EP0238607A1 - Filtration of aluminium-lithium alloys - Google Patents
Filtration of aluminium-lithium alloysInfo
- Publication number
- EP0238607A1 EP0238607A1 EP19860905891 EP86905891A EP0238607A1 EP 0238607 A1 EP0238607 A1 EP 0238607A1 EP 19860905891 EP19860905891 EP 19860905891 EP 86905891 A EP86905891 A EP 86905891A EP 0238607 A1 EP0238607 A1 EP 0238607A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- aluminium
- porous ceramic
- ceramic body
- foam
- alloy
- 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
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
L'oxyde d'alumine et d'autres composés non métalliques, tels que l'oxyde de lithium, sont extraits d'alliages d'aluminium-lithium en fusion par filtrage à travers un corps céramique poreux comprenant du carbure de silicium. Le corps céramique poreux peut être, par exemple, une structure en nid-d'abeilles ou une mousse possédant des pores communiquants.Alumina oxide and other non-metallic compounds, such as lithium oxide, are extracted from molten aluminum-lithium alloys by filtering through a porous ceramic body comprising silicon carbide. The porous ceramic body can be, for example, a honeycomb structure or a foam having communicating 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
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 .
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 |
|---|---|
| EP0238607A1 true EP0238607A1 (en) | 1987-09-30 |
Family
ID=10586130
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP19860905891 Pending EP0238607A1 (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) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4885263A (en) * | 1987-03-23 | 1989-12-05 | Swiss Aluminium Ltd. | Ceramic foam filter and process for preparing same |
| GB2269185A (en) * | 1992-07-30 | 1994-02-02 | Rolls Royce Plc | Improvements in or relating to removal of contaminants from molten metal. |
| US5667839A (en) * | 1993-01-28 | 1997-09-16 | Collagen Corporation | Human recombinant collagen in the milk of transgenic animals |
| 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 |
| RU2675127C2 (en) | 2013-02-04 | 2018-12-17 | ОЛМЕКС ЮЭсЭй, ИНК. | Process and apparatus for minimising the potential for explosions in direct chill casting of aluminium lithium alloys |
| US9936541B2 (en) | 2013-11-23 | 2018-04-03 | Almex USA, Inc. | Alloy melting and holding furnace |
Family Cites Families (9)
| 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 |
| DE2517380C3 (en) * | 1975-04-19 | 1979-03-22 | Rosenthal Ag, 8672 Selb | Process for the production of ceramic silicon nitride foam bodies or silicon carbide foam 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 |
| US4560478A (en) * | 1982-02-26 | 1985-12-24 | Bridgestone Tire Co., Ltd. | Porous ceramic article |
| JPS60171282A (en) * | 1984-02-10 | 1985-09-04 | 黒崎窯業株式会社 | Manufacture of si3n4-sic ceramic sintered body |
-
1985
- 1985-10-03 GB GB858524400A patent/GB8524400D0/en active Pending
-
1986
- 1986-10-01 EP EP19860905891 patent/EP0238607A1/en active Pending
- 1986-10-01 WO PCT/GB1986/000588 patent/WO1987002069A1/en unknown
Non-Patent Citations (1)
| Title |
|---|
| See references of WO8702069A1 * |
Also Published As
| Publication number | Publication date |
|---|---|
| WO1987002069A1 (en) | 1987-04-09 |
| GB8524400D0 (en) | 1985-11-06 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
| AK | Designated contracting states |
Kind code of ref document: A1 Designated state(s): CH DE FR GB LI |
|
| STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN |
|
| RIN1 | Information on inventor provided before grant (corrected) |
Inventor name: CHILD, NICHOLAS, RONALD6 OXFORD HOUSE |