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US3400752A - Treatment of readily oxidisable metals - Google Patents

Treatment of readily oxidisable metals Download PDF

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Publication number
US3400752A
US3400752A US686085A US68608567A US3400752A US 3400752 A US3400752 A US 3400752A US 686085 A US686085 A US 686085A US 68608567 A US68608567 A US 68608567A US 3400752 A US3400752 A US 3400752A
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United States
Prior art keywords
treatment
readily oxidisable
sulphur
mould
metals
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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
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US686085A
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Unsworth William
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Magnesium Elektron Ltd
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Magnesium Elektron Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D27/00—Treating the metal in the mould while it is molten or ductile ; Pressure or vacuum casting
    • B22D27/006—Treating the metal in the mould while it is molten or ductile ; Pressure or vacuum casting by using reactive gases
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D21/00—Casting non-ferrous metals or metallic compounds so far as their metallurgical properties are of importance for the casting procedure; Selection of compositions therefor
    • B22D21/002—Castings of light metals
    • B22D21/007—Castings of light metals with low melting point, e.g. Al 659 degrees C, Mg 650 degrees C
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D27/00—Treating the metal in the mould while it is molten or ductile ; Pressure or vacuum casting
    • B22D27/003—Treating the metal in the mould while it is molten or ductile ; Pressure or vacuum casting by using inert gases

Definitions

  • This application relates to the protection of readily oxidisable metals during casting especially magnesium and magnesium base alloys.
  • Sulphur hexafluoride has the advantages of being a colourless, non-toxic gas and, unlike sulphur dioxide, is also odourless.
  • the beneficial effect of using sulphur hexafluoride is illustrated by the following table which compares the incidence of oxide skins found on fracture testing of an experimental sand casting poured under various conditions. The elfect is shown in terms of both the number of oxide skins per unit area and also the fractional area occupied by the skins.
  • This invention is also applicable to the production of gravity die castings. It is particularly suitable for use in precision and instrument castings of all types, and may be used in the production of cast stock for working.
  • the invention may also be applied to the production of castings in mangesium lithium alloys or in other metals which are specially liable to undergo oxidation during filling of the mould, for example aluminium alloys containing lithium.
  • a sand mould 10 may be loosely covered with a metal plate 11 and a pipe 12 for introducing sulphur hex-afluoride may be entered into the sprue 12 into which the molten metal is subsequently poured.
  • the sulphur hex-afluoride enters the mould and replaces substantially all the air in the mould cavities 14.
  • the invention is not only useful for flushing moulds but sulphur hexafiuoride may also be used for protecting molten oxidisable metal in a crucible or pressure vessel or for protecting a stream of the metal.
  • metal is selected from the group consisting of magnesium and magnesium base alloys.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Moulds For Moulding Plastics Or The Like (AREA)
  • Other Surface Treatments For Metallic Materials (AREA)

Description

p 0, 1968 w. UNSWORTH 3,400,752
TREATMENT OF READILY OXIDISABLE METALS Filed Nov. 28, 1967 INVEIVTOR.
(Jim- 9m UN5WORTH- B'TTORAJETS United States Patent 3,400,752 TREATMENT OF READILY OXIDISABLE METALS William Unsworth, Swinton, England, assignor to Magnesium Elektron Limited, Swinton, England Filed Nov. 28, 1967, Ser. No. 686,085
Claims priority, application Great Britain, Dec. 2, 1966,
54,112/ 66 3 Claims. (Cl. 16466) ABSTRACT OF THE DISCLOSURE Readily oxidisable metal is protected from oxidation by applying sulphur hexofluoride to the molten metal.
This application relates to the protection of readily oxidisable metals during casting especially magnesium and magnesium base alloys.
It is well known that small oxide skin inclusions arise in the running systems of magnesium alloy sand castings during the actual pouring operation. With good foundry practice these inclusions are not, however, large or numerous enough to materially affect the mechanical properties of commercial alloy castings but in the case of the high strength zirconium alloys castings they can have a detrimental effect. Inclusions of this type are too small to be detected by normal radiographic techniques but are visible on fractured surfaces, particularly when examined under a low power microscope.
It is well known in the magnesium foundry art that flushing the mould with sulphur dioxide before pouring assists in minimising oxidation but the degree of protection is not sufficient to avoid the formation of these very small oxide skins.
It has now been discovered that by flushing the mould with sulphur hexafiuoride the incidence of these small oxide skins can be greatly suppressed. Sulphur hexafluoride has the advantages of being a colourless, non-toxic gas and, unlike sulphur dioxide, is also odourless. The beneficial effect of using sulphur hexafluoride is illustrated by the following table which compares the incidence of oxide skins found on fracture testing of an experimental sand casting poured under various conditions. The elfect is shown in terms of both the number of oxide skins per unit area and also the fractional area occupied by the skins.
Number of Percentage oxide skin inarea covered Conditions clusions by oxide Per sq. cm. Skins 3,400,752 Patented Sept. 10, 1968 The alloy was that known as ZE63 containing about six percent zinc, 3 per-cent rare earth metals and 0.7% zirconium (the subject of patent application No. 45,142/ 63).
This invention is also applicable to the production of gravity die castings. It is particularly suitable for use in precision and instrument castings of all types, and may be used in the production of cast stock for working.
The invention may also be applied to the production of castings in mangesium lithium alloys or in other metals which are specially liable to undergo oxidation during filling of the mould, for example aluminium alloys containing lithium.
The invention is illustrated in the accompanying diagrammatic drawing which shows a sectional view of a mould.
A sand mould 10 may be loosely covered with a metal plate 11 and a pipe 12 for introducing sulphur hex-afluoride may be entered into the sprue 12 into which the molten metal is subsequently poured. The sulphur hex-afluoride enters the mould and replaces substantially all the air in the mould cavities 14.
The invention is not only useful for flushing moulds but sulphur hexafiuoride may also be used for protecting molten oxidisable metal in a crucible or pressure vessel or for protecting a stream of the metal.
Iclaim:
1. A method of preventing oxidation of readily oxidisable metal wherein sulphur hexafluoride is applied to the molten metal.
2. A method of casting readily oxidisable metal wherein the mould cavity of a mould is flushed with sulphur hexafiuoride whereupon the molten metal is poured into the cavity.
3. A method as claimed in claim 1 wherein the metal is selected from the group consisting of magnesium and magnesium base alloys.
References Cited UNITED STATES PATENTS 1,720,286 7/1929 Michel -96 3,119,745 1/1964 Caillat et al 75-96 X FOREIGN PATENTS 404,518 1/1934 Great Britain.
I. SPENCER OVERHOLSER, Primary Examiner.
V. RISING, Assistant Examiner.
US686085A 1966-12-02 1967-11-28 Treatment of readily oxidisable metals Expired - Lifetime US3400752A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB54112/66A GB1149788A (en) 1966-12-02 1966-12-02 Improvements in or relating to the treatment of readily oxidisable metals during casting

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Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3998261A (en) * 1974-06-18 1976-12-21 British Steel Corporation Casting steel ingots
US4089678A (en) * 1975-08-01 1978-05-16 Hanawalt Joseph D Method and product for protecting molten magnesium
EP0016671A1 (en) * 1979-03-09 1980-10-01 Union Carbide Corporation Method for the addition of a reactive metal to a molten metal bath
US4579166A (en) * 1984-04-10 1986-04-01 Amax Inc. Magnesium alloy casting in plaster molds
US4806156A (en) * 1987-07-24 1989-02-21 Liquid Air Corporation Process for the production of a bath of molten metal or alloys
US4848751A (en) * 1987-07-24 1989-07-18 L'air Liquide Lance for discharging liquid nitrogen or liquid argon into a furnace throughout the production of molten metal
US4854370A (en) * 1986-01-20 1989-08-08 Toshiba Kikai Kabushiki Kaisha Die casting apparatus
US5404929A (en) * 1993-05-18 1995-04-11 Liquid Air Corporation Casting of high oxygen-affinity metals and their alloys
WO1998024572A1 (en) * 1996-12-05 1998-06-11 Cast Centre Pty., Ltd. Mould lubricant
US6398844B1 (en) * 2000-02-07 2002-06-04 Air Products And Chemicals, Inc. Blanketing molten nonferrous metals and alloys with gases having reduced global warming potential
US20080182022A1 (en) * 2006-09-27 2008-07-31 La Sorda Terence D Production of an Inert Blanket in a Furnace
US20090064821A1 (en) * 2006-08-23 2009-03-12 Air Liquide Industrial U.S. Lp Vapor-Reinforced Expanding Volume of Gas to Minimize the Contamination of Products Treated in a Melting Furnace
US20090288520A1 (en) * 2006-08-23 2009-11-26 Air Liquide Industrial U.S. Lp Vapor-Reinforced Expanding Volume Of Gas To Minimize The Contamination Of Products Treated In A Melting Furnace

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1720286A (en) * 1925-08-18 1929-07-09 Michel Gilbert Process for the protection of the surface of baths of easily-oxidizable metals such as magnesium
GB404518A (en) * 1932-06-17 1934-01-18 Dow Chemical Co Improved method for inhibiting the oxidation of readily oxidisable metals
US3119745A (en) * 1958-04-25 1964-01-28 Commissariat Energie Atomique Process for preventing oxidation of nuclear reactor coolant channel magnesium sheaths

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1720286A (en) * 1925-08-18 1929-07-09 Michel Gilbert Process for the protection of the surface of baths of easily-oxidizable metals such as magnesium
GB404518A (en) * 1932-06-17 1934-01-18 Dow Chemical Co Improved method for inhibiting the oxidation of readily oxidisable metals
US3119745A (en) * 1958-04-25 1964-01-28 Commissariat Energie Atomique Process for preventing oxidation of nuclear reactor coolant channel magnesium sheaths

Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3998261A (en) * 1974-06-18 1976-12-21 British Steel Corporation Casting steel ingots
US4089678A (en) * 1975-08-01 1978-05-16 Hanawalt Joseph D Method and product for protecting molten magnesium
EP0016671A1 (en) * 1979-03-09 1980-10-01 Union Carbide Corporation Method for the addition of a reactive metal to a molten metal bath
US4579166A (en) * 1984-04-10 1986-04-01 Amax Inc. Magnesium alloy casting in plaster molds
US4854370A (en) * 1986-01-20 1989-08-08 Toshiba Kikai Kabushiki Kaisha Die casting apparatus
US4806156A (en) * 1987-07-24 1989-02-21 Liquid Air Corporation Process for the production of a bath of molten metal or alloys
US4848751A (en) * 1987-07-24 1989-07-18 L'air Liquide Lance for discharging liquid nitrogen or liquid argon into a furnace throughout the production of molten metal
US5404929A (en) * 1993-05-18 1995-04-11 Liquid Air Corporation Casting of high oxygen-affinity metals and their alloys
WO1998024572A1 (en) * 1996-12-05 1998-06-11 Cast Centre Pty., Ltd. Mould lubricant
US6269862B1 (en) * 1996-12-05 2001-08-07 Cast Centre Pty Ltd. Mould lubricant
US6398844B1 (en) * 2000-02-07 2002-06-04 Air Products And Chemicals, Inc. Blanketing molten nonferrous metals and alloys with gases having reduced global warming potential
US20090064821A1 (en) * 2006-08-23 2009-03-12 Air Liquide Industrial U.S. Lp Vapor-Reinforced Expanding Volume of Gas to Minimize the Contamination of Products Treated in a Melting Furnace
US20090288520A1 (en) * 2006-08-23 2009-11-26 Air Liquide Industrial U.S. Lp Vapor-Reinforced Expanding Volume Of Gas To Minimize The Contamination Of Products Treated In A Melting Furnace
US8568654B2 (en) 2006-08-23 2013-10-29 Air Liquide Industrial U.S. Lp Vapor-reinforced expanding volume of gas to minimize the contamination of products treated in a melting furnace
US9267187B2 (en) 2006-08-23 2016-02-23 Air Liquide Industrial U.S. Lp Vapor-reinforced expanding volume of gas to minimize the contamination of products treated in a melting furnace
US20080182022A1 (en) * 2006-09-27 2008-07-31 La Sorda Terence D Production of an Inert Blanket in a Furnace
US8403187B2 (en) 2006-09-27 2013-03-26 Air Liquide Industrial U.S. Lp Production of an inert blanket in a furnace

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Publication number Publication date
GB1149788A (en) 1969-04-23

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