Metal founding – Process – Shaping liquid metal against a forming surface
Patent
1988-12-09
1991-11-26
Lin, Kuang Y.
Metal founding
Process
Shaping liquid metal against a forming surface
164469, 164423, 164508, B22D 1106
Patent
active
050675540
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a method of using the "centrifugal melt extraction" technique for producing mineral fibres and powder, inter alia solidified filaments from mineral materials such as metal oxides, carbides, nitrides, borides or the like, and obtained from these materials in the molten state and in the form of a relatively viscous liquid pool.
This kind of technique is known and used for easily-melting materials which flow easily when hot, e.g. certain metals and alloys and certain salts or metal derivatives having properties, when molten, near those of the metals themselves.
For example document U.S. Pat. No. 3,838,158 (MARINGER) describes a method of obtaining filaments by solidification of films from a molten material having a viscosity not exceeding one poise and a surface tension of 0.25 N/m, the material comprising metals and alloys, inter alia Sn, Zn, Cu, Ni, Al, Al bronze, Fe, steel, stainless steel, etc. and inorganic substances inter alia alkali-metal nitrates which have properties, when molten, similar to those of metals.
This method, which is defined by the terms "centrifugal extraction from a molten pool" (melt-extraction method) comprises the following successive steps:
(a) heating with appropriate heating means said mineral material to melt it into a pool of liquid molten material;
b) immersing into said pool the rim of a metal or ceramic extraction disk, with a V-shaped peripheral edge to a depth sufficient to ensure a superficial contact between said periphery and the liquid;
c) rotating the disk around an axis parallel to, or slightly sloped relative to, the liquid surface at a speed sufficient for providing a skimming action of said liquid by said rim and freezing said liquid with a film-like strip which first adheres to the surface of the rim and then is expelled away from the disk by the centrifugal force in the form of the desired said filaments, fibres on particles which can then be collected.
Document U.S. Pat. No. 4,397,623 describes a device, using an effect apparently similar to that in the preceding document, for extracting the molten material from a bath of molten mineral material (inter alia blast-furnace slag or basalt) in the form of solidified filaments. The device comprises a set of disks immersed in the molten pool and driven rapidly in revolution. It is found, however, that the depth at which the disks are immersed is excessive and cannot give a thin film of solidified product adhering to the disk periphery. The document states (see e.g. column 3, lines 9-14) that the rotation of the disks expels molten material in the form of droplets or filaments of liquid which are laterally entrained by a stream of air and converted to fibres by the lateral air stream.
Similar or related techniques are described by the following documents: U.S. Pat. No. 3,896,203, U.S. Pat. No. 3,938,583; U.S. Pat. No. 4,154,284; FR-A-2 519 418.
Although the technique described in document U.S. Pat. No. 3,838,185 is very efficient for manufacturing metal fibres a few .mu.m in thickness and from a few .mu.m to a few cm in length, it is not directly suitable for manufacturing fibres from molten material having a viscosity, in the molten state, which is normally from a few poises to a few hundred poises, in which case the materials are viscous liquids having reduced mobility and tending to thicken at rest (thixotropy). The inventors therefore have tried to remedy this situation and modify the process described in the aforementioned document in order to obviate the aforementioned problems.
They have finally succeeded by the methods summarised in claim 1.
The invention will be more clearly understood from the following description with reference to the accompanying drawings in which:
FIG. 1 is a diagram showing the basic features of the "melt extraction" technique.
FIG. 2 is a diagrammatic perspective view, partly cut away, of a device for working the method according to the invention;
FIG. 3 is a diametrical diagrammatic section through a detail of the device in FIG. 1;
FIG. 4 is a diagrammatic se
REFERENCES:
patent: 3838185 (1974-09-01), Maringer et al.
patent: 3863700 (1975-02-01), Bedell et al.
patent: 4582116 (1986-04-01), Ray et al.
patent: 4705656 (1987-11-01), Onoyama et al.
Berce Tatjana
Bosswell Peter
Negaty-Hindi Guy
Richter Dag
Battelle Development Corporation
Bissell Barry S.
Lin Kuang Y.
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