WO1987002069A1 - Filtration of aluminium-lithium alloys - Google Patents

Filtration of aluminium-lithium alloys Download PDF

Info

Publication number
WO1987002069A1
WO1987002069A1 PCT/GB1986/000588 GB8600588W WO8702069A1 WO 1987002069 A1 WO1987002069 A1 WO 1987002069A1 GB 8600588 W GB8600588 W GB 8600588W WO 8702069 A1 WO8702069 A1 WO 8702069A1
Authority
WO
WIPO (PCT)
Prior art keywords
aluminium
porous ceramic
ceramic body
foam
alloy
Prior art date
Application number
PCT/GB1986/000588
Other languages
French (fr)
Inventor
Nicholas Ronald Child
Original Assignee
Foseco International Limited
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 Foseco International Limited filed Critical Foseco International Limited
Publication of WO1987002069A1 publication Critical patent/WO1987002069A1/en

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
    • B01D39/2068—Other inorganic materials, e.g. ceramics
    • B01D39/2093—Ceramic foam
    • 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
    • C04B35/515—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics
    • C04B35/56—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on carbides or oxycarbides
    • C04B35/565—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on carbides or oxycarbides based on silicon carbide
    • 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
    • C04B38/06—Porous 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
    • C04B38/0615—Porous 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
    • 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
    • C22B21/00—Obtaining aluminium
    • C22B21/06—Obtaining aluminium refining
    • C22B21/066—Treatment of circulating aluminium, e.g. by filtration

Definitions

  • This invention relates to the filtration of alum nium-lit ium alloys.
  • aluminium-lithium alloys are particularly reactive compared with most other aluminium alloys they will attack the materials commonly used for filtering molten aluminium alloys
  • a method of filtering a molten aluminium- -lithium alloy which comprises passing the molten alloy through a porous ceramic body comprising silicon carbi de .
  • the porous body may be for example a honey ⁇ comb type of structure having pores which extend from one face of the body to another face or a structure having interconnecting pores such as a ceramic foam.
  • Foam structures are preferred and such structures may be made using a known method of making ⁇ a ceramic foam in which an organic foam, usually a polyurethane foam, is impregnated with an aqueous slurry of ceramic material containing a binder, the impregnated foam is dried to remove water and the dried impregnated foam is fired to burn off the organic foam to produce a ceramic foam.
  • the production of ceramic foams by this method is described in United States Patent 3090094 and in British Patents 923862, 916784, 1004352, 1054421 , 1377691, 1388911, 1388912 and 1388913.
  • the porous ceramic body used-as the filter in the present invention is made solely from silicon carbide apart from minor amounts of oxides which are present as residues from binders, for example phosphorous pentoxide from monoal u i ni urn phosphate, and/or from additives which may have been used in the production of the porous body, for example silica from clay which may be added to improve the rheological properties of the slurry when the body is produced by impregnation of an organic foam with a silicon carbide-containing slurry,
  • the body may also contain a proportion, usually not exceeding 45% by weight, of a refractory oxide such as alumina.
  • a ceramic foam having the following com ⁇ position by weight:-
  • the foam was fixed to a refractory tube by means of a high temperature resistant adhesive, the tube was attached to a steel rod, and the foam was then immersed in molten LITAL aluminium-lithium alloy at 760-765°C. The foam was unaffected by the molten alloy after immersion for 60 minutes.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Organic Chemistry (AREA)
  • Materials Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Structural Engineering (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Geology (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Filtering Materials (AREA)
  • Manufacture And Refinement Of Metals (AREA)

Abstract

Alumina oxide and other non-metallic compounds, such as lithium oxide, are removed from molten aluminium-lithium alloys by filtration through a porous ceramic body comprising silicon carbide. The porous ceramic body may be, for example, a honeycomb type of structure or a foam having interconnecting pores.

Description

*
FILTRATION OF ALUMINIUM-LITHIUM ALLOYS
This invention relates to the filtration of alum nium-lit ium alloys.
It is well known, in order to remove alumini-um oxide from molten aluminium or aluminium 5 alloys to pass the aluminium or aluminium alloy through a filter such as a fibreglass cloth, a bed of refractory particles such as alumina balls or a ceramic foam made from a material such as alumina, an al umi nosi 1 i cate such as mullite, or cordierite.
10 Molten aluminium-lithium alloys which contain 1.0 to 4.5% lithium, usually 1.1 to 2.5%, contain other non-metallic compounds in addition to aluminium oxide, for example lithium oxide, which will produce inclusions if they are not removed before
15 the metal is cast.
However because aluminium-lithium alloys are particularly reactive compared with most other aluminium alloys they will attack the materials commonly used for filtering molten aluminium alloys
20 so that to date no satisfactory method of filtering aluminium-lithium alloys has been found. Instead it is necessary to take special precautions to minimise oxidation of the lithium and thereby minimise the formation of non-metallic compounds, for example by
25 melting the alloy under an inert atmosphere or under a thick layer of flux, and before casting to remove the non-metallic compounds present by a method other than filtration. According to the present invention there is provided a method of filtering a molten aluminium- -lithium alloy which comprises passing the molten alloy through a porous ceramic body comprising silicon carbi de .
The porous body may be for example a honey¬ comb type of structure having pores which extend from one face of the body to another face or a structure having interconnecting pores such as a ceramic foam.
Foam structures are preferred and such structures may be made using a known method of making ■ a ceramic foam in which an organic foam, usually a polyurethane foam, is impregnated with an aqueous slurry of ceramic material containing a binder, the impregnated foam is dried to remove water and the dried impregnated foam is fired to burn off the organic foam to produce a ceramic foam. The production of ceramic foams by this method is described in United States Patent 3090094 and in British Patents 923862, 916784, 1004352, 1054421 , 1377691, 1388911, 1388912 and 1388913.
It is preferred that the porous ceramic body used-as the filter in the present invention is made solely from silicon carbide apart from minor amounts of oxides which are present as residues from binders, for example phosphorous pentoxide from monoal u i ni urn phosphate, and/or from additives which may have been used in the production of the porous body, for example silica from clay which may be added to improve the rheological properties of the slurry when the body is produced by impregnation of an organic foam with a silicon carbide-containing slurry,
However the body may also contain a proportion, usually not exceeding 45% by weight, of a refractory oxide such as alumina.
The following example will serve to illustrate the invention:-
A ceramic foam having the following com¬ position by weight:-
silicon carbide 53.0% al umi na 34.2% silica 4.1% phosphorous pentoxide 8.7%
was made by impregnating a reticulated polyurethane foam with an aqueous slurry containing silicon carbide, alumina, clay and aluminium orthophosphate as binder, and drying and then, firing the impregnated foam.
In order to assess the suitability of the foam as a fi 1 er for aluminium-li hium alloys the foam was fixed to a refractory tube by means of a high temperature resistant adhesive, the tube was attached to a steel rod, and the foam was then immersed in molten LITAL aluminium-lithium alloy at 760-765°C. The foam was unaffected by the molten alloy after immersion for 60 minutes.
Similar tests were also performed on other types of filter materials. Honeycomb type structures of mullite, cordierite and mul 1 i te/cordi eri te and ceramic foams of alumina and al umi nosi 1 i cate were all attacked and severely weakened after 10 minutes immersion in the molten aluminium-lithium alloy, while silica based cloth withstood 60 minutes immersion but was extremely brittle on removal .

Claims

C L A I MS
1. A method of filtering a molten aluminium alloy wherein the molten alloy is passed through a porous ceramic body characterised in that the alloy is an aluminium-lithium alloy and the porous ceramic body comprises silicon carbide.
2. A method according to claim 1 characterised in that the porous ceramic body has pores which extend from one face of the body to another face.
3. A method according to clai 1 characterised in that the porous ceramic body is a ceramic foam.
4. " A method according to claim 1 characterised in that the porous ceramic body contains a minor amount of phosphorus pentoxide.
5. A method according to claim 1 characterised in that the porous ceramic body contains a minor amount of silica.
6. A method according to claim 1 characterised in that the porous ceramic body contains alumina.
7. A method according to claim 6 characterised in that al umi na • content is not more than 45% by weight .
PCT/GB1986/000588 1985-10-03 1986-10-01 Filtration of aluminium-lithium alloys WO1987002069A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB858524400A GB8524400D0 (en) 1985-10-03 1985-10-03 Filtration of aluminium-lithium alloys
GB8524400 1985-10-03

Publications (1)

Publication Number Publication Date
WO1987002069A1 true WO1987002069A1 (en) 1987-04-09

Family

ID=10586130

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1986/000588 WO1987002069A1 (en) 1985-10-03 1986-10-01 Filtration of aluminium-lithium alloys

Country Status (3)

Country Link
EP (1) EP0238607A1 (en)
GB (1) GB8524400D0 (en)
WO (1) WO1987002069A1 (en)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1988007403A1 (en) * 1987-03-23 1988-10-06 Schweizerische Aluminium Ag Ceramic foam filter
GB2269185A (en) * 1992-07-30 1994-02-02 Rolls Royce Plc Improvements in or relating to removal of contaminants from molten metal.
US6111165A (en) * 1993-01-28 2000-08-29 Cohesion Technologies, Inc. Production of human recombinant collagen in the milk of transgenic animals
US8365808B1 (en) 2012-05-17 2013-02-05 Almex USA, Inc. Process and apparatus for minimizing the potential for explosions in the direct chill casting of aluminum lithium alloys
US8479802B1 (en) 2012-05-17 2013-07-09 Almex USA, Inc. Apparatus for casting aluminum lithium alloys
US9616493B2 (en) 2013-02-04 2017-04-11 Almex USA, Inc. Process and apparatus for minimizing the potential for explosions in the direct chill casting of aluminum lithium alloys
US9936541B2 (en) 2013-11-23 2018-04-03 Almex USA, Inc. Alloy melting and holding furnace

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3039864A (en) * 1958-11-21 1962-06-19 Aluminum Co Of America Treatment of molten light metals
GB923862A (en) * 1960-03-09 1963-04-18 Ivor James Holland Porous refractory materials
US3408180A (en) * 1966-09-12 1968-10-29 Gen Foam Corp Method of producing an inorganic foam and product
DE2333422A1 (en) * 1972-07-03 1974-01-24 Gullhoegens Bruk Ab HARD MATERIAL AND PROCESS FOR ITS MANUFACTURING
DE2517380A1 (en) * 1975-04-19 1976-10-21 Rosenthal Ag Foamed ceramic bodies contg silicon nitride or carbide - produced by nitriding or carburising foamed silicon bodies
US4067731A (en) * 1975-07-18 1978-01-10 Southwire Company Method of treating molten metal
JPS55154536A (en) * 1979-05-18 1980-12-02 Nippon Rutsubo Kk Impurity removing method for molten metal
EP0087789A1 (en) * 1982-02-26 1983-09-07 Bridgestone Tire Company Limited Porous ceramic article
DE3504393A1 (en) * 1984-02-10 1985-08-14 Kurosaki Refractories Co., Ltd., Kitakyushu, Fukuoka METHOD FOR PRODUCING A SINTERED CERAMIC BODY FROM A SI (DOWN ARROW) 3 (DOWN ARROW) N (DOWN ARROW) 4 (DOWN ARROW) -SIC SYSTEM

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3039864A (en) * 1958-11-21 1962-06-19 Aluminum Co Of America Treatment of molten light metals
GB923862A (en) * 1960-03-09 1963-04-18 Ivor James Holland Porous refractory materials
US3408180A (en) * 1966-09-12 1968-10-29 Gen Foam Corp Method of producing an inorganic foam and product
DE2333422A1 (en) * 1972-07-03 1974-01-24 Gullhoegens Bruk Ab HARD MATERIAL AND PROCESS FOR ITS MANUFACTURING
DE2517380A1 (en) * 1975-04-19 1976-10-21 Rosenthal Ag Foamed ceramic bodies contg silicon nitride or carbide - produced by nitriding or carburising foamed silicon bodies
US4067731A (en) * 1975-07-18 1978-01-10 Southwire Company Method of treating molten metal
JPS55154536A (en) * 1979-05-18 1980-12-02 Nippon Rutsubo Kk Impurity removing method for molten metal
EP0087789A1 (en) * 1982-02-26 1983-09-07 Bridgestone Tire Company Limited Porous ceramic article
DE3504393A1 (en) * 1984-02-10 1985-08-14 Kurosaki Refractories Co., Ltd., Kitakyushu, Fukuoka METHOD FOR PRODUCING A SINTERED CERAMIC BODY FROM A SI (DOWN ARROW) 3 (DOWN ARROW) N (DOWN ARROW) 4 (DOWN ARROW) -SIC SYSTEM

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENTS ABSTRACTS OF JAPAN, Volume 5, No. 28, (C-44) (700) 20 February 1981 & JP, A, 55154536 (Nippon Rutsubo K.K.) 2 December 1980 *

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1988007403A1 (en) * 1987-03-23 1988-10-06 Schweizerische Aluminium Ag Ceramic foam filter
GB2269185A (en) * 1992-07-30 1994-02-02 Rolls Royce Plc Improvements in or relating to removal of contaminants from molten metal.
US5336294A (en) * 1992-07-30 1994-08-09 Rolls-Royce Plc Removal of contaminants from molten metals
US6111165A (en) * 1993-01-28 2000-08-29 Cohesion Technologies, Inc. Production of human recombinant collagen in the milk of transgenic animals
US9849507B2 (en) 2012-05-17 2017-12-26 Almex USA, Inc. Process and apparatus for minimizing the potential for explosions in the direct chill casting of aluminum lithium alloys
US8479802B1 (en) 2012-05-17 2013-07-09 Almex USA, Inc. Apparatus for casting aluminum lithium alloys
US8365808B1 (en) 2012-05-17 2013-02-05 Almex USA, Inc. Process and apparatus for minimizing the potential for explosions in the direct chill casting of aluminum lithium alloys
US9895744B2 (en) 2012-05-17 2018-02-20 Almex USA, Inc. Process and apparatus for direct chill casting
US10646919B2 (en) 2012-05-17 2020-05-12 Almex USA, Inc. Process and apparatus for direct chill casting
US10946440B2 (en) 2012-05-17 2021-03-16 Almex USA, Inc. Process and apparatus for minimizing the potential for explosions in the direct chill casting aluminum alloys
US9616493B2 (en) 2013-02-04 2017-04-11 Almex USA, Inc. Process and apparatus for minimizing the potential for explosions in the direct chill casting of aluminum lithium alloys
US9764380B2 (en) 2013-02-04 2017-09-19 Almex USA, Inc. Process and apparatus for direct chill casting
US9950360B2 (en) 2013-02-04 2018-04-24 Almex USA, Inc. Process and apparatus for minimizing the potential for explosions in the direct chill casting of lithium alloys
US10864576B2 (en) 2013-02-04 2020-12-15 Almex USA, Inc. Process and apparatus for minimizing the potential for explosions in the direct chill casting of lithium alloys
US9936541B2 (en) 2013-11-23 2018-04-03 Almex USA, Inc. Alloy melting and holding furnace
US10932333B2 (en) 2013-11-23 2021-02-23 Almex USA, Inc. Alloy melting and holding furnace

Also Published As

Publication number Publication date
EP0238607A1 (en) 1987-09-30
GB8524400D0 (en) 1985-11-06

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