Boron nitride-reinforced copper matrix composite material and method for manufacturing the same

Abstract

This disclosure provides a boron nitride-reinforced copper matrix composite material and a method for producing the same, the method comprising the steps of: producing a boron nitride-copper composite powder; producing a boron nitride-copper composite material from the composite powder using a powder metallurgy process; and performing mechanical deformation on the composite material to densify it, forming a laminated structure of boron nitride and copper, thereby obtaining a boron nitride-reinforced copper matrix composite material, wherein the angle difference between the boron nitrides in the laminated structure along the main deformation direction is less than 10°.

Description

[Technical Field]

[0001] This disclosure relates to the field of composite materials technology, and more specifically to boron nitride-reinforced copper matrix composite materials and methods for manufacturing the same. [Background technology]

[0002] Copper has excellent conductivity and is widely used as an important conductive material in key fields such as electrical engineering and electronics. However, with the rapid development of fields such as fifth-generation mobile communication technology (5G), new energy, and power semiconductors, the current required by equipment is increasing, and the amount of heat generated is also rising, creating new demands on the performance of copper materials. To ensure power supply and heat dissipation to devices, copper materials need to have excellent conductivity and thermal conductivity, and in particular, it needs to maintain high conductivity and thermal conductivity at high temperatures. Furthermore, the operating conditions faced by electronic equipment are becoming increasingly complex, and they often come into contact with various liquid media. Under alkaline or high-salinity conditions, pure copper can corrode severely, leading to device failure.

[0003] To solve the problem of metal corrosion, conventional methods have employed coating metal surfaces with organic or inorganic coatings as an effective protective measure. For example, PVC or PE is used as an insulating sheath in power transmission lines, and resin is used as an insulating layer in enameled wires. These coatings provide good corrosion protection to copper materials as insulating layers and do not affect the conductivity and thermal conductivity of the copper material itself. However, for the use of copper materials in fields such as micro- and nanoelectronics, coatings affect the contact between copper conductors and electronic devices, making conventional organic or inorganic coating methods unsuitable. Alloying is a commonly used corrosion prevention method in fields such as micro- and nanoelectronics. In alloying, the corrosion resistance of copper materials can be significantly improved by adding appropriate amounts of alloying elements such as tin and zinc to pure copper. However, the introduction of alloying elements drastically reduces the conductivity and thermal conductivity of copper materials. For example, adding only 0.15 wt.% of tin reduces the conductivity of copper to below 90% IACS.

[0004] Therefore, there is an urgent need to develop highly corrosion-resistant copper composite materials that can maintain and even improve electrical and thermal conductivity. [Overview of the Initiative]

[0005] In view of this, in order to solve at least some of the above technical problems, this disclosure provides a boron nitride-reinforced copper matrix composite material and a method for manufacturing the same.

[0006] A first aspect of this disclosure provides a method for producing a boron nitride-reinforced copper matrix composite material, comprising the steps of: producing a boron nitride-copper composite powder; producing a boron nitride-copper composite material from the composite powder using a powder metallurgy process; and performing mechanical deformation on the composite material to densify it, forming a laminated structure of boron nitride and copper, thereby obtaining a boron nitride-reinforced copper matrix composite material, wherein the angle difference between the boron nitrides in the laminated structure along the main deformation direction is less than 10°.

[0007] According to the embodiments of this disclosure, the manufacturing method further includes a step of surface modification by introducing copper nanoparticles into a composite powder in order to improve the interfacial bonding performance between boron nitride and copper.

[0008] According to the embodiments of this disclosure, the mass ratio of boron nitride to copper in the composite powder is (0.01~5):(95~99.9).

[0009] According to the embodiments of this disclosure, the total deformation of the composite material is increased to over 30% by mechanical deformation processing.

[0010] According to the embodiments of this disclosure, the boron nitride is a boron nitride nanosheet, the transverse dimension of the boron nitride nanosheet is 0.5 to 20 μm, and the thickness is 1 to 10 nm.

[0011] According to the examples of this disclosure, the composite powder further contains a doping metal, the amount of doping metal being 0-5% of the composite powder, and the doping metal includes one or more of silver, chromium, tin, iron, lanthanum, and zirconium.

[0012] According to the embodiments of this disclosure, the mechanical deformation process includes a step of hot rolling the composite material at a temperature of 800 to 1000°C, wherein the reduction ratio per hot rolling treatment is 8 to 12%, and the cumulative reduction ratio is 50 to 75%.

[0013] According to the embodiments of this disclosure, after mechanical deformation processing, the density of the obtained boron nitride-reinforced copper matrix composite material exceeds 99.5%, the interlayer pitch between boron nitrides in the boron nitride-reinforced copper matrix composite material is 0.1 to 2 μm, and the lateral dimension of the boron nitrides in the boron nitride-reinforced copper matrix composite material is 100 to 1000 nm.

[0014] According to a second aspect of this disclosure, a boron nitride-reinforced copper matrix composite material manufactured by the above manufacturing method is provided, wherein the angle difference between boron nitrides along the main deformation direction in the laminated structure of the boron nitride-reinforced copper matrix composite material is less than 10°.

[0015] According to the embodiments of this disclosure, the boron nitride-reinforced copper matrix composite material contains boron nitride, copper, and impurity elements, and the content of boron nitride and copper in the boron nitride-reinforced copper matrix composite material exceeds 95%.

[0016] Based on the above technical solutions, the boron nitride-reinforced copper matrix composite material and its manufacturing method provided in this disclosure involve preparing a composite material from boron nitride-copper composite powder, performing mechanical deformation processing on the composite material to induce mechanical deformation in the boron nitride-copper composite material, and forming a laminated structure of boron nitride and copper during the mechanical deformation process. Furthermore, by controlling the angle difference between boron nitrides in the laminated structure along the main deformation direction to less than 10°, the composite material can be further densified, achieving a highly oriented arrangement of boron nitride in the copper matrix, reducing the scattering of electrons and boron nitride, maintaining the conductivity of the boron nitride-reinforced copper matrix composite material at 95 IACS% or higher, and fully demonstrating the superiority of boron nitride's high in-plane thermal conductivity, thus maintaining excellent thermal conductivity even at high temperatures. In addition, boron nitride has excellent corrosion resistance, and the corrosion resistance of copper materials can be effectively improved by manufacturing boron nitride-copper composite materials. Therefore, the boron nitride-reinforced copper matrix composite material obtained by this manufacturing method has high thermal conductivity, electrical conductivity, and corrosion resistance. [Brief explanation of the drawing]

[0017] [Figure 1] Figure 1 is a flowchart of the method for manufacturing a boron nitride-reinforced copper matrix composite material in an embodiment of the present disclosure. [Figure 2] Figure 2 is a scanning electron microscope image of the boron nitride distribution in the boron nitride-reinforced copper matrix composite material in Example 1 of this disclosure. [Figure 3] Figure 3 is a schematic diagram of the distribution of boron nitride in a boron nitride-reinforced copper matrix composite material in Example 1 of this disclosure. [Figure 4] Figure 4 is a transmission electron microscope image of the boron nitride-reinforced copper matrix composite material in Example 1 of this disclosure. [Figure 5] Figure 5 is a transmission electron microscope image of the interface of the boron nitride-reinforced copper matrix composite material in Example 1 of this disclosure. [Figure 6] Figure 6 is a curve showing how the horizontal thermal conductivity of a boron nitride-reinforced copper matrix composite and pure copper in Example 1 of this disclosure changes with temperature. [Figure 7]Figure 7 is a graph showing the change in the thermal conductivity in the vertical direction of the boron nitride reinforced copper-based composite material and pure copper in Example 1 of the present disclosure according to temperature. [Figure 8] Figure 8 is a polarization curve diagram of the boron nitride reinforced copper-based composite material and pure copper in Example 1 of the present disclosure. [Figure 9] Figure 9 is a Nyquist diagram of the boron nitride reinforced copper-based composite material and pure copper in Example 1 of the present disclosure. [Figure 10] Figure 10 is a board line diagram (frequency / impedance) of the boron nitride reinforced copper-based composite material and pure copper in Example 1 of the present disclosure. [Figure 11] Figure 11 is a board line diagram (frequency / phase angle) of the boron nitride reinforced copper-based composite material and pure copper in Example 1 of the present disclosure. [Figure 12] Figure 12 is a scanning electron microscope photograph of the boron nitride distribution in the boron nitride reinforced copper-based composite material in Example 2 of the present disclosure. [Figure 13] Figure 13 is a scanning electron microscope photograph of the boron nitride distribution in the boron nitride reinforced copper-based composite material in Example 3 of the present disclosure.

Modes for Carrying Out the Invention

[0018] In order to further clarify the object, technical solution and advantages of the present disclosure, the present disclosure will be described in more detail below by combining specific examples and referring to the drawings.

[0019] Examples of the present disclosure will be described below with reference to the drawings. However, it should be understood that these descriptions are illustrative and do not limit the scope of the present disclosure. The following detailed descriptions include many specific details for the sake of clarity and to provide a full understanding of the examples of the present disclosure. However, it is clear that one or more examples can be implemented without these specific details. Also, the following descriptions omit explanations of well-known structures and technologies so as not to unnecessarily obscure the concepts of the present disclosure. The terms used herein are for the purpose of describing specific examples and are not intended to limit the present disclosure. The terms “equipped with,” “included,” etc., as used herein mean the presence of features, processes, operations, and / or parts, but do not exclude the presence or addition of one or more other features, processes, operations, or parts.

[0020] All terms used herein (including technical and scientific terms) have the meanings generally understood by those skilled in the art unless otherwise defined. It should be noted that terms used herein should be interpreted as having the meaning consistent with the surrounding context and not as ideally or excessively literal.

[0021] When using expressions such as "at least one of A, B, and C," they should generally be interpreted in the sense that would be ordinarily understood by a person skilled in the art (for example, "a system having at least one of A, B, and C" includes, but is not limited to, a system having A alone, a system having B alone, a system having C alone, a system having A and B, a system having A and C, a system having B and C, and / or a system having A, B, and C).

[0022] Boron nitride has an in-plane thermal conductivity of approximately 2000 W·m -1 ·K -1It exhibits excellent oxidation resistance (>900°C) and corrosion resistance. After combining boron nitride with copper, it is desirable that the thermal conductivity and corrosion resistance of the copper material be significantly improved. Furthermore, if a highly oriented arrangement of boron nitride in the copper matrix can be achieved, the superior in-plane thermal conductivity of boron nitride can be fully utilized, thereby improving the thermal conductivity of the composite material. In addition, the excellent corrosion resistance of boron nitride nanosheets extends the diffusion pathway of the corrosive medium in the copper matrix, contributing to further improvement of the corrosion resistance of the copper material. In particular, by having a thickness of only a few atomic layers of boron nitride and arranging it along the horizontal direction, the scattering of electrons within the copper matrix can be limited to the greatest extent possible, thereby maintaining the high conductivity of the material.

[0023] In the process of realizing this disclosure, it was discovered that boron nitride-copper composite powders can be produced by an in-situ production method or by an external addition method, with the external addition method mainly including the mechanical ball mill method and the molecular-level mixing method. Of these, the mechanical ball mill method can solve the problem of boron nitride aggregation, but the boron nitride structure is severely damaged during the ball milling process, and the interfacial bonding between boron nitride and copper is weak, making it difficult to meet the practical requirements for strength, ductility, conductivity, and thermal conductivity of the produced composite material. The molecular-level mixing method can effectively enhance phase dispersibility and interfacial bonding, but the dimensions and thickness of the externally added boron nitride nanosheets are non-uniform, making it difficult to ensure the stability of the material's performance. Compared to the external addition method, the in-situ production method can achieve a tighter interfacial bonding between the reinforcing phase and the matrix, and by fully demonstrating the performance advantages of the reinforcing phase, the overall performance of the material can be improved. Furthermore, compared to single-structure composite materials, layered composite materials can better exhibit the superior performance within the boron nitride surface. However, conventionally, the temperature required to produce boron nitride on a copper surface generally exceeds 900°C, and expensive raw materials such as ammonia borane are frequently used, making it difficult to achieve large-scale and controllable production of boron nitride on a copper powder surface.

[0024] In view of this, the present disclosure provides a boron nitride-reinforced copper matrix composite material and a method for producing the same, wherein boron nitride is produced in large quantities and in a controllable manner on the copper surface to obtain a boron nitride-copper composite powder, and after fabrication of the composite material, mechanical deformation processing is performed to form a laminated structure of boron nitride and copper, thereby obtaining good interfacial bonding and orientational arrangement of boron nitride, and producing a high-performance boron nitride-reinforced copper matrix composite material.

[0025] A first aspect of this disclosure provides a method for manufacturing a boron nitride-reinforced copper matrix composite material. Figure 1 is a flowchart of a method for manufacturing a boron nitride-reinforced copper matrix composite material in an embodiment of the present disclosure. As shown in Figure 1, the manufacturing method includes steps S101 to S103. In step S101, a boron nitride-copper composite powder is prepared; in step S102, the composite powder is transformed into a boron nitride-copper composite material using a powder metallurgy process; and in step S103, the composite material is subjected to mechanical deformation to densify it, forming a layered structure of boron nitride and copper, thereby obtaining a boron nitride-reinforced copper matrix composite material.

[0026] According to the embodiments of this disclosure, the angle difference between boron nitrides in the stacked structure along the main deformation direction is less than 10°, ensuring a high degree of consistency in the orientation of the boron nitrides.

[0027] According to the embodiments of this disclosure, the boron nitride-copper composite material produced by the powder metallurgy process has a certain density, and after machining, a laminated structure is formed in the composite material, further densifying the composite material and highly oriented the boron nitride in the copper substrate, which reduces the scattering of electrons and boron nitride, and furthermore, the advantage of the high in-plane thermal conductivity of boron nitride can be fully demonstrated, and excellent thermal conductivity can be maintained even at high temperatures. In addition, boron nitride has excellent corrosion resistance, and the boron nitride in the copper substrate improves the corrosion resistance of the copper material, so the manufactured boron nitride-copper composite material can exhibit good corrosion resistance.

[0028] According to the embodiments of this disclosure, the method for producing the boron nitride-copper composite powder in step S101 includes one or more of physical vapor deposition, chemical vapor deposition, and chemical reduction, preferably chemical vapor deposition. The interface between boron nitride and copper in the composite powder produced by chemical vapor deposition has superior bonding performance. The particle size of the composite powder may be 1 to 200 μm, for example, 5 μm, 80 μm, 120 μm, 160 μm, 180 μm, etc., but is not limited to the values ​​listed, and other unlisted values ​​within that range are also applicable. The dimensions of the copper powder may be 0.1 to 200 μm, and the morphology of the metallic copper is not limited. Its morphology may be spherical, approximately spherical, dendritic, irregular, sheet-like, etc., and may be selected according to the actual situation. The metallic copper powder may be copper powder or copper alloy powder (copper-silver alloy, copper-iron alloy, copper-lanthanum alloy, etc.). By using copper alloy powder, the strength of the composite material can be improved by approximately 200 MPa without significantly reducing the electrical conductivity and thermal conductivity of the material (reduced by less than 10%), effectively expanding the range of applications for boron nitride-reinforced copper matrix composite materials.

[0029] According to the embodiments of this disclosure, boron nitride is preferably introduced into the composite powder by in-situ synthesis, and the boron material used to produce boron nitride may be boron oxide or other boron-containing salts, and the nitrogen raw material may be ammonia gas or other substances that can decompose and release ammonia gas. Furthermore, boron nitride and copper powder may be introduced and mixed by other methods, but in any case, the mass fraction of boron nitride must be controlled to 0.01 to 5 wt.%.

[0030] According to the embodiments of this disclosure, the manufacturing method further includes a step of surface modification by introducing copper nanoparticles into a composite powder to improve the interfacial bonding performance between boron nitride and copper.

[0031] According to the embodiments of this disclosure, after supporting the boron nitride in the composite powder obtained in step S101 on the copper powder surface, surface modification may be performed by further introducing copper nanoparticles based on the composite ratio of boron nitride and copper powder, thereby ensuring good interfacial bonding between copper and boron nitride and giving the composite material good moldability. In particular, the average particle size of the copper nanoparticles may be 100 nm to 1000 nm, the mass fraction of the introduced copper nanoparticles may be 10% to 50% of the composite powder, and the modification method may be one or more of the following: electrodeposition, chemical plating, and copper salt impregnation reduction.

[0032] According to the embodiments of this disclosure, the mass ratio of boron nitride to copper in the composite powder is (0.01~5):(95~99.9), and may be, for example, 0.2:99.8, 1.5:98.5, 3:97, 4.55:95.45, etc., but is not limited to the values ​​listed, and other unlisted values ​​within that range are also applicable. Composite materials with too high a boron nitride content will develop cracks during the thermal processing process, and their electrical conductivity and thermal conductivity will decrease. This mass ratio range ensures the moldability and performance of the composite material. By adjusting the mass ratio of boron nitride to copper in the composite powder, a denser structure can be formed in the composite material, and a laminated structure can be formed by the action of mechanical stretching / compression deformation, thereby improving thermal conductivity and corrosion resistance while ensuring the electrical conductivity of the copper material.

[0033] According to the embodiments of this disclosure, in step S102, the boron nitride-copper composite material is in the form of a mass and / or pellets, and the powder metallurgy process includes one or more of cold press sintering, hot press sintering, and granulation, and the density of the mass and / or pellets of the composite material produced by the powder metallurgy process should be ensured to be more than 90% in order to ensure that a laminated structure is formed by mechanical deformation processing in a subsequent operation step.

[0034] According to the embodiments of this disclosure, in step S103, the composite material is manufactured to desired dimensions and shape by mechanical deformation, the method of mechanical deformation includes one or more of pressing, pressing / rolling, and tensioning, and the deformation temperature in the initial stage when performing mechanical deformation should exceed the thermal softening temperature of the pellet or mass (>300°C).

[0035] According to the embodiments of this disclosure, the total deformation of the composite material due to mechanical deformation processing exceeds 30%. Here, the total deformation of the composite material may be 35%, 50%, 65%, 80%, 95%, etc., but is not limited to the values ​​listed, and other values ​​within the range not listed are also applicable. In the process of causing deformation of the composite material by mechanical deformation processing, the boron nitride is oriented and arranged in the copper matrix due to the action of shear force, and a laminated structure of boron nitride and copper is obtained, and the density of the composite material after deformation can be made >99.5%.

[0036] According to the embodiments of this disclosure, preferably, the shape of the boron nitride is a boron nitride nanosheet, the lateral dimension of the boron nitride nanosheet may be 0.5 to 20 μm, for example 1 μm, 5 μm, 12 μm, 15 μm, etc., and the thickness of the boron nitride nanosheet may be 1 to 10 nm, for example 2 nm, 4 nm, 6 nm, 8 nm, etc. It should be noted that the values ​​are not limited to those given, and other unlisted values ​​within that range may also be applied.

[0037] According to the embodiments of this disclosure, the composite powder further contains a doping metal. By adding a doping metal to the composite powder, a composite material containing other metallic elements may be formed, thereby expanding the application range of the boron nitride-reinforced copper-based composite material. The doping metal includes one or more of the following: silver (Ag), chromium (Cr), tin (Pb), iron (Fe), lanthanum (La), and zirconium (Zr). This is advantageous for improving the strength, thermal stability, and other properties of the boron nitride-reinforced copper-based composite material.

[0038] According to the embodiments of this disclosure, the amount of doping metal added is 0-5% of the composite powder, for example, 0.5%, 1.2%, 2.6%, 3.5%, 4.9%, etc., but is not limited to the values ​​listed, and other unlisted values ​​within that range are also applicable. Here, the amount of each type of doping metal added may be Ag (<5%), Cr (<0.5%), Sn (<1%), Fe (<1%), La (<1%), Zr (<0.15%), and by controlling the total content of the added doping metal elements to 5% or less, it is possible to guarantee that the boron nitride-reinforced copper matrix composite material has high conductivity.

[0039] According to the embodiments of this disclosure, the mechanical deformation process involves hot rolling the composite material at a temperature of 800 to 1000°C, where the temperature may be, for example, 820°C, 850°C, 900°C, 920°C, 980°C, etc. Within this temperature range, the plasticity and ductility of the composite material are significantly improved, the material becomes more easily deformable during the hot rolling process, contributes to filling voids inside the filler material, and can improve density.

[0040] According to the embodiments of this disclosure, the reduction ratio per hot rolling treatment may be 8 to 12%, for example, 8.5%, 9.2%, 10.5%, 11%, 11.5%, etc., and the cumulative reduction ratio may be 50 to 75%, for example, 50%, 55%, 58%, 62%, 72%, etc., preferably 70%. However, the values ​​are not limited to those listed, and other unlisted values ​​within that range are also applicable. Multiple rolling treatments contribute to sufficient plastic deformation of the material, breaking and refining the original grain structure, making the material structure more uniform, and forming a highly oriented arrangement of boron nitride within the copper matrix material. As density improves and the material structure becomes more uniform, the mechanical properties of the composite material (e.g., strength, hardness, and wear resistance) also improve accordingly, allowing for better performance in actual applications.

[0041] According to the embodiments of this disclosure, after mechanical deformation processing, the density of the resulting boron nitride-reinforced copper matrix composite material exceeds 99.5%, resulting in a low porosity within the material and contributing to improvements in the material's mechanical properties and durability.

[0042] According to the embodiments of this disclosure, the interlayer pitch between boron nitrides in the boron nitride-reinforced copper matrix composite is 0.1 to 2 μm, and may be, for example, 0.2 μm, 0.5 μm, 0.8 μm, 1.4 μm, 1.8 μm, etc. The lateral dimension of the boron nitrides in the boron nitride-reinforced copper matrix composite is 100 to 1000 nm, and may be, for example, 120 nm, 280 nm, 360 nm, 520 nm, 750 nm, etc. The values ​​are not limited to those listed, and other unlisted values ​​within that range are also applicable. Generally speaking, the smaller the interlayer pitch and the larger the dimensions of the boron nitrides, the more the excellent thermal conductivity and corrosion resistance of boron nitrides can be fully demonstrated, thereby improving the thermal conductivity and corrosion resistance of the composite material.

[0043] According to a second aspect of this disclosure, a boron nitride-reinforced copper matrix composite material is provided which is manufactured by the above manufacturing method, wherein the angle difference between boron nitrides along the main deformation direction in the laminated structure of the boron nitride-reinforced copper matrix composite material is less than 10°.

[0044] According to the embodiments of this disclosure, the boron nitride is highly oriented and arranged on the copper matrix, fully demonstrating the advantage of boron nitride's high in-plane thermal conductivity, and the thermal conductivity of the fabricated boron nitride-reinforced copper matrix composite is 424 W·m -1 ·K -1 This can be achieved, representing a 10% improvement over pure copper. Furthermore, copper-based materials with added boron nitride exhibit an order of magnitude lower self-corrosion current density in alkaline environments, resulting in excellent corrosion resistance.

[0045] According to the embodiments of this disclosure, the boron nitride-reinforced copper matrix composite material contains boron nitride, copper, and impurity elements, and the content of boron nitride and copper in the boron nitride-reinforced copper matrix composite material exceeds 95%.

[0046] According to the embodiments of this disclosure, impurity elements are introduced during the process of producing boron nitride-reinforced copper matrix composites, so it is necessary to control the content of impurity elements to less than 5%. The impurity elements and their content are oxygen (O<0.1%), phosphorus (P<0.01%), silicon (Si<0.03%), lead (Pb<0.05%), sulfur (S<0.03%), and arsenic (As<0.01%).

[0047] To further clarify the purpose, technical solutions, and advantages of this disclosure, the technical solutions and principles of this disclosure will be further described below with reference to specific embodiments and drawings. The following specific embodiments are for illustrative purposes only, and the scope of protection of this disclosure is not limited thereto.

[0048] Unless otherwise specified, the test materials and reagents used in the following examples may all be commercially available. Unless otherwise stated, any specific techniques or conditions described in the examples are general methods and may be carried out according to techniques or conditions described in the literature in this art, or according to product specifications. [Examples]

[0049] Example 1 0.25 g of boron oxide was weighed and dissolved in 25 mL of deionized water. The solution was stirred until clear, then 50 mL of alcohol was added and stirred until homogeneous. Next, 25 g of sheet-like copper powder was placed in the boron oxide solution and stirred in a 75°C water bath until the solution completely evaporated and became dry. The resulting mixture was left in a vacuum oven and dried at 70°C for 2 hours, followed by polishing to obtain a boron oxide-copper precursor powder. Subsequently, 25 g of the boron oxide-copper precursor powder was weighed and left in a graphite boat. It was reacted with ammonia gas at 600°C for 15 minutes, with the ammonia gas flow rate set to 50 mL / min. After the reaction was complete, the temperature was rapidly lowered to obtain a boron nitride-copper composite powder.

[0050] 96 g of copper nitrate trihydrate was weighed and dissolved in 250 mL of alcohol. 25 g of boron nitride-copper composite powder was then added, and the solution was stirred in a 75°C water bath until it completely evaporated to obtain a composite powder coated with copper nitrate. This powder was then reduced in a 400°C hydrogen gas atmosphere for 2 hours, with a hydrogen gas flow rate of 200 mL / min, to obtain a boron nitride-copper composite powder modified with nano-copper.

[0051] 50 g of boron nitride-copper composite powder modified with nanocopper was weighed and placed in a 30 mm diameter graphite mold, and hot press sintering was performed. The hot press temperature was set to 900°C, the pressure to 50 MPa, and the holding time to 1 hour, yielding a block-shaped boron nitride-copper composite material.

[0052] Furthermore, by densifying the composite material using a hot rolling press and mechanically deforming the lump of boron nitride-copper composite material at 900°C, and controlling the reduction rate per pass to 10%, the cumulative reduction rate reached 70%. That is, the deformation amount of the composite material was 70%, and a boron nitride-reinforced copper matrix composite material was obtained, which was described as a BN / Cu composite material. Here, the boron nitride content was 0.18%, and the density of the composite material at this time was 8.83 g / cm³. 3 (The relative density was 99.8%).

[0053] Figure 2 is a scanning electron microscope image of the boron nitride distribution in the boron nitride-reinforced copper matrix composite material in Example 1 of this disclosure. Figure 3 is a schematic diagram of the boron nitride distribution in the boron nitride-reinforced copper matrix composite material in Example 1 of this disclosure. As can be seen from Figure 2, the boron nitride is almost horizontally distributed in the copper matrix, and the schematic diagram shown in Figure 3 is obtained from Figure 2, and the boron nitride nanosheets have a stacking orientation distribution in the copper matrix.

[0054] Figure 4 is a transmission electron microscope image of the boron nitride-reinforced copper matrix composite material in Example 1 of this disclosure. As can be seen from Figure 4, the crystal grains of the boron nitride-reinforced copper matrix composite material are plate-shaped, with a length of about 1 μm and a thickness of about 200 nm.

[0055] Figure 5 is a transmission electron micrograph of the interface of the boron nitride reinforced copper-based composite material in Example 1 of the present disclosure. As can be seen from Figure 5, it is observed that the interface bonding between boron nitride and copper in the boron nitride reinforced copper-based composite material is tight and clean, ensuring that heat passes smoothly through the interface by the material and is conducted to the boron nitride nanosheet.

[0056] As can be seen from Figures 2 to 5, the boron nitride nanosheets in the boron nitride reinforced copper-based composite material are highly oriented and arranged in the copper matrix, showing a layered structure.

[0057] According to the measurement results, the strength of the boron nitride reinforced copper-based composite material is 265 MPa, which is 25% higher than that of pure copper (202 MPa). The self-corrosion current density of the boron nitride reinforced copper-based composite material in 0.1 M NaOH solution is 4.76×10 -5 A·cm -2 and is only one-fourth of that of pure copper (1.66×10 -4 A·cm -2 ), showing excellent corrosion resistance.

[0058] Furthermore, the thermal conductivity of the boron nitride reinforced copper-based composite material is measured. Figure 6 is a graph showing the change in the thermal conductivity of the boron nitride reinforced copper-based composite material and pure copper in the horizontal direction in Example 1 of the present disclosure as a function of temperature. Figure 7 is a graph showing the change in the thermal conductivity of the boron nitride reinforced copper-based composite material and pure copper in the vertical direction in Example 1 of the present disclosure as a function of temperature.

[0059] As can be seen from Figure 6, in the horizontal direction, the boron nitride reinforced copper-based composite material has a thermal conductivity of 424 W·m -1 ·K -1 at room temperature, which is 10% higher than that of pure copper (387 W·m -1 ·K -1 ). When the temperature is 400 °C, the thermal conductivity of the boron nitride reinforced copper-based composite material is increased by 20%. As can be seen from Figure 7, there is no significant decrease in the thermal conductivity of the boron nitride reinforced copper-based composite material in the vertical direction, and when the temperature is above 100 °C, the thermal conductivity of the boron nitride reinforced copper-based composite material is higher than that of pure copper.

[0060] Figure 8 shows the polarization curves of a boron nitride-reinforced copper matrix composite and pure copper in Example 1 of this disclosure. As can be seen from Figure 8, the vertical axis is the corrosion current and the horizontal axis is the voltage. The voltage corresponding to the minimum corrosion current is the self-corrosion potential of the material. The self-corrosion potential of the boron nitride-reinforced copper matrix composite is 10 mV higher than that of pure copper. When the linear region in the logJ vs E (V vs Ag / AgCl) figure is extrapolated to the intersection of the self-corrosion potentials, the current density at the intersection is the self-corrosion current density of the material, which reflects the corrosion rate of the material under natural conditions. The self-corrosion current of the boron nitride-reinforced copper matrix composite is only one-quarter that of pure copper.

[0061] Figure 9 is a Nyquist diagram of the boron nitride-reinforced copper-based composite and pure copper in Example 1 of this disclosure. As can be seen from the figure, the impedance curve of the boron nitride-reinforced copper-based composite is part of the larger radius impedance circle, so the boron nitride-reinforced copper-based composite has a higher impedance. Figure 10 is a Bode plot (frequency / impedance) of the boron nitride-reinforced copper-based composite and pure copper in Example 1 of this disclosure. As can be seen from the figure, the impedance (|Z|) of the composite at low frequencies is clearly higher than that of pure copper. As can be seen from Figures 9 and 10, the boron nitride-reinforced copper-based composite has a high impedance and can inhibit the passage of corrosive media, so boron nitride can improve the corrosion resistance of the composite.

[0062] Figure 11 shows the Bode plots (frequency, phase) of the boron nitride-reinforced copper matrix composite and pure copper in Example 1 of this disclosure. As can be seen from Figure 11, the minimum phase angle is -36.5° for pure copper, while it is -44.9° for the boron nitride-reinforced copper matrix composite, indicating that the boron nitride-reinforced phase inhibits the penetration of the corrosive medium to some extent, thereby improving the corrosion resistance of the material.

[0063] Example 2 In Example 1, a boron nitride-reinforced copper matrix composite material was manufactured using the same manufacturing method as in Example 1, except that the cumulative reduction ratio during mechanical deformation processing was adjusted to 30%, i.e., the amount of deformation of the composite material was adjusted to 30%.

[0064] Figure 12 is a scanning electron microscope image of the boron nitride distribution in the boron nitride-reinforced copper matrix composite material in Example 2 of this disclosure. The boron nitride exhibits an almost horizontal distribution in the copper matrix, but the angle with the rolling direction is larger than that of the boron nitride distribution in Example 1. The boron nitride in the boron nitride-reinforced copper matrix composite material obtained in Example 2 basically has a layered distribution, and according to the measurement results, the density of the composite material at this time is 8.82 g / cm³. 3 The relative density is 99.62%. The material density is >99.5%.

[0065] Example 3 In Example 1, a boron nitride-reinforced copper matrix composite material was manufactured using the same manufacturing method as in Example 1, except that the cumulative reduction ratio during mechanical deformation processing was adjusted to 20%, i.e., the amount of deformation of the composite material was adjusted to 20%.

[0066] Figure 13 is a scanning electron microscope image of the boron nitride distribution in the boron nitride-reinforced copper matrix composite in Example 3 of this disclosure. In the copper matrix, some of the boron nitride is still randomly distributed, for example, some of the boron nitride is still perpendicular to the rolling direction. The boron nitride in the boron nitride-reinforced copper matrix composite obtained in Example 3 does not show a perfect stacked distribution, and according to the measurement results, the density of the composite material is 8.81 g / cm³. 3 The relative density is 99.54%.

[0067] The electrical conductivity of the boron nitride-reinforced copper matrix composite materials manufactured in Examples 1 to 3 was detected, and the results are shown in Table 1.

[0068] [Table 1]

[0069] As can be seen from Table 1, the addition of boron nitride does not cause a significant decrease in the conductivity of the composite material. When the cumulative reduction ratio is 70%, the conductivity of the boron nitride-reinforced copper-based composite material is 96.7% IACS. When the cumulative reduction ratio is 30%, the conductivity of the boron nitride-reinforced copper-based composite material is 96% IACS. When the cumulative reduction ratio is 20%, the conductivity of the boron nitride-reinforced copper-based composite material is only 91.4% IACS. As can be seen, by exceeding 30% deformation of the composite material during mechanical deformation processing, the boron nitride-reinforced copper-based composite material can be better aligned and arranged by the action of shear force, which is advantageous for improving the conductivity of the composite material.

[0070] Example 4 The only difference from Example 1 was that the amount of boron oxide was changed from 0.25 g to 0.125 g, resulting in a boron nitride content of 0.1% in the resulting boron nitride-reinforced copper matrix composite material. Otherwise, the same manufacturing method as in Example 1 was used to produce the boron nitride-reinforced copper matrix composite material.

[0071] Example 5 A boron nitride-reinforced copper matrix composite material was manufactured using the same manufacturing method as in Example 1, except that the amount of boron oxide was changed from 0.25 g to 0.375 g, resulting in a boron nitride content of 0.25% in the obtained boron nitride-reinforced copper matrix composite material.

[0072] Example 6 The only difference from Example 1 was that the amount of boron oxide was changed from 0.25 g to 0.5 g, resulting in a boron nitride content of 0.33% in the obtained boron nitride-reinforced copper matrix composite material. Otherwise, the same manufacturing method as in Example 1 was used to produce the boron nitride-reinforced copper matrix composite material.

[0073] The performance of the boron nitride-reinforced copper matrix composite materials produced in Example 1 and Examples 4-6 was detected, and the results are shown in Table 2.

[0074] [Table 2]

[0075] As shown in Table 2, adding boron nitride to a boron nitride-reinforced copper matrix composite material can improve the material's strength and corrosion resistance. Furthermore, the degree of decrease in the electrical conductivity of the boron nitride-reinforced copper matrix composite material is reduced, and the thermal conductivity of the boron nitride-reinforced copper matrix composite material decreases depending on whether the boron nitride content is high or low. When the boron nitride content is preferably 0.18 to 0.25, the thermal conductivity of the material can be significantly improved.

[0076] Example 7 0.25 g of boron oxide was weighed and dissolved in 25 mL of deionized water. The solution was stirred until clear, then 50 mL of alcohol was added and stirred until homogeneous. Next, 25 g of sheet-like copper powder was placed in the boron oxide solution and stirred in a 75°C water bath until the solution completely evaporated and became dry. The resulting mixture was left in a vacuum oven and dried at 70°C for 2 hours, followed by polishing to obtain a boron oxide-copper precursor powder. Subsequently, 30 g of the boron oxide-copper precursor powder was weighed and left in a graphite boat. It was reacted with ammonia gas at 600°C for 15 minutes, with the ammonia gas flow rate set to 50 mL / min. After the reaction was complete, the temperature was rapidly reduced and further ball milling was performed. Here, the ball mill parameters were set to a ball-to-raw material ratio of 15:1, a rotation speed of 400 r / min, and a polishing time of 2 hours to obtain a boron nitride-copper composite powder.

[0077] The boron nitride-copper composite powder obtained by ball milling was placed in a 30 mm diameter graphite mold and subjected to hot press sintering. The hot press temperature was set to 900°C, the pressure to 50 MPa, and the holding time to 1 hour to obtain a block-shaped boron nitride-copper composite material.

[0078] Furthermore, the composite material was densified by hot rolling, and the boron nitride-copper composite material was mechanically deformed at 900°C. The reduction ratio per pass was controlled to 10%, and the cumulative reduction ratio reached 70%, meaning that the deformation amount of the composite material was 70%, thus obtaining a boron nitride-reinforced copper matrix composite material.

[0079] According to the measurement results, the boron nitride-reinforced copper matrix composite material manufactured in Example 7 has a strength of 320 MPa and can maintain an electrical conductivity of 93% IACS.

[0080] Example 8 The only difference from Example 1 was that 25 g of sheet-like copper powder was replaced with 25 g of sheet-like copper-silver alloy powder containing 1% silver by mass. Otherwise, the same manufacturing method as in Example 1 was used to produce the boron nitride-reinforced copper matrix composite material.

[0081] Example 9 The only difference from Example 1 was that 25 g of sheet-like copper powder was replaced with 25 g of sheet-like copper-lanthanum alloy powder having a lanthanum mass fraction of 0.5%, otherwise the boron nitride-reinforced copper matrix composite material was manufactured using the same manufacturing method as in Example 1.

[0082] The performance of the boron nitride-reinforced copper matrix composite materials produced in Example 1 and Examples 8 and 9 was detected, and the results are shown in Table 3.

[0083] [Table 3]

[0084] As can be seen from Table 3, the boron nitride-reinforced copper matrix composites produced in Examples 8 and 9 exhibited high strengths of 450 MPa and 410 MPa, respectively, representing a one-fold improvement over pure copper, and a one-order-of-magnitude reduction in self-corrosion current density. By using copper alloys as the base material for boron nitride-reinforced copper matrix composites, the strength and corrosion resistance of the material can be clearly improved. Compared to copper materials, they can be used in environments with higher mechanical properties and in more severe operating conditions, further expanding the potential applications of boron nitride-reinforced copper matrix composites.

[0085] Based on the above technical solutions, the boron nitride-reinforced copper matrix composite material and its manufacturing method provided in this disclosure adjust the mixing ratio of boron nitride and copper powder in the composite powder, control the amount of deformation of the composite material by mechanical deformation processing, orient and arrange the boron nitride in the composite material, form a laminated structure of boron nitride and copper, and reduce the scattering of electrons and boron nitride. Furthermore, by demonstrating the advantages of boron nitride's high in-plane thermal conductivity and corrosion resistance, a boron nitride-reinforced copper matrix composite material with high thermal conductivity, electrical conductivity, and corrosion resistance is obtained, which is expected to be widely applied in the fields of electrical engineering and electronics, ensuring low energy consumption, low heat generation, and high reliability.

[0086] The above specific examples have further illustrated the purpose, technical solutions, and beneficial effects of this disclosure. However, these examples are merely specific embodiments of this disclosure and are not intended to limit it. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this disclosure should be understood to fall within the scope of protection of this disclosure.

Claims

1. The process for producing a boron nitride-copper composite powder, A step of using a powder metallurgy process to produce the composite powder into a boron nitride-copper composite material, The process involves mechanically deforming the composite material to densify it, forming a layered structure of boron nitride and copper, and obtaining a boron nitride-reinforced copper matrix composite material. Includes, A method for manufacturing a boron nitride-reinforced copper matrix composite material, wherein the angle difference between boron nitrides in the laminated structure along the main deformation direction is less than 10°.

2. The manufacturing method according to claim 1, further comprising the step of surface modification by introducing copper nanoparticles into the composite powder in order to improve the interfacial bonding performance between boron nitride and copper.

3. The manufacturing method according to claim 1, wherein the mass ratio of boron nitride to copper in the composite powder is (0.01 to 5):(95 to 99.9).

4. The manufacturing method according to claim 1, wherein the total amount of deformation of the composite material by the mechanical deformation process exceeds 30%.

5. The boron nitride is a boron nitride nanosheet. The manufacturing method according to claim 3, wherein the transverse dimension of the boron nitride nanosheet is 0.5 to 20 μm and the thickness is 1 to 10 nm.

6. The composite powder further contains a doping metal, The amount of the doping metal added is 0 to 5% of the composite powder. The manufacturing method according to claim 1, wherein the doping metal comprises one or more of silver, chromium, tin, iron, lanthanum, and zirconium.

7. The mechanical deformation method includes a step of hot rolling the composite material at a temperature of 800 to 1000°C. The manufacturing method according to claim 1, wherein the reduction ratio per hot rolling process is 8 to 12%, and the cumulative reduction ratio is 50 to 75%.

8. After the mechanical deformation process, the density of the resulting boron nitride-reinforced copper matrix composite material exceeds 99.5%. The interlayer pitch between boron nitrides in the boron nitride-reinforced copper matrix composite material is 0.1 to 2 μm. The manufacturing method according to claim 1, wherein the lateral dimension of the boron nitride in the boron nitride-reinforced copper matrix composite material is 100 to 1000 nm.

9. A boron nitride-reinforced copper matrix composite material manufactured by the manufacturing method described in any one of claims 1 to 8, A boron nitride-reinforced copper matrix composite material wherein the angle difference between boron nitrides along the main deformation direction in the laminated structure of the boron nitride-reinforced copper matrix composite material is less than 10°.

10. The boron nitride-reinforced copper matrix composite material contains boron nitride, copper, and impurity elements. The boron nitride-reinforced copper matrix composite material according to claim 9, wherein the content of boron nitride and copper in the boron nitride-reinforced copper matrix composite material exceeds 95%.

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