CN108817357B - Double-function casting furnace for fine crystal and single crystal - Google Patents
Double-function casting furnace for fine crystal and single crystal Download PDFInfo
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- CN108817357B CN108817357B CN201810517844.1A CN201810517844A CN108817357B CN 108817357 B CN108817357 B CN 108817357B CN 201810517844 A CN201810517844 A CN 201810517844A CN 108817357 B CN108817357 B CN 108817357B
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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
- B22D27/02—Use of electric or magnetic effects
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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
- B22D27/04—Influencing the temperature of the metal, e.g. by heating or cooling the mould
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- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B11/00—Single-crystal growth by normal freezing or freezing under temperature gradient, e.g. Bridgman-Stockbarger method
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Abstract
The invention discloses a fine crystal and single crystal dual-function casting furnace, a single crystal casting method and a fine crystal casting method, belongs to the technical field of precision casting equipment, solves the problem that the casting furnace in the prior art cannot have the functions of a single crystal furnace and a fine crystal furnace at the same time, and improves the quality of produced single crystals and fine crystals. The device comprises a casting chamber and a pull-down water-cooling crystallizer positioned below the casting chamber; the casting mold chamber comprises a first electrified coil and a second electrified coil, the inner spaces of the first electrified coil and the second electrified coil form a static magnetic field applying region, and the static magnetic field applying region is also a temperature heating region; the first electrified coil is positioned above the second electrified coil; the intensity and the temperature of the static magnetic field in the second electrified coil are higher than those in the first electrified coil; when the refractory heat-insulating layer is used for fine grain casting, a refractory heat-insulating layer is arranged between the down-drawing water-cooled crystallizer and the casting mould. The casting furnace can be used for casting single crystal and fine crystal, and can reach the degree of idealization of respective fields.
Description
Technical Field
The invention relates to precision casting equipment, in particular to an unprecedented fine crystal and single crystal dual-function casting furnace designed and manufactured by adopting asynchronous bending supercooling technology, and a single crystal casting method and a fine crystal casting method which are different from a common single crystal furnace and a common fine crystal furnace in use.
Background
A single crystal furnace and a fine crystal furnace are two important devices in the casting field, wherein the single crystal furnace is used for producing single crystal castings, and the fine crystal furnace is used for producing fine crystal castings. The grain structure of the single crystal casting is different from the grain structure of the fine crystal casting, wherein the grain structure of the single crystal casting has no crystal boundary, and the whole casting is a grain; the more crystal grains contained in the grain structure of the fine-grained casting, the better, and the finer the grain size, the better.
In the prior art, a casting furnace with the functions of a single crystal furnace and a fine crystal furnace is not available.
In addition, the existing industrial single crystal furnace grows in a dendritic crystal mode, once a dendritic crystal falls off, the fallen dendritic crystal residual block can deteriorate the growth condition of the single crystal, the growth of the single crystal is influenced, and even if the dendritic crystal does not fall off, the dendritic crystal single crystal is far inferior to a plane solidification type single crystal which is not used for industrial production at present, because the dendritic crystal has dendritic crystal component segregation, and solidification porosity, small-angle grain boundaries and the like are easy to appear between the dendritic crystals.
Anyville, Shanghai university, discloses that a Cusp magnetic field overcomes the damage of thermoelectric magnetic force to the dendritic structure of single crystal high temperature alloy and the influence of thermoelectric magnetic force on component distribution and phase precipitation. The influence of the direct-current static magnetic field on the growth of the single crystal is mentioned, the direct-current static magnetic field in the longitudinal direction or the horizontal direction can destroy dendrites of a liquid-solid interface, and the fallen dendrite residual blocks can deteriorate the growth condition of the single crystal. Therefore, if a Cusp magnetic field (a magnetic field consisting of direct-current static magnetic fields with two opposite directions in the longitudinal direction) is used, a zero magnetic surface can be generated at the liquid-solid interface of the single crystal growth, which is not only beneficial to the radial alloy composition uniformity of the liquid-solid interface of the single crystal growth, but also can not damage dendrites of the liquid-solid interface. It can be seen that the magnetic field generates a zero magnetic surface at the liquid-solid interface of the single crystal growth, thereby reducing the damage of dendrites at the liquid-solid interface, but the single crystal prepared by the method is still in a dendritic form, and the dendrites still exist, so that the segregation of dendritic form components cannot be avoided, and solidification porosity and small-angle grain boundaries are easy to appear between the dendrites.
The existing various fine crystal furnaces can not form uniform, isotropic, balanced and stable fine isometric crystals, and the fine crystal furnaces can not form deep super-cooling pure liquid to fill a cavity and stably solidify, so that the filling capacity and the grain refinement degree are poor.
At present, a steady magnetic field is applied to a device for casting low-pressure aluminum alloy, and the alloy melt is applied with the steady magnetic field to reduce the temperature of the melt to a set temperature between a liquid phase line of the alloy and a nucleation temperature under the magnetic field intensity, so that the alloy melt can be in a supercooled state. However, the melt in the supercooled state is not a supercooled single-phase pure liquid, and therefore, the above-described solution can be used only for die casting, and cannot be used for casting. In addition, the way of refining the crystal grains is to crush the primary dendrites in the supercooled congeal liquid, and the crushed dendrites are used to generate more crystal cores, which also indicates that the melt in the supercooled state in the above patent is not supercooled single-phase pure liquid, because the supercooled single-phase pure liquid has no dendrites for crushing.
Disclosure of Invention
In view of the above analysis, the present invention provides a dual-function casting furnace for fine crystals and single crystals, which is designed and manufactured by using asynchronous bending supercooling technology, and a using method thereof, which is different from a common single crystal furnace and a common fine crystal furnace in use, so that the problem that the casting furnace in the prior art cannot simultaneously have the functions of the single crystal furnace and the fine crystal furnace is solved, and the quality of the produced single crystals and the fine crystals is improved, so that the produced single crystals and the fine crystals respectively reach the extreme ideal level of the quality in respective fields.
The purpose of the invention is mainly realized by the following technical scheme:
on one hand, the invention provides a fine-grain and single-crystal dual-function casting furnace, which comprises a casting chamber and a pull-down water-cooling crystallizer positioned below the casting chamber; the casting mold chamber comprises a first electrified coil and a second electrified coil, the inner spaces of the first electrified coil and the second electrified coil form a static magnetic field applying area, and the static magnetic field applying area is also a temperature heating area; the first electrified coil and the second electrified coil are respectively positioned in the bearing groove, and the first electrified coil is positioned above the second electrified coil; the intensity of a static magnetic field in the second electrified coil is higher than that of a static magnetic field in the first electrified coil, and the temperature in the second electrified coil is higher than that in the first electrified coil; when the casting furnace is used for fine grain casting, a refractory heat-insulating layer is arranged between the pull-down water-cooled crystallizer and the casting mould.
Furthermore, the static magnetic field intensity in the first electrified coil is 2-5T, and the static magnetic field intensity in the second electrified coil is more than 5T.
Furthermore, the casting furnace also comprises a direct current power supply unit which is electrically connected with the first electrified coil and the second electrified coil respectively; the ratio of the wall thickness of the second electrified coil to the wall thickness of the first electrified coil is 1.5-2.5: 1.
further, the self-height of the first electrified coil is larger than that of the second electrified coil.
Further, the first energizing coil includes a plurality of layers of energizing sub-coils arranged in the axial direction of the molding chamber; the second electrified coil is a layer of electrified sub-coil; the force bearing groove comprises a groove for accommodating an electrified sub-coil.
Furthermore, the first electrified coil and the second electrified coil are formed by winding tungsten alloy wires.
Furthermore, the casting furnace also comprises a heat-insulating layer which is arranged on the peripheral surface of the bearing groove and the upper end surface of the bearing groove.
Further, the casting mold chamber also comprises a magnetic receptor heat insulation screen, and the magnetic receptor heat insulation screen is arranged on the lower end face of the second electrified coil.
On the other hand, the invention also provides a fine crystal casting method, which adopts the fine crystal and single crystal dual-function casting furnace and comprises the following steps:
placing the casting mold in a static magnetic field applying area and on a pull-down water-cooled crystallizer, and placing a heat insulation layer between the casting mold and the pull-down water-cooled crystallizer;
the first electrified coil and the second electrified coil are electrified, so that the temperature in the casting mold chamber reaches a set temperature, and internal static magnetic fields in the first electrified coil and the second electrified coil reach a set strength;
pouring the molten mother alloy liquid into a casting mold;
the energizing power of the first energizing coil and the second energizing coil is reduced, so that the temperature of the master alloy liquid in the casting mould is reduced to a set temperature below the melting point, and the static magnetic field strength enough for maintaining the metal liquid as super-cooled single-phase pure liquid is maintained.
The first electrified coil and the second electrified coil are powered off, and the supercooled single-phase pure liquid of the master alloy generates nucleation and crystallization at each part in the casting mold to finish fine crystal solidification.
In another aspect, the invention further provides a single crystal casting method, which adopts the above-mentioned double-function casting furnace for fine crystal and single crystal, and the single crystal casting method comprises the following steps:
placing the single crystal casting mold in a static magnetic field applying area and on a pull-down water-cooled crystallizer;
the temperature in the casting mold chamber reaches a set temperature, and static magnetic fields in the first electrified coil and the second electrified coil reach a set strength;
pouring the melted mother alloy liquid into a single crystal casting mold;
and driving the pull-down water-cooled crystallizer to move downwards, and solidifying the mother alloy liquid from bottom to top to finish the growth of the single crystal.
Compared with the prior art, the invention has the following beneficial effects:
the double-function casting furnace for fine grains and single crystals provided by the invention has two functions of producing fine grains and single crystals. The quality level of the plane solidified single crystal can be realized under the rough condition of industrial production and reaches the magnitude of industrial production by adopting the double-function casting furnace for producing the single crystal; the fine-grained casting produced by adopting the fine-grained and single-crystal dual-function casting furnace can obtain extremely fine isometric crystal grains which have the grain size difference of less than 8 percent and the maximum grain size of less than 0.02 millimeter, are uniform and consistent, have the grain fineness reaching or even exceeding the forging level, have no forging and rolling structure and storage energy and are isotropic and balanced and stable fine isometric crystals at present on the whole casting section of the casting.
Meanwhile, the fine-grain and single-crystal dual-function casting chamber can prolong the maintaining time of deep supercooling of alloy or metal liquid in a casting cavity, the mold filling capacity can reach the mold filling capacity of pure liquid, and the pure liquid can be maintained for a period of time after the mold filling is finished, so that the required time is provided for gas, inclusion and solidification feeding, and the compactness of the casting chamber is equivalent to that of forging and rolling.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
Drawings
The drawings are only for purposes of illustrating particular embodiments and are not to be construed as limiting the invention, wherein like reference numerals are used to designate like parts throughout.
FIG. 1 is a schematic structural diagram of a mold cavity in a fine-grain, single-crystal dual-function casting furnace according to an embodiment of the present invention;
fig. 2 is a sectional view a-a of fig. 1.
Reference numerals:
1-a magnetic receptor heat shield; 2-a first energized coil; 3-a second electrified coil; 4-bearing groove; 5-insulating layer; 6-water cooling tube.
Detailed Description
The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form a part hereof, and which together with the embodiments of the invention serve to explain the principles of the invention.
Example one
The embodiment provides a fine-grain and single-crystal dual-function casting furnace, which comprises a casting chamber and a pull-down water-cooling crystallizer (not shown in the figure) positioned below the casting chamber; the whole structure of the single crystal furnace is the same as that of a common single crystal furnace in a mode of a pull-down water-cooled crystallizer, but the structure and the operation mechanism of a casting mold chamber are completely unique, the structure of the single crystal furnace is shown in figures 1 to 2, the casting mold chamber comprises a first electrified coil 2 and a second electrified coil 3, the inner spaces of the first electrified coil 2 and the second electrified coil 3 form a static magnetic field applying area, and the static magnetic field applying area is also a temperature heating area; the first electrified coil 2 and the second electrified coil 3 are respectively positioned in the bearing groove 4, and the first electrified coil 2 is positioned above the second electrified coil 3; the intensity of the static magnetic field in the second electrified coil 3 is higher than that in the first electrified coil 2, and the temperature in the second electrified coil 3 is higher than that in the first electrified coil 2; when the casting furnace is used for fine grain casting, a heat insulation layer (for example, refractory bricks, not shown in the figure) is arranged between the pull-down water-cooled crystallizer and the casting mould.
When the casting mold is implemented, the casting mold is positioned in a static magnetic field application area, high-power direct current is conducted in the first electrified coil 2 and the second electrified coil 3, the first electrified coil 2 and the second electrified coil 3 generate heat to generate high temperature, and simultaneously, the first electrified coil 2 and the second electrified coil 3 also generate an axial static magnetic field (a stable and constant magnetic field) which has enough magnetic field intensity to cause that an electric part and a neutral part of metal liquid atoms are bent asynchronously to generate a solidification undercooling phenomenon, and the physical process of the phenomenon is detailed as follows: the design principle of the double-function casting furnace for fine crystal and single crystal.
The design principle of the double-function casting furnace for fine crystals and single crystals provided by the embodiment is as follows:
at present, the physics of gravitational fields has proven to be spatio-temporal warping, both mathematically and observably. In the four kinds of interaction force in the nature, the action force of the universal gravitation is weaker, the action force of the static magnetic field is stronger, and the electromagnetic force is dozens of times greater than the action strength of the universal gravitation by ten times, so the space-time bending degree of the electromagnetic force field is far greater than that of the universal gravitation field. That is, due to the application of the static magnetic field, the spatiotemporal intervals of the electric portion and the neutral portion of the atoms are bent asynchronously.
Specifically, the metal or alloy is composed of atoms, which include an electrical portion and a neutral portion, the electrical portion being a negative electron and a positive electron, the positive electron and the neutral electron constituting a proton, the proton constituting the nucleus, and the negative electron running outside the nucleus. Whether the material is magnetic or non-magnetic, the space-time interval in which the positive and negative electrons in the atoms are located is necessarily bent in a strong acting gravitational field such as an electrostatic electromagnetic field. The bending degree of the space-time interval of the neutral part of the atom still maintains the bending degree of the space-time interval of the weak-force gravitational field such as the gravitational force, which means that the bending degree of the space-time interval of the electric part and the neutral part of the atom is asynchronous. Thus, the space-time interval of the electrical part of the atoms of the substance is reduced. Since the neutral portion of the atoms of this substance accounts for 99.9% of the mass of the atomic nucleus, and the mass of the positron is equal to that of the negative electron, the spatio-temporal position determined by the degree of spatio-temporal curvature of the atomic nucleus in a weak-force gravitational field cannot be changed significantly even in a strong-force gravitational field such as an electrostatic electromagnetic field having a small mass. Thus, the distance of the substance's nuclei from each other does not change. The distance between them is determined only by the magnitude of their average translational kinetic energy, i.e. by the temperature. The solidification of the liquid is that the negative electron clouds of adjacent atoms are contacted to generate electron exchange bonding crystallization, so that if the distance between adjacent atomic nuclei is not changed and the electron clouds are reduced, the electron clouds cannot be contacted with each other to form bonding crystallization, therefore, under the condition of space-time bending by applying electromagnetic force of a static magnetic field, the liquid temperature of the substance is lower than the freezing point, and the substance cannot be solidified or crystallized, thereby generating liquid supercooling.
It should be noted that, all of the conventional liquid supercooling techniques are passive supercooling, and only interference with the liquid, for example, improvement of purity of the liquid, reduction of disturbance of the liquid, etc., is minimized, so that there is no energy fluctuation in the liquid, and thus solidification or crystallization does not occur, and further supercooling occurs with a decrease in temperature. However, the above-mentioned passive supercooling method cannot realize large depth supercooling, and the industrial condition is difficult to meet the requirement; the casting furnace provided by the embodiment adopts the asynchronous bending supercooling technology, the active supercooling is realized, the intervention is realized by an applying means, the forced supercooling is realized by applying a static magnetic field under the rough industrial environment condition, and the static magnetic field has no heating function, so that the strength of the static magnetic field can be improved as far as possible, and the possibility of the supercooling with larger depth is provided.
The single crystal is produced by adopting the double-function casting furnace for fine crystal and single crystal, the quality level of the single crystal solidified in a plane (namely the level without dendrites, which is the extremely ideal level of the quality of the single crystal) can be realized under the rough condition of industrial production, and reaches the magnitude of the industrial production; the fine-grained casting produced by the fine-grained and single-crystal dual-function casting furnace can obtain completely uniform and uniform extremely fine isometric crystal grains in size on the whole casting section of any section, the fine degree of the crystal grains reaches or even exceeds the forging level, and the fine isometric crystal has no forging and rolling structure and storage energy and is isotropic and balanced and stable.
Meanwhile, the fine-grain and single-crystal dual-function casting mold chamber can prolong the maintaining time of deep supercooling of alloy or metal liquid in a casting mold cavity, the mold filling capacity can reach the mold filling capacity of pure liquid, and the pure liquid can be maintained for a period of time after the mold filling is finished, so that the required time is provided for gas, inclusion and solidification feeding, the density of the casting mold chamber is equivalent to that of forging and rolling, and the casting mold chamber is an ideal level for casting fine grain quality.
The advantage and disadvantage of single crystal solidification for single crystal furnaces is the temperature gradient at the front of the solidified liquid-solid interface, the larger the temperature gradient the better. The traditional method is to increase the overheating temperature of the melt, the overheating of the melt can increase the temperature gradient, and we adopt the static magnetic field forcing measure to make the freezing point of the substance drop, so that the overheating degree of the melt is further increased under the same overheating temperature, because the overheating temperature of the melt is superposed with the section of the dropping of the freezing point, the temperature gradient is increased, thus when the strength of the applied static magnetic field is high enough (different magnetic field strength required by different metal liquids) the solidification of the single crystal can reach plane solidification without dendrite, which is the extremely ideal level of the quality of the single crystal. In addition, the effect of weakening the developed degree of the dendrite which can be achieved only by the larger superheat degree of a common single crystal furnace can be achieved by using a smaller superheat degree, and the method brings benefits for prolonging the service life of the single crystal furnace.
Meanwhile, the casting furnace can enable the temperature gradient of the industrial single crystal furnace to reach the level of plane solidification. This makes it possible to make directional eutectic (if the single crystal is compared to a cement body, then the directional eutectic is a reinforced cement body) a self-growing fiber composite material that people have dreams to make in the world only a few laboratories. The autogenous fiber composite material is different from the external fiber composite material, and the combination perfection degree of the fibers of the external fibers and the matrix can never catch up with the combination perfection degree of the fibers of the autogenous fibers and the matrix due to natural reasons. In addition, in terms of high-temperature stability, since the self-formed fiber composite material is formed by directional eutectic solidification, the self-formed fiber composite material is in a thermodynamic equilibrium state and the high-temperature stability of the self-formed fiber composite material is not changed until the self-formed fiber composite material is melted. When the temperature of the added fiber composite material is high to a certain degree, the added fiber can react with the matrix to reduce the fiber strength of the added fiber composite material. However, the autogenous fiber composite material must be directionally eutectic solidified, and the directional eutectic solidification must be planar solidification, and if not planar solidification, the eutectic phase grows not in a fiber shape but in a sunflower shape, which is a conventional solidification structure of the eutectic alloy component.
In addition, solidification segregation is inevitable for the production of single crystal products, that is, the cast microstructure is a microstructure with uneven alloy composition which grows into a dendritic shape, preferably a cellular shape, and the single crystal products produced by industrial single crystal furnaces in the world are dendritic at present. The reason why the single crystal blade of the present aeroengine needs to be subjected to high-temperature heat treatment is to eliminate the segregation of the dendritic components, and the segregation cannot be completely eliminated at present, so that the mechanical property is damaged to a certain extent. Moreover, the heat treatment with the highest temperature close to the melting point for the high-temperature alloy not only has high energy consumption, but also has to use a temperature-controllable high-temperature vacuum heat treatment furnace which can be manufactured only by a few traditional aviation engine countries in the world, so the cost is very high, and the heat treatment brings a lot of uncertainty to the final qualification of the finished single crystal blade which is produced after a lot of difficulties, which is a difficult problem to solve by the non-traditional aviation engine countries at present. The temperature gradient of the novel single crystal furnace can achieve plane solidification of single crystal alloy components, namely, perfect single crystal blades without dendritic segregation can be directly grown, so that the heat treatment with the highest temperature close to the melting point for high-temperature alloys can be avoided.
For the fine grain furnace, it should be noted that the technical solution provided in this embodiment is different from the present inventor in the chinese patent applications CN107042298A and CN102513523A, which disclose that the low-frequency steady magnetic field without stirring is used to supercool the metal liquid to increase the nucleation rate, so as to obtain fine grains. Since a high intensity low frequency magnetic field will have a greater heating effect on the metal liquid, a low frequency will limit the deep supercooling of the metal liquid. The patent adopts a pure steady magnetic field without low frequency, so that the magnetic field intensity can be improved as much as possible due to no heating effect, and the supercooling depth is not limited according to the asynchronous bending theory. Therefore, not only can the crystal grains be thinner, but also the time for maintaining the supercooled liquid in the cavity of the casting mold can be prolonged, so that the absolute mold filling is possible, the required time is provided for the escape and solidification feeding of gas and impurities in the liquid, the defect that the supercooled liquid is instantly solidified once entering the cavity of the patent of the inventor is overcome, the density of the fine-grained casting can be equivalent to that of a forged and rolled part, and all advantages of forging and rolling are achieved. Casting can be used for casting parts with any complicated shapes, and forging and rolling are not carried out. In addition, compared with forging and rolling, the casting process has the advantages of less processes, small occupied area, less used raw materials and less energy consumption. Therefore, the prospect is very wide.
Illustratively, the static magnetic field intensity inside the first electrified coil 2 is 2-5T, and the static magnetic field intensity inside the second electrified coil 3 is more than 5T. For single crystal production, the temperature of the first energized coil 2 can only reach 1400-1600 ℃, and there is no specific requirement on the magnetic field strength because it does not require supercooling because it does not participate in increasing the temperature gradient. The intensity of the static magnetic field of the second electrified coil 3 is at least greater than 5T, since a static magnetic field greater than 5T is strong, and the temperature gradient is increased depending on the width of the supercooling temperature section for freezing point depression of the superimposed melt.
In order to make the static magnetic field intensity inside the second energized coil 3 higher than the static magnetic field intensity inside the first energized coil 2, the following two methods are available. Illustratively, the casting furnace further comprises a first power supply unit and a second power supply unit (both are direct current power supply units), the first electrified coil 2 is connected with the first power supply unit, the second electrified coil 3 is connected with the second power supply unit, the first electrified coil 2 and the second electrified coil 3 have the same structure and size, but the current of the second power supply unit is larger than that of the first power supply unit; alternatively, the first electrical coil 2 and the second electrical coil 3 have the same supply current, the first electrical coil 2 and the second electrical coil 3 have the same inner diameter, but the second electrical coil 3 has an outer diameter larger than the outer diameter of the first electrical coil 2, that is, the wall thickness of the second electrical coil 3 is larger than the wall thickness of the first electrical coil 2. Or, the second power supply unit current is larger than the first power supply unit current, and meanwhile, the outer diameter of the second electrified coil 3 is also larger than the outer diameter of the first electrified coil 2, that is, the wall thickness of the second electrified coil 3 is also larger than that of the first electrified coil 2.
The third mode is selected if conditions allow it to be selected as much as possible. Illustratively, the ratio of the wall thickness of the second electrical coil 3 to the wall thickness of the first electrical coil 2 may be 1.5 to 2.5, i.e., the difference between the outer diameter and the inner diameter of the second electrical coil 3 is 1.5 to 2.5 times the difference between the outer diameter and the inner diameter of the first electrical coil 2. Meanwhile, the current of the second power supply unit is 3-5 times larger than that of the first power supply unit. Therefore, the temperature gradient caused by the asynchronous bending supercooling capability can be obtained to a greater extent, and the production of single crystals can be facilitated.
In order to achieve a ratio of the wall thickness of the second current carrying coil 3 to the wall thickness of the first current carrying coil 2 of 1.5 to 2.5: 1, the number of turns of the tungsten alloy wire constituting the second energizing coil 3 may be 1.5 to 2.5 times the number of turns of the tungsten alloy wire constituting the first energizing coil 2.
In order to save energy, the first energized coil 2 may have a height that is greater than the height of the second energized coil 3. Because the temperature of the first electrified coil 2 is lower, the temperature of the second electrified coil 3 is higher, and the stay time of the alloy in the casting mold is too long in an environment with too high temperature, elements in the alloy can volatilize and burn, and the control precision of alloy components is not facilitated, so that the self height of the second electrified coil 3 cannot be too high; in addition, the height of the second electrified coil 3 is smaller than that of the first electrified coil, so that energy can be saved.
In order to facilitate the arrangement of the first energized coil 2, the first energized coil 2 may have a multi-layer structure (for example, 2 to 5 layers), and specifically, may include a plurality of layers of first energized sub-coils arranged in the axial direction of the molding chamber. It will be appreciated that the force-bearing groove 4 comprises a plurality of sub-grooves for receiving the first energized coil. And for the second electrified coil 3, because the height of the second electrified coil cannot be too high, the second electrified coil is of a single-layer structure and comprises a layer of second electrified coils, and meanwhile, the force bearing groove 4 also comprises a sub-groove for accommodating the second electrified coils. The bearing groove 4 can bear limited weight at high temperature, the first electrified coil 2 needs to have a certain use height, the first electrified coil 2 can be of a multilayer structure, each layer of first electrified sub-coil is arranged in the corresponding sub-groove, the pressure of the first electrified coil 2 on the bearing groove can be reduced, and the safety and stability of the whole structure of the casting mold chamber are guaranteed.
In order to avoid burning out of the first electrified coil 2 and the second electrified coil 3 due to overlarge electrified current, the first electrified coil 2 and the second electrified coil 3 can be formed by winding tungsten alloy wires, and the fire-resistant insulating sleeve is sleeved outside the tungsten alloy wires. Because the melting point of the tungsten alloy is close to 3000 degrees and is far higher than the melting point of the copper wire (close to 1000 degrees), the problem that the first electrified coil 2 and the second electrified coil 3 are burnt due to overlarge electrified current can be avoided by adopting the tungsten alloy wire.
In order to prevent heat and magnetic lines in the mold chamber from passing through the mold chamber, the casting furnace further includes a magnetic receptor heat shield 1 (for example, a graphite carbon felt magnetic receptor heat shield), and the magnetic receptor heat shield 1 is provided on a lower end surface of the second electrified coil 3. The magnetic receptor heat shield 1 can isolate heat radiation and absorb magnetic force lines in the casting mold chamber, so that the heat radiation and the magnetic force lines are prevented from penetrating through the casting mold chamber and extending downwards, and the inside of the casting mold chamber and the lower part of the magnetic receptor heat shield have higher temperature gradient generated due to high temperature and temperature gradient generated due to melt freezing point depression caused by asynchronous bending due to strong static magnetic field (the conventional common single crystal furnace has no temperature gradient generated due to melt freezing point depression and only has temperature gradient generated due to high temperature, so the temperature gradient of the conventional common single crystal furnace is certainly smaller than that of the dual-function casting furnace in the process of operating single crystal casting).
In order to provide the accuracy of the temperature control of the casting furnace, the casting furnace further comprises a heat insulation layer 5, and the heat insulation layer 5 is arranged on the outer peripheral surface of the bearing groove and the upper end surface of the bearing groove. Because the temperature of the casting mold chamber is high (generally reaching 1500-1600 ℃), and the arrangement of the heat preservation layer 5 can avoid the damage of high temperature to the furnace wall.
The casting chamber further comprises a water-cooling pipe 6, and the water-cooling pipe 6 is arranged on the outer peripheral surface of the heat-insulating layer 5. The water-cooling pipe 6 may be a square water-cooling non-magnetic stainless steel pipe or a copper pipe, for example. Because the heat preservation layer 5 can only partially block high temperature, the water cooling pipe 6 can be cooled by circulating cooling water, and therefore the furnace can be protected from being damaged by high temperature.
The static magnetic field application region of the mold chamber has a cylindrical shape with a central axis symmetry.
Example two
The embodiment provides a fine crystal casting method, which adopts the fine crystal single-function casting furnace provided by the embodiment one, and the fine crystal casting method comprises the following steps:
step 1: placing the casting mold in a static magnetic field applying area and on a pull-down water-cooled crystallizer, and placing a heat insulation layer between the casting mold and the pull-down water-cooled crystallizer;
step 2: placing the master alloy in a melting crucible, adding the required deoxidized carbon, and then checking whether a temperature measuring device and a peephole are normally usable or not;
and step 3: closing the furnace door and vacuumizing, wherein the vacuum degree is less than or equal to 5Pa, the first electrified coil and the second electrified coil are electrified, the electrified power is 100KW, the casting temperature is 1400 ℃, the intensity of a static magnetic field in the first electrified coil reaches 2T, the intensity of a static magnetic field in the second electrified coil is more than 5T, and the intensity of the static magnetic field which is enough to maintain the metal liquid as the supercooled single-phase pure liquid is maintained;
and 4, step 4: melting the mother alloy in the melting crucible according to a conventional method, and then pouring the melted mother alloy liquid into a casting mold;
and 5: reducing the direct current power introduced into the tungsten alloy coil, cooling the mother alloy liquid in the casting mould to a temperature below the melting point, and maintaining the time required for inclusion and air hole escape to be about 100 s;
step 6: the direct current led into the tungsten alloy coil is closed, the first electrified coil and the second electrified coil are powered off, and the alloy liquid is at a certain temperature below the melting point of the alloy liquid, namely, deep supercooling, so that a static magnetic field does not exist even if the direct current is closed, asynchronous bending of the space-time interval of the atomic nucleus neutral part of the liquid and the electron of the atomic nucleus neutral part of the liquid returns to synchronous bending, and therefore the deep supercooling alloy liquid uniformly and explosively generates a large amount of nucleation crystals at each part in the casting mold under a very large thermodynamic driving force to form a super fine crystal structure. And then taking out the casting mold after the mother alloy liquid is filled and solidified until the whole process is finished.
Compared with the prior art, the beneficial effects of the fine crystal casting method of the fine crystal single-function casting furnace provided by the embodiment are basically the same as the beneficial effects of the fine crystal single-function casting furnace provided by the embodiment one, and are not repeated herein.
The casting obtained by the single crystal casting method obtains uniform and consistent extremely fine isometric crystal grains with the grain size difference of less than 8 percent and the maximum grain size of less than 0.02 millimeter on the whole casting section of any section of the casting.
It should be noted that, in the case of drawing an oriented eutectic product, the above single crystal mother alloy is replaced with a eutectic mother alloy, and the preheating temperature of the mold and the static magnetic field strength of the environment in which the mold is located are further increased if necessary.
EXAMPLE III
The embodiment provides a single crystal casting method, which adopts the double-function casting furnace for fine crystal and single crystal provided by the embodiment one, and the single crystal pouring method comprises the following steps:
step A: placing the single crystal casting mold in a static magnetic field applying area and on a pull-down water-cooled crystallizer, and cleaning the space between the single crystal casting mold and the upper plane of the crystallizer without any substance which hinders heat transfer;
and B: placing the master alloy in a melting crucible, adding the required deoxidized carbon, and then checking whether a temperature measuring device and a peephole are normally available;
and C: the furnace door is closed and vacuum pumping is carried out, the vacuum degree is less than or equal to 5Pa, the tungsten alloy coil is not oxidized, the first electrified coil and the second electrified coil are electrified, the electrified power is 120KW, the casting mold temperature is 1450 ℃, the temperature range can meet the requirements of crystal pulling overheating temperature of most of single crystal alloy, the internal static magnetic field intensity of the first electrified coil reaches 2T, and the internal static magnetic field intensity of the second electrified coil is more than 5T;
step D: melting the mother alloy in the melting crucible according to a conventional method, overheating and cooling the single crystal mother alloy according to the conventional method, wherein the overheating is to continuously supply power which exceeds the melting point of the alloy by 200 ℃, and pouring can be carried out when the power is cut off and the temperature is reduced to 1450 ℃, and then pouring the mother alloy liquid into a single crystal casting mold which is a single crystal casting mold with an opening at the lower part;
step E: maintaining the temperature equalization stabilization time required by the conventional single crystal pulling process of the mother alloy liquid and the single crystal casting mold for 15min, then starting a crystal pulling lifting system, pulling down the water-cooled crystallizer according to a set descending speed (5mm/min), and at the moment, the liquid begins to solidify from bottom to top in sequence.
Step F: when the single crystal casting mould containing mother alloy liquid arranged on the pulling-down water-cooled crystallizer is completely pulled out of the position below the graphite carbon felt magnetic receptor heat shield, the mother alloy liquid contained in the single crystal casting mould is completely and sequentially solidified into single crystals from bottom to top, and the single crystal casting mould is taken out until the whole process is finished.
Compared with the prior art, the beneficial effects of the single crystal casting method provided by the embodiment are basically the same as the beneficial effects of the dual-function fine crystal casting furnace provided by the embodiment one, and are not repeated herein.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention.
Claims (7)
1. A double-function casting furnace for fine crystal and single crystal is characterized by comprising a casting mold chamber and a pull-down water-cooling crystallizer positioned below the casting mold chamber;
the casting mold chamber comprises a first electrified coil, a second electrified coil and a bearing groove, the inner spaces of the first electrified coil and the second electrified coil form a static magnetic field applying region, and the static magnetic field applying region is also a temperature heating region;
the first electrified coil and the second electrified coil are respectively positioned in the bearing groove, and the first electrified coil is positioned above the second electrified coil;
the intensity of a static magnetic field in the second electrified coil is higher than that in the first electrified coil, and the temperature in the second electrified coil is higher than that in the first electrified coil;
when the casting furnace is used for fine grain casting, a refractory heat-insulating layer is arranged between the pull-down water-cooled crystallizer and the casting mold;
the static magnetic field intensity in the first electrified coil is 2-5T, and the static magnetic field intensity in the second electrified coil is more than 5T;
the casting furnace also comprises a direct current power supply unit which is electrically connected with the first electrified coil and the second electrified coil respectively.
2. The furnace of claim 1, wherein the ratio of the wall thickness of the second electrical coil to the wall thickness of the first electrical coil is 1.5 to 2.5: 1.
3. the fine grain, single crystal dual function casting furnace of claim 1 wherein the first electrically energized coil has a height that is greater than a height of the second electrically energized coil.
4. The fine crystal, single crystal dual function casting furnace of claim 1 wherein the first electrical coil comprises a plurality of layers of electrical coils arranged axially along the mold chamber;
the second electrified coil comprises a layer of electrified sub-coil;
the force bearing groove comprises a sub-groove for accommodating an electrified sub-coil.
5. The fine grain, single crystal dual function casting furnace of claim 1 wherein the first energized coil and the second energized coil are each formed by winding tungsten alloy wire.
6. The dual-function fine-grain and single-crystal casting furnace as claimed in claim 1, further comprising an insulating layer disposed on the outer peripheral surface of the force-bearing groove and on the upper end surface of the force-bearing groove.
7. The furnace of claim 1, wherein the mold chamber further comprises a magnetic receptor thermal insulation layer disposed on a lower end surface of the second electrically conductive coil.
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| CN109989102A (en) * | 2019-04-24 | 2019-07-09 | 赵京晨 | A kind of casting mold room, foundry furnace and monocrystalline, fine grain, amorphous casting method |
| RU2754215C1 (en) * | 2020-11-02 | 2021-08-30 | Федеральное государственное унитарное предприятие "Всероссийский научно-исследовательский институт авиационных материалов" (ФГУП "ВИАМ") | Device for producing large-sized castings with directional and single-crystal structure |
| CN113279049B (en) * | 2021-04-14 | 2024-04-12 | 上海大学 | Device and method for controlling formation of monocrystalline metal casting platform impurity crystals and application thereof |
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