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WO2007115275A1 - Filtres à liaison de carbone comprenant un frevêtement résistant à l'oxydation - Google Patents

Filtres à liaison de carbone comprenant un frevêtement résistant à l'oxydation Download PDF

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Publication number
WO2007115275A1
WO2007115275A1 PCT/US2007/065813 US2007065813W WO2007115275A1 WO 2007115275 A1 WO2007115275 A1 WO 2007115275A1 US 2007065813 W US2007065813 W US 2007065813W WO 2007115275 A1 WO2007115275 A1 WO 2007115275A1
Authority
WO
WIPO (PCT)
Prior art keywords
filter
carbon
ceramic
fibers
glaze
Prior art date
Application number
PCT/US2007/065813
Other languages
English (en)
Inventor
Jeffrey R. Morris
David C. Smith
Original Assignee
Vesuvius Crucible Company
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 Vesuvius Crucible Company filed Critical Vesuvius Crucible Company
Publication of WO2007115275A1 publication Critical patent/WO2007115275A1/fr

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B9/00—General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals
    • C22B9/02—Refining by liquating, filtering, centrifuging, distilling, or supersonic wave action including acoustic waves
    • C22B9/023—By filtering
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C9/00—Moulds or cores; Moulding processes
    • B22C9/08—Features with respect to supply of molten metal, e.g. ingates, circular gates, skim gates
    • B22C9/086—Filters
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

Definitions

  • This invention relates to ceramic filters for use in the processing of molten
  • the processing of molten metals preferably removes exogenous intermetallic
  • inclusions such as impurities from the raw materials, slag, dross and oxides which
  • One method of producing these ceramic filters includes preparing a slurry or
  • An alternative method produces an open pore filter comprising a series of parallel ducts passing through the material.
  • the method includes pressing a damp
  • perforated structure which can be in the form of a disk or block.
  • perforated article is then fired at a temperature in the range of from 1000 to 1700° C.
  • a honeycomb filter may also be produced via
  • WO 01/40414 A describes the use of a pressurized mold. This patent depends
  • GB-A 970 591 concerns a process for producing high density, low permeability
  • the process uses an organic solvent, namely furfuryl alcohol as
  • Binder in the form of pitch is used at 25%.
  • the porosity is closed cell rather than open porosity.
  • U.S. Pat. No. 3,309,433 describes a method for manufacturing high density Graphite using hot pressing as a means to obtain high density graphite articles for nuclear applications. It used special material called dibenzanthrone to bind the graphite. It has no useful application in metal filtration field and does not include any ceramic in the process. Process temperatures can reach 2700° C.
  • EP 0 251 634 Bl describes an appropriate process for making defined porous ceramic bodies having smooth walled cells formed by the pore formers, and pores with round edges, which interconnect the cells.
  • U.S. Pat. No. 5,520,823 relates to filters for aluminum only.
  • the bonding is obtained using borosilicate glass. Firing is carried out in air and a considerable amount of graphite is lost because of oxidation.
  • Filters used for aluminum filtration are usually fired at around 1200° C. while those intended for the use of iron are fired at temperatures of 1450° C. and for steel at above 1600° C.
  • the invention disclosed relates to a ceramic filter suitable for molten metal filtration comprising a ceramic powder and fibers bonded by a network of graphitized carbon.
  • graphitizable means that the carbon bonding obtained by pyrolysis of the carbon precursor can be converted into a graphite-like bond on heating to an elevated temperature in a reducing atmosphere.
  • Graphitizable carbon is distinguished from that of a glassy carbon by the fact that it is impossible to convert glassy carbon to a graphite like bond no matter how high temperature it was heated to.
  • the present invention relates to carbon-bonded molten metal filters.
  • the filters are glazed with an oxidation-resistant glaze.
  • Figure 1 shows a graph of weight loss versus time for carbon-bonded filters with and without glazing.
  • the invention relates to a ceramic filter suitable for molten metal filtration comprising a ceramic powder and fibers bonded by a network of graphitized carbon.
  • US application number 10/5169,443 is hereby incorporated by reference.
  • graphitizable means a carbon precursor that can be converted to graphite- or graphite-like bonding. Conversion can occur by pyrolizing the carbon precursor in a non-oxidizing environment at elevated temperature. Graphitizable carbon is distinguished from glassy carbon by the fact that a glassy carbon cannot be
  • the entire The improvement is mainly
  • the filter comprises graphitized carbon and a refractory ceramic.
  • graphitized carbon should be present as a network of up to 15% by weight of the filter
  • metal fibers either metal fibers, organic fibers such as polyester fibers, viscose fibers, polyethylene
  • PAN polyacrylonitrile
  • aramid fibers polyamide fibers, etc.
  • ceramic fibers such as aluminosilicate fibers, alumina fibers or glass fibers, or carbon
  • the beneficial effect of the addition of fibers depends on the amount of fibers added, length of the fibers, nature and type of fibers added. The higher the level of fibers added the stronger the filter become. However very high level of fibers is not desirable because it has a negative effect on the rheology of the slurry. Best results are obtained from incorporating carbon fiber followed by ceramic fibers. On the other hand, carbon fibers are the most expensive while organic fibers are the cheapest. Organic fibers are the most economic to use since they are added at much lower level than either carbon or ceramic fibers (less than 2%). However, organic fibers interfere with the rheology of the slurry more than the ceramic or the carbon fibers. The form of fibers is either chopped or bulk fibers to be added during mixing of the filter ingredients. No extra mixing technique is required.
  • the filters according to the present invention preferably contain 0.1 to 20% by weight, in particular 1 to 10% by weight of said fibers, more particularly 5%.
  • the fibers used according to the present invention preferably have a length
  • the slurry preferably contains or consists of polyurethane.
  • control the rheology which in one embodiment of the invention may be present in an
  • bonded ceramic filter is produced by a process comprising the steps
  • the source of the carbon bond that is, the carbon bond precursor is preferably
  • HMP high melting pitch
  • bond precursors can also be used to produce carbon bonded materials, such as
  • the product suffers from low oxidation resistance, low mechanical strength, high
  • precursors may be used as well.
  • these processes use a slurry (for the production of a
  • a graphitizable carbon bonding precursor in the range of from 2 (5) to 15 (25) parts by weight
  • ceramic powder in the range of from 0 (20) to 95 (80) parts by weight
  • anti- oxidation material d) in the range of from 0 to 80 parts by weight
  • graphite in the range of from 0 to 90 parts by weight
  • organic binder in the range of from 0 to 10, in particular 0.2 to 2 parts by weight
  • dispersion agent in the range of from 0 to 4, in particular 0.1 to 2 parts by weight. Water is added in a quantity as required.
  • slurry-preparation for the purpose of slurry-preparation,
  • the ceramic powder may comprise zirconia, silica, alumina, brown fused alumina, magnesia, any type of clay, talcum, mica, silicon carbide, silicon nitride and the like or any mixture thereof.
  • Graphite may also be used as a substitute for ceramic powder.
  • Preferred anti-oxidation materials according to the present invention are metallic powder such as steel, iron, bronze, silicon, magnesium, aluminum, boron, zirconium boride, calcium boride, titanium boride and the like, and/or glass fits containing 20 to 30% by weight of boric oxide.
  • Organic binders that are preferred according to the present invention are green binders such as polyvinyl alcohol (PVA), starch, gum arabic, sugar or the like or any combination thereof. These binders may be added to improve the mechanical properties of the fillers during handling prior to firing. Starch and gum arabic may
  • Preferred dispersion agents according to the present invention are:
  • Despex.RTM. Despex.RTM., ligninsulphonate or the like, or any combination thereof which help to
  • mixture may comprise a plasticizer such as polyethylene glycol (preferred molecular
  • an anti-foam agent such as silicon anti-foam in the range of
  • the carbon-bonded filters furthermore are of the carbon-bonded filters.
  • External means at least some portion of the exposed
  • the exposed surface area would include the faces of the filter.
  • the faces include the inlet and outlet faces of the filter.
  • Glaze means any material that substantially reduces oxidation of the filter
  • the glaze may include a barrier that
  • the glaze may include a barrier that scavenges oxygen before the oxygen
  • Oxygen scavengers include, for
  • the glaze is preferably applied to the
  • the glaze may be applied to the
  • the glaze may be dried to remove excess water.
  • the glaze may be fired.
  • the filter is dipped in a glaze material.
  • the filter is left in the glaze long enough for the glaze to substantially cover the external surface of the filter. This may take, for example, about thirty (30) seconds.
  • the filter is removed from the glaze material and centrifuged to ensure that the pores of the filter are not clogged by the glaze material and to remove any excess glaze.
  • the filter is dried in accordance with ASTM 028.
  • the glaze material is sprayed on the filter instead of dipping the filter in the glaze material.
  • the glaze material is applied by electrostatic application. Any suitable glaze material known to those skilled in the art may be used in accordance with the present invention.
  • a glaze of the following composition may be used:

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Filtering Materials (AREA)

Abstract

L'invention concerne un filtre céramique permettant la filtration d'un métal en fusion, comprenant une poudre céramique liée par un réseau de carbone graphitisé, le filtre céramique étant recouvert de vernis.
PCT/US2007/065813 2006-04-04 2007-04-03 Filtres à liaison de carbone comprenant un frevêtement résistant à l'oxydation WO2007115275A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US78891806P 2006-04-04 2006-04-04
US60/788,918 2006-04-04

Publications (1)

Publication Number Publication Date
WO2007115275A1 true WO2007115275A1 (fr) 2007-10-11

Family

ID=38420516

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US2007/065813 WO2007115275A1 (fr) 2006-04-04 2007-04-03 Filtres à liaison de carbone comprenant un frevêtement résistant à l'oxydation

Country Status (1)

Country Link
WO (1) WO2007115275A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2018039026A1 (fr) * 2016-08-26 2018-03-01 Vesuvius Crucible Company Article doté d'une surface fibreuse résistante à l'oxydation

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1288178A1 (fr) * 2001-09-01 2003-03-05 Carbon Application Technology Ltd. Filtre pour filtration de métal fondu et procédé de fabrication correspondant
EP1369158A1 (fr) * 2002-05-31 2003-12-10 Carbon Application Technology Ltd. Filtre renforcé de fibres pour la filtration de métaux fondus et procédé de sa fabrication
WO2003101644A1 (fr) * 2002-06-03 2003-12-11 Carbon Application Technology Ltd. Dispositif de filtre pour filtration d'acier en fusion
WO2007028556A1 (fr) * 2005-09-05 2007-03-15 Vesuvius Crucible Company Dispositif de filtres pour le filtrage du métal en fusion et procédé de production de tels filtres

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1288178A1 (fr) * 2001-09-01 2003-03-05 Carbon Application Technology Ltd. Filtre pour filtration de métal fondu et procédé de fabrication correspondant
EP1369158A1 (fr) * 2002-05-31 2003-12-10 Carbon Application Technology Ltd. Filtre renforcé de fibres pour la filtration de métaux fondus et procédé de sa fabrication
WO2003101644A1 (fr) * 2002-06-03 2003-12-11 Carbon Application Technology Ltd. Dispositif de filtre pour filtration d'acier en fusion
WO2007028556A1 (fr) * 2005-09-05 2007-03-15 Vesuvius Crucible Company Dispositif de filtres pour le filtrage du métal en fusion et procédé de production de tels filtres

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2018039026A1 (fr) * 2016-08-26 2018-03-01 Vesuvius Crucible Company Article doté d'une surface fibreuse résistante à l'oxydation

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