Copper-based composite material and preparation method thereof

Abstract

The invention belongs to the technical field of material preparation, and relates to a copper-based composite material and a preparation method thereof.The preparation method comprises the steps that ceramic particles are generated in situ in a molten salt mixture through an electrochemical method, then the molten salt mixture containing the ceramic particles is added into a copper melt, and therefore the ceramic particles are evenly dispersed in a copper matrix; and the copper-based composite material is obtained. According to the method, the ceramic particles are prepared in situ in the molten salt mixture by adopting an electrochemical method, the ceramic particles are directly generated through electrochemical reaction, and the particle size of the ceramic particles can be accurately controlled by regulating and controlling the current density and the electrolysis time; the ceramic particles can be fully dispersed and uniformly distributed in a copper matrix through a stirring process, so that the stable performance of the composite material is guaranteed; in addition, low-cost molten salt is adopted as a reaction medium, the method has the double advantages of being low in production cost and high in generated particle quality, and the industrial application potential is outstanding.

Description

Technical Field

[0001] This invention belongs to the field of materials preparation technology, and relates to a copper-based composite material and its preparation method. Background Technology

[0002] Copper-based composite materials are widely used in extreme application environments such as ultra-high temperature, ultra-low temperature, high stress, and high current because they can improve the strength, high temperature resistance, and wear resistance of materials without significantly affecting their electrical conductivity. They have great application potential in the development of high-end domestic equipment.

[0003] The preparation methods for copper-based composite materials typically include powder metallurgy, additive manufacturing, and conventional casting. Powder metallurgy and additive manufacturing methods are more expensive than conventional casting, resulting in lower yields and higher costs, making them unsuitable for large-scale, stable production. Conventional casting, however, has lower equipment requirements and holds promise for large-scale production of copper-based composite materials. Furthermore, improving the performance of copper-based composite materials requires the introduction of a micro / nano-sized second phase into the matrix. A high specific surface area can easily lead to agglomeration and oxidation of the second phase before its introduction into the copper matrix, affecting yield and product quality.

[0004] Ceramic particles, generally stable inorganic compounds at room temperature, possess high hardness, high melting point, good electrical and thermal conductivity, resistance to high-temperature oxidation, and good corrosion resistance, making them widely used as high-temperature coating materials and raw materials for heating elements. However, the preparation of micro- and nano-sized ceramic particles typically involves high-temperature chemical reactions, airflow crushing, and ball milling, which suffers from complex processes, high costs, and low yields. Inorganic compounds dissolve at high temperatures, ionizing into metal ions. Electrochemical methods can be used to achieve in-situ generation of micro- and nano-sized ceramic particles at the atomic level within molten salt systems (molten salt mixtures), significantly reducing the production cost of ceramic particles.

[0005] In summary, in order to address the problems of long preparation processes, high costs, and easy agglomeration and oxidation of micro- and nano-sized ceramic particles, which make it difficult to directly introduce them into the copper matrix using the casting method, there is an urgent need to propose a method for preparing copper-based composite materials. Summary of the Invention

[0006] In view of this, the purpose of the present invention is to provide a copper-based composite material and its preparation method, which generates micro-nano-sized ceramic particles in situ in a molten salt mixture, and then introduces the particles into the copper melt using a mixture of molten salt and ceramic particles, thereby preparing a copper-based composite material. This solves the problems of long preparation process, high cost, and easy agglomeration and oxidation of micro-nano-sized ceramic particles, which make it difficult to directly introduce them into the copper matrix using the casting method.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A method for preparing a copper-based composite material involves generating ceramic particles in situ in a molten salt mixture using an electrochemical method, and then adding the molten salt mixture containing the ceramic particles to a copper melt to achieve uniform dispersion of the ceramic particles in the copper matrix, thereby obtaining the copper-based composite material.

[0008] Furthermore, the molten salt mixture comprises an alkali metal or alkaline earth metal halide as a solvent and a metal oxyacid salt as a solute; The electrochemical method employs constant current electrolysis, and a reduction reaction occurs on the surface of the working electrode; The ceramic particles are A. x B y A is selected from Cr, Nb, W or Mo, and B is selected from C or Si.

[0009] Furthermore, the solvent of the molten salt mixture is selected from at least one of LiCl, NaCl, KCl, MgCl2, CaCl2, LiF, NaF, KF, MgF2, or CaF2; The solute in the molten salt mixture is selected from at least one of Na2WO4, Na2CrO4, K2CrO4, LiNbO3, Na2MoO4 or K2MoO4, and its molar percentage content is 1-20 mol.

[0010] Furthermore, the molten salt mixture also includes boron-containing inorganic compounds as additives, wherein the additives in the molten salt mixture are selected from at least one of B2O3, Na2B4O7 or K2B4O7, and their molar percentage content is 1-10 mol.

[0011] Furthermore, the electrochemical method is carried out in a graphite crucible, which is used as the counter electrode connected to an electrochemical workstation, and a non-metallic conductive rod is used as the working electrode connected to the electrochemical workstation. The material of the non-metallic conductive rod is selected from C or B. Alternatively, the graphite crucible may also be connected to an electrochemical workstation as a reference electrode.

[0012] Furthermore, the current density of the constant current electrolysis is 5-50 mA / cm². 2 The electrode area is the surface area of ​​the electrode portion that enters the molten salt mixture, and the electrolysis time is 30-720 min; The diameter of the non-metallic conductive electrode does not exceed 1 / 3 of the inner diameter of the graphite crucible, and the bottom of the non-metallic conductive electrode is 1-2 cm away from the bottom of the graphite crucible.

[0013] Furthermore, the melting temperature of the molten salt mixture is set to be 200°C-400°C higher than its melting point, and the melting is carried out in a closed reactor with vacuum pumping and argon filling functions to maintain a positive pressure inert atmosphere.

[0014] Furthermore, before placing the molten salt mixture into the reactor, it undergoes vacuum drying at a temperature of 200°C for at least 12 hours.

[0015] Furthermore, after adding the molten salt mixture containing ceramic particles to the copper melt, the time for standing and holding at a constant temperature is 10-60 minutes; The copper melt is obtained by smelting Cu particles or Cu rods with a purity of ≥99%, and a covering agent is added above the Cu particles or Cu rods during smelting; The covering agent is selected from at least one of charcoal powder, graphite powder or alkali metal / alkaline earth metal halides, and its thickness is not less than 1 / 3 of the height of the copper liquid. After the static heat preservation is completed, stirring is carried out using a graphite stirring rod at a speed of 10-1000 rpm for 1-30 min. After stirring, the copper melt is cast to obtain a copper-based composite material.

[0016] On the other hand, the present invention also provides a copper-based composite material, which is prepared by the method for preparing the copper-based composite material described above.

[0017] The beneficial effects of this invention are as follows: 1. This invention employs an electrochemical method to prepare ceramic particles in situ within a molten salt mixture. These ceramic particles are directly generated through an electrochemical reaction, and their particle size can be precisely controlled by adjusting the current density and electrolysis time. The particles nucleate and grow at the atomic level, exhibiting excellent sphericity and resisting agglomeration in the molten salt mixture. Furthermore, the specific type and size of the ceramic particles can be targeted and controlled by selecting the type of metal oxide in the molten salt and appropriately adding additives.

[0018] 2. Compared with the prior art, the present invention generates ceramic particles in situ through electrochemical processes, thereby avoiding the agglomeration problem caused by the introduction of external particles. By utilizing the oxygen-isolation properties of the molten salt mixture, the oxidation of the copper liquid surface can be effectively inhibited, significantly improving the wettability of ceramic particles and copper liquid, and helping the particles to be uniformly integrated into the copper liquid. Combined with the stirring process, the ceramic particles can be fully dispersed and uniformly distributed in the copper matrix, ensuring the stability of the composite material. Furthermore, this invention uses low-cost molten salt as the reaction medium, which has the dual advantages of low production cost and high particle quality, and has outstanding potential for industrial application.

[0019] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0020] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein: Figure 1 This is a scanning electron microscope image of the molten salt mixture after electrolysis in Example 1; Figure 2 This is a scanning electron microscope image of the molten salt mixture after electrolysis in Example 2. Detailed Implementation

[0021] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0022] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0023] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0024] This invention utilizes an electrochemical method to add metal oxoacid salts and boron-containing inorganic compound additives to an alkali metal / alkaline earth metal halide solvent to generate micro / nano ceramic particles in situ. Subsequently, the molten salt mixture containing the micro / nano ceramic particles is mixed with molten copper at high temperature with stirring to achieve uniform dispersion of the micro / nano ceramic particles in a copper matrix, thus preparing a copper-based composite material. This invention includes two preparation processes: Process 1: preparation of the molten salt mixture containing micro / nano ceramic particles; and Process 2: preparation of the copper-based composite material containing micro / nano ceramic particles.

[0025] Process 1 contains the following components: electrolyte: alkali metal or alkaline earth metal inorganic compound (solvent: alkali metal or alkaline earth metal halide, solute: metal acid oxide, optional additive: boron inorganic compound), electrode: non-metallic conductive electrode, electrochemical workstation, graphite crucible, reaction vessel, and its specific steps are as follows: Step 1: Place the graphite crucible in the resistance furnace, add solvent, solute, and additives (optional), and then place the graphite crucible into a sealed reaction vessel equipped with an electrode connection device.

[0026] Specifically, the molten salt mixture needs to be dried at 200°C for more than 12 hours. The lid of the reactor is equipped with a plastic O-ring to ensure airtightness. The reactor has vacuum pumping and argon filling functions.

[0027] Step 2: Heat up and melt the mixture.

[0028] Specifically, the melting temperature should be set according to the melting point of the molten salt mixture, approximately 200°C to 400°C higher than the melting point.

[0029] Step 3: Once the molten salt mixture reaches the specified temperature and melts, insert the non-metallic conductive electrode into the center of the graphite crucible, and connect the graphite crucible and the non-metallic conductive electrode as electrodes to the electrochemical workstation.

[0030] Specifically, the diameter of the non-metallic conductive electrode should not exceed 1 / 3 of the inner diameter of the graphite crucible, and the bottom of the electrode should be 1-2 cm away from the bottom of the graphite crucible.

[0031] More specifically, in the two-electrode system, a non-metallic conductive electrode is used as the working electrode and connected to the electrochemical workstation, while a graphite crucible is used as the counter electrode and connected to the electrochemical workstation; in the three-electrode system, a non-metallic conductive electrode is used as the working electrode and connected to the electrochemical workstation, while a graphite crucible is used as both the counter electrode and the reference electrode and connected to the electrochemical workstation.

[0032] Step 4: Electrochemical workstation is powered on to perform electrolysis.

[0033] Specifically, the electrolysis method uses constant current electrolysis, and a reduction current is introduced into one side of the working electrode, that is, a reduction reaction occurs on the surface of the working electrode. More specifically, the current density is 5-50 mA / cm2, the electrode area is the surface area of ​​the electrode part entering the molten salt mixture, and the electrolysis time is 30 min-720 min. When using a small current density, a long electrolysis time should be used.

[0034] Step 5: After electrolysis is complete, raise the non-metallic conductive electrode above the molten salt mixture, turn off the heating, and allow it to cool.

[0035] Step 6: After cooling is complete, remove the molten salt mixture from the graphite crucible and perform simple crushing.

[0036] Process 2 contains the following components: a molten salt mixture containing ceramic particles and Cu, and its specific steps are as follows: Step 1: Place the crucible in the medium-frequency induction furnace and add Cu granules or Cu rods.

[0037] Specifically, the purity of Cu particles or Cu rods is ≥99%.

[0038] Step 2: Add a covering agent over Cu and heat it to melt it.

[0039] Specifically, the covering agent is at least one of charcoal powder, graphite powder, or alkali metal / alkaline earth metal halide, with a thickness of not less than 1 / 3 of the height of the molten copper, and the smelting temperature range is set to 1100-1400℃.

[0040] Step 3: Wait for melting. Add the molten salt mixture containing ceramic particles to the copper melt and let it stand to keep warm.

[0041] Specifically, the heat preservation time is 10-60 minutes.

[0042] Step 4: Stir the melt using a mechanical stirring rod.

[0043] Specifically, the stirring rod is made of graphite, the stirring speed is 10-1000 rpm, and the stirring time is 1-30 min. Step 5: Cast the melt.

[0044] Specifically, the casting crucible is made of graphite, and the covering agent is removed before casting, and the ingot is water-cooled.

[0045] Example 1 The present invention will be further described in detail below with reference to the embodiments, but the present invention is not limited to the following embodiments.

[0046] In this embodiment, the alkali metal halide solvent used in the molten salt mixture is a mixture of LiF, KF, and KCl, wherein the content of solvent LiF is 40wt%, the content of KF is 40wt%, and the content of KCl is 20wt%. The solute of the alkali metal halide solvent is a metal oxyacid salt, and the additive is a boron-containing inorganic compound; specifically, the metal oxyacid salt is selected as Na2WO4, with a content of 10 mol% of the mixture, and the additive is B2O3, with a content of 5 wt% of the mixture.

[0047] The experimental procedure is as follows: 1. After mixing all the molten salt mixtures according to the formula, place them in a high-purity graphite crucible, and then place the graphite crucible in a vacuum drying oven at 200℃ for 12 hours to dry.

[0048] 2. Place the dried molten salt mixture and graphite crucible into a sealed reactor equipped with an electrode connection device, and perform vacuum evacuation and Ar gas exchange circulation three times, finally maintaining a slightly positive pressure Ar atmosphere.

[0049] 3. A dual-electrode electrochemical system is adopted. The working electrode is a φ10mm high-purity graphite rod, while the counter electrode and reference electrode are connected to the graphite crucible using an electrode connection device.

[0050] 4. Place the reactor in a resistance wire heating furnace and heat it to 900℃.

[0051] 5. After the molten salt mixture has completely melted, reduction electrolysis begins at a current density of 10 mA cm⁻¹. -2 The electrolysis time is 60 min.

[0052] 6. After electrolysis, remove the electrodes from the surface of the molten salt mixture, allow it to cool, and then remove the molten salt mixture from the graphite crucible. The state of the molten salt mixture after electrolysis is shown in the reference diagram. Figure 1 .

[0053] 7. Place the graphite crucible in the medium-frequency induction furnace, and add Cu particles and charcoal covering agent in sequence. The charcoal covering agent should be 1 / 3 the thickness of the Cu particles.

[0054] 8. After the Cu particles melt, add the molten salt mixture containing ceramic particles to the copper melt and let it stand for 30 minutes.

[0055] 9. Use a graphite stirring rod to stir the copper melt at a speed of 150 rpm for 20 minutes.

[0056] 10. After stirring, the copper melt is cast to obtain a copper-based composite material.

[0057] Specifically, the casting crucible is made of graphite, and the covering agent is removed before casting, and the ingot is water-cooled.

[0058] Example 2 The present invention will be further described in detail below with reference to the embodiments, but the present invention is not limited to the following embodiments.

[0059] In this embodiment, the alkali metal halide solvent used in the molten salt mixture is a mixture of LiF, KF, and KCl, wherein the content of solvent LiF is 40wt%, the content of KF is 40wt%, and the content of KCl is 20wt%. The solute in the alkali metal halide solvent is a metal oxyacid salt, and no additives are used; specifically, the metal oxyacid salt is selected as Na2WO4, and the content is 10 mol of the mixture.

[0060] The experimental procedure is as follows: 1. After mixing all the molten salt mixtures according to the formula, place them in a high-purity graphite crucible, and then place the graphite crucible in a vacuum drying oven at 200℃ for 12 hours to dry.

[0061] 2. Place the dried molten salt mixture and graphite crucible into a sealed reactor equipped with an electrode connection device, and perform vacuum evacuation and Ar gas exchange circulation three times, finally maintaining a slightly positive pressure Ar atmosphere.

[0062] 3. A dual-electrode electrochemical system is adopted. The working electrode is a φ10mm high-purity graphite rod, while the counter electrode and reference electrode are connected to the graphite crucible using an electrode connection device.

[0063] 4. Place the reactor in a resistance wire heating furnace and heat it to 900℃.

[0064] 5. After the molten salt mixture has completely melted, reduction current electrolysis begins at a current density of 10 mA cm⁻² and an electrolysis time of 60 min.

[0065] 6. After electrolysis, remove the electrodes from the surface of the molten salt mixture, allow it to cool, and then remove the molten salt mixture from the graphite crucible. The state of the molten salt mixture after electrolysis is shown in the reference diagram. Figure 2 .

[0066] 7. Place the graphite crucible in the medium-frequency induction furnace, and add Cu particles and charcoal covering agent in sequence. The charcoal covering agent should be 1 / 3 the thickness of the Cu particles.

[0067] 8. After the Cu particles melt, add the molten salt mixture containing ceramic particles to the copper melt and let it stand for 30 minutes.

[0068] 9. Use a graphite stirring rod to stir the copper melt at a speed of 150 rpm for 20 minutes.

[0069] 10. After stirring, the copper melt is cast to obtain a copper-based composite material.

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing a copper-based composite material, characterized in that: Ceramic particles are generated in situ in a molten salt mixture using an electrochemical method. The molten salt mixture containing the ceramic particles is then added to a copper melt to achieve uniform dispersion of the ceramic particles in the copper matrix, thereby obtaining a copper-based composite material.

2. The method for preparing the copper-based composite material according to claim 1, characterized in that: The molten salt mixture comprises an alkali metal or alkaline earth metal halide as a solvent and a metal oxyacid salt as a solute; The electrochemical method employs constant current electrolysis, and a reduction reaction occurs on the surface of the working electrode; The ceramic particles are A. x B y A is selected from Cr, Nb, W or Mo, and B is selected from C or Si.

3. The method for preparing the copper-based composite material according to claim 2, characterized in that: The solvent of the molten salt mixture is selected from at least one of LiCl, NaCl, KCl, MgCl2, CaCl2, LiF, NaF, KF, MgF2 or CaF2; The solute in the molten salt mixture is selected from at least one of Na2WO4, Na2CrO4, K2CrO4, LiNbO3, Na2MoO4 or K2MoO4, and its molar percentage content is 1-20 mol.

4. The method for preparing the copper-based composite material according to any one of claims 1-3, characterized in that: The molten salt mixture also includes boron-containing inorganic compounds as additives, wherein the additives are selected from at least one of B2O3, Na2B4O7 or K2B4O7, and their molar percentage content is 1-10 mol.

5. The method for preparing the copper-based composite material according to claim 2, characterized in that: The electrochemical method is carried out in a graphite crucible, which is used as the counter electrode connected to an electrochemical workstation, and a non-metallic conductive rod is used as the working electrode connected to the electrochemical workstation. The material of the non-metallic conductive rod is selected from C or B. Alternatively, the graphite crucible may also be connected to an electrochemical workstation as a reference electrode.

6. The method for preparing the copper-based composite material according to claim 5, characterized in that: The current density of the constant current electrolysis is 5-50 mA / cm². 2 The electrode area is the surface area of ​​the electrode portion that enters the molten salt mixture, and the electrolysis time is 30-720 min; The diameter of the non-metallic conductive electrode does not exceed 1 / 3 of the inner diameter of the graphite crucible, and the bottom of the non-metallic conductive electrode is 1-2 cm away from the bottom of the graphite crucible.

7. The method for preparing the copper-based composite material according to claim 5, characterized in that: The melting temperature of the molten salt mixture is set to be 200°C-400°C higher than its melting point, and the melting is carried out in a closed reactor with vacuum pumping and argon filling functions to maintain a positive pressure inert atmosphere.

8. The method for preparing the copper-based composite material according to claim 7, characterized in that: Before the molten salt mixture is placed into the reactor, it is subjected to vacuum drying at a temperature of 200°C for at least 12 hours.

9. The method for preparing the copper-based composite material according to claim 1, characterized in that: After adding the molten salt mixture containing ceramic particles to the copper melt, the time for standing and holding at a constant temperature is 10-60 minutes. The copper melt is obtained by smelting Cu particles or Cu rods with a purity of ≥99%, and a covering agent is added above the Cu particles or Cu rods during smelting; The covering agent is selected from at least one of charcoal powder, graphite powder or alkali metal / alkaline earth metal halides, and its thickness is not less than 1 / 3 of the height of the copper liquid. After the static heat preservation is completed, stirring is carried out using a graphite stirring rod at a speed of 10-1000 rpm for 1-30 min. After stirring, the copper melt is cast to obtain a copper-based composite material.

10. A copper-based composite material, characterized in that: The copper-based composite material is prepared by the method for preparing copper-based composite materials according to any one of claims 1 to 9.

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