US3498359A - Moulds for use in metal casting - Google Patents

Moulds for use in metal casting Download PDF

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Publication number
US3498359A
US3498359A US621680A US3498359DA US3498359A US 3498359 A US3498359 A US 3498359A US 621680 A US621680 A US 621680A US 3498359D A US3498359D A US 3498359DA US 3498359 A US3498359 A US 3498359A
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US
United States
Prior art keywords
mould
carbon
moulds
nitrogen
furnace
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.)
Expired - Lifetime
Application number
US621680A
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English (en)
Inventor
Adam Dunlop
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.)
Imperial Metal Industries Kynoch Ltd
Original Assignee
Imperial Metal Industries Kynoch 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
Priority claimed from GB1221766A external-priority patent/GB1144174A/en
Application filed by Imperial Metal Industries Kynoch Ltd filed Critical Imperial Metal Industries Kynoch Ltd
Application granted granted Critical
Publication of US3498359A publication Critical patent/US3498359A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C23/00—Tools; Devices not mentioned before for moulding
    • B22C23/02—Devices for coating moulds or cores
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C1/00—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds
    • B22C1/02—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by additives for special purposes, e.g. indicators, breakdown additives
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C1/00—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds
    • B22C1/02—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by additives for special purposes, e.g. indicators, breakdown additives
    • B22C1/04—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by additives for special purposes, e.g. indicators, breakdown additives for protection of the casting, e.g. against decarbonisation
    • B22C1/06—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by additives for special purposes, e.g. indicators, breakdown additives for protection of the casting, e.g. against decarbonisation for casting extremely oxidisable metals
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C3/00—Selection of compositions for coating the surfaces of moulds, cores, or patterns
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C9/00—Moulds or cores; Moulding processes
    • B22C9/02—Sand moulds or like moulds for shaped castings
    • B22C9/04—Use of lost patterns
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C9/00—Moulds or cores; Moulding processes
    • B22C9/12—Treating moulds or cores, e.g. drying, hardening
    • B22C9/123—Gas-hardening

Definitions

  • ABSTRACT OF THE DISCLOSURE A process for making a mould for use in casting highly reactive metals such as titanium and zirconium in which the mould is impregnated with pure carbon by heating the mould in an atmosphere containing a hydrocarbon gas or vapor.
  • the present invention relates to the art of metal founding and is concerned with the construction of moulds for casting the more reactive metals such as titanium and zirconium.
  • a pattern of the casting to be made is formed in wax, thermoplastic material or other suitable materials.
  • a monolithic mould is built up by the application of a layer of a refractory slurry consisting of a finely divided refractory material in a liquid vehicle, usually a partially hydrolysed ethyl silicate solution, the wet coating is dusted with a dry, usually coarser, refractory and finally hardened by air-drying or exposure to a suitable gas such as ammonia. This coating procedure is repeated until a shell of sufiicient thickness is built up.
  • the pattern is removed by melting out or by dissolving in a suitable solvent.
  • a suitable solvent for steel, nickelbase alloys, cobalt-base alloys and the like the refractories used are usually silica, alumina, aluminium silicate such as molochite and siliminite, zirconia, zirconium silicate and the like, the bonding agent frequently being silica sol.
  • the castings produced from such moulds in these alloys have good surface finish and accuracy. However, when such moulds are used for such reactive metals as titanium and zirconium, interreaction between mould and metal occurs with resulting unsoundness and surface contamination in the castings.
  • Machined graphite moulds have been used to produce titanium castings which are sound and relatively free from contamination. Such moulds are expensive to produce and are restricted to simple shapes. Solid graphite moulds have a further disadvantage in that they have a severe chilling action on the liquid metal, making the filling of fine detail in the casting difficult.
  • mould suitable for highly reactive metals such as titanium and zirconium is made of refractory material impregnated with carbon.
  • the mould is preferably made by any suitable lost wax method.
  • the carbon impregnation may be performed in various ways, and the following examples are given by way of illustration.
  • EXAMPLE 1 A ceramic shell lost Wax mould is made using Camshell, a proprietary investment material. A wax replica of the casting required is coated by dipping into the Camshell slurry which consists of a partially hydrolysed ethyl silicate solution made into the consistency of thin cream by the addition of 200' mesh aluminium silitil ice
  • the wet coating is dusted with 30 mesh refractory powder and then hardened by exposure to ammonia gas or by air drying. This coating procedure is repeated about 7 times to build up a refractory shell mould about Aa" to A in thickness. The wax pattern is then removed by melting. The dewaxed mould is impregnated with carbon in the apparatus illustrated diagrammatically in FIGURE 1. Nitrogen in container 1 is fed via a reducing valve 3 and flow meter 5 to the furnace tube 7 via a two-way cock 9 making it possible for nitrogen alone to be passed through or to be mixed with benzene vapour by bubbling through warm liquid benzene from containers in a water bath 13.
  • EXAMPLE 2 A ceramic shell lost wax mould is made as described in Example 1.
  • the dewaxed mould is impregnated with carbon in the apparatus illustrated diagrammatically in FIGURE 2.
  • the gas generator part of the equipment is as shown in FIGURE 1.
  • the impregnation chamber consists of a two piece heat resisting steel assembly comprising a base 19 and a cover 21.
  • a heat resisting steel tube 23 leads into the base of the chamber and then to the centre of a perforated carbon block 25.
  • the ceramic shell mould 27 is placed on the carbon block 25 and the cover 21 fitted over the mould into the base, the junction of the cover and the base being sealed with dry sand.
  • a vent 29 is provided in the cover.
  • the heat resisting steel tube is connected to the gas generator by a flexible pipe 31.
  • Nitrogen in container 1 is fed via the reducing valve 3 and flow meter 5 to the impregnation box via the two-way cock 9 making it possible for nitrogen alone to be passed through or to be mixed with benzene vapour by bubbling through liquid benzene.
  • the equipment is purged with nitrogen, then the box is introduced into the furnace with nitrogen continuing to flow, the mould and box are brought up to furnace temperature when the two-Way cock is adjusted so that nitrogen is bubbled through the liquid benzene.
  • the benzene vapour on contacting the hot mould dissociates with the deposition of finely divided carbon on the surface and in the pores of the mould.
  • the two-way cock When impregnation is completed, the two-way cock is readjusted so that only nitrogen is flowing, the box is then removed from the furnace and allowed to cool while nitrogen fiows. With a liquid benzene temperature of 53 C. and a furnace temperature of 885 C., after 4 hours treatment about 10% by weight of carbon was impregnated into the mould. From this mould, titanium castings were made having good surface finish and relatively free from surface contamination.
  • benzene has been cited as a means of providing a source of carbon impregnation, it will be obvious that many other hydrocarbons can be used such as butane, propane and the like. Gaseous hydrocarbons may also be used such as acetylene.
  • EXAMPLE 4 Zircon sand mixed with sufficient sodium silicate to form a mouldable mixture is rammed against a conventional pattern.
  • the compacted mould is hardened by gassing with carbon dioxide gas and then stripped from the pattern and impregnated with carbon by the method described in Example 2.
  • zircon sand is cited in this example, it will be perfectly obvious to those skilled in the art that silica sand and the like could also be used.
  • EXAMPLE 6 A ceramic shell lost wax mould was made and dewaxed according to any of the Examples 1 to 4. It was then heated to about 1,000 C. in air to eliminate volatile material. Oncooling the mould was saturated with hydrochloric acid vapour by being suspended over boiling acid. The mould was then filled with furfuryl alcohol which had previously been refluxed in air for 48 hours and contained as a polymerisation catalyst 0.25% by volume of 11 N hydrochloric acid. When absorption of the liquid ceased the excess was poured from the mould and the mould heat-treated, to cause resinification and then carbonisation as follows:

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Mold Materials And Core Materials (AREA)
US621680A 1966-03-09 1967-03-08 Moulds for use in metal casting Expired - Lifetime US3498359A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB10282/66A GB1140451A (en) 1966-03-09 1966-03-09 Improvements in or relating to moulds for use in metal casting
GB1221766A GB1144174A (en) 1966-03-19 1966-03-19 Improvements in or relating to moulds for use in metal casting

Publications (1)

Publication Number Publication Date
US3498359A true US3498359A (en) 1970-03-03

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
US621680A Expired - Lifetime US3498359A (en) 1966-03-09 1967-03-08 Moulds for use in metal casting

Country Status (5)

Country Link
US (1) US3498359A (fr)
CH (1) CH472253A (fr)
DE (1) DE1558104B1 (fr)
FR (1) FR1513844A (fr)
GB (1) GB1140451A (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3978908A (en) * 1975-01-06 1976-09-07 Research Corporation Method of die casting metals

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2742096C1 (ru) * 2020-07-02 2021-02-02 Владимир Михайлович Волков Способ изготовления форм при литье по выплавляемым моделям

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US698889A (en) * 1901-11-22 1902-04-29 Herbert B Atha Process of preparing sand molds for steel castings.
US1893286A (en) * 1928-05-25 1933-01-03 Westinghouse Lamp Co Method of carbonizing metals and alloys
US2245651A (en) * 1940-09-11 1941-06-17 Linde Air Prod Co Mold coating
GB750196A (en) * 1952-12-10 1956-06-13 Mannesmann Ag Improvements relating to processes for the continuous casting of iron and steel
US2948034A (en) * 1953-12-18 1960-08-09 Sulzer Ag Casting mold and method of casting carbon-containing alloys
US3075847A (en) * 1960-11-28 1963-01-29 Gen Motors Corp Mold coating
US3126597A (en) * 1961-04-07 1964-03-31 Decarburization in casting of steel
US3177084A (en) * 1956-08-23 1965-04-06 British Aluminum Company Ltd Method of making carbide-coated graphite dies and coated article
US3321005A (en) * 1965-04-19 1967-05-23 Howmet Corp Method of making shell molds for casting reactive metals

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE641029C (de) * 1933-12-29 1937-01-18 Maurer Ernst Verfahren zum UEberziehen von Kokillen und anderen Dauerformen vor dem Guss
DE760892C (de) * 1942-02-24 1954-03-15 Aluminiumwerke Nuernberg G M B Verfahren zum Verfestigen der Oberflaechen von getrockneten Sandformen
GB834864A (en) * 1958-02-21 1960-05-11 Ici Ltd Improvements relating to moulds for the casting of metals
US3284862A (en) * 1964-05-06 1966-11-15 Gen Electric Pyrolitic graphite coated casting mold and method of making same

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US698889A (en) * 1901-11-22 1902-04-29 Herbert B Atha Process of preparing sand molds for steel castings.
US1893286A (en) * 1928-05-25 1933-01-03 Westinghouse Lamp Co Method of carbonizing metals and alloys
US2245651A (en) * 1940-09-11 1941-06-17 Linde Air Prod Co Mold coating
GB750196A (en) * 1952-12-10 1956-06-13 Mannesmann Ag Improvements relating to processes for the continuous casting of iron and steel
US2948034A (en) * 1953-12-18 1960-08-09 Sulzer Ag Casting mold and method of casting carbon-containing alloys
US3177084A (en) * 1956-08-23 1965-04-06 British Aluminum Company Ltd Method of making carbide-coated graphite dies and coated article
US3075847A (en) * 1960-11-28 1963-01-29 Gen Motors Corp Mold coating
US3126597A (en) * 1961-04-07 1964-03-31 Decarburization in casting of steel
US3321005A (en) * 1965-04-19 1967-05-23 Howmet Corp Method of making shell molds for casting reactive metals

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3978908A (en) * 1975-01-06 1976-09-07 Research Corporation Method of die casting metals

Also Published As

Publication number Publication date
CH472253A (fr) 1969-05-15
FR1513844A (fr) 1968-02-16
GB1140451A (en) 1969-01-22
DE1558104B1 (de) 1971-11-25

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