A continuous casting apparatus and a continuous casting method for a metal matrix composite

Abstract

The application discloses a continuous casting device and a continuous casting method for metal matrix composites. The continuous casting device comprises a No. 1 melting crucible, a No. 2 melting crucible, a composite crucible, a discharge pipe, a cooling device, an atmosphere protection device, a heating device, a heat preservation device, a mechanical stirring device, an electromagnetic stirring device and a traction device. In the continuous casting device, two metal melts are fully subjected to liquid-phase in-situ reaction in the composite cavity, and then the mechanical stirring device is used to promote the uniform distribution of the reinforcing particles. Subsequently, the metal melts are driven by the traction device to flow through the electromagnetic stirring area and the cooling area, and are subjected to melt cooling and continuous casting forming. The continuous casting method can not only realize in-situ compounding, but also effectively solve the problems of particle agglomeration in the metal melts and particle agglomeration in the cooling process. The process flow is short, the equipment is simple, and continuous production can be realized.

Description

Technical Field

[0001] This invention belongs to the field of composite material preparation technology, specifically relating to a continuous casting apparatus and method for metal matrix composite materials. Background Technology

[0002] Composite materials are mixtures of two or more immiscible materials that possess superior properties compared to any single component. Metal matrix composites are combinations of a tough metal (such as magnesium, aluminum, iron, or copper) or alloy matrix with other metals, nonmetals, or organic compounds. They are made by embedding reinforcing materials into a metal matrix and are important structural and functional building blocks. Common preparation methods include powder metallurgy and casting methods (such as die casting, rheocasting, and stir casting).

[0003] Currently, powder metallurgy is the most common method for preparing metal matrix composites. The equipment and processes for preparing copper matrix composites by powder metallurgy are relatively mature, and the common sintering methods include hot pressing, spark plasma sintering, and hot isostatic pressing. Its advantages include uniform distribution of reinforcing phase and flexible design of reinforcing phase content. However, it has many disadvantages: (1) Powder is easily contaminated in intermediate process steps, such as the introduction of impurities such as iron during mechanical alloying; (2) The density of the sintered sample is difficult to guarantee, and further densification is required through processes such as hot extrusion, making product quality control difficult; (3) The complex process and lengthy process flow result in low production efficiency and high production cost of powder metallurgy for preparing composite materials.

[0004] Stir casting is a promising casting technology for metal matrix composites. The design of the stir casting apparatus is crucial for preparing high-performance metal matrix composites with uniform microstructure. The main problems to be overcome in the stir casting process are: (1) poor wettability between the added particles and the metal matrix, making it difficult to fully bond; (2) metal elements are easily oxidized and burned off during stirring, generating a large amount of slag. The slag is stirred into the molten metal, which seriously deteriorates the performance of the composite material.

[0005] Existing equipment for preparing metal matrix composites using the stirred casting method suffers from low yield and difficulty in continuous production. Developing and designing continuously operating stirred casting equipment is of great significance for reducing the preparation cost of metal matrix composites and expanding their production applications. Summary of the Invention

[0006] To address the challenges of continuous production of metal matrix composites in existing technologies and the particle agglomeration problem in metal matrix composites prepared by melting and casting, the first objective of this invention is to provide a continuous casting apparatus for metal matrix composites that combines stirred casting and in-situ reaction. This continuous casting apparatus includes a No. 1 melting crucible, a No. 2 melting crucible, a composite crucible, a discharge pipe, a cooling device, an atmosphere protection device, a heating device, a heat preservation device, a mechanical stirring device, an electromagnetic stirring device, and a traction device. Using this continuous casting apparatus, after two streams of molten metal undergo sufficient in-situ liquid-phase reaction in the composite chamber, the mechanical stirring device promotes the uniform distribution of reinforcing particles. Subsequently, the molten metal, driven by the traction device, flows through the electromagnetic stirring zone and the cooling zone for melt cooling and continuous casting.

[0007] The second objective of this invention is to provide a continuous casting method for metal matrix composites. This continuous casting method not only achieves in-situ composite formation but also effectively solves the problems of particle agglomeration in the molten metal and during cooling. The process is short, requires simple equipment, and allows for continuous production.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] This invention discloses a continuous casting apparatus for metal matrix composite materials, comprising: a No. I melting crucible, a No. II melting crucible, a composite reaction furnace, and a continuous casting device, wherein the No. I melting crucible and the No. II melting crucible are used for melting metal.

[0010] The composite reactor includes a composite crucible and a mechanical stirrer; wherein the mechanical stirrer consists of a stirring connecting rod and a stirring paddle, the composite crucible is connected to the liquid outlets of the No. I melting crucible and the No. II melting crucible through a discharge pipe, the composite crucible is provided with an upper liquid outlet and a lower liquid outlet, and a stopper rod perpendicular to the upper liquid outlet and the lower liquid outlet is provided between the upper liquid outlet and the lower liquid outlet to control the opening and closing of the upper liquid outlet and the flow rate of the composite melt;

[0011] The continuous casting device includes a descending mold, a traction rod, a heat preservation device, a crystallizer, and an electromagnetic stirring device. The descending mold is connected to the lower outlet of the composite crucible at the top and is closely attached to the traction rod at the bottom. The heat preservation device and the crystallizer are arranged sequentially from top to bottom on the outside of the descending mold. The electromagnetic stirring device is wrapped around the upper outlet, lower outlet of the composite crucible, as well as the heat preservation device and the crystallizer.

[0012] The continuous casting apparatus provided by this invention employs a mechanical stirrer in the composite crucible. The mechanical stirrer introduces strong turbulence into the melt, creating a powerful stress field. This improves the mixing effect and the dispersion of reinforcing particles, ensuring the uniformity of the microstructure and composition of the final product. Appropriate mechanical stirring promotes the full in-situ reaction, reducing the residual proportion of elements participating in the in-situ reaction in the melt, which is crucial for improving the conductivity of the final product. Some elements participating in the in-situ reaction, such as Ti and B, tend to float to the surface of the melt during the melting process, making it difficult to fully dissolve. This not only causes element loss and increases raw material costs, but more importantly, it makes it difficult to determine the proportion of raw materials for the in-situ reaction. Ultimately, this makes it difficult to guarantee the quantity of reinforcing particles in the melt, deteriorating the final product performance. In practice, the mechanical stirring apparatus of this invention introduces strong turbulence, promoting the full melting of alloying elements, effectively solving the problem of alloying element loss (such as Ti), reducing raw material costs, ensuring that the elements participating in the in-situ reaction react in proportion in the melt, and effectively guaranteeing sufficient reinforcing particles and the final product performance.

[0013] After the molten material enters the lower mold from the composite crucible, it does not immediately solidify; a solid-liquid zone exists during continuous casting. Particles readily agglomerate in this zone. This invention addresses this by incorporating an electromagnetic stirring device to generate induced electromagnetic force within the solid-liquid zone of the melt. This force drives the melt flow, effectively suppressing the agglomeration of reinforcing particles and facilitating their capture at the solid-liquid interface. Furthermore, the induced electromagnetic force promotes grain refinement and microstructure uniformity in the continuously cast material, improving the overall performance of the product.

[0014] Furthermore, this invention cleverly places a stopper rod perpendicular to the upper and lower outlets of the composite crucible. Since the stopper rod is located at the bottom of the crucible's exterior, rather than inserted into the melt, its temperature is much lower than the melt temperature during melting, improving safety and significantly simplifying operation. By controlling the length of the stopper rod's withdrawal, the size of the melt outlet can be adjusted, allowing control over the melt flow rate. Because the stopper rod does not directly contact the melt, wear and tear are reduced, increasing its service life. In practical applications, it has been found that the stopper rod and composite crucible can be reused more than five times, significantly reducing equipment costs. Additionally, the stopper rod does not occupy internal space in the composite crucible, significantly increasing the volume of melt that can be contained within the crucible and significantly improving production efficiency. Another significant advantage of the stopper rod not occupying internal space is that it facilitates mechanical stirring. If the stopper rod were located inside the crucible, it would not only interfere with the flow field and stress field of the melt under mechanical stirring, affecting particle dispersion, but also reduce the installation space for the mechanical stirring device. If the stopper rod and mechanical stirring device coexist inside the crucible, they may even collide during stirring, causing equipment damage and safety accidents. Furthermore, since the stopper rod is located at the bottom of the composite crucible, its operation will not affect the atmosphere protection effect inside the crucible. If the stopper rod is located inside the crucible, removing it from the top can easily introduce air into the crucible, causing the melt to oxidize and slag, ultimately affecting product quality.

[0015] In a preferred embodiment, the agitator is selected from one of agitator A, agitator B, and agitator C. Agitator A is a straight-blade agitator, agitator B is a slanted-blade agitator with its blades at a 30° angle to the horizontal plane, and agitator C is a slanted-blade agitator with its blades at a -30° angle to the horizontal plane.

[0016] The inventors discovered that in the preparation of metal matrix composites containing reinforcing phases, selecting a suitable mechanical stirring impeller can enable the melt to obtain a well-distributed flow field and stress field, promoting the uniform distribution of reinforcing particles in the melt. The stirring impeller rotates clockwise during stirring. When the melt density is comparable to the particle density, stirring impeller A is used; when the melt density is greater than the particle density, stirring impeller B is used; and when the melt density is less than the particle density, stirring impeller C is used.

[0017] In a preferred embodiment, the composite reactor is further equipped with an atmosphere protection device; the atmosphere protection device is connected to a vent pipe. During the stirring process, the atmosphere protection device provides inert gas protection to the melt in the composite crucible, reducing element loss and slag.

[0018] In a further preferred embodiment, the atmosphere protection device is provided with a central through hole, through which the stirring connecting rod passes, and the diameter of the stirring connecting rod is 5-10 mm smaller than the diameter of the central through hole. The central through hole serves as both a mechanical stirring rod channel and an air outlet channel.

[0019] In a preferred embodiment, the composite reactor further includes a servo motor connected to the top of the mechanical stirrer. This provides power for the mechanical stirring, and the rotation speed can be adjusted as needed.

[0020] In a preferred embodiment, the distance between the top of the traction rod and the stopper rod of the composite reactor is 5-20 mm. The inventors have found that controlling the distance between the top of the traction rod and the stopper rod of the composite reactor within the above-mentioned range results in the optimal performance of the final ingot. If the distance is too large, it can easily lead to poor product quality at the sprue, such as internal porosity and surface defects; if the distance is too small, the melt is not easy to solidify, the solid-liquid interface is difficult to form effectively, and it affects the capture of reinforcing particles and the electromagnetic stirring effect of the solidification interface.

[0021] In a preferred embodiment, the continuous casting apparatus further includes a heating device, which is an induction heater, for heating the composite crucible, melting crucible I, and melting crucible II.

[0022] Furthermore, it also includes temperature sensing elements for the composite crucible, melting crucible I, and melting crucible II.

[0023] In a preferred embodiment, the crystallizer is a water-cooled crystallizer.

[0024] Furthermore, the cooling water flow rate of the crystallizer can be adjusted as needed, and the cooling speed can be controlled by adjusting the cooling water flow rate.

[0025] Furthermore, the crucible, discharge pipe, stirrer, atmosphere protection device, and stopper rod are made of graphite or refractory materials.

[0026] Furthermore, the atmosphere protection device can be used not only for composite crucibles, but also, if necessary, for both No. I melting crucible and No. II melting crucible.

[0027] Furthermore, the insulation device includes, but is not limited to, asbestos, refractory ceramics, and refractory bricks.

[0028] Furthermore, the traction device is controlled by a pneumatic valve and employs electromechanical traction.

[0029] Furthermore, the electromagnetic stirring device is controlled by adjusting the current; the greater the current, the stronger the electromagnetic stirring effect.

[0030] Furthermore, the heating device is connected to a computer device, and power control is performed through software to ensure precise temperature control.

[0031] This invention discloses a continuous casting method for a metal matrix composite material. The method involves melting raw materials according to the composition of alloy A in a No. 1 melting crucible to obtain melt A, and melting raw materials according to the composition of alloy B in a No. 2 melting crucible to obtain melt B. Melt A and melt B are then fed into a composite crucible through a discharge pipe and mixed under mechanical stirring to undergo an in-situ reaction, resulting in a composite melt. The stopper rod of the composite crucible is then removed, allowing the composite melt to flow through the heat-preserving area of ​​the descending mold and the water-cooled crystallizer. During this process, electromagnetic stirring is performed to continuously cast the composite melt into a metal matrix composite material.

[0032] In a preferred embodiment, alloy A is Cu-Ti and alloy B is Cu-B.

[0033] In the preferred embodiment, after melt A and melt B flow into the composite crucible through the discharge pipe, microalloying elements are added to either melting crucible I or melting crucible II. After melting, the melt flows into the composite crucible through the discharge pipe again. The composite melt is then mixed under mechanical stirring to carry out an in-situ reaction and obtain a composite melt.

[0034] In a further preferred embodiment, the microalloying element is selected from at least one of Cr, Zr, Mg, P, Sn, Zn, Ag, Si, In, Nd, Re (Ce, Y, La, etc.).

[0035] The preferred method is to first start mechanical stirring, and then let melt A and melt B flow into the composite crucible through the discharge pipe.

[0036] In a preferred embodiment, the mechanical stirring speed is controlled at 50-150 r / min, preferably 80-120 r / min. In actual operation, the initial mechanical stirring speed is first set to less than 50 r / min to avoid molten splashing caused by excessively fast initial speed.

[0037] In a preferred embodiment, the composite crucible is purged with a protective atmosphere.

[0038] In a preferred embodiment, the electromagnetic stirring current is 20A-100A. Controlling the electromagnetic stirring speed within this range ensures effective dispersion of particles in the melt during solidification.

[0039] In a preferred embodiment, the cooling water flow rate of the crystallizer is 200~2000 L / h.

[0040] In a preferred embodiment, the downward traction speed of the traction rod is 0.1~1 mm / s. The melt is rapidly cooled and solidified through a cold mold (water-cooled crystallizer), and continuously pulled out under the traction of the traction rod to achieve continuous production of metal matrix composite materials.

[0041] By modifying the lower die, the prepared metal matrix composite material can be in the form of rods, plates, strips, wires, pipes, or profiles.

[0042] By modifying the lower drawing mold and the composite crucible, the continuous casting method can be any of the upper drawing, lower drawing, or horizontal methods.

[0043] This invention discloses a continuous casting method for a metal matrix composite material. Pure copper and Cu-25Ti alloy are added to a No. 1 melting crucible at a mass ratio of 3-6:1 and heated to 1280-1320℃ to obtain a Cu-Ti melt. Pure copper and Cu-4B are added to a No. 2 melting crucible at a mass ratio of 1-3:1 and heated to 1280-1320℃ to obtain a Cu-B melt. Simultaneously, the composite crucible is heated to 1280-1320℃ and held for at least 5 minutes. Then, mechanical stirring is initiated using a stirring paddle B, and the stirring speed is controlled. The flow rate is 80-120 r / min. Then, Cu-Ti melt and Cu-B melt flow into the composite crucible through the discharge pipe. Under mechanical stirring, they are mixed and reacted in situ for 2-5 minutes to obtain a composite melt. Then, the stopper rod of the composite crucible is removed, and the composite melt flows through the heat preservation area of ​​the downward die of the wire rod and the crystallizer. During this process, electromagnetic stirring is performed, and the current of electromagnetic stirring is controlled at 60-90A. The composite melt is continuously cast to obtain a metal matrix composite material, which is Cu-TiB2 composite material.

[0044] The TiB2-reinforced copper-based composite material prepared by this invention exhibits excellent macroscopic surface quality, free from internal defects such as pores, looseness, and cracks, and demonstrates strong processability. The reinforcing phase particles are fine, maintain good interfacial bonding with the matrix, and are uniformly dispersed within the matrix. The electrical conductivity and mechanical properties of the Cu-TiB2 composite material prepared by this invention are significantly superior to those of Cu-TiB2 composite materials prepared without mechanical stirring.

[0045] This invention discloses a continuous casting method for metal matrix composites. Taking the preparation of Cu-Cr-Zr-TiB2 composite material as an example, pure copper and Cu-25Ti alloy are added to a composite crucible at a mass ratio of 3-6:1 and heated to 1280-1320℃ to obtain Cu-Ti melt. Pure copper and Cu-4B are added to a No. II melting crucible at a mass ratio of 1-3:1 and heated to 1280-1320℃ to obtain Cu-B melt. Pure Cu is placed in a No. I melting crucible and heated to 1280-1320℃ to obtain pure copper liquid. After holding at this temperature for more than 5 minutes, pure Cr and pure Zr are added to the No. I melting crucible. Using a stirrer B, mechanical stirring is started, and the stirring speed is controlled at 50-150 r / min. Then, the Cu-B melt is passed through... The material flows into the composite crucible through the discharge pipe. After mechanical stirring for 1-2 minutes, the Cu-Cr-Zr melt obtained from the No. 1 melting crucible flows into the composite crucible. The mass ratio of Cu-Ti:Cu-B melt:Cu-Cr-Zr melt is controlled at 1:1-2:1.5-3. The composite melt is obtained by in-situ reaction in the composite crucible for 1-2 minutes. Then, the stopper rod of the composite crucible is removed, and the composite melt flows through the heat preservation area of ​​the downward mold of the plate and the water-cooled crystallizer. During this process, electromagnetic stirring is performed. The current of electromagnetic stirring is controlled at 60-90A, and the traction speed is controlled at 0.3-0.6mm / s. The composite melt is continuously cast to obtain a metal matrix composite material, which is a Cu-Cr-Zr-TiB2 composite material.

[0046] This invention combines Cu-Cr-Zr alloy with TiB2 ceramic particles to leverage the coupling effect of precipitation strengthening and particle strengthening. Through cold rolling (90% deformation) and aging treatment (450℃ / 2h), Cr is fully precipitated. The precipitation of Cr ensures the strength of the composite material, while Zr and TiB2 particles help improve the high-temperature performance and softening resistance of the composite material. TiB2 also significantly enhances the wear resistance and arc-quenching performance of the composite material. Furthermore, the introduction of mechanical stirring in the smelting process mainly solves the following problems: (1) The turbulence introduced by mechanical stirring promotes the full melting of alloying elements such as Ti, Zr, and B, reducing raw material loss and ensuring more accurate composition. (2) The turbulence introduced by mechanical stirring promotes the full in-situ reaction, refines the in-situ generated strengthening particles, and ensures their uniform distribution in the melt. In addition, the present invention introduces a powerful electromagnetic stirring process in the downward continuous casting process, which has the following advantages: (1) effectively inhibits the agglomeration of strengthening particles at the solid-liquid interface during the solidification process; (2) promotes the capture of strengthening particles at the solidification interface; and (3) promotes the grain refinement and uniform structure of the material.

[0047] Using the apparatus and method of this invention, metal matrix composites were prepared, effectively achieving the coupling of age precipitation strengthening and particle strengthening. By incorporating dual-scale particles into copper matrix composites, the application fields of metal matrix composites are expanded. Taking the prepared Cu-0.4Cr-0.1Zr-1TiB2 (wt%) as an example, the uniformly distributed dual-scale particles (i.e., nanoscale Cr particles and submicron-scale TiB2 particles) inhibit the recrystallization process of the composite material at high temperatures, contributing to improved high-temperature mechanical properties and heat resistance. After simple heat treatment, the continuously cast plate ultimately achieved excellent comprehensive properties, with a conductivity of 84% IACS and a hardness of 181 HV.

[0048] Principles and advantages:

[0049] The continuous casting apparatus provided by this invention employs a mechanical stirrer in the composite crucible. The mechanical stirrer introduces strong turbulence into the melt, creating a powerful stress field. This improves the mixing effect and the dispersion of reinforcing particles, ensuring the uniformity of the microstructure and composition of the final product. Appropriate mechanical stirring promotes the full in-situ reaction, reducing the residual amount of alloying elements participating in the in-situ reaction in the melt, which is crucial for improving the conductivity of the final product. Some alloying elements participating in the in-situ reaction, such as Ti and B, easily float to the surface of the melt during the melting process, making it difficult to fully dissolve. This not only causes element loss and increases raw material costs, but more importantly, it makes it difficult to precisely control the composition of the mixed melt in the in-situ reaction, ultimately resulting in an unreliable number of reinforcing particles in the melt and deteriorating the overall performance of the composite material. In the preparation process, the mechanical stirring apparatus of this invention introduces strong turbulence, promoting the full melting and uniform distribution of alloying elements, solving the problem of easy alloying element loss, reducing raw material costs, ensuring that the elements participating in the in-situ reaction react in the melt according to the designed proportions, and guaranteeing sufficient reinforcing particles and overall performance of the composite material.

[0050] After the molten material enters the lower mold from the composite crucible, it does not immediately solidify; a solid-liquid zone exists during continuous casting. Particles readily agglomerate in this zone. This invention addresses this by incorporating an electromagnetic stirring device to generate induced electromagnetic force within the solid-liquid zone of the melt. This force drives the melt flow, effectively suppressing the agglomeration of reinforcing particles and facilitating their capture at the solid-liquid interface. Furthermore, the induced electromagnetic force promotes grain refinement and microstructure uniformity in the continuously cast material, improving the overall performance of the product.

[0051] The preparation method of this invention utilizes precise temperature control and stirring speed regulation to control the continuous casting process, ensuring uniform melting, thorough in-situ reaction, uniform particle distribution, and rapid solidification. Ultimately, it produces copper-based composite materials with excellent surface quality, fine and uniformly distributed reinforcing phase particles, and no internal defects, achieving continuous and efficient production. Compared to powder metallurgy, the equipment of this invention produces materials with high density, a shorter process, higher efficiency, and lower cost. Attached Figure Description

[0052] Figure 1 This is a schematic diagram of the structure of a continuous casting device for a metal matrix composite material according to the present invention (hereinafter referred to as continuous casting).

[0053] Figure 2 This is a schematic diagram of the composite crucible 6.

[0054] Figure 3 Three-dimensional structural diagrams of three different types of impellers 8 are shown. Figure 3 (a) is the agitator A; Figure 3 (b) is the agitator B; Figure 3 (c) is the agitator C.

[0055] Figure 4 This is a three-dimensional structural diagram of four different models of the lower guide mold 22. Figure 4 (a) Round billet lowering mold; Figure 4 (b) Sheet metal lowering mold; Figure 4 (c) Wire rod lowering die; Figure 4 (d) Billet lowering mold

[0056] Figure 5 Here is a schematic diagram of the billet lower drawing die: Figure 5 (a, b) 3D schematic diagrams from different perspectives; Figure 5 (c) Cross-sectional view.

[0057] Figure 6 This is a three-dimensional structural diagram of the main body of a metal matrix composite continuous casting device that combines stirred casting and in-situ reaction, as disclosed in this invention.

[0058] Figure 7 The scanning electron microscope (SEM) morphology of the Cu-2TiB2 rod prepared according to this invention.

[0059] Figure 8 The scanning electron microscope (SEM) morphology of the Cu-0.4Cr-0.1Zr-1TiB2 rod prepared according to this invention.

[0060] Figure 9 The elemental surface distribution results of the Cu-0.4Cr-0.1Zr-1TiB2 plate prepared according to the present invention. Detailed Implementation

[0061] The following will describe the embodiments of the present invention clearly and completely with reference to the schematic diagrams. These embodiments are specific examples of the present invention, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0062] Figure 1 The present invention provides a continuous casting apparatus for metal matrix composite materials that combines stirred casting and in-situ reaction, comprising: a servo motor 1, a long stirring connecting rod 2, a vent pipe 3, an atmosphere protection device 4, a discharge pipe 5, a composite crucible 6, a short stirring connecting rod 7, a stirring paddle 8, an induction heater 9, a mixed molten metal 10, a thermocouple 11, an electromagnetic stirring device 12, a water-cooled crystallizer 13, a cooling water inlet 131, a cooling water outlet 132, a traction rod 14, a traction power device 15, a No. II melting crucible 16, a stopper rod 17, a No. I melting crucible 18, melt A 19, melt B 20, a heat preservation device 21, and a lower drawing mold 22.

[0063] The composite crucible 6 is connected to the outlets of melting crucibles 18 and 16 via the discharge pipe 5. The melted A and B substances in melting crucibles 18 and 16 are transported to the composite crucible 6 via the discharge pipe 5. The inlet of the lower mold 22 is connected to the outlet of the composite crucible 7. The outer wall of the lower mold 22 is in close contact with the inner wall of the crystallizer 13, thereby achieving good heat transfer. After the molten metal in the composite crucible 7 enters the lower mold 22, it is cooled and crystallized by the crystallizer 13. To improve cooling and casting efficiency, the crystallizer 13 is a water-cooled crystallizer 13. The atmosphere protection device 4 is connected to the vent pipe 3, and its function is to provide atmosphere protection for the molten metal in the composite crucible 6.

[0064] like Figure 1 The servo motor 1, the long stirring rod 2, the short stirring rod 7, and the stirring paddle 8 are connected by threads to ensure their concentricity.

[0065] like Figure 1 The stirring connecting rod (length) 2 must penetrate the central through hole of the atmosphere protection device 4. To ensure smooth mechanical stirring and the outflow of protective gas, the diameter of the stirring connecting rod (length) 2 needs to be 5-10 mm smaller than the diameter of the central through hole of the atmosphere protection device 4.

[0066] like Figure 1 The ventilation pipe 3 and the atmosphere protection device 4 are connected by threads to ensure the reliability and airtightness of the ventilation process.

[0067] like Figure 1 The discharge pipe 5 and the composite crucible 6 are connected by threads to ensure the flow of melt and prevent leakage.

[0068] like Figure 1 The No. I melting crucible 18, the No. II melting crucible 16, and the composite crucible 6 need to be spaced a certain distance apart because their heating devices 9 cannot be too close together. The heating devices of the three need to be spaced at least 50 mm apart.

[0069] like Figure 1 The stopper rod 17 is used to control the transfer of molten metal from melting crucible 18 and melting crucible 16 to the composite crucible 6. When the stopper rod 17 is pulled out, the molten metal from melting crucible 18 and melting crucible 16 is transferred to the composite crucible 6 through the discharge pipe 5.

[0070] The metals in melting crucibles 18 (No. I) and 16 (No. II) do not require atmosphere protection during melting because the resulting oxides will float to the surface and will not enter the composite crucible 6. If atmosphere protection is required for the molten metals in melting crucibles 18 and 16, atmosphere protection device 4 can be installed. The molten metals in the composite crucible 6 must be protected by atmosphere during melting to ensure the quality of the finished product.

[0071] See Figure 1 and Figure 2 The electromagnetic stirring device 12 is fixed between the composite crucible 6 and the crystallizer 13 to perform electromagnetic stirring of different degrees on the unsolidified molten metal below the liquid outlet 604 of the composite crucible 6.

[0072] like Figure 1 The heat preservation device 21 keeps the molten material inside warm, reducing heat loss and preventing the molten material from solidifying too quickly. If the molten material solidifies too quickly, it will affect the electromagnetic stirring effect of the electromagnetic stirring device 12 and the continuity of the downward continuous casting.

[0073] See Figure 1 The traction rod 14 is made of high-temperature resistant material, and its dimensions should match those of the lower drawing mold 22. Taking continuous casting of wire rod as an example, under the premise of ensuring normal traction by the traction device 15, the outer wall of the traction rod 14 should be tightly attached to the lower drawing mold 22. The melting point of the traction rod 14 should be at least 200 degrees Celsius higher than that of the molten metal in the composite crucible 6.

[0074] Referring to Figure 1, to achieve precise temperature control of all crucibles, thermocouples 11 are installed on the side walls of each crucible for temperature measurement. Thermocouples 11 are connected to the heating systems of their respective components via wires. The heating systems receive the measured temperature feedback from the thermocouples 11 and then control the power of the heating system to achieve precise adjustment of the melt temperature. The connection, temperature measurement, and temperature control functions of the thermocouples are all existing technologies and will not be described in detail here. The connection and control of the electromagnetic stirring device are also existing technologies and will not be described in detail here.

[0075] See Figure 2 The stopper rod 601 of the composite crucible 6 is placed at the bottom. After the melt is stirred and mixed, the stopper rod 601 is pulled out, and the melt flows into the lower mold 22 from the lower outlet 604. The lower outlet 604 and the upper outlet 602 need to be concentric to ensure the smooth flow of the melt. 606 is the interface of the feed pipe 5. 603 is the interface of the stopper rod 601. The advantages of this device are: (1) it can be reused; (2) the stopper rod 604 will not affect the normal operation of the stirring device.

[0076] See Figure 3 The stirring paddle 8 is designed in three different models for different applications, depending on the density difference between the melt and the in-situ generated particles. The stirring paddle rotates clockwise during stirring. Stirring paddle A (a) is used when the melt density is similar to the particle density; stirring paddle B (b) is used when the melt density is greater than the particle density; and stirring paddle C (c) is used when the melt density is less than the particle density. During installation, the stirring paddle 8 should be kept 20-30 mm away from the bottom of the melt to ensure good stirring effect.

[0077] Figure 4 These are three-dimensional structural schematic diagrams of different models of the downward drawing mold 22 designed in this invention. Four different models of the downward drawing mold 22 are designed for use according to different needs. The downward drawing mold 22 and the composite crucible 6 are connected by threads to ensure their concentricity. Figure (a) shows the downward drawing mold for round billets, Figure (b) shows the downward drawing mold for plate sheets, Figure (c) shows the downward drawing mold for wire rods, and Figure (d) shows the downward drawing mold for tube billets.

[0078] Figure 5 Figure (a) and (b) are schematic diagrams of the tube blank lower drawing die designed for this invention. (a) and (b) are three-dimensional schematic diagrams from different perspectives, and (c) is a cross-sectional view. The eight small holes above the die in Figure (b) are channels for melt flow, and their dimensions can be designed according to the melt characteristics.

[0079] Figure 6 This is a three-dimensional structural diagram of the main body of a metal matrix composite continuous casting device that combines stirred casting and in-situ reaction, as disclosed in this invention. It can be used as an installation reference and for understanding the overall structure of the device.

[0080] This invention provides a continuous casting method for metal matrix composite materials that combines stirred casting and in-situ reaction.

[0081] Furthermore, the specific steps include the following:

[0082] Step 1: Place the required raw materials for Alloy A into melting crucible 18 (No. I) according to the specified ratio, heat to Ta and hold at that temperature; if there are special requirements, such as the raw materials being easily burned, the corresponding raw materials can be added after the crucible reaches the target temperature. Place Alloy B into melting crucible 16 (No. II) according to the specified ratio, heat to Tb and hold at that temperature; if there are special requirements, such as the relevant raw materials being easily burned, the corresponding raw materials can be added after the crucible reaches the target temperature.

[0083] Step 2: While heating alloys A and B, an inert gas is introduced into the composite crucible 6 for protection, and the temperature is maintained at Tc. Before heating, the cooling water of the water-cooled crystallizer 13 is turned on, and the flow rate is controlled at 200~1000 L / h.

[0084] Step 3: After the metal in melting crucible 18 (No. I) and melting crucible 16 (No. II) has melted and reached the target temperature, maintain the temperature for at least 5 minutes to ensure complete melting. Turn on servo motor 1 to drive the stirring paddle 8 to rotate, ensuring the initial speed is below 50 r / min for safety.

[0085] Step 4: Simultaneously remove the stoppers 17 from both melting crucibles, allowing the molten metals A and B to flow completely into the composite crucible 6 via the feed pipe 5. Under mechanical stirring, the melts will mix thoroughly and react in situ. Then, turn on the electromagnetic stirring device 12, initially controlling the current below 20 A to ensure safety. Adjust the current according to different needs, up to a maximum of 100 A. The higher the current, the stronger the electromagnetic stirring effect.

[0086] Step 5: After the melt has fully reacted and mixed in the composite crucible 6, remove the stopper rod 601, and the melt enters the lower mold through the outlet at the bottom of the composite crucible. At this time, the current of the electromagnetic stirring device 12 should be adjusted to a suitable level to ensure the dispersion effect of particles in the melt during solidification. The traction rod 14 should be assembled into a suitable position before heating, and the distance between its head and the stopper rod 601 should be 5~20 mm.

[0087] Step 6: Activate the traction device to move the traction rod downwards at a speed of 0.1~0.8 mm / s. The melt is rapidly cooled and solidified through a cold mold, and continuously pulled out under the traction of the traction rod, thus continuously producing metal matrix composite materials.

[0088] The present invention will be further described below with reference to specific embodiments.

[0089] Example 1: Continuous casting of Cu-2wt.%TiB2 composite material into bars.

[0090] Cu-Ti and Cu-B melts were mixed, and TiB2 particles were generated in situ in the melt as a reinforcing phase to prepare Cu-TiB2 composite rods with a diameter of 12 mm.

[0091] Step 1: Assemble as follows Figure 1 After the apparatus is set up, pure copper and Cu-25Ti raw materials are placed in melting crucible I 18 at a mass ratio of approximately 5:1 and heated, while pure copper and Cu-4B raw materials are placed in melting crucible II 16 at a mass ratio of approximately 2:1 and heated. Simultaneously, argon gas is introduced into the composite crucible 6 through atmosphere protection device 4 at a flow rate of 20 L / h. Heating of the composite crucible 6 begins. The water flow rate of the water-cooled crystallizer 13 is adjusted to 400 L / h.

[0092] Step 2: Real-time temperature measurement is performed using thermocouple 11. After the temperature in all three crucibles reaches 1300℃ and is maintained for more than 5 minutes, the servo motor 1 is turned on to drive the stirring device 8 (using stirring paddle B) to rotate at a speed of 100 r / min. Subsequently, the stopper rods 17 in melting crucible I 18 and melting crucible II 16 are simultaneously removed, allowing the Cu-Ti and Cu-B melts to enter the composite crucible 6 along the discharge pipe 5.

[0093] Step 3: Turn on the electromagnetic stirring device 12 and adjust the current to 80 A. After the mixed melt 10 has undergone mechanical stirring and in-situ reaction for 2 minutes, remove the stopper rod 601 of the composite crucible 6 to allow the melt to flow into the lower mold. During this period, keep the mechanical stirring device 8 running continuously.

[0094] Step 4: Activate the traction device 15, set its speed to 0.3 mm / s, and move the traction rod 14 downwards. The macroscopic surface quality of the continuously cast bar is good, with no obvious internal defects.

[0095] Under the above process, the scanning electron microscope (SEM) morphology of the prepared Cu-TiB2 rods is as follows: Figure 7 As shown, the reinforcing particles are small and uniformly distributed. The as-cast sample has a conductivity of 83% IACS and a hardness of 101 HV. After 90% cold rolling, the conductivity is 80% IACS, the hardness is 184 HV, the tensile strength is 605 MPa, and the elongation is 3.6%.

[0096] The Cu-2wt.%TiB2 composite material prepared by unstirred melting has a conductivity of 67% IACS, a hardness of 153 HV, a tensile strength of 520 MPa, and an elongation of 2.2% after 90% cold rolling.

[0097] Furthermore, the Cu-1wt.%TiB2 composite material prepared using the method described in Example 1 above, after 90% cold rolling, exhibits a conductivity of 90% IACS, a hardness of 145 HV, a tensile strength of 480 MPa, and an elongation of 7.4%. The Cu-1wt.%TiB2 composite material prepared without mechanical stirring and melting, after 90% cold rolling, exhibits a conductivity of 84% IACS, a hardness of 125 HV, a tensile strength of 423 MPa, and an elongation of 4.1%.

[0098] Comparative Example 1:

[0099] Other conditions were the same as in Example 1, except that electromagnetic stirring was canceled during the downward drawing process, i.e., the electromagnetic stirring device 12 was turned off. The resulting composite material contained a large number of agglomerated TiB2 particles at the grain boundaries, and the grains were even coarser. The as-cast sample had a conductivity of only 75% IACS and a hardness of 89 HV.

[0100] Comparative Example 2:

[0101] Other conditions were the same as in Example 1, except that electromagnetic stirring was used instead of mechanical stirring in the composite crucible. The resulting composite material contained a large number of agglomerated B-rich particles. ICP results showed that the Ti content in the matrix was only 0.62 wt.% (designed content was 1.4 wt%). This was because the flow field induced by electromagnetic stirring was insufficient to fully melt the Ti, causing it to float and form slag, resulting in losses. The as-cast sample had a conductivity of only 68% IACS and a hardness of 92 HV.

[0102] Example 2:

[0103] Plate casting of Cu-0.4Cr-0.1Zr-1TiB2 composite material.

[0104] A Cu-0.4Cr-0.1Zr-1TiB2 composite material plate with a width of 40 mm and a thickness of 10 mm was prepared by mixing Cu-Ti, Cu-B, and Cu-Cr-Zr melts, first generating TiB2 particles in situ in the melt as a reinforcing phase, and then introducing microalloying elements Cr and Zr.

[0105] Step 1: Assemble as follows Figure 1 After the apparatus is set up, pure copper and Cu-25Ti raw materials are placed in the composite crucible 6 at a mass ratio of approximately 5:1 and heated. Pure copper and Cu-4B raw materials are placed in melting crucible 16 (II) at a mass ratio of approximately 2:1 and heated. Pure Cu is placed in melting crucible 18 (I) and heated. Simultaneously, argon gas is introduced into the composite crucible 6 through the atmosphere protection device 4 at a flow rate of 15 L / h. Heating of the composite crucible 6 begins. The water flow rate of the water-cooled crystallizer 13 is adjusted to 400 L / h.

[0106] Step 2: Real-time temperature measurement is performed using thermocouple 11. After the temperature in all three crucibles reaches 1300℃ and is maintained for at least 5 minutes, Cr and Zr elements are added sequentially to melting crucible I (18) to obtain Cu-0.8Cr-0.2Zr molten metal. Servo motor 1 is turned on to drive the stirring device 8 (using stirring paddle B) to rotate at a speed of 100 r / min. Subsequently, stopper rod 17 in melting crucible II (16) is simultaneously removed, allowing Cu-B melt to enter composite crucible 6 through discharge pipe 5, where it reacts and mixes in situ with Cu-Ti melt in composite crucible 6. After 1 minute, stopper rod 17 in melting crucible I (18) is removed, allowing Cu-Cr-Zr melt to enter composite crucible 6 and mix thoroughly with the melt therein for 1 minute. The mass ratio of Cu-Ti:Cu-B melt:Cu-Cr-Zr melt is maintained at 1:1:2.

[0107] Step 3: Turn on the electromagnetic stirring device 12 and adjust the current to 90A. Pull out the stopper rod 601 of the composite crucible 6 to allow the melt to flow into the lower mold. During this period, keep the mechanical stirring device 8 running continuously.

[0108] Step 4: Activate the traction device 15, set its speed to 0.5 mm / s, and move the traction rod 14 downwards. The macroscopic surface quality of the continuously cast bar is good, with no obvious internal defects.

[0109] Figure 8 The scanning electron microscope (SEM) morphology of the Cu-0.4Cr-0.1Zr-1TiB2 substrate prepared according to this invention shows that the particles are uniformly distributed in the sample, the surface is free of pores, and the particles are well bonded to the matrix.

[0110] Figure 9 The elemental distribution of the Cu-0.4Cr-0.1Zr-1TiB2 plate prepared according to this invention is shown. The reinforcing particles mainly include TiB2 and Cr particles.

[0111] The resulting as-cast sample had a conductivity of 32% IACS and a hardness of 91 HV. After subsequent aging treatment (450℃ / 2h), the final plate had a conductivity of 84% IACS and a hardness of 181 HV.

[0112] Comparative Example 3:

[0113] Other conditions were the same as in Example 2, except that all materials were directly added to the composite crucible for melting. Because boron reacts with zirconium, a large number of zirconium particles were present in the resulting composite material. Some titanium (Ti) remained in the matrix, severely degrading the conductivity of the composite. After 90% cold rolling and aging (450°C / 2h), the conductivity was only 47% IACS, and the hardness was 162 HV.

[0114] Comparative Example 4:

[0115] Other conditions were the same as in Example 2, except that electromagnetic stirring was used instead of mechanical stirring in the composite crucible. The resulting composite material exhibited a large number of agglomerated B-rich particles at the grain boundaries. ICP results showed that the Ti content in the matrix was only 0.23 wt.% (designed composition: 0.7 wt%), and Zr was almost undetectable. This is because the flow field induced by electromagnetic stirring was insufficient to fully melt Ti and Zr, causing them to float and form slag, resulting in losses. After 90% cold rolling and aging (450℃ / 2h), the composite material had an electrical conductivity of only 64% IACS and a hardness of 149 HV.

[0116] Comparative Example 5:

[0117] Other conditions were the same as in Example 2, except that electromagnetic stirring was canceled during the downward drawing process, i.e., the electromagnetic stirring device 12 was turned off. The resulting composite material contained a large number of agglomerated TiB2 particles at the grain boundaries, and its grains were even coarser. After 90% cold rolling and aging (450℃ / 2h), the composite material had a conductivity of only 74% IACS and a hardness of 153 HV.

[0118] Comparative Example 6:

[0119] Other conditions were the same as in Example 2, except that no protective atmosphere was used during the preparation process. ICP results showed that the Ti content in the matrix was only 0.35 wt.% (design composition was 0.7 wt%), and the Zr content was almost zero (design composition was 0.1 wt%). This was because the lack of protective atmosphere caused the Ti and Zr elements to burn off. After 90% cold rolling and aging (450℃ / 2h), the composite material had an electrical conductivity of only 71% IACS and a hardness of 156 HV.

Claims

1. A continuous casting apparatus for metal matrix composite materials, characterized in that: include: The equipment includes Melting Crucible I, Melting Crucible II, a composite reactor, and a continuous casting device. Melting Crucible I and Melting Crucible II are used for smelting metals. The composite reactor includes a composite crucible and a mechanical stirrer; wherein the mechanical stirrer consists of a stirring connecting rod and a stirring paddle; the composite crucible is connected to the liquid outlets of the No. I melting crucible and the No. II melting crucible through a discharge pipe; the composite crucible is provided with an upper liquid outlet and a lower liquid outlet, and a stopper rod perpendicular to the upper liquid outlet and the lower liquid outlet is provided between the upper liquid outlet and the lower liquid outlet to control the opening and closing of the upper liquid outlet and the flow rate of the composite melt; the composite reactor is also equipped with an atmosphere protection device; the atmosphere protection device is connected to a vent pipe; The continuous casting device includes a descending mold, a traction rod, a heat preservation device, a crystallizer, and an electromagnetic stirring device. The descending mold is connected to the lower outlet of the composite crucible at the top and is closely attached to the traction rod at the bottom. The heat preservation device and the crystallizer are arranged sequentially from top to bottom on the outside of the descending mold. The electromagnetic stirring device is wrapped around the upper outlet, lower outlet of the composite crucible, as well as the heat preservation device and the crystallizer.

2. The continuous casting apparatus for metal matrix composite materials according to claim 1, characterized in that: The agitator is selected from agitator A, agitator B, and agitator C. Agitator A is a straight-blade agitator, agitator B is a slanted-blade agitator with its blades at a 30° angle to the horizontal plane, and agitator C is a slanted-blade agitator with its blades at a -30° angle to the horizontal plane.

3. The continuous casting apparatus for metal matrix composite materials according to claim 1, characterized in that: The atmosphere protection device is provided with a central through hole, and the stirring connecting rod passes through the central through hole of the atmosphere protection device. At the same time, the diameter of the stirring connecting rod is 5-10 mm smaller than the diameter of the central through hole.

4. The continuous casting apparatus for metal matrix composite materials according to claim 1, characterized in that: The distance between the top of the traction rod and the stopper rod of the composite reactor is 5~20 mm.

5. A continuous casting method for metal matrix composite materials, characterized in that, Using the continuous casting apparatus according to any one of claims 1-4, the corresponding raw materials according to the composition of alloy A are placed in melting crucible I to obtain melt A, and the corresponding raw materials according to the composition of alloy B are placed in melting crucible II to obtain melt B. Then, melt A and melt B are allowed to flow into a composite crucible through the discharge pipe and mixed under mechanical stirring to carry out an in-situ reaction to obtain a composite melt. Then, the stopper rod of the composite crucible is pulled out, and the composite melt flows through the heat preservation area of ​​the downward mold and the water-cooled crystallizer. During this process, electromagnetic stirring is carried out to continuously cast the composite melt to obtain a metal matrix composite material. The composite crucible is purged with a protective atmosphere.

6. The continuous casting method for a metal matrix composite material according to claim 5, characterized in that, Alloy A is Cu-Ti, and alloy B is Cu-B; After melt A and melt B flow into the composite crucible through the discharge pipe, microalloying elements are added to melting crucible I or melting crucible II. After melting, melts flow into the composite crucible through the discharge pipe. The composite melt is then mixed under mechanical stirring to carry out an in-situ reaction and obtain the composite melt. The microalloying element is selected from at least one of Cr, Zr, Mg, P, Sn, Zn, Ag, Si, In, Nd, and Re.

7. A continuous casting method for a metal matrix composite material according to claim 5 or 6, characterized in that, First, start the mechanical stirring, and then let melt A and melt B flow into the composite crucible through the discharge pipe; control the mechanical stirring speed to be 50-150 r / min.

8. A continuous casting method for a metal matrix composite material according to claim 5 or 6, characterized in that, The current of the electromagnetic stirrer is 20A-100A; The cooling water flow rate of the water-cooled crystallizer is 200~2000 L / h; The downward traction speed of the traction rod is 0.1~1 mm / s.

9. A continuous casting method for metal matrix composite materials, characterized in that, Using the continuous casting apparatus described in claim 2, pure copper and Cu-25Ti alloy are added to melting crucible I at a mass ratio of 3-6:1 and heated to 1280-1320℃ to obtain Cu-Ti melt. Pure copper and Cu-4B are added to melting crucible II at a mass ratio of 1-3:1 and heated to 1280-1320℃ to obtain Cu-B melt. Simultaneously, the composite crucible is heated to 1280-1320℃ and held for at least 5 minutes. Then, mechanical stirring is started using stirring paddle B, and the stirring speed is controlled at 80-120. The flow rate is r / min. Then, Cu-Ti melt and Cu-B melt are fed into the composite crucible through the discharge pipe. They are mixed under mechanical stirring and reacted in situ for 2-5 minutes to obtain a composite melt. Then, the stopper rod of the composite crucible is removed, and the composite melt is allowed to flow through the heat preservation area of ​​the downward die of the wire rod and the crystallizer. During this process, electromagnetic stirring is performed, and the current of electromagnetic stirring is controlled at 60-90A. The composite melt is continuously cast to form a metal matrix composite material, which is Cu-TiB2 composite material. The composite crucible is purged with a protective atmosphere.

10. A continuous casting method for metal matrix composite materials, characterized in that, Using the continuous casting apparatus described in claim 2, pure copper and Cu-25Ti alloy are added to a composite crucible at a mass ratio of 3-6:1 and heated to 1280-1320℃ to melt and obtain Cu-Ti melt. Pure copper and Cu-4B are added to a No. II melting crucible at a mass ratio of 1-3:1 and heated to 1280-1320℃ to melt and obtain Cu-B melt. Pure Cu is placed in a No. I melting crucible and heated to 1280-1320℃ to obtain pure copper liquid. After holding at this temperature for more than 5 minutes, pure Cr and pure Zr are added to the No. I melting crucible. Using a stirring paddle B, mechanical stirring is started, and the stirring speed is controlled at 80-120. The flow rate is r / min, and then the Cu-B melt flows into the composite crucible through the discharge pipe. After mechanical stirring for 1-2 minutes, the Cu-Cr-Zr melt obtained from the No. 1 melting crucible flows into the composite crucible. The mass ratio of Cu-Ti:Cu-B melt:Cu-Cr-Zr melt is controlled at 1:1-2:1.5-3. In-situ reaction is carried out in the composite crucible for 1-2 minutes to obtain the composite melt. Then the stopper rod of the composite crucible is pulled out, and the composite melt flows through the heat preservation area of ​​the descending mold of the plate and the crystallizer. During this process, electromagnetic stirring is carried out, and the current of electromagnetic stirring is controlled at 60-90A and the traction speed is controlled at 0.3-0.6mm / s. The composite melt is continuously cast to obtain a metal matrix composite material, which is a Cu-Cr-Zr-TiB2 composite plate. The composite crucible is purged with a protective atmosphere.

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