Molybdenum-copper alloy production and processing technology

Abstract

The invention relates to the technical field of preparation of metal composite materials, in particular to a molybdenum-copper alloy production and processing technology which comprises the following steps: S1, preparation of a precursor solution and nano composite sol: dissolving a molybdenum source compound and a copper source compound in a solvent together, and adding a complexing agent to form a uniform molecular-level precursor solution; then, uniform sol containing molybdenum-copper composite nanoparticles is prepared through chemical reduction and solation treatment; s2, gelation forming: injecting the uniform sol into a mold, and curing the uniform sol into a wet gel blank; s3, drying: drying the wet gel blank body to obtain a dry gel blank body; and S4, densification: carrying out heating heat treatment on the xerogel blank in a protective or reducing atmosphere to realize final densification of the alloy. According to the preparation method, the molybdenum-copper composite nanoparticles are constructed in a liquid phase in a chemical mode from a molecular precursor solution, so that the two phases are uniformly mixed at the nanoscale, and the problem of macrosegregation of preparation by a traditional infiltration method is solved.

Description

Technical Field

[0001] This invention relates to the field of metal composite material preparation technology, and in particular to a production and processing technology for molybdenum-copper alloy. Background Technology

[0002] Molybdenum-copper alloys combine the high melting point and low coefficient of thermal expansion of molybdenum with the high thermal and electrical conductivity of copper, making them key materials for high-end electronic packaging, heat sinks, and high-voltage electrical contacts. However, molybdenum and copper are immiscible and have poor wettability, and achieving uniform composite composition and strong interfacial bonding between the two phases is the core challenge of the preparation technology.

[0003] The current mainstream production process is the melt infiltration method: first, a porous molybdenum framework is prepared, and then molten copper is infiltrated into it. Although this process is relatively mature, it has inherent drawbacks:

[0004] 1. Limited uniformity: The starting materials are micron-sized molybdenum powder and copper powder. Mechanical mixing makes it difficult to achieve uniform distribution at the atomic scale, which can easily lead to fluctuations in the composition and uneven performance of the final product.

[0005] 2. Weak interfacial bonding: The copper liquid has poor wettability to molybdenum, and the interface is mostly mechanically bonded, resulting in high interfacial thermal resistance and electrical resistance.

[0006] Existing technological improvements mainly focus on optimizing powder morphology, adding activating elements, or improving melting parameters. For example, CN108913927B describes a method for mixing raw materials for a molybdenum-copper alloy used in heat sinks. The raw materials for this alloy include copper powder and molybdenum powder. The method is characterized by first adjusting the loose specific gravity of the molybdenum powder to ensure the difference between the loose specific gravity of the molybdenum powder and copper powder is less than 0.5 g / cm³, and then uniformly mixing the copper powder and molybdenum powder according to the required mixing ratio. This invention effectively solves the problem of copper powder agglomeration in the molybdenum-copper powder mixture, which melts during copper infiltration sintering, forming large copper pools and affecting the uniformity of copper distribution in the alloy material. It improves the mixing uniformity of the molybdenum-copper mixture, thereby improving the uniformity of the physical properties of the molybdenum-copper alloy. Another example is CN103170616B, which describes a molybdenum-copper alloy foil and its preparation method. The molybdenum-copper alloy foil has a thickness of 0.1–1.0 mm, with the molybdenum and copper phases uniformly distributed in a short fibrous form, and the copper phases overlapping each other. A method for preparing molybdenum-copper alloy foil with copper comprising 20wt%–50wt% and the balance being molybdenum includes high-energy ball milling of mixed powders, followed by pressing, pre-sintering, and melt infiltration sintering to obtain molybdenum-copper alloy plates. The alloy plates are then hot-rolled, heat-treated, and cold-rolled to obtain alloy foil. This invention employs high-energy ball milling combined with melt infiltration sintering and a suitable rolling process, solving the problems of poor deformation processing performance and low density of existing molybdenum-copper alloys. Although improvements to existing technologies can enhance alloy properties to some extent, the fundamental problems remain difficult to solve.

[0007] Therefore, the present invention provides a production and processing technology for molybdenum-copper alloy to solve the above problems. Summary of the Invention

[0008] To achieve the above objectives, the present invention provides the following technical solution: a production and processing technology for molybdenum-copper alloy, comprising the following steps:

[0009] S1. Preparation of precursor solution and nanocomposite sol: Molybdenum source compound and copper source compound are dissolved together in a solvent, and a complexing agent containing carbon is added to form a uniform molecular-level precursor solution; subsequently, a uniform sol containing molybdenum-copper composite nanoparticles is prepared through chemical reduction and sol-gel treatment; S2. Gelation molding: The uniform sol is injected into a mold and solidified into a wet gel preform; S3. Drying: The wet gel preform is dried to obtain a dry gel preform; S4. Densification: The dry gel preform is subjected to heat treatment in a protective or reducing atmosphere to achieve final densification of the alloy.

[0010] Preferably, an interface modifier is introduced into the precursor solution of S1. The interface modifier is a carbon-, boron-, or nitrogen-containing compound that can generate a carbide, boride, or nitride intermediate layer in situ at the molybdenum-copper interface during subsequent heat treatment.

[0011] Preferably, the gelation molding process of S2 is carried out under the induction of an external physical field, which is used to guide the composite nanoparticles to oriented alignment so that the wet gel preform forms an anisotropic preform with an ordered microstructure.

[0012] Preferably, the external physical field is a static magnetic field with an intensity of not less than 2T, and the direction of the magnetic field is either vertical or horizontal.

[0013] Preferably, the chemical reduction and sol-gel treatment in S1 is achieved by adding a reducing agent and a dispersant; the particle size of the molybdenum-copper composite nanoparticles is 5-100 nm.

[0014] Preferably, the molybdenum source compound is selected from at least one of molybdate and molybdenum oxide halide; the copper source compound is selected from at least one of copper nitrate, copper acetate, copper chloride, and copper sulfate; the complexing agent is a polycarboxylic acid or an aminopolycarboxylic acid; the reducing agent is hydrazine hydrate, ascorbic acid, sodium borohydride, or an alcohol; and the dispersant is a polymeric surfactant.

[0015] Preferably, the drying in S3 is freeze drying.

[0016] Preferably, the heating heat treatment in S4 is coupled with the processes of organic component removal, metal oxide reduction, porous framework formation, and molten metal infiltration; the process includes: degreasing and pre-reduction at 400-650℃, followed by heating to 1150-1400℃ for sintering and infiltration.

[0017] Preferably, when the process heats up to the highest temperature range, a uniaxial or isostatic pressure of 5-50 MPa is applied simultaneously.

[0018] A molybdenum-copper alloy material is prepared by the above-mentioned technical solution.

[0019] The beneficial effects of this invention are:

[0020] 1. This invention, starting from a molecular precursor solution, constructs molybdenum-copper composite nanoparticles in the liquid phase through chemical means, fundamentally achieving uniform mixing of the two phases at the nanoscale and solving the macroscopic segregation problem of traditional powder metallurgy.

[0021] 2. This invention introduces a carbon source through a precursor during the nanocomposite particle formation stage, thereby generating a beneficial transition layer in situ at the molybdenum-copper interface, which can significantly enhance interfacial bonding and reduce interfacial thermal resistance and electrical resistance.

[0022] 3. This invention utilizes a strong magnetic field to orient nanoparticles, which can "freeze" ordered microstructures, such as chain-like or layered arrangements, during the gelation process, thereby actively constructing anisotropic thermal / electrical conduction pathways and achieving customizable performance. Attached Figure Description

[0023] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0024] Figure 1 This is a schematic diagram of the process structure of the present invention. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] The production and processing technology of the molybdenum-copper alloy of the present invention, such as Figure 1 As shown, it includes the following steps:

[0027] S1: Preparation of precursor solution and nanocomposite sol: Molybdenum source compound and copper source compound are dissolved together in solvent, and a complexing agent containing carbon element is added to form a uniform molecular-level precursor solution; then, a uniform sol containing molybdenum-copper composite nanoparticles is prepared by chemical reduction and sol-gel treatment.

[0028] Specifically, the mixed solution is prepared by accurately measuring the molybdenum source and copper source according to the target alloy ratio and dissolving them together in deionized water to prepare a clear solution with a total metal ion concentration of 0.5-1.5 mol / L.

[0029] Adding chelating and dispersing agents: A certain amount of citric acid (CA) is added to the above solution as a chelating agent, with the molar ratio of CA to total metal ions controlled between 1.5:1 and 2.5:1. Simultaneously, 0.5%-1% of polyvinylpyrrolidone (PVP) is added as a dispersing agent. The solution is stirred at a constant temperature of 60-80℃ for 1-2 hours to form a stable, uniform, blue-green transparent complex solution. The carboxyl and hydroxyl groups of citric acid can react with Mo... 6+ and Cu 2+ The ions simultaneously form stable complexes, preventing selective precipitation or phase separation of the two metal ions in the solution due to different hydrolysis rates; while the long molecular chains of polyvinylpyrrolidone adsorb on the surface of the generated nanoparticles, preventing the nanoparticles from prematurely agglomerating, growing or settling in the sol through steric hindrance, thus maintaining the long-term stability of the sol.

[0030] Reduction and Sol-gelation Initiation: Under continuous stirring and constant temperature conditions, a reducing agent (such as hydrazine hydrate or ascorbic acid) is slowly added dropwise, and the dropping rate is controlled to allow the pH value of the system to change slowly. As the reduction reaction proceeds, the solution gradually changes from transparent to dark, accompanied by an increase in viscosity, eventually forming a dark brown, fluid, homogeneous molybdenum-copper composite nanosol. Dynamic light scattering monitoring ensures that the particle size distribution of the composite particles in the sol is within 5-30 nanometers. The role of the reducing agent is twofold: firstly, to partially reduce the Mo... 6+ and Cu 2+ The reduction to a lower valence state promotes the formation of complex oxide / metal clusters containing Mo-O-Cu bonds; secondly, its consumption and reaction byproducts alter the local chemical environment, inducing the sol-gel transition.

[0031] S2: Gel molding: The uniform sol is injected into a mold and solidified into a wet gel preform.

[0032] Specifically, the obtained sol is injected into a polytetrafluoroethylene mold. The mold is then placed in a 60°C constant temperature oven and allowed to gel for 12-48 hours to obtain a wet gel preform.

[0033] S3: Drying: The wet gel preform is dried to obtain a dry gel preform.

[0034] Specifically, the wet gel preform is placed in a freeze dryer and pre-frozen at -50°C or below. Then, it is sublimated under vacuum to remove most of the water and some of the volatile organic compounds from the gel. This step maximizes the preservation of the gel's nanoporous structure and oriented arrangement, preventing drying cracking. The result is a "dry gel" preform with high porosity and a nano-framework structure.

[0035] S4: Densification: The dry gel preform is subjected to heat treatment in a protective or reducing atmosphere to achieve final densification of the alloy.

[0036] Specifically, the dry gel preform is placed in a high-temperature sintering furnace (such as a hot press or gas pressure sintering furnace). In a flowing argon-hydrogen mixed atmosphere, the temperature is increased to 400-500℃ at a rate of 1-3℃ / min and held for 1-2 hours. This stage thoroughly decomposes and removes residual citric acid, PVP, and other organic matter, and initially reduces the composite oxide nanoparticles to metallic / alloyed molybdenum and copper nanoparticles. Due to the extremely fine and uniformly mixed initial particles, this reduction process can be completed at low temperatures; the temperature is then increased again in a pure hydrogen or vacuum environment at a rate of 5-10℃ / min. This is the key to coupling: when the temperature exceeds the melting point of copper (1083℃), the uniformly distributed copper nanoparticles in the preform melt first. Since the molybdenum nanoparticles, which form the framework, are only connected by weak sintering necks, forming a highly interconnected and uniform nanoporous network, the molten copper, under capillary force, instantly and without resistance penetrates and fills all the pores. Meanwhile, the temperature continues to rise to 1200-1300℃ and is held at that temperature briefly, promoting further sintering and densification of the molybdenum framework. Finally, under pressure assistance (such as applying 10-20 MPa axial pressure), complete densification is achieved.

[0037] Example 1

[0038] Weigh 18g of ammonium molybdate and 12g of copper nitrate (trihydrate), dissolve them in 200ml of deionized water, and stir until completely dissolved. Add 30g of citric acid as a complexing agent, and stir in a 70℃ water bath for 1 hour to obtain a clear blue solution. Subsequently, add 2g of polyvinylpyrrolidone as a dispersant and stir until homogeneous. Under continuous stirring and at 70℃, slowly add 10ml of hydrazine hydrate (85%). The solution gradually turns dark brown, the viscosity increases, and finally a uniform and stable molybdenum-copper composite nanosol is formed. Dynamic light scattering analysis shows that the average particle size of the composite particles in the sol is approximately 15nm.

[0039] The obtained sol was injected into a polytetrafluoroethylene mold. The mold was placed in a 60℃ constant temperature oven and allowed to gel for 24 hours to obtain a wet gel preform. The wet gel preform was pre-frozen in a -50℃ freezer for 6 hours, and then transferred to a freeze dryer and dried under a vacuum of <10 Pa for 48 hours to obtain a dry gel preform.

[0040] Finally, the dry gel preform is placed in a graphite mold and then placed in a hot press sintering furnace. First, a vacuum of 10... -2 The pressure was increased to 500°C at 2°C / min and held for 1 hour to remove organic matter and achieve preliminary reduction. The temperature was then increased to 1250°C at 10°C / min, and a uniaxial pressure of 15 MPa was applied starting at 1100°C. The furnace was held at 1250°C and pressure for 1 hour. Afterward, the furnace was cooled to obtain a dense molybdenum-copper alloy ingot.

[0041] Example 2

[0042] This embodiment, based on Embodiment 1, introduces a strong static magnetic field to prepare a molybdenum-copper alloy with a directional structure. Specifically:

[0043] Weigh 18g of ammonium molybdate and 12g of copper nitrate (trihydrate), dissolve them in 200ml of deionized water, and stir until completely dissolved. Add 30g of citric acid as a complexing agent, and stir in a 70℃ water bath for 1 hour to obtain a clear blue solution. Subsequently, add 2g of polyvinylpyrrolidone as a dispersant and stir until homogeneous. Under continuous stirring and at 70℃, slowly add 10ml of hydrazine hydrate (85%). The solution gradually turns dark brown, the viscosity increases, and finally a uniform and stable molybdenum-copper composite nanosol is formed. Dynamic light scattering analysis shows that the average particle size of the composite particles in the sol is approximately 15nm.

[0044] The resulting sol was injected into an identical polytetrafluoroethylene mold. The mold was placed in a room-temperature homogeneous region of a superconducting magnet system, which provided a strong static magnetic field of 10 T in the vertical direction. Under the condition of maintaining the magnetic field, the sol was left to stand at 40°C for 36 hours, allowing the sol to slowly gel under the magnetic field induction. During this process, the paramagnetic molybdenum-copper composite nanoparticles were oriented and fixed along the direction of the magnetic field;

[0045] The wet gelled preform was pre-frozen at -50°C for 6 hours, then transferred to a freeze dryer and dried under a vacuum of <10 Pa for 48 hours to obtain a dry gelled preform. Finally, the dry gelled preform was placed in a graphite mold and then placed in a hot-pressing sintering furnace. A vacuum of <10 Pa was first applied. -2 The pressure was increased by 15 MPa, followed by the introduction of a flowing argon-hydrogen mixture atmosphere. The temperature was then increased to 500°C at 2°C / min and held for 1 hour to remove organic matter and achieve preliminary reduction. Subsequently, the temperature was increased to 1250°C at 10°C / min, and a uniaxial pressure of 15 MPa was applied starting at 1100°C. The temperature and pressure were then held at 1250°C for 1 hour. After the process, the furnace was cooled to obtain a dense molybdenum-copper alloy ingot with a microscopic oriented structure.

[0046] Comparative Example 1

[0047] To compare with Examples 1 and 2 above, a molybdenum-copper alloy with the same composition as the above examples was prepared using the conventional melt infiltration method.

[0048] In this comparative example, molybdenum powder with an average particle size of 3 μm was used and placed in a steel mold, then pressed into a 20 mm diameter compact under a pressure of 200 MPa. The compact was placed in a hydrogen sintering furnace and sintered at 1400 °C for 2 hours to obtain a porous molybdenum framework with a certain strength. The required amount of copper was calculated based on the pore volume of the framework, and oxygen-free copper sheets of the corresponding mass were placed on top of the molybdenum framework. The assembly was placed in a high-temperature furnace under a protective atmosphere, heated to 1300 °C, and held for 2 hours to allow the copper to completely melt and penetrate into the pores of the molybdenum framework. After cooling, the sample surface was polished to remove excess copper, yielding the final molybdenum-copper alloy.

[0049] The following tests were conducted on the performance of the molybdenum-copper alloys prepared in Examples 1, 2, and Comparative Example 1, including: determining the density using the Archimedes displacement method; testing the thermal conductivity at 25°C using a laser scintillation thermal conductivity meter; measuring the electrical conductivity using the four-probe method; and testing the bending strength using the three-point bending method on a universal testing machine. The specific test results are shown in Table 1 below.

[0050] Test Project Comparative Example 1 Example 1 Example 2 Density (%) 98.2 99.5 99.6 Thermal conductivity (W / m·K) 180 205 Vertical magnetic field direction: 195 Electrical conductivity (%IACS) 78 85 Vertical magnetic field direction: 82 Bending strength (MPa) 620 680 720

[0051] Table 1

[0052] In summary, the molybdenum-copper alloy production and processing technology of the present invention, by using a powder mixing method that differs from the existing technology, prepares a uniform sol containing molybdenum-copper composite nanoparticles, and introduces an external field to achieve active control of the structure, ultimately achieving a comprehensive improvement in density, thermal and electrical conductivity, and mechanical properties.

[0053] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A manufacturing process for molybdenum-copper alloys, characterized in that: Includes the following steps: S1. Preparation of precursor solution and nanocomposite sol: Molybdenum source compound and copper source compound are dissolved together in a solvent, and a complexing agent containing carbon is added to form a uniform molecular-level precursor solution; subsequently, a uniform sol containing molybdenum-copper composite nanoparticles is prepared through chemical reduction and sol-gel treatment; S2. Gelation molding: The uniform sol is injected into a mold and solidified into a wet gel preform; S3. Drying: The wet gel preform is dried to obtain a dry gel preform; S4. Densification: The dry gel preform is subjected to heat treatment in a protective or reducing atmosphere to achieve final densification of the alloy.

2. The production and processing technology of molybdenum-copper alloy as described in claim 1, characterized in that: The gelation molding process of S2 is carried out under the induction of an external physical field, which is used to guide the composite nanoparticles to oriented alignment so that the wet gel preform forms an anisotropic preform with an ordered microstructure.

3. The production and processing technology of molybdenum-copper alloy as described in claim 2, characterized in that: The applied physical field is a static magnetic field with a strength of not less than 2T.

4. The production and processing technology of molybdenum-copper alloy as described in claim 1, characterized in that: The chemical reduction and sol-gel treatment in S1 is achieved by adding a reducing agent and a dispersant; the particle size of the molybdenum-copper composite nanoparticles is 5-100 nm.

5. The production and processing technology of molybdenum-copper alloy as described in claim 4, characterized in that: The molybdenum source compound is selected from at least one of molybdate and molybdenum oxide halide; the copper source compound is selected from at least one of copper nitrate, copper acetate, copper chloride, and copper sulfate; the complexing agent is a polycarboxylic acid or an aminopolycarboxylic acid; the reducing agent is hydrazine hydrate, ascorbic acid, sodium borohydride, or an alcohol; and the dispersant is a polymeric surfactant.

6. The production and processing technology of molybdenum-copper alloy as described in claim 1, characterized in that: The drying process in S3 is freeze drying.

7. The production and processing technology of molybdenum-copper alloy as described in claim 1, characterized in that: The heating process in S4 is coupled with the removal of organic components, reduction of metal oxides, formation of porous framework and melting infiltration of molten metal; the process includes: degreasing and pre-reduction at 400-650℃, followed by sintering and melting infiltration at 1150-1400℃.

8. The production and processing technology of molybdenum-copper alloy as described in claim 7, characterized in that: When the process heats up to the highest temperature range, a uniaxial or isostatic pressure of 5-50 MPa is applied simultaneously.

9. The production and processing technology of molybdenum-copper alloy as described in claim 1, characterized in that: An interface modifier is introduced into the precursor solution of S1. The interface modifier is a carbon-containing compound that can generate a carbide intermediate layer in situ at the molybdenum-copper interface during subsequent heat treatment.

10. A molybdenum-copper alloy material, characterized in that: It is produced by the production and processing technology of molybdenum-copper alloy as described in any one of claims 1-9.

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