L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des

Ghislain Gilbert

Gerard Bentz

Jean Galey

Pierre Karinthi

Serge Devalois

This invention relates to an arrangement for the automatic distribution in free air of metered quantities of the liquid phase of a cryogenic fluid, and comprises a container to hold the liquid phase, a system to control the supply to the said container, metering means, forced discharge means, means for distributing the cryogenic liquid, and a system for controlling the said metering member and the said discharge means. The invention is applicable in particular to the casting of metals, to the production of articles formed from different metals, and to the moulding of articles in series.

Arrangements for the controlled injection of cryogenic fluid

The cooling of molten metal, such as metal continuously cast into an ingot mold, is retarded by establishing on the upper surface of the metal in the mold, a layer of cryogenic liquid such as nitrogen, helium or argon, with a finely divided material in homogeneous and stable suspension in the liquid. The finely divided material is in the form of particles having a size between 200 and 2,000 A and is present in a quantity between 10 and 1,000 grams per liter of cryogenic liquid. The suspended material may be aluminum, titanium, zirconium, niobium, calcium, lithium, magnesium, solid glass, or an oxide of aluminum, titanium, zirconium, niobium, calcium, lithium or magnesium, and is highly reflective to infrared radiation from the metal so as to reduce the transparency of the cryogenic liquid to this infrared radiation.

Method of retarding the cooling of molten metal

A phase-separating member of annular form supplies a liquid phase, which converges towards a molten stream of metal. The liquid phase is distributed in the form of at least two layers, the upper layer meeting the metal stream at a distance h which is not greater than 300 mm from the bottom of the upper supply container, each layer forming an angle .gamma. greater than 30.degree. with the said stream and being intended to protect a proportion of the vertical extent of the stream h not greater than 600 mm. The invention is applicable to protecting casting streams of large diameter and considerable height, in particular between the ladle and the tundish in the continuous casting of slabs.

Protection of molten metal

A surface of molten metal is covered with a polyphase mixture of a cryogenic fluid and at least one additional constituent in the form of particles, the particles having a size less than 50 microns and forming a homogeneous and stable suspension in the boiling liquefied gas. The particles may be metal or metal oxide or glass or carbon or vegetable or mineral oil, and serve to reduce radiative heat losses from the metal by reflection and/or to serve as a lubricant of the metal in a mold.

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Bures-sur-Yvette, France

Ghislain Gilbert