina porous body 1 is preferably used as a ceramic filter. This makes it possible to provide a ceramic filter with high initial strength and excellent corrosion resistance against alkaline chemical solutions, and also enables the ceramic filter to achieve a sufficient amount of permeation of the target substance.
  • the ceramic filter comprises the above-mentioned alumina porous body 1 and a porous ceramic membrane provided on the surface of the alumina porous body 1.
  • the porous ceramic membrane has an average pore diameter smaller than that of the alumina porous body 1.
  • the method for producing an alumina porous body 1 according to the present invention includes a step of forming a raw material mixture containing Al2O3 particles and TiO2 particles into a molded body (step S11), and a step of firing the molded body to obtain an alumina porous body (step S12). This allows the production of an alumina porous body 1 having a desired porosity, average pore diameter, and high strength.
  • the TiO2 particles contained in the raw material mixture are preferably coated with aluminum hydroxide, which allows for the production of a high-strength alumina porous body 1 having the desired porosity and average pore size.
  • the total content of Al 2 O 3 particles and TiO 2 particles in the materials constituting the alumina porous body 1 in the raw material mixture is 100 mass %, which can reduce the production cost of the alumina porous body 1.
  • a sintering aid containing Cu and Mn it is possible to prevent the firing furnace from being contaminated by Cu and Mn.
  • the raw material mixture further contains a sintering aid containing Ca.
  • the content of the sintering aid in the material constituting the alumina porous body 1 in the raw material mixture is 0.1 mass % or more and 1.5 mass % or less. This increases the bonding ratio between the TiO2 domains and the Al2O3 particles constituting the alumina porous body 1 , as described above, and as a result, the initial strength and post-treatment strength of the alumina porous body 1 can be increased.
  • the firing temperature in step S12 is preferably 1200°C or higher and 1450°C or lower. This makes it possible to achieve optimal sintering of the alumina porous body 1 while suppressing damage to the alumina porous body 1 during firing.
  • the above-described alumina porous body 1 and method for manufacturing the alumina porous body 1 can be modified in various ways.
  • the alumina porous body 1 may contain substances other than Al 2 O 3 , TiO 2 and substances derived from the sintering aid.
  • the Ca content in the alumina porous body 1, calculated as oxide may be less than 0.1 mass% or may be greater than 1.5 mass%.
  • the initial strength of the alumina porous body 1 may be less than 15 MPa.
  • the above-mentioned strength reduction rate of the alumina porous body 1 may be greater than 20%.
  • the above-mentioned ceramic filter may be used for various purposes other than as a filter for solid-liquid separation.
  • the ceramic filter may be used as a filter for gas-solid separation.
  • the alumina porous body 1 does not necessarily have to be used as a substrate for a ceramic filter, but may also be used for a variety of other purposes.
  • the raw material mixture used to manufacture the alumina porous body 1 may contain substances other than Al 2 O 3 particles, TiO 2 particles, and a sintering aid as materials constituting the alumina porous body 1 .
  • the content of the sintering aid in the materials constituting the alumina porous body 1 in the raw material mixture may be less than 0.1% by mass or more than 1.5% by mass.
  • the firing conditions and heat treatment conditions in step S12 may be changed as appropriate.
  • the firing temperature for the compact may be less than 1200°C or higher than 1450°C.
  • the alumina porous body of the present invention can be suitably used as a substrate for filters used in water treatment.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Organic Chemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Geology (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Composite Materials (AREA)
  • Manufacturing & Machinery (AREA)
  • Filtering Materials (AREA)

Abstract

L'invention concerne un corps poreux en alumine (1) contenant de l'Al2O3 et du TiO2. La teneur en TiO2 dans le corps poreux en alumine (1) est de 10 à 40 % en masse. La porosité du corps poreux en alumine (1) est de 10 à 45 %. Le corps poreux en alumine (1) a un diamètre de pore moyen de 2 à 12 µm. Dans le corps poreux en alumine (1), le rapport de liaison de particules d'Al2O3 (92) à des domaines de TiO2 (93) est de 5 % ou plus. Par conséquent, il est possible d'augmenter la résistance du corps poreux en alumine (1) présentant une porosité et un diamètre de pore moyen souhaités.
PCT/JP2025/010767 2024-03-22 2025-03-19 Corps poreux d'alumine, filtre céramique et procédé de production d'un corps poreux d'alumine Pending WO2025197973A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2024-046416 2024-03-22
JP2024046416 2024-03-22

Publications (1)

Publication Number Publication Date
WO2025197973A1 true WO2025197973A1 (fr) 2025-09-25

Family

ID=97139539

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2025/010767 Pending WO2025197973A1 (fr) 2024-03-22 2025-03-19 Corps poreux d'alumine, filtre céramique et procédé de production d'un corps poreux d'alumine

Country Status (1)

Country Link
WO (1) WO2025197973A1 (fr)

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2000169254A (ja) * 1998-12-08 2000-06-20 Kyocera Corp 透気性セラミックス構造体とそれを用いた流体透過部材
JP2005534474A (ja) * 2002-07-31 2005-11-17 コーニング インコーポレイテッド ムライト・チタン酸アルミニウム製ディーゼル微粒子フィルタ
JP2005534597A (ja) * 2002-07-31 2005-11-17 コーニング インコーポレイテッド チタン酸アルミニウムベースのセラミック製品
JP2007510615A (ja) * 2003-11-04 2007-04-26 コーニング インコーポレイテッド チタン酸アルミニウムベースのセラミック体
JP2008508185A (ja) * 2004-07-29 2008-03-21 コーニング インコーポレイテッド 細孔サイズ分布の狭いチタン酸アルミニウム物体およびその製造方法
CN101412620A (zh) * 2008-11-14 2009-04-22 西安交通大学 溶胶作为助剂制备多孔氧化铝陶瓷支撑体的方法
JP2010077008A (ja) * 2008-08-28 2010-04-08 Kyocera Corp 多孔質セラミック部材およびその製法ならびにフィルタ
JP2010228946A (ja) * 2009-03-26 2010-10-14 Ngk Insulators Ltd アルミナ質多孔質及びその製造方法
JP2010228948A (ja) * 2009-03-26 2010-10-14 Ngk Insulators Ltd アルミナ質多孔体及びその製造方法
JP2014519470A (ja) * 2011-05-27 2014-08-14 コーニング インコーポレイテッド チタン酸アルミニウムセラミックフィルタ特性を制御する方法

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2000169254A (ja) * 1998-12-08 2000-06-20 Kyocera Corp 透気性セラミックス構造体とそれを用いた流体透過部材
JP2005534474A (ja) * 2002-07-31 2005-11-17 コーニング インコーポレイテッド ムライト・チタン酸アルミニウム製ディーゼル微粒子フィルタ
JP2005534597A (ja) * 2002-07-31 2005-11-17 コーニング インコーポレイテッド チタン酸アルミニウムベースのセラミック製品
JP2007510615A (ja) * 2003-11-04 2007-04-26 コーニング インコーポレイテッド チタン酸アルミニウムベースのセラミック体
JP2008508185A (ja) * 2004-07-29 2008-03-21 コーニング インコーポレイテッド 細孔サイズ分布の狭いチタン酸アルミニウム物体およびその製造方法
JP2010077008A (ja) * 2008-08-28 2010-04-08 Kyocera Corp 多孔質セラミック部材およびその製法ならびにフィルタ
CN101412620A (zh) * 2008-11-14 2009-04-22 西安交通大学 溶胶作为助剂制备多孔氧化铝陶瓷支撑体的方法
JP2010228946A (ja) * 2009-03-26 2010-10-14 Ngk Insulators Ltd アルミナ質多孔質及びその製造方法
JP2010228948A (ja) * 2009-03-26 2010-10-14 Ngk Insulators Ltd アルミナ質多孔体及びその製造方法
JP2014519470A (ja) * 2011-05-27 2014-08-14 コーニング インコーポレイテッド チタン酸アルミニウムセラミックフィルタ特性を制御する方法

Similar Documents

Publication Publication Date Title
JP5231304B2 (ja) アルミナ質多孔体及びその製造方法
JP5253261B2 (ja) アルミナ質多孔質及びその製造方法
AU2011341609B2 (en) Alumina ceramic membranes
KR101591932B1 (ko) 세라믹 코팅층을 가지는 다공질 점토 기반 세라믹 분리막 제조방법 및 이에 의해 제조된 세라믹 분리막
EP2767329B1 (fr) Filtre céramique
KR100805180B1 (ko) 세라믹 필터
JP7169401B2 (ja) セラミック膜フィルタの製造方法
JP4917234B2 (ja) セラミックフィルター及び浄水方法
JP6043279B2 (ja) ハニカム形状セラミック製分離膜構造体
JP2010228949A (ja) セラミック多孔体及びその製造方法
WO2025197973A1 (fr) Corps poreux d'alumine, filtre céramique et procédé de production d'un corps poreux d'alumine
JP2018199608A (ja) 多孔質材料、ハニカム構造体、及び多孔質材料の製造方法
JP4398105B2 (ja) セラミック膜フィルター
ES2970053T3 (es) Elemento filtrante cerámico
WO2015151699A1 (fr) Structure de membrane de séparation monolithique
JP6579281B2 (ja) 吸着部材及びその製造方法
JP2007254222A (ja) セラミックス多孔質膜、セラミックスフィルターとその製造方法
CN112969673A (zh) 堇青石-印度石-铁板钛矿结构陶瓷体、批料组合物混合物及其制造陶瓷体的方法
JP2023021136A (ja) セラミックフィルタ
KR100299351B1 (ko) 알루미나계 분말 합성 방법 및 이를 이용한 세라믹 분리막 제조
JP4933740B2 (ja) セラミックフィルタの製造方法
WO2025053017A1 (fr) Stratifié poreux en céramique, et membrane de séparation
CN116490259A (zh) 非氧化物陶瓷过滤膜的制备方法
WO2025053015A1 (fr) Stratifié poreux en céramique, et membrane de séparation
CN119746652A (zh) 过滤膜及其制备方法、过滤装置

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 25774124

Country of ref document: EP

Kind code of ref document: A1