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GB2168335A - A ceramic foam filter - Google Patents
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GB2168335A - A ceramic foam filter - Google Patents

A ceramic foam filter Download PDF

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Publication number
GB2168335A
GB2168335A GB08527210A GB8527210A GB2168335A GB 2168335 A GB2168335 A GB 2168335A GB 08527210 A GB08527210 A GB 08527210A GB 8527210 A GB8527210 A GB 8527210A GB 2168335 A GB2168335 A GB 2168335A
Authority
GB
United Kingdom
Prior art keywords
ceramic
strands
micrometers
foam filter
slip
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.)
Granted
Application number
GB08527210A
Other versions
GB8527210D0 (en
GB2168335B (en
Inventor
Yoshihisa Kato
Masashi Fujimoto
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.)
Coorstek KK
Original Assignee
Toshiba Ceramics Co 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 Toshiba Ceramics Co Ltd filed Critical Toshiba Ceramics Co Ltd
Publication of GB8527210D0 publication Critical patent/GB8527210D0/en
Publication of GB2168335A publication Critical patent/GB2168335A/en
Application granted granted Critical
Publication of GB2168335B publication Critical patent/GB2168335B/en
Expired legal-status Critical Current

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Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D39/00Filtering material for liquid or gaseous fluids
    • B01D39/14Other self-supporting filtering material ; Other filtering material
    • B01D39/20Other self-supporting filtering material ; Other filtering material of inorganic material, e.g. asbestos paper, metallic filtering material of non-woven wires
    • B01D39/2068Other inorganic materials, e.g. ceramics
    • B01D39/2093Ceramic foam
    • CCHEMISTRY; METALLURGY
    • C04CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04BLIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B38/00Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof
    • C04B38/06Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof by burning-out added substances by burning natural expanding materials or by sublimating or melting out added substances
    • C04B38/0615Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof by burning-out added substances by burning natural expanding materials or by sublimating or melting out added substances the burned-out substance being a monolitic element having approximately the same dimensions as the final article, e.g. a porous polyurethane sheet or a prepreg obtained by bonding together resin particles

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

Abstract

A ceramic foam filter has a three-dimensionally reticulated ceramic structure composed of many interconnected strands each having fine pores therein. It is derived by adding a carbon material to a ceramic oxide material, mixing them to form a slip, impregnating a starting foam with the slip, drying them, and firing them, whereby the starting foam material and the carbon material disappear on firing, thereby to form large pores among the strands and fine pores therein.

Description

SPECIFICATION A ceramic foam filter and a method for manufacturing the same This invention relates to a ceramic foam filter and a method for manufacturing the same, and in particular relates to a ceramic foam filter for filtering or removing metal oxides or slugs contained in a molten metal.
A ceramic foam filter is used to filter metal oxides or slugs contained in a molten metal. Filtering efficiency of such a ceramic foam filter depends upon only pores of the ceramic foam.
In such a conventional ceramic foam, it is difficult to improve the filtering efficiency. However, it is strongly desired to improve the filtering efficiency of the ceramic foam filter.
The object of this invention is to provide a ceramic foam filter and a method for manufacturing the same, which has an improved filtering efficiency.
The present invention is a ceramic foam filter having a three-dimensionally reticulated ceramic structure composed of many interconnected ceramic strands and having continuous large pores among the strands characterized in that each of the strands has a large number of fine pores therein.
The present invention is also a method for manufacturing a ceramic foam filter, comprising the steps of: mixing an oxide ceramic material composed of small particles with water and a binder thereby to form a slip; infusing or impregnating a starting foam with the slip; drying the starting foam and the slip; firing the starting foam and the slip thereby to form a three-dimensionally reticulated ceramic structure composed of many interconnected strands and having large continuous pores among the strands while the starting foam disappears on firing; characterized in that a carbon material composed of small particles is added to the oxide ceramic material prior to the impregnating step so that the carbon material disappears on firing thereby to form a large number of fine pores in each of the strands.
A carbon material composed of small particles is added to an oxide ceramic material composed of small particles. The carbon material disappears on firing so as to form fine pores in each of many ceramic strands which are interconnected thereby to constitute a three-dimensionally reticulated ceramic structure corresponding in shape to a starting foam material such as a soft urethane foam which also disappears on firing thereby to form an opening in each strand. Also, continuous large pores are formed among many strands in the ceramic reticulated structure.
If a molten metal is a molten Aluminium and an oxide ceramic material is an Al203 material, due to a contact angle between A1203 and Al, the molten Aluminium cannot come into the fine pores of the strands. Therefore, only the metal oxides or slugs in the molten Aluminium are trapped in the fine pores of the strands.
Embodiments of the present invention will now be described, by way of example.
An A1203 material is used as an oxide ceramic material. The A1203 material is composed of small particles, the sizes of which are between 10 micrometers and 0.1 micrometers. The mean particle size thereof ranges from 5 micrometers to 0.5 micrometers.
The carbon material to be added to the A1203 material is also composed of small particles, the particle size distribution of which ranges from 20 micrometers to 100 micrometers. The mean particle size of them is between 20 micrometers and 100 micrometers.
The 3% by weight carbon material is added to the A1203 material.
Such starting materials are mixed with water, a binder such as PVA and a large number of small balls such as ceramic balls within a ball mill so as to have a viscosity between 2 poise and 15 poise thereby to obtain a slip or slurry for the ceramic manufacturing purpose. A soft urethane foam having a well-known three-dimensionally reticulated structure composed of many interconnected strands with large continuous pores is infused or impregnated with the slip, preferably plural times, and dried to be hardened at each time. In other words, the infusing or impregnating and drying steps are repeated a plurality of times.
The details of such a method for infusing or impregnating the urethane foam with the slip will be described. The soft urethane foam is impregnated with the slip having a viscosity of 2-15 poise thereby to form a first layer. At that time, surplus slip is removed from the surfaces of the strands in order to prevent the slip from stopping in the large pores among the strands. The slip is dried to be hardened at a temperature from 50"C to 100 C thereby to form the first layer.
In addition, a second layer is formed on the first layer by infusing or impregnating the first layer with same or different slip having a viscosity from 2 poise to 15 poise. At this time, also, surplus slip is removed in order to prevent the slip from stopping in the large pores among the strands. Thereafter, it is dried to be hardened thereby to form the second layer.
Further, a third layer is formed on the second layer by impregnating or infusng the second layer with same or different slip having a viscosity from 1 poise to 10 poise. At this time, also, excess slip is removed in order to avoid stopping thereof in the large pores among the strands. Thereafter, it is dried to be hardened thereby to form the third layer.
Whenever the soft urethane foam is infused or impregnated with the slip or slurry, the ceramic layer is increased in thickness to become a multi-layer consisting of three ceramic layers.
Thereafter, it is fired at a temperature of 1 500"C or more. Thus, the ceramic multi-layer becomes a porcelain ceramic body having a threedimensionally reticulated structure which is composed of a large number of interconnected strands.
The reticulated structure of the ceramic body corresponds in shape to the starting urethane foam so that is has large continuous pores among the strands. At the same time, the carbon material disappears on firing thereby to form many fine pores in each strand. The fine pores of the strands correspond in size to the particles of the carbon material. Also, the soft urethane foam disappears on firing so that a long opening is formed in a central portion of each strand.
As can be seen from the foregoing description, the ceramic foam filter has a three-dimensionally reticulated ceramic structure composed of many strands each of which has a multi-layer having many fine pores therein. Preferably, the apparent porosity of the strands is about 20%, and the pore diameters of the fine pores in the strands range between 20 and 100 micrometers.
For instance, if an A1203 material is used as an oxide ceramic material, and the molten metal is a molten Aluminium, due to a contact angle between Al203 and Al, the molten Aluminium cannot come into the fine pores of the strands so that only the metal oxides or slugs in the molten Aluminium are trapped in the fine pores thereof. Accordingly, since only the slugs in the molten metal can be trapped in the fine pores of the strands, they can be filtered not only by the large pores of the reticulated structure but also by the fine pores of the strands thereof. As a result, the filtering efficiency and the life time of the filter can be remarkably increased.
Due to the contact angle between Awl203 and Al, even if pores having the pore diameter of 30 micrometers are formed, the filtering function can be obtained like in the case of the pore diameter of 20 micrometers with the improved filtering efficiency and long lifetime.
Although in the above-stated embodiment an A1203 material is used as oxide ceramic material, this invention is not limited to such a mode. For instance, A1203-ZrO2, cordierite, mullite or the like can be used as an oxide ceramic material.
As can be seen from the foregoing description, according to this invention, a ceramic foam filter has a three-dimensionally reticulated ceramic structure which is composed of many interconnected ceramic strands having a large number of fine pores therein so as to obtain a reasonable apparent porosity. As compared with the prior art methods, the filtering efficiency of the ceramic foam filter can be advantageously improved.

Claims (21)

1. A ceramic foam filter having a threedimensionally reticulated ceramic structure composed of many interconnected ceramic strands and having continuous large pores among the strands characterized in that each of the strands has a large number of fine pores therein.
2. The ceramic foam filter of claim 1, wherein each of the strands has a multi-layer ceramic structure and a long opening in a central portion thereof.
3. The ceramic foam filter of claim 1,wherein an apparent porosity of the strands is about 20%.
4. The ceramic foam filter of claim 1, wherein pore diameters of the fine pores of the strands are between 20 micrometers and 100 micrometers.
5. The ceramic foam filter of claim 1, wherein the mean pore diameter of the fine pores of the strands is between 20 micrometers and 100 micrometers.
6. The ceramic foam filter of claim 1, wherein each of the strands consists of plural ceramic layers.
7. The ceramic foam filter of claim 1, wherein the plural layers are the same in composition.
8. The ceramic foam filter of claim 1, wherein the plural layers are different to each other in composition.
9. The ceramic foam filter of claim 1, wherein the reticulated structure is made of a porcelain ceramic material.
10. A method for manufacturing a ceramic foam filter, comprising the steps of: mixing an oxide ceramic material composed of small particles with water and a binder thereby to form a slip; infusng or impregnating a starting foam with the slip; drying the starting foam and the slip; firing the starting foam and the slip thereby to form a three-dimensionally reticulated ceramic structure composed of many interconnected strands and having large continuous pores among the strands while the starting foam disappears on firing; characterized in that a carbon material composed of small particles is added to the oxide ceramic material prior to the impregnating step so that the carbon material disappears on firing thereby to form a large number of fine pores in each of the strands.
11. A method as claimed in claim 10, wherein the sizes of the particles of the oxide ceramic material are between 10 micrometers and 0.1 micrometers, and the mean particle size thereof is between 5 micrometers and and 0.5 micrometers.
12. A method as claimed in claim 10, wherein the sizes of the particles of the carbon material are between 20 micrometers and 100 micrometers, and the mean particle size thereof is between 20 micrometers and 100 micrometers.
13. A method as claimed in claim 10, wherein the carbon material of 3% by weight is added to the oxide ceramic material.
14. A method as claimed in claim 10, wherein the carbon material and the oxide ceramic material are mixed with the water and the binder by means of a ball mill thereby to form the slip.
15. A method as claimed in claim 10, wherein the slip has a viscosity between 2 poise and 15 poise.
16. A method as claimed in claim 10, wherein the oxide ceramic material is A12O3, Al203-ZrO2, cordierite or mullite.
17. A method as claimed in claim 10, wherein the steps of impregnating and drying steps are repeated so as to form a multi-layer.
18. A method as claimed in claim 10, wherein an apparent porosity of the strands is about 20%.
19. A method as claimed in claim 10, wherein pore diameters of the fine pores in the strands are between 20 micrometers and 100 micrometers.
20. A ceramic foam filter as claimed in claim 1 and substantially as hereinbefore described.
21. A method of manufacturing a ceramic foam filter as claimed in claim 10 and substantially as hereinbefore described.
GB08527210A 1984-12-12 1985-11-05 A ceramic foam filter Expired GB2168335B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP26089984A JPS61138512A (en) 1984-12-12 1984-12-12 Preparation of ceramic filter

Publications (3)

Publication Number Publication Date
GB8527210D0 GB8527210D0 (en) 1985-12-11
GB2168335A true GB2168335A (en) 1986-06-18
GB2168335B GB2168335B (en) 1988-03-02

Family

ID=17354300

Family Applications (1)

Application Number Title Priority Date Filing Date
GB08527210A Expired GB2168335B (en) 1984-12-12 1985-11-05 A ceramic foam filter

Country Status (3)

Country Link
JP (1) JPS61138512A (en)
DE (1) DE3540451A1 (en)
GB (1) GB2168335B (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0864550A1 (en) * 1997-03-13 1998-09-16 Frank Drache Process for manufacturing coated ceramics with increased microporosity, coated ceramic with increased microporosity and article made thereof
EP1634646A1 (en) * 2004-09-13 2006-03-15 Mangold, Matthias Process for producing exhaust gas purification means and purification means
US8158053B2 (en) * 2000-08-31 2012-04-17 Foseco International Limited Refractory articles

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS63140070A (en) * 1986-12-03 1988-06-11 Nkk Corp Apparatus for removing fine impurity in hot dipping bath
DE4242491C2 (en) * 1992-12-16 1996-07-18 Oberflaechentechnik Pallas Gmb Process for the production of a microfilter
DE10044656B4 (en) 2000-09-04 2005-12-29 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Open cell silicon carbide foam ceramic and process for its preparation
KR100463921B1 (en) * 2002-03-19 2004-12-30 박경순 Alumina based ceramic filter for casting and method of producing the same
KR100458471B1 (en) * 2002-07-05 2004-11-26 대주엔지니어링(주) Manufacturing method of the ceramics filter
US8986581B2 (en) 2012-07-27 2015-03-24 Carbron Basis Company Ltd. Biochar products and method of manufacture thereof
CN108138028A (en) 2015-10-08 2018-06-08 碳基有限公司 Charcoal product and its manufacturing method
DE102016216555A1 (en) 2016-09-01 2018-03-01 Bayerische Motoren Werke Aktiengesellschaft Shaped electrochemical cell

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0107345A2 (en) * 1982-09-30 1984-05-02 Corning Glass Works Improved alumina molten metal filters

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0107345A2 (en) * 1982-09-30 1984-05-02 Corning Glass Works Improved alumina molten metal filters

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0864550A1 (en) * 1997-03-13 1998-09-16 Frank Drache Process for manufacturing coated ceramics with increased microporosity, coated ceramic with increased microporosity and article made thereof
US8158053B2 (en) * 2000-08-31 2012-04-17 Foseco International Limited Refractory articles
EP1634646A1 (en) * 2004-09-13 2006-03-15 Mangold, Matthias Process for producing exhaust gas purification means and purification means

Also Published As

Publication number Publication date
GB8527210D0 (en) 1985-12-11
DE3540451A1 (en) 1986-06-19
GB2168335B (en) 1988-03-02
JPS61138512A (en) 1986-06-26

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PCNP Patent ceased through non-payment of renewal fee