RU2144573C1 - Device for introduction of finely divided components into matrix metal melt - Google Patents

Abstract

FIELD: device for production of alloys and composite materials by introduction of finely divided components into matrix melt, particularly, devices for commercial production of composite materials of metal-metal and metal-nonmetal types. SUBSTANCE: device has vessel for melt provided with tightly closed cover, inductor generating travelling magnetic field, batcher of finely divided component and plasma generator located above level of melt and connected with batcher by pipeline. Plasma generator is installed for motion in horizontal plane between vertical axis of vessel for melt and its wall, pipeline for supply of finely divided component is brought into nozzle of plasma generator, directly into zone of plasma arc. Inductor has several groups of windings which provide for mixing of melt simultaneously in vertical and horizontal planes. EFFECT: higher degree of assimilation of finely divided components, extended nomenclature of components assimilated by matrix melt, increased efficiency and uniform distribution of introduced particles. 6 cl, 10, dwg, 7 ex

Description

 The invention relates to the field of metallurgy. More specifically, to devices for the production of alloys and composite materials by introducing finely dispersed components into the matrix melt.

 A device is known (US patent 4473103, publ. 25.09.84) containing a melt container equipped with a mechanical stirrer or stirrer in the form of an inductor generating a traveling magnetic field, a finely dispersed component dispenser and a matrix melt supply device. The blades of a mechanical stirrer are mounted obliquely and, when used, mixing is carried out in the vertical and horizontal planes. The use of a mechanical stirrer does not allow to achieve intensive, without the formation of zones of stagnation, mixing of the melt. In addition, when using mechanical mixers, fouling of the melt occurs. Due to the high chemical activity of some types of matrix melts, such as aluminum, magnesium, titanium, the development and manufacture of a mechanical stirrer is a complex technical task. When used for mixing the inductor, pollution of the melt is eliminated. However, the device as a whole does not provide a high level of assimilation of the finely divided component. The mixing process in the described device after the completion of the supply of particles lasts 30 to 45 minutes. In this case, 50 to 70% of the particles are absorbed by the melt.

 Some components cannot be introduced at all and, accordingly, are absorbed by the melt in industrial production.

 Particle heating before being introduced into the melt contributes to their better absorption. A device is known (Canadian patent N 802133, publ. 24.12.68) containing a plasma torch with a nozzle and a container for the melt placed inside the induction coil. The nozzle is screwed onto the burner. The nozzle is a housing with a landing hole made therein, channels for supplying a finely dispersed component and a nozzle. The nozzle nozzle is a continuation of the nozzle of a plasma torch. The nozzle provides a fine component supply under the cut of the burner nozzle. That is, to the place where the ionized gas under pressure escapes from the nozzle. In addition to the cathode and anode of the plasma torch, a nozzle and a container for the melt are connected to the power source in this device. Thus, a melt is used as one of the electrodes in this installation. At the point of contact of the arc with the melt, a high temperature develops, which can reach the temperature of evaporation of the melt. The speed of the particles along the tourniquet is small. Once on the surface of the melt, the particles do not penetrate inward, but form a crust of a sufficiently high density on its surface. Overheating of particles and their low speed leads to a low degree of assimilation of particles by the melt. In some cases, assimilation can be increased by more intensive mixing of the melt. However, a simple induction coil does not provide the desired mixing characteristics.

 As a prototype, we have selected a device designed to introduce finely dispersed components into a matrix metal melt and described in US Pat. No. 5,305,817, publ. 04/26/94. The prototype contains a melt container equipped with a hermetically sealed lid, an inductor generating a traveling magnetic field, a finely dispersed component dispenser, and a plasmatron. The plasma torch is located above the melt level and is connected by a pipeline to the dispenser.

 The finely dispersed component is piped into the stream of ionized gas formed by the plasma torch. In a stream of ionized gas, the particles are purified from adsorbed oxygen and impurities and heated. Then particles with a gas flow rate fall on the surface of the matrix melt. The mixing of the matrix melt in the vertical plane is carried out using an inductor.

The disadvantages of the prototype:
- low degree of assimilation of the finely dispersed component;
- a relatively narrow range of digestible components:
- low installation performance:
- uneven distribution of the introduced particles in the volume of the obtained material.

When developing the proposed technical solution, the task was to create a device that allows:
- produce already well-known composite materials and alloys, but with better characteristics and greater productivity;
- to produce new materials and alloys on an industrial scale.

Technical Results:
a) increasing the degree of assimilation of finely dispersed components;
b) expanding the range of components assimilated by the matrix metal melt;
c) increase in productivity;
d) a more uniform distribution of the introduced particles over the volume of the material obtained.

 We give some explanations regarding the technical results a) and b).

 a) The prototype device is intended for introduction into the melt of fine non-metallic particles, such as graphite, titanium diboride, nitride and aluminum oxide. Thus, using the prototype, composite materials are produced in the classical sense, that is, non-metal metal. With the introduction of such particles, it is believed that it is assimilated if full contact is made between the particle and the matrix melt, that is, each particle is completely wetted by the matrix melt. The proposed device increases the degree of assimilation of non-metallic particles.

 b) The proposed device allows, in contrast to the prototype, in addition to non-metallic particles to introduce particles of another metal into the matrix melt, and to carry out this process on an industrial scale. In this case, the output is a composite material of the metal-metal type. Such a composite material acquires the necessary technological and operational qualities when the grain size of the introduced component is not more than 2 - 10 microns. It is this grain size that is accepted as a criterion for assimilation.

 The proposed device for introducing finely dispersed components into a matrix metal melt contains a container for a matrix melt equipped with a hermetically sealed lid, an inductor generating a traveling magnetic field, a finisher of a finely dispersed component, and a plasma torch. The plasma torch is located above the melt level and is connected by a pipeline to the dispenser.

 The proposed device differs from the prototype in that the plasma torch is mounted with the ability to move in a horizontal plane between the central axis of the melt container and its wall, the pipeline connecting the dispenser with the plasma torch is brought into its nozzle directly into the plasma arc formation zone, and the inductor has several groups of windings, providing mixing of the melt simultaneously in the vertical and horizontal planes.

 The proposed design allows the introduction of a finely dispersed component without using a nozzle. Thus, the design provides an increase in the mean free path of particles in the ionized gas stream and, as a result, a higher degree of cleaning and activation of the particle surface, an increase in the kinetic energy of the particles, and a reduction in the distance from the plasma torch nozzle to the melt surface (due to the nozzle size). As a result, the particles, firstly, are treated more intensively by the ionized gas, and secondly, they do not lose speed before they get into the melt. These advantages can be used only with very intensive and uniform mixing of the melt, as well as with a certain stable distance between the plasma torch nozzle and the surface of the melt.

 An inductor containing several groups of windings is used to mix the melt. Such an inductor allows mixing at the same time in the vertical and horizontal planes and creating a stable and convenient melt surface shape for introducing the finely divided component. When the melt is stirred, a toroidal bulge arises on its surface. The convexity diameter is 0.7 - 0.95 of the diameter of the vessel for the melt. The plasma torch is installed with the help of an adjusting device over the top of this bulge, that is, between the axis of the melt tank and its wall. The introduction of finely divided components is carried out in the upper part of the bulge.

 Particular cases of the proposed invention are the following two options for the location of the groups of windings of the inductor.

 The first case. The inductor has two groups of windings, providing mixing of the melt simultaneously in vertical and horizontal planes throughout the volume of the melt. At each point of the melt, mixing is carried out in two planes. In this case, the windings of both groups of the inductor are located at the same height level around the vessel for the melt.

 The second case. The inductor has three groups of windings. The first group of windings is located at the level of the upper third of the tank and provides mixing of the melt in a vertical plane. The second group of windings is located at the level of the middle third of the capacity and provides mixing of the melt in the horizontal plane. The third group of windings is located at the level of the lower third of the tank and provides mixing of the melt in a vertical plane.

 The installation made in the second embodiment may be provided with channels for the continuous supply of matrix melt and the continuous output of the finished mixture. The channel for continuous supply of melt is connected to the tank in its upper part, and the channel for continuous output of the mixture is connected to the tank in its lower part. This installation ensures the continuity of the process.

 The installation, made according to the second embodiment, can be equipped with a channel for continuous supply of matrix melt and a mold for continuous casting of ingots, which also ensures the continuity of the process.

 The plasma torch can be placed inside a casing sealed on the lid of the melt container. Such a casing serves to provide shielding gas relative to the internal volume of the vessel for the melt. Such a constructive solution completely eliminates the penetration of oxygen molecules into the melt vessel through the micro-slots at the place of installation of the plasma torch on the vessel cover. Hydrogen molecules penetrating through these gaps into the vessel react with oxygen molecules released from the surface of the particles of the finely dispersed component due to plasma treatment. Thus, oxygen molecules are prevented from entering the working volume through the slits and neutralization of oxygen molecules entering the working volume on the particles of the introduced component is ensured. To ensure supply of gas under pressure inside the casing, it is equipped with a connecting element, for example, a fitting or a flange.

List of drawings
FIG. 1 - a device for introducing finely dispersed components into a matrix metal melt. The general scheme.

 Figure 2 - plasmatron.

 FIG. 3, 4 - micrographs of Al-Fe material (9%) obtained respectively in the proposed installation and in the installation of the prototype.

 FIG. 5, 6 - arrangement of the windings, providing simultaneous rotation of the melt in the vertical and horizontal planes throughout the volume. The vertical and horizontal sections are presented respectively.

 7 is a device equipped with three groups of windings.

 FIG. 8 - a device equipped with a channel for continuous supply of melt and a channel for outputting the finished mixture.

 FIG. 9 - a device equipped with a channel for continuous supply of the melt and the mold.

 FIG. 10 is a device provided with a casing.

Case Studies
A device for introducing finely dispersed components into a matrix metal melt contains (Fig. 1) a melt container 1 with a lid 2, an inductor 3 generating a traveling magnetic field, a finisher of finely dispersed component 4 and a plasma torch 5, which is rigidly fixed to the plate 6 and connected to the batcher by a pipeline 7. The guides 8 and the bracket 9 with the adjusting screw 10 are fixed on the lid 2. The reference numeral 11 denotes the melt.

 The plasma torch device is illustrated in figure 2. The plasma torch contains a housing 12, anode 13 and cathode 14. In the anode 13 and cathode 14, coolant channels are made, indicated respectively 15 and 16. The anode 13 is mounted in the housing 12 using a nut 17. The cathode 14 is mounted in the housing using a nut 18. Gaskets 19 located in annular grooves in the housing serve to prevent leakage of coolant. Between the cathode 14, the nut 18 and the housing 12 placed insulating pads 20.

 In the central hole of the cathode 14, a holder 21 is fixed by means of a threaded connection with a tungsten consumable electrode 22 pressed into it to excite the arc. A channel 23 for supplying a plasma-forming gas passes through the holder 21. The channel for supplying a finely dispersed component passing through the housing and the anode is indicated by 24. The plasma torch can be equipped with solenoids (not shown in the diagram) that stabilize the burning of the arc.

 The inductor 3 has two groups of windings - the upper 25 and lower 26 (Fig. 1). The upper group of windings is designed to mix the melt in the upper part of the tank in a vertical plane. The lower group of windings is designed to mix the melt in the lower part of the tank in a horizontal plane.

 Inductor designs, i.e. groups of windings designed to act on a liquid metal and providing its mixing in a given direction are known in the art. In the device we offer, the design described in A.S. is used. 196163, publ. 05/16/67.

 Let us explain the operation of the device by the example of manufacturing an aluminum-iron composite material by introducing an iron powder into an aluminum melt.

 The aluminum melt 11, placed in the tank 1, is mixed in its upper part in a vertical plane by means of a group of 25 windings and in its lower part in a horizontal plane by means of a group of 26 windings. A toroidal bulge is formed on the surface of the melt, above which the nozzle of the plasma torch 5 is located. Iron powder with particles of 10-50 μm in size from the dispenser 4 through the pipeline 7 and channel 24 enters the ionized gas stream into the plasma arc formation zone.

 In the flow of ionized gas, the surface of the particles is cleaned and activated.

 In a stream of ionized gas moving at a speed of 100 - 300 m / s, iron particles fly out of the nozzle of the plasma torch and fall on the upper part of the toroidal bulge formed on the surface of the melt. And then, thanks to significant kinetic energy, they penetrate beneath the surface and are carried away by the stream deep into the melt, where they are mixed and absorbed.

 Upon completion of the introduction of the desired amount of component, the melt is poured and cooled.

 In FIG. 3, 4 are micrographs of Al-Fe material (9%) obtained using the proposed device (Fig. 3) and using the prototype device (Fig. 4). The photographs show a fundamental difference in the morphology of the structure-forming phases of materials and, therefore, a difference in their mechanical and technological (for example, foundry) properties. The difference in morphology observed in the photographs confirms the increased assimilation of the material.

 The increase in productivity and uniform distribution of particles in the material is explained by the fact that their degree of purification and activation increases. In this case, the stirring intensity increases accordingly.

 Figure 5 presents the claimed device with an inductor, providing mixing of the melt simultaneously in the vertical and horizontal planes throughout the volume of the melt.

 The location of the groups of windings of the inductor is also illustrated in Fig.6, which shows a section aa. Position 27 marked windings, providing mixing of the melt in a vertical plane. Position 28 marked windings, providing mixing of the melt in the horizontal plane. This arrangement of the windings provides a more intensive, uniform and without stagnation zones mixing of the melt. The disadvantage of this design is its complexity.

 About the same result, but with a simpler design can be achieved by using an inductor containing three groups of windings (Fig.7). The upper winding group 29 and the lower winding group 30 provide melt mixing in a vertical plane. The middle group of 31 windings provides mixing of the melt in a horizontal plane.

 In FIG. 8 shows a device with a tank equipped with a channel 32 for continuous supply of melt and a channel 33 for outputting the finished mixture. The described design allows to achieve the continuity of the process and increase the productivity of the installation.

 It is possible to use the proposed installation for continuous casting of ingots. In this case, the installation is equipped with a mold 34, which is combined with the lower part of the tank (Fig.9).

 To prevent particles of atmospheric oxygen from entering the tank 1 through the gap between the cover 2 and the plasma torch 5 on the cover 2, a casing 35 is sealed (Fig. 10). The casing 35 is provided with a flange 36. The flange serves to supply a protective gas line under pressure. Thus, a protective gas back-up is created inside the casing, which prevents the penetration of oxygen into the container 1. To bind the oxygen molecules, it is advisable to supply a small amount of hydrogen to the line.

 The installation, equipped with a casing, reduces the amount of impurities in the finished material by about 50 - 80%.

Claims (6)

 1. A device for introducing finely dispersed components into a matrix metal melt containing a melt container equipped with a hermetically sealed lid, a traveling magnetic field inductor, a finely dispersed component dispenser and a plasmatron located above the melt level and connected by a pipeline to the dispenser, characterized in that the plasmatron installed with the ability to move in a horizontal plane between the vertical axis of the vessel for the melt and its wall, a pipeline for supplying finely divided the component is discharged directly into the plasma arc zone into the plasma torch nozzle, and the inductor has several groups of windings providing melt mixing simultaneously in the vertical and horizontal planes.  2. The device according to claim 1, characterized in that the inductor has two groups of windings, providing melt mixing simultaneously in the vertical and horizontal planes throughout the volume of the melt.  3. The device according to claim 1, characterized in that the inductor has three groups of windings, providing melt mixing at the same time in the upper and lower parts of the vessel in the vertical plane, and in the middle-high part of the vessel in the horizontal plane.  4. The device according to claims 1 and 3, characterized in that the melt tank is provided in its upper part with a channel for continuous melt supply, and in its lower part with a channel for outputting the finished mixture.  5. The device according to claims 1 and 3, characterized in that the melt tank is provided in its upper part with a channel for continuous supply of matrix melt, and its lower part is combined with a mold for continuous casting of ingots.  6. The device according to claim 1, characterized in that the plasmatron is placed inside a casing sealed on the lid of the melt container and equipped with a fitting or flange for connection to the protective gas supply line under pressure.

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