US2396636A - Casting of rare earth metals - Google Patents

Description

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. I oasrmd or Harold Marland Broadh urst, iiiverpool,

1 aasignor to Imperial Chemical Industries Lim ited, a corporation of Great Brl No Drawing. Appllcatio 543,950. In Great Britai tetra-20o) I v v pass over the surfaces of This invention relates to improvements in casting rare earth metals and alloys thereof. and to moulds therefor.

Rare earth metal alloys can be. cast into flints for pyrophoric lighters by pouring a molten alloy or mixture of iron and mischmetall, with or with-.

out additions or small amounts oi other metals, into appropriately sized moulds constructed of a ferrous metal shaped to produce sticks oi small into small pieces for use. flints have a rough or unpolished surface and may disintegrate on storage, possibly from attack by the atmosphere. .It has been proposed to 'cast rare earth metals from beneath a protecting layer of molten salt into a mould dusted or otherwise coated with magnesia or other inert material such as rolling scale or tin plating so that the pieces of cast metal may be easily removed from the mould.

According to the present invention a process The sticks are subsequently. broken Made in this way the g it July 7, 1944,

Serial ha areas 3 surface layers are oxidised to the black magnetic oxide. The temperature of the air should be controlled so that the mould does not become too 'hot during the oxidation and cause general break up or loss of shape of the mould. The

moulds may then be allowed to cool and can then be used by pouring the molten alloy, for example an alloy of mlschmetall and iron, into them from a suitable container, and allowing the cast metal to cool oil. It is also possible to cast the metal into the moulds before they have cooled completely, for example while they are still at a temperature of the order of 100 0., and the moulds for the production of rare earth metal alloy flints suitable for pyrophoric lighters includes the step of casting the rare earth metal alloy in a ferrous metal mould the surface layers of which mould coming into contact with the molten alloy have i been converted by treatment under oxidising confrom the mould readbut in addition the stability of the fiints in air is considerably increased, and the fiints have a more attractive appearance.

In one method or carrying out the invention the moulds are heated in a vessel to a dull red heat and air is blown through the vesselso as to invention it is not only and the casts may then be allowed to cool together. The sticks of metal as removed from the moulds are found to have a smooth, almost black appearance, and have an improved resistance to disintegration in the air.

Iclaim:

1. A process for the production of rare earth metal alloy flints suitable for use in pyrophorlc lighters, and having improved resistance to disintegration in the air which includes the step of casting the rare earth metal alloy in a terrous metal mould, the surface layers of which mould coming into direct contact with the molten alloy have been converted by treatment under oxidising conditions to a substantially continuous film of black iron oxide.

2. A process for the production of flints suitable for use in pyrophoric lighters. and having improved resistance to disintegration in the air which includes the step of casting an alloy of iron and mischmetall in a ferrous metal mould the surface layers or which coming into direct contact with the molten alloy have been converted by treatment-under oxidising conditions to a substantially continuous film ofblack iron oxide. HAROLD MARLAND BROADHURST.

the mould until the