High thermal conductive tungsten-copper alloy and preparation method thereof

Abstract

The application belongs to the technical field of tungsten-copper alloy, and particularly relates to a high-thermal-conductivity tungsten-copper alloy and a preparation method thereof. The preparation method comprises the following steps: S1, obtaining ammonium paratungstate, copper oxide, copper tungstate, basic copper carbonate, a silver-containing compound, an organic complexing agent, a rare earth oxide and copper powder as raw materials; S2, ball-milling the raw materials except the copper powder to obtain a composite sol, drying the composite sol to obtain a precursor powder, and heat-treating the precursor powder to obtain a composite powder; and S3, layering and pressing the composite powder and the copper powder according to a structure of 'bottom layer copper powder-composite powder-top layer copper powder' to obtain a composite compact, and sintering the composite compact by melting and infiltrating to obtain the tungsten-copper alloy. The application forms a three-level core-shell structure of 'tungsten core-copper-silver solid solution shell-rare earth transition layer', and the comprehensive performance is better than that of an existing silver nitrate / silver powder system, and no harmful gas is discharged, so that the green manufacturing demand is met.

Description

Technical Field

[0001] This application relates to the field of tungsten copper alloy technology, specifically, to a high thermal conductivity tungsten copper alloy and its preparation method. Background Technology

[0002] Tungsten-copper alloys, as a typical metal-based composite material, combine the high melting point (3410℃), high strength, and arc erosion resistance of tungsten with the excellent electrical and thermal conductivity and ductility of copper, making them indispensable key materials in cutting-edge fields such as aerospace, electronics, and defense. In the aerospace field, the "sweating cooling" effect of copper is used to achieve thermal protection of rocket engine nozzles under extreme environments. In microelectronic packaging, its low coefficient of thermal expansion combined with high thermal conductivity solves the heat dissipation problem of high-power devices. Furthermore, industrial applications such as EDM electrodes and resistance welding heads also heavily rely on the high-temperature stability and conductivity of tungsten-copper alloys.

[0003] However, traditional tungsten-copper alloys suffer from poor uniformity of tungsten-copper phase dispersion, leading to poor copper-copper interconnectivity and limited thermal and electrical conductivity. Furthermore, the poor wettability of the tungsten and copper phases further exacerbates the obstruction of electron flow due to interfacial resistance, impacting the alloy's thermal and electrical conductivity. Silver, as the most conductive metal, can significantly improve the conductivity of alloys and can form silver-copper alloys with copper, enhancing both electrical and thermal conductivity. Current research on tungsten-copper-silver alloys mainly focuses on high-silver-content alloys, with silver compounds often using silver powder or silver nitrate. Silver powder is costly and has poor dispersibility, easily leading to silver phase agglomeration in the alloy. While silver nitrate can dissolve and disperse, its decomposition temperature is high (above 300℃), producing harmful NO2 gas during decomposition, which not only pollutes the environment but may also cause silver particles to grow, making it difficult to achieve nanoscale uniform dispersion and limiting the improvement of alloy performance.

[0004] The addition of trace amounts of silver greatly improves the electrical and thermal conductivity of tungsten-copper alloys. However, it is greatly affected by the type of silver compound and the dispersion process. Existing silver compounds (silver powder, silver nitrate) cannot meet the requirements of "low pollution, high dispersion, and low cost". At the same time, in the existing process, tungsten-copper composite powder is prone to agglomeration and oxidation. After sintering, the alloy is prone to problems such as high porosity and weak interfacial bonding, which further limits the improvement of the performance of tungsten-copper alloys. Summary of the Invention

[0005] To solve the above-mentioned technical problems, this application provides a method for preparing a high thermal conductivity tungsten-copper alloy, comprising the following steps: S1, obtaining ammonium paratungstate, copper oxide, copper tungstate, basic copper carbonate, silver-containing compound, organic ligand, rare earth oxide, and copper powder as raw materials; by weight percentage, the copper content in the raw materials is 9.85-39.95 wt%, the tungsten content in the raw materials is 60-90 wt%, the silver content in the raw materials is 0.05-0.15 wt%, the rare earth oxide content in the raw materials is 0.01-0.05 wt%, and the organic ligand content in the raw materials is 0.015-0.12 wt%;

[0006] S2. The ammonium paratungstate, copper oxide, copper tungstate, basic copper carbonate, silver-containing compound, organic ligand, and rare earth oxide are ball-milled to obtain a composite sol. The composite sol is dried to obtain a precursor powder. The precursor powder is then heat-treated to obtain a composite powder.

[0007] S3. The composite powder and the copper powder are laid up and pressed in a structure of "bottom copper powder-composite powder-top copper powder" to obtain a composite compact. The composite compact is then melt-infiltrated and sintered to obtain a tungsten-copper alloy.

[0008] In a preferred embodiment of the preparation method of a high thermal conductivity tungsten-copper alloy as described in this application, in step S1, the source of copper in the raw materials is copper oxide, copper tungstate, basic copper carbonate, and copper powder, wherein the mass ratio of copper oxide, copper tungstate, basic copper carbonate, and copper powder is (7-9):(4-10):(0.5-1.5):1;

[0009] The tungsten in the raw materials is derived from ammonium paratungstate and copper tungstate, wherein the mass ratio of ammonium paratungstate to copper tungstate is (2.5-7):1;

[0010] The silver in the raw materials is derived from silver-containing compounds, including at least one of silver isooctanoate or silver carbonate; the organic ligand includes at least one of disodium ethylenediaminetetraacetate or citric acid; and the rare earth oxide includes at least one of La2O3 or CeO2.

[0011] In a preferred embodiment of the preparation method of the high thermal conductivity tungsten-copper alloy described in this application, in step S1, the ammonium paratungstate is a single-crystal ammonium paratungstate with a smooth, crack-free surface and a tungsten content greater than 68%; the copper oxide is spherical with a particle size of 0.5-2 μm; the purity of the copper tungstate is ≥99.9%; the purity of the basic copper carbonate is ≥99.5% with a particle size of 1-3 μm; the purity of the copper powder is ≥99.95% with a particle size of 1-3 μm; the purity of the rare earth oxide is ≥99.9% with a particle size of 50-100 nm; and the purity of the organic ligand is ≥99%.

[0012] As a preferred embodiment of the preparation method of a high thermal conductivity tungsten-copper alloy according to this application, in step S2, the ball milling method is specifically as follows: the ammonium paratungstate, copper oxide, copper tungstate, basic copper carbonate, silver-containing compound, organic ligand, and rare earth oxide are mixed and loaded into a high-energy mixer, and dispersed at a cutter speed of 2500-3000 r / min and a spindle speed of 50-60 r / min for 1-1.5 h to fully disperse the components; then the mixture is placed in a high-energy ball mill, anhydrous ethanol and polyvinyl alcohol dispersant are added, and ball milling is performed at a ball-to-material ratio of (5-6):1 and a frequency of 40-50 Hz for 4-5 h to obtain the composite sol;

[0013] The drying method specifically involves: conveying the composite sol to a spray drying tower via a peristaltic pump, employing a combination of centrifugal spraying and side pressure atomization; the inlet temperature is 210-225℃, the outlet temperature is 88-92℃, the spray disc rotation speed is 14000-16000 r / min, the side atomization pressure is 0.2-0.4 MPa, and the feed rate is 700-800 mL / min; after the slurry is atomized into tiny droplets, it is instantly dried by countercurrent contact with hot air, resulting in a sphericity ≥95%, D50 = 5-18 μm, and a bulk density of 1.95-2.1 g / cm³. 3 The precursor powder.

[0014] As a preferred embodiment of the preparation method of the high thermal conductivity tungsten-copper alloy described in this application, in step S2, the heat treatment method specifically involves: calcining the precursor powder in air at 450-550℃ for 1-2 hours to decompose the metal salt into oxides, obtaining WO3-CuO-CuWO4-Ag-rare earth oxide composite oxide spherical powder; after calcination, nitrogen gas is introduced to purge air and CO2 for 20-30 minutes; subsequently, hydrogen reduction and passivation treatment are performed, specifically as follows:

[0015] Phase 1: Temperature 350-450℃, hydrogen flow rate 10-15m³ / h 3 / h, the heat preservation time is 1-2h; the powder spreading height is no more than 1 / 2 of the height of the ceramic boat containing the powder;

[0016] Second stage: Temperature 750-800℃, hydrogen flow rate 15-25m³ / h 3 / h, heat preservation time is 1-2h;

[0017] Phase 3: Temperature 850-950℃, hydrogen flow rate 20-30m³ / h 3 / h, heat preservation time is 1-2h;

[0018] Fourth stage: The cooling rate is 5-10℃ / min, the passivation temperature is 300-350℃, the atmosphere is a mixture of O2-N2 gas with a volume fraction of 5-8%, and the holding time is 30-60min.

[0019] As a preferred embodiment of the preparation method of the high thermal conductivity tungsten-copper alloy described in this application, in step S3, the layup method specifically involves: laying the composite powder and copper powder in a "bottom copper powder-composite powder-top copper powder" structure, with a mass ratio of bottom copper powder to top copper powder of 1:(1.2-1.5); the pressing method specifically involves: first holding the pre-pressed blank under a pressure of 80-100 MPa for 15-20 seconds in a hydraulic press to obtain a pre-pressed blank, then cold isostatically pressing the pre-pressed blank under a pressure of 180-230 MPa for 30-50 seconds to obtain a density of 12.8-13.2 g / cm³. 3 Composite pressed preform.

[0020] As a preferred embodiment of the preparation method of the high thermal conductivity tungsten-copper alloy described in this application, in step S3, the melting and infiltration sintering method specifically involves: placing the composite compact in an alumina boat of matching dimensions, placing a pure tungsten counterweight on top, and then placing them together in a hydrogen furnace (vacuum degree <5×10). -3 Pa), sintered according to the following process:

[0021] Exhaust stage: Hold at 1000-1100℃ for 1-2 hours, with a hydrogen flow rate of 3-8L / min to remove residual gas from the compact;

[0022] Primary melting and infiltration: Heat to 1200-1300℃ at 3-5℃ / min, apply pressure of 0.5-1.5MPa and hold for 1-2 hours, with hydrogen flow rate of 2-5L / min, and copper phase initially infiltrates the tungsten framework;

[0023] Deep melting and infiltration: continue heating to 1300-1400℃, pressurize to 1-1.5MPa and hold for 0.5-2h, with a hydrogen flow rate of 3-8L / min, until the copper phase completely fills the pores;

[0024] Cooling: The furnace is cooled to room temperature to obtain the tungsten-copper alloy.

[0025] This application also provides a high thermal conductivity tungsten copper alloy, which is prepared by the above-described method for preparing high thermal conductivity tungsten copper alloy.

[0026] As a preferred embodiment of the high thermal conductivity tungsten-copper alloy described in this application, the tungsten-copper alloy forms a three-level core-shell structure of "tungsten core-copper-silver solid solution shell-rare earth transition layer". The size of the tungsten core is 1-3 μm, the size of the copper-silver solid solution shell is 50-100 nm, the size of the rare earth transition layer is 1-5 nm, the CV value of the tungsten particles in the tungsten-copper alloy is ≤12%, the tungsten-copper alloy forms a silver nanophase and a copper phase, the silver nanophase penetrates the copper phase to form a continuous thermally conductive channel in the tungsten-copper alloy, and the porosity of the tungsten-copper alloy is ≤0.3%.

[0027] As a preferred embodiment of the high thermal conductivity tungsten-copper alloy described in this application, the tungsten-copper alloy has a density ≥99.5%, an electrical conductivity ≥78% IACS, a thermal conductivity ≥235 W / (m·K), a hardness ≥235 HV, and an interfacial thermal resistance ≤1.8 × 10⁻⁶. -4 m 2 ·K / W.

[0028] The beneficial effects of this application are as follows:

[0029] This application proposes a high thermal conductivity tungsten-copper alloy and its preparation method. Ammonium paratungstate and copper tungstate are used as a mixed tungsten source, while copper oxide, copper tungstate, and basic copper carbonate are used as a composite copper source. An organic / low-toxicity inorganic silver-containing compound-organic ligand composite silver system (preferably silver isooctanoate, alternatively silver carbonate) is added, and trace amounts of rare earth oxides are introduced to regulate the interface. This improves the alloy's electrical and thermal conductivity, powder coating uniformity, and interfacial bonding strength while avoiding harmful gas emissions. A tungsten-copper-silver composite powder is prepared, and this composite powder is used to prepare a silver-reinforced tungsten-copper alloy. The tungsten-copper alloy exhibits excellent thermal and electrical conductivity, high strength, and extremely low interfacial heat. The process involves using ammonium paratungstate and copper tungstate as a mixed tungsten source, with copper in copper tungstate inducing the reduction of elemental copper to coat the tungsten matrix; a composite copper source (copper oxide + copper tungstate + basic copper carbonate) provides a portion of the copper in the tungsten-copper alloy, and the calcination and decomposition of basic copper carbonate produces CO2, achieving "in-situ pore creation and copper replenishment" to fill the micropores in the tungsten skeleton; in the composite silver system, organic ligands control the low-temperature decomposition rate of silver-containing compounds, allowing silver to be uniformly dispersed in the copper phase in the form of nanoparticles / short fibers; rare earth oxides preferentially accumulate at the tungsten-copper interface, forming a 1-5 nm thick rare earth doped transition layer to reduce interfacial thermal resistance; the remaining copper is obtained by copper powder melt infiltration.

[0030] This application employs a four-stage integrated calcination-reduction-passivation process to prepare composite powder: The precursor powder is calcined in air at 450-550℃ for 1-2 hours to decompose the metal salt into oxides (basic copper carbonate decomposes into CuO, CO2, and H2O, and silver-containing compounds are initially decomposed into Ag elemental), yielding spherical WO3-CuO-CuWO4-Ag-rare earth oxide composite oxide powder. After calcination, nitrogen gas is introduced for 20-30 minutes to purge the air and CO2, followed by hydrogen reduction and passivation treatment. The specific process is as follows:

[0031] First stage (low-temperature reduction + silver dispersion):

[0032] The temperature is 350-400℃ for the silver isooctanoate system and 380-450℃ for the silver carbonate system, with a hydrogen flow rate of 10-15 m³ / s. 3 / / h, the heat preservation time is 1-2h; the powder spreading height is no more than 1 / 2 of the height of the ceramic boat containing the powder;

[0033] Through core reactions:

[0034] Decomposition of silver isooctanoate: 2C 16 H 30 AgO4→2Ag (nanoparticles)+32CO2↑+30H2O↑+alkane (small amount);

[0035] Decomposition of silver carbonate: Ag₂CO₃ → 2Ag (nanoparticles) + CO₂↑;

[0036] Reduction of copper oxides: CuO + H2 → Cu + H2O↑;

[0037] The silver-containing compound is completely decomposed and attached to the copper phase surface in a nano-form, while some copper tungstate is decomposed and reduced, achieving a copper-silver synergistic coating.

[0038] Second stage (deep reduction of oxides):

[0039] Temperature is 750-800℃, hydrogen flow rate is 15-25m³ / h 3 / / h, the heat preservation time is 1-2h;

[0040] Through core reactions:

[0041] WO3 (yellow) + 0.1H2 → WO 2.9 (Blue) + 0.1H₂O;

[0042] WO 2.9 (Blue) + 0.18H2 → WO 2.72 (Purple) + 0.18H₂O;

[0043] WO 2.72(Purple) + 0.72H2 → WO2 (Brown) + 0.72H2O;

[0044] WO2 (brown) + 2H2 → W (metallic tungsten) + 2H2O↑;

[0045] CuWO4 + 2H2 → W + Cu + 2H2O↑;

[0046] After all oxides are reduced, rare earth elements migrate to the tungsten-copper interface to obtain 1-3 μm W-Cu-Ag composite powder.

[0047] Third stage (high-temperature homogenization and purification):

[0048] Temperature: 850-950℃, Hydrogen flow rate: 20-30m³ 3 / / h, the heat preservation time is 1-2h;

[0049] Through core reactions:

[0050] WO2 + 2H2 → W + 2H2O↑ (Residual WO2 is reduced);

[0051] It promotes the interdiffusion of tungsten, copper, and silver atoms, and rare earth elements form a doped transition layer at the interface, reducing powder defects.

[0052] Fourth stage (low-temperature passivation to prevent oxidation):

[0053] The cooling rate is 5-10℃ / min, the passivation temperature is 300-350℃, the atmosphere is a mixture of O2-N2 gas with a volume fraction of 5-8%, and the holding time is 30-60min.

[0054] Through the core reaction: 2Cu + O2 (trace amount) → Cu2O (1-2nm passivation film);

[0055] To prevent agglomeration and oxidation of the powder during subsequent molding, the passivation film can be reduced to copper by hydrogen during sintering, without affecting the alloy composition.

[0056] Through a four-stage process, a three-level core-shell structure is formed, consisting of a tungsten core, a copper-silver solid solution shell, and a rare earth transition layer.

[0057] This application lays composite powder and copper powder in a "bottom layer copper powder - composite powder - top layer copper powder" structure: bottom layer copper powder (vibrated and compacted), middle layer tungsten-copper-silver composite powder, and top layer copper powder (utilizing gravity to promote downward penetration of the copper phase). A pre-pressed blank is obtained by holding the pre-pressed blank under a hydraulic press at 80-100 MPa for 15-20 seconds. The pre-pressed blank is then cold isostatically pressed at 180-230 MPa for 30-50 seconds to obtain a density of 12.8-13.2 g / cm³. 3 Composite pressed preform.

[0058] In this application, the composite compact is placed in an alumina boat of matching dimensions, and a pure tungsten counterweight is placed on top, and then placed together in a hydrogen furnace (vacuum degree <5×10). -3 Pa), sintered according to the following process:

[0059] Exhaust stage: Hold at 1000-1100℃ for 1-2 hours, with a hydrogen flow rate of 3-8L / min to remove residual gas from the compact;

[0060] Primary melting and infiltration: Heat to 1200-1300℃ at 3-5℃ / min, apply pressure of 0.5-1.5MPa and hold for 1-2 hours, with hydrogen flow rate of 2-5L / min, and copper phase initially infiltrates the tungsten framework;

[0061] Deep melting and infiltration: continue heating to 1300-1400℃, pressurize to 1-1.5MPa and hold for 0.5-2h, with a hydrogen flow rate of 3-8L / min, until the copper phase completely fills the pores;

[0062] Cooling: The furnace is cooled to room temperature to obtain the tungsten-copper alloy.

[0063] Furthermore, the ammonium paratungstate is a single-crystal ammonium paratungstate with no obvious cracks on the surface and a tungsten content of more than 68%. By controlling the crystal morphology of ammonium paratungstate, the surface smoothness of tungsten powder is adjusted, promoting the adhesion of copper and silver on the tungsten matrix and reducing the residue of impurities during calcination.

[0064] Furthermore, the precursor powder is calcined at 450-550℃ and held for 1-2 hours. Calcination allows all components to be fully oxidized, and the CO2 generated by the decomposition of basic copper carbonate clears the powder channels, removes the binder and organic ligand decomposition products, avoids powder agglomeration, and improves the uniformity of coating.

[0065] Furthermore, the four-stage processing is carried out continuously without the need for multiple furnace openings; hydrogen reduces oxides to a metallic phase, and low-temperature passivation forms a protective film, solving the problems of easy oxidation and agglomeration of powders in existing processes and achieving efficient preparation.

[0066] Furthermore, dynamic pressure melting infiltration achieves densification through gradient heating and pressure control; low-temperature flexible melting infiltration prevents the copper phase from escaping, while high temperature and high pressure drive the copper phase to fill the micropores and improve the interfacial bonding strength.

[0067] The technological innovations of this application are as follows:

[0068] (1) Synergistic dispersion of “composite silver system + organic ligand”: Silver isooctanoate / silver carbonate is used instead of silver nitrate, decomposition without harmful gas, and organic ligand controls the uniform dispersion of silver in nano-form, which is superior to the dispersion effect of existing silver-containing compounds.

[0069] (2) "Composite copper source + in-situ hole making" design: Basic copper carbonate, copper oxide and copper tungstate work together to decompose and generate CO2 to clear the powder channels, and the copper interconnection rate is increased by more than 10%, solving the problem of insufficient filling of traditional copper sources;

[0070] (3) Four-stage integrated process: Low-temperature silver dispersion-deep reduction-homogenization-passivation are carried out in a continuous manner, reducing energy consumption by 15% and avoiding powder oxidation, so as to achieve precise and controllable composite powder structure;

[0071] (4) Gradient copper layer + dynamic pressure melting and infiltration: The upper thick copper layer utilizes gravity-assisted infiltration and dynamic pressure control to achieve complete filling of the copper phase, increasing the density to 99.5%-99.9% and reducing the interface thermal resistance by more than 30%.

[0072] The microstructural advantages of this application are:

[0073] A three-level core-shell structure is formed, consisting of a tungsten core, a copper-silver solid solution shell, and a rare earth transition layer. The CV value of the tungsten particles in the tungsten-copper alloy is ≤12%. The tungsten-copper alloy forms a silver nanophase and a copper phase. The silver nanophase penetrates the copper phase to form a continuous heat-conducting channel in the tungsten-copper alloy. The porosity of the tungsten-copper alloy is ≤0.3%.

[0074] The performance advantages of this application:

[0075] The prepared tungsten-copper alloy has a density ≥99.5%, electrical conductivity ≥78% IACS, thermal conductivity ≥235 W / (m·K), hardness ≥235 HV, and interfacial thermal resistance ≤1.8×10⁻⁶. -4 m 2 • K / W, with overall performance superior to existing silver nitrate / silver powder systems, and with no harmful gas emissions, meeting the requirements of green manufacturing. Attached Figure Description

[0076] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0077] Figure 1 This is an electron micrograph of the composite powder prepared in Example 1 of this application;

[0078] Figure 2 Metallographic image of the tungsten-copper alloy prepared in Example 1 of this application;

[0079] Figure 3 Metallographic image of the tungsten-copper alloy prepared in Example 2 of this application;

[0080] Figure 4 Metallographic image of the tungsten-copper alloy prepared in Comparative Example 1 of this application;

[0081] Figure 5 Metallographic image of the tungsten-copper alloy prepared in Comparative Example 2 of this application;

[0082] Figure 6 This is an electron microscope image of the composite powder prepared in Comparative Example 3 of this application.

[0083] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0084] The technical solutions in the embodiments will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0085] This application provides a method for preparing a high thermal conductivity tungsten-copper alloy, comprising the following steps:

[0086] S1. Obtain ammonium paratungstate, copper oxide, copper tungstate, basic copper carbonate, silver-containing compounds, organic ligands, rare earth oxides, and copper powder as raw materials; by weight percentage, the raw materials contain 9.85-39.95 wt% copper, 60-90 wt% tungsten, 0.05-0.15 wt% silver, 0.01-0.05 wt% rare earth oxides, and 0.015-0.12 wt% organic ligands.

[0087] The copper in the raw materials comes from copper oxide, copper tungstate, basic copper carbonate, and copper powder, wherein the mass ratio of copper oxide, copper tungstate, basic copper carbonate, and copper powder is (7-9):(4-10):(0.5-1.5):1;

[0088] The tungsten in the raw materials is derived from ammonium paratungstate and copper tungstate, wherein the mass ratio of ammonium paratungstate to copper tungstate is (2.5-7):1;

[0089] The silver in the raw materials is derived from silver-containing compounds, including at least one of silver isooctanoate or silver carbonate; the organic ligand includes at least one of disodium ethylenediaminetetraacetate or citric acid; and the rare earth oxide includes at least one of La2O3 or CeO2.

[0090] The ammonium paratungstate is a single-crystal ammonium paratungstate with a smooth, crack-free surface and a tungsten content greater than 68%; the copper oxide is spherical with a particle size of 0.5-2 μm; the copper tungstate has a purity ≥99.9%; the basic copper carbonate has a purity ≥99.5% with a particle size of 1-3 μm; the copper powder has a purity ≥99.95% with a particle size of 1-3 μm; the rare earth oxide has a purity ≥99.9% with a particle size of 50-100 nm; and the organic ligand has a purity ≥99%.

[0091] S2. The ammonium paratungstate, copper oxide, copper tungstate, basic copper carbonate, silver-containing compound, organic ligand, and rare earth oxide are ball-milled to obtain a composite sol. The composite sol is dried to obtain a precursor powder. The precursor powder is then heat-treated to obtain a composite powder.

[0092] The ball milling method is as follows: the ammonium paratungstate, copper oxide, copper tungstate, basic copper carbonate, silver-containing compound, organic ligand, and rare earth oxide are mixed and loaded into a high-energy mixer, and dispersed at a cutter speed of 2500-3000 r / min and a spindle speed of 50-60 r / min for 1-1.5 hours to fully disperse the components; then the mixture is placed in a high-energy ball mill, anhydrous ethanol and polyvinyl alcohol dispersant are added, and ball milling is performed at a ball-to-material ratio of (5-6):1 and a frequency of 40-50 Hz for 4-5 hours to obtain the composite sol;

[0093] The drying method specifically involves: conveying the composite sol to a spray drying tower via a peristaltic pump, employing a combination of centrifugal spraying and side pressure atomization; the inlet temperature is 210-225℃, the outlet temperature is 88-92℃, the spray disc rotation speed is 14000-16000 r / min, the side atomization pressure is 0.2-0.4 MPa, and the feed rate is 700-800 mL / min; after the slurry is atomized into tiny droplets, it is instantly dried by countercurrent contact with hot air, resulting in a sphericity ≥95%, D50 = 5-18 μm, and a bulk density of 1.95-2.1 g / cm³. 3 The precursor powder.

[0094] The heat treatment method specifically involves calcining the precursor powder in air at 450-550℃ for 1-2 hours to decompose the metal salt into oxides, obtaining spherical powders of WO3-CuO-CuWO4-Ag-rare earth oxide composite oxides; after calcination, nitrogen gas is introduced to purge air and CO2 for 20-30 minutes; subsequently, hydrogen reduction and passivation treatment are performed, specifically: the first stage: temperature 350-450℃, hydrogen flow rate 10-15 m³ / h. 3 / h, heat preservation time is 1-2h; powder spreading height is no more than 1 / 2 of the height of the ceramic boat containing the powder; second stage: temperature is 750-800℃, hydrogen flow rate is 15-25m 3 The first stage involves holding the hydrogen gas at a flow rate of 20-30 m³ / h for 1-2 hours. The second stage involves maintaining the temperature at 850-950℃ for 1-2 hours. 3 / h, holding time is 1-2h; fourth stage: cooling rate is 5-10℃ / min, passivation temperature is 300-350℃, atmosphere is O2-N2 mixed gas with volume fraction of 5-8%, holding time is 30-60min.

[0095] S3. The composite powder and the copper powder are laid up and pressed in a structure of "bottom copper powder-composite powder-top copper powder" to obtain a composite compact. The composite compact is then melt-infiltrated and sintered to obtain a tungsten-copper alloy.

[0096] The layup method specifically involves: laying the composite powder and copper powder in a "bottom copper powder - composite powder - top copper powder" structure, with a mass ratio of bottom copper powder to top copper powder of 1:(1.2-1.5); the pressing method specifically involves: first holding the pre-pressed blank under a hydraulic press at 80-100 MPa for 15-20 seconds to obtain a pre-pressed blank, then cold isostatically pressing the pre-pressed blank under a pressure of 180-230 MPa for 30-50 seconds to obtain a density of 12.8-13.2 g / cm³. 3 Composite pressed preform.

[0097] The specific method of melt infiltration sintering is as follows: the composite compact is placed in an alumina boat of matching size, a pure tungsten counterweight is placed on top, and then placed together in a hydrogen furnace (vacuum degree <5×10). -3 The tungsten alloy is sintered according to the following process: Degassing stage: 1000-1100℃ for 1-2 hours, hydrogen flow rate 3-8 L / min, to remove residual gas from the pressed billet; Primary melting and infiltration: heating to 1200-1300℃ at 3-5℃ / min, applying pressure of 0.5-1.5 MPa and holding for 1-2 hours, hydrogen flow rate 2-5 L / min, copper phase initially wets the tungsten framework; Deep melting and infiltration: continuing to heat to 1300-1400℃, pressurizing to 1-1.5 MPa and holding for 0.5-2 hours, hydrogen flow rate 3-8 L / min, copper phase completely fills the pores; Cooling: cooling to room temperature in the furnace to obtain the tungsten-copper alloy.

[0098] The technical solution of this application will be further described below with reference to specific embodiments.

[0099] Example 1

[0100] A method for preparing a high thermal conductivity tungsten-copper alloy, the specific steps of which are as follows:

[0101] S1. Obtain ammonium paratungstate, copper oxide, copper tungstate, basic copper carbonate, silver-containing compounds, organic ligands, rare earth oxides, and copper powder as raw materials; by weight percentage, the raw materials contain 29.8 wt% copper, 70 wt% tungsten, 0.1 wt% silver, 0.05 wt% rare earth oxides, and 0.05 wt% organic ligands.

[0102] The mass ratio of copper oxide, copper tungstate, basic copper carbonate, and copper powder is 8.26:8.26:1.25:1; the mass ratio of ammonium paratungstate and copper tungstate is 3.01:1; the silver-containing compound is silver isooctanoate; the organic ligand is disodium ethylenediaminetetraacetate; the rare earth oxide is La2O3; the ammonium paratungstate is a single crystal with a smooth, crack-free surface and a tungsten content greater than 68%; the copper oxide is spherical with a particle size of 1.5 μm; the purity of copper tungstate is ≥99.9%; the purity of basic copper carbonate is ≥99.5% with a particle size of 2 μm; the purity of copper powder is ≥99.95% with a particle size of 2 μm; the purity of rare earth oxide is ≥99.9% with a particle size of 80 nm; and the purity of the organic ligand is ≥99%.

[0103] S2. Ammonium paratungstate, copper oxide, copper tungstate, basic copper carbonate, silver-containing compounds, organic ligands, and rare earth oxides are ball-milled to obtain a composite sol. The composite sol is dried to obtain a precursor powder. The precursor powder is then heat-treated to obtain a composite powder.

[0104] The ball milling method is as follows: ammonium paratungstate, copper oxide, copper tungstate, basic copper carbonate, silver-containing compounds, organic ligands, and rare earth oxides are mixed and loaded into a high-energy mixer, and dispersed at a cutter speed of 2800 r / min and a spindle speed of 55 r / min for 1.2 h to fully disperse the components; then the mixture is placed in a high-energy ball mill, anhydrous ethanol and polyvinyl alcohol dispersant are added, and ball milling is performed at a ball-to-material ratio of 5.5:1 and a frequency of 45 Hz for 4.5 h to obtain a composite sol;

[0105] The drying method is as follows: the composite sol is transported to a spray drying tower via a peristaltic pump, employing a combination of centrifugal spraying and side pressure atomization; the inlet temperature is 220℃, the outlet temperature is 90℃, the spray disc rotation speed is 15000 r / min, the side atomization pressure is 0.3 MPa, and the feed rate is 750 mL / min; after the slurry is atomized into tiny droplets, it is instantly dried by countercurrent contact with hot air, resulting in a sphericity of 96%, D50=10μm, and a bulk density of 2.0 g / cm³. 3 Precursor powder;

[0106] The heat treatment method is as follows: the precursor powder is calcined in air at 500℃ for 1.5h to decompose the metal salt into oxides, obtaining spherical powder of WO3-CuO-CuWO4-Ag-rare earth oxide composite oxide; after calcination, nitrogen gas is introduced to purge air and CO2 for 25min; subsequently, hydrogen reduction and passivation treatment are performed, specifically as follows:

[0107] Phase 1: Temperature 380℃, hydrogen flow rate 12m³ / h 3 / h, heat preservation time is 1.5h; powder spreading height is 1 / 3 of the height of the ceramic boat containing powder;

[0108] Phase 2: Temperature 770℃, hydrogen flow rate 20m³ / h 3 / h, heat preservation time is 1.5h;

[0109] Phase 3: Temperature 920℃, hydrogen flow rate 25m³ / h 3 / h, heat preservation time is 1.5h;

[0110] Fourth stage: The cooling rate is 8℃ / min, the passivation temperature is 325℃, the atmosphere is a mixture of O2-N2 gas with a volume fraction of 8%, and the holding time is 45min.

[0111] S3. The composite powder and the copper powder are laid up and pressed in a structure of "bottom copper powder-composite powder-top copper powder" to obtain a composite compact. The composite compact is then melt-infiltrated and sintered to obtain a tungsten-copper alloy.

[0112] The layup method is as follows: composite powder and copper powder are laid out in a "bottom layer copper powder - composite powder - top layer copper powder" structure, with a mass ratio of bottom layer copper powder to top layer copper powder of 1:1.3. The pressing method is as follows: first, the pre-pressed blank is held under a hydraulic press at 90 MPa for 18 seconds to obtain a pre-pressed blank, and then cold isostatically pressed at 200 MPa for 40 seconds to obtain a density of 13.0 g / cm³. 3 Composite pressed preform;

[0113] The specific method of melt infiltration sintering is as follows: the composite compact is placed in an alumina boat of matching size, a pure tungsten counterweight is placed on top, and then placed together in a hydrogen furnace (vacuum degree <5×10). -3 Pa), sintered according to the following process:

[0114] Exhaust stage: Hold at 1050℃ for 1.5h, with a hydrogen flow rate of 5L / min to remove residual gas from the pressed blank;

[0115] Primary melting and infiltration: The temperature is increased to 1250℃ at 4℃ / min, and the pressure of 1.0MPa is applied and the temperature is held for 1.5h. The hydrogen flow rate is 3L / min, and the copper phase initially wets the tungsten skeleton.

[0116] Deep melting and infiltration: continue heating to 1350℃, pressurize to 1.25MPa and hold for 1 hour, with a hydrogen flow rate of 5L / min, until the copper phase completely fills the pores;

[0117] Cooling: The tungsten-copper alloy is obtained by cooling the furnace to room temperature.

[0118] The tungsten-copper alloy prepared in Example 1 was tested, and the results showed that:

[0119] Please see Figure 1 and Figure 2 , Figure 1 This is an electron micrograph of the composite powder prepared in Example 1 of this application; Figure 2 Metallographic image of the tungsten-copper alloy prepared in Example 1 of this application;

[0120] The tungsten-copper alloy forms a three-level core-shell structure of "tungsten core - copper-silver solid solution shell - rare earth transition layer". The size of the tungsten core is 2.1 μm, the size of the copper-silver solid solution shell is 60 nm, and the size of the rare earth transition layer is 2 nm. The CV value of the tungsten particles in the tungsten-copper alloy is 10%. The tungsten-copper alloy forms a silver nanophase and a copper phase. The tungsten phase is uniform, the copper phase is continuous and non-porous, and the interface is tightly bonded. The silver nanophase penetrates the copper phase to form a continuous heat conduction channel in the tungsten-copper alloy.

[0121] The composition of the tungsten-copper alloy is: W - 70.1wt%, Cu - 29.75wt%, Ag - 0.09wt%, La2O3 - 0.06wt%;

[0122] The density is 99.8%, the hardness is 242 HV, the electrical conductivity is 81% IACS, the thermal conductivity is 242 W / (m·K) (laser flare method), and the interfacial thermal resistance is 1.5 × 10⁻⁶. -4 m 2 • K / W, porosity 0.2%.

[0123] Example 2

[0124] The difference between this embodiment and Embodiment 1 is that, in step S1, the raw materials contain 29.8 wt% copper, 70 wt% tungsten, 0.12 wt% silver, 0.03 wt% rare earth oxides, and 0.05 wt% organic ligand by weight percentage.

[0125] The mass ratio of copper oxide, copper tungstate, basic copper carbonate, and copper powder is 7.06:4.71:1.27:1; the mass ratio of ammonium paratungstate and copper tungstate is 4.63:1; the silver-containing compound is silver carbonate; the organic ligand is citric acid; and the rare earth oxide is CeO2.

[0126] In step S2:

[0127] Phase 1: Temperature 350℃, hydrogen flow rate 15m³ / h 3 / h, heat preservation time is 2h; powder spreading height is 1 / 3 of the height of the ceramic boat containing powder;

[0128] Phase 2: Temperature 750℃, hydrogen flow rate 15m³ / h 3 / h, heat preservation time 2h;

[0129] Phase 3: Temperature 850℃, hydrogen flow rate 30m³ / h 3 / h, heat preservation time 2h;

[0130] Fourth stage: The cooling rate is 5℃ / min, the passivation temperature is 350℃, the atmosphere is a 5% volume fraction O2-N2 mixed gas, and the holding time is 30min;

[0131] In step S3:

[0132] The mass ratio of bottom copper powder to top copper powder is 1:1.2. The pressing method is as follows: first, the pre-pressed blank is held under a pressure of 80MPa for 20 seconds in a hydraulic press to obtain a pre-pressed blank. Then, the pre-pressed blank is cold isostatically pressed under a pressure of 180MPa for 50 seconds to obtain a density of 12.8g / cm³. 3 Composite pressed preform;

[0133] Exhaust stage: Hold at 1000℃ for 2 hours, with hydrogen flow rate of 3L / min to remove residual gas from the compact;

[0134] Primary melting and infiltration: The temperature is increased to 1200℃ at 3℃ / min, and the pressure of 0.5MPa is applied and the temperature is held for 2h. The hydrogen flow rate is 2L / min, and the copper phase initially wets the tungsten skeleton.

[0135] Deep melting and infiltration: continue heating to 1300℃, pressurize to 1.5MPa and hold for 2 hours, with hydrogen flow rate of 3L / min, until the copper phase completely fills the pores;

[0136] Cooling: The furnace is cooled to room temperature to obtain the tungsten-copper alloy.

[0137] All other steps are the same as in Example 1.

[0138] The tungsten-copper alloy prepared in Example 2 was tested, and the results showed that: Please refer to [link / reference needed]. Figure 3 , Figure 3 Metallographic image of the tungsten-copper alloy prepared in Example 2 of this application;

[0139] The tungsten-copper alloy forms a three-level core-shell structure of "tungsten core - copper-silver solid solution shell - rare earth transition layer". The size of the tungsten core is 2.4 μm, the size of the copper-silver solid solution shell is 50 nm, and the size of the rare earth transition layer is 3 nm. The CV value of the tungsten particles in the tungsten-copper alloy is 11%. The tungsten-copper alloy forms a silver nanophase and a copper phase. The silver nanophase penetrates the copper phase to form a continuous heat conduction channel in the tungsten-copper alloy.

[0140] The composition of the tungsten-copper alloy is: W - 70.1wt%, Cu - 29.76wt%, Ag - 0.11wt%, CeO2 - 0.03wt%;

[0141] Density: 99.7%, Hardness: 238 HV, Electrical Conductivity: 79% IACS; Thermal Conductivity: 238 W / (m·K), Interfacial Thermal Resistance: 1.6 × 10⁻⁶ -4 m 2 K / W, porosity 0.3%.

[0142] Example 3

[0143] The difference between this embodiment and Embodiment 1 is that, in step S1, the content of copper in the raw material is 19.86 wt%, the content of tungsten in the raw material is 80 wt%, the content of silver in the raw material is 0.08 wt%, the content of rare earth oxides in the raw material is 0.02 wt%, and the content of organic ligand in the raw material is 0.04 wt%.

[0144] The mass ratio of copper oxide, copper tungstate, basic copper carbonate, and copper powder is 8.73:7.28:0.94:1; the mass ratio of ammonium paratungstate and copper tungstate is 6.61:1; the silver-containing compound is silver isooctanoate; the organic ligand is disodium ethylenediaminetetraacetate; and the rare earth oxide is La2O3.

[0145] In step S2:

[0146] Phase 1: Temperature 450℃, hydrogen flow rate 10m³ / h 3 / h, the heat preservation time is 1h; the powder spreading height is 1 / 3 of the height of the ceramic boat containing the powder;

[0147] Phase Two: Temperature 800℃, Hydrogen Flow Rate 25m³ / h 3 / h, heat preservation time 1h;

[0148] Phase 3: Temperature 950℃, hydrogen flow rate 20m³ / h 3 / h, heat preservation time 1h;

[0149] Fourth stage: The cooling rate is 10℃ / min, the passivation temperature is 300℃, the atmosphere is a mixture of O2-N2 gas with a volume fraction of 8%, and the holding time is 60min;

[0150] In step S3:

[0151] The mass ratio of bottom copper powder to top copper powder is 1:1.5. The pressing method is as follows: first, the pre-pressed blank is held at 100 MPa for 15 seconds using a hydraulic press to obtain a pre-pressed blank; then, the pre-pressed blank is cold isostatically pressed at 230 MPa for 30 seconds to obtain a density of 13.2 g / cm³. 3 Composite pressed preform;

[0152] Exhaust stage: Hold at 1100℃ for 1 hour, with hydrogen flow rate of 8L / min to remove residual gas from the compact;

[0153] Primary melting and infiltration: The temperature is increased to 1300℃ at 5℃ / min, and the pressure of 1.5MPa is applied and the temperature is held for 1h. The hydrogen flow rate is 5L / min, and the copper phase initially wets the tungsten skeleton.

[0154] Deep melting and infiltration: continue heating to 1400℃, pressurize to 1MPa and hold for 0.5h, hydrogen flow rate is 8L / min, copper phase completely fills the pores;

[0155] Cooling: The furnace is cooled to room temperature to obtain the tungsten-copper alloy.

[0156] All other steps are the same as in Example 1.

[0157] The tungsten-copper alloy prepared in Example 3 was tested, and the results showed that the alloy composition was W-80.2wt%, Cu-19.7wt%, Ag-0.081wt%, and La2O3-0.019wt%.

[0158] The tungsten-copper alloy forms a three-level core-shell structure of "tungsten core - copper-silver solid solution shell - rare earth transition layer". The size of the tungsten core is 2.9 μm, the size of the copper-silver solid solution shell is 70 nm, and the size of the rare earth transition layer is 5 nm. The CV value of the tungsten particles in the tungsten-copper alloy is 9%. The tungsten-copper alloy forms a silver nanophase and a copper phase. The silver nanophase penetrates the copper phase to form a continuous heat conduction channel in the tungsten-copper alloy.

[0159] It has a density of 99.6%, a hardness of 285 HV, an electrical conductivity of 78% IACS, a thermal conductivity of 282 W / (m·K), and an interfacial thermal resistance of 1.8 × 10⁻⁶. -4 m 2 K / W, porosity 0.3%.

[0160] Comparative Example 1

[0161] The difference between this comparative example and Example 1 is that there is no silver source and no rare earth oxides are added for reinforcement in the comparative example, while all other steps are the same as in Example 1.

[0162] The tungsten-copper alloy prepared in Comparative Example 1 was tested, and the results showed that: Please refer to [link / reference needed]. Figure 4, Figure 4 Metallographic image of the tungsten-copper alloy prepared in Comparative Example 1 of this application;

[0163] The tungsten-copper alloy composition is W-70.1wt% and Cu-29.9wt%.

[0164] Without silver phase reinforcement, the copper phase thermal conductivity channels are discontinuous, resulting in decreased thermal conductivity; the density is 98.9%, the hardness is 226 HV, the electrical conductivity is 74% IACS, the thermal conductivity is 215 W / (m·K), and the interfacial thermal resistance is 1.9 × 10⁻⁶. -4 m 2 • K / W, porosity 0.4%.

[0165] Comparative Example 2

[0166] The difference between this comparative example and Example 1 is that the comparative example uses a non-melting infiltration preparation method, and the tungsten-copper alloy is prepared by hot pressing sintering. The raw materials are exactly the same as in Example 1. Copper powder is added to the raw materials, mixed, granulated, and reduced to prepare composite powder. Then, the obtained powder is loaded into a graphite mold and placed in a hot pressing sintering furnace along with the mold. First, a vacuum is drawn to 10. -2 -10 -3 Pa, introduce Ar2 at 3L / min, then heat to 750℃ at a heating rate of 8℃ / min and hold for 60min, then heat to 1200℃ at a heating rate of 5℃ / min and hold for 90min, while applying a pressure of 25MPa at around 1086℃ for pressure sintering. After sintering, maintain the pressure and cool down to around 300℃. All other steps are the same as in Example 1.

[0167] The tungsten-copper alloy prepared in Comparative Example 2 was tested, and the results are as follows: Please refer to [link / reference needed]. Figure 5 , Figure 5 Metallographic image of the tungsten-copper alloy prepared in Comparative Example 2 of this application;

[0168] The composition of the tungsten-copper alloy is: W - 70.1wt%, Cu - 29.8wt%, Ag - 0.08wt%, La2O3 - 0.02wt%.

[0169] The alloy prepared by hot pressing and sintering has a relatively high porosity, slightly higher interfacial thermal resistance, lower thermal conductivity, and lower hardness. Its density is 98.3%, hardness is 219 HV, electrical conductivity is 73% IACS, thermal conductivity is 219 W / (m·K), and interfacial thermal resistance is 2.8 × 10⁻⁶. - 4 m 2 • K / W, porosity 0.7%.

[0170] Comparative Example 3

[0171] The difference between this comparative example and Example 1 is that copper tungstate is not used as the copper source to prepare the alloy, and ammonium paratungstate is used as the only tungsten source. The mass ratio of copper oxide, basic copper carbonate and copper powder is 8.26:1.25:1.

[0172] All other steps are the same as in Example 1.

[0173] The tungsten-copper alloy prepared in Comparative Example 3 was tested, and the results show that: Please refer to [link / reference needed]. Figure 6 , Figure 6 This is an electron microscope image of the composite powder prepared in Comparative Example 3 of this application;

[0174] The tungsten-copper alloy composition is W-70.1wt%, Cu-29.781wt%, Ag-0.09wt%, and La2O3-0.029wt%.

[0175] The tungsten particles were severely agglomerated, lacking a core-shell structure, with a density of 98.2% (due to insufficient copper phase filling in the tungsten matrix without CuWO4-induced copper coating). The hardness was 225 HV, and the electrical conductivity was 72% IACS (due to poor copper interconnectivity and decreased silver phase dispersion uniformity). The thermal conductivity was 210 W / (m·K) (due to the lack of CuWO4-assisted formation of continuous thermal conduction channels), and the interfacial thermal resistance was 2.8 × 10⁻⁶. -4 m 2 K / W, porosity 0.8%.

[0176] Comparative Example 4

[0177] The difference between this comparative example and Example 1 is that there is no silver source in the comparative example, but all other steps are the same as in Example 1.

[0178] The tungsten-copper alloy prepared in Comparative Example 4 was tested, and the results showed that there was no silver phase bridging, the copper phase thermal conduction channel was discontinuous, and the thermal conductivity decreased.

[0179] The tungsten-copper alloy composition is W-70.1wt%, Cu-29.852wt%, and La2O3-0.048wt%.

[0180] The density is 99.1%, the hardness is 236 HV, the electrical conductivity is 76% IACS, the thermal conductivity is 208 W / (m·K), and the interfacial thermal resistance is 1.88 × 10⁻⁶. -4 m 2 • K / W, porosity 0.4%.

[0181] Comparative Example 5

[0182] The difference between this comparative example and Example 1 is that the composite powder was prepared by one-step reduction and the tungsten-copper alloy was prepared by subsequent melt infiltration sintering. The raw materials were exactly the same as those in Example 1. The reduction temperature of the composite powder was 750 / 800 / 850℃ and the holding time was 30 / 90 / 60min. All other steps were the same as those in Example 1.

[0183] The tungsten-copper alloy prepared in Comparative Example 5 was tested, and the results showed that the prepared composite powder had some sandwich structure and insufficient reduction, which led to an increase in impurity phases in the alloy and a decrease in performance.

[0184] The composition of the tungsten-copper alloy is: W - 70.1wt%, Cu - 29.8wt%, Ag - 0.07wt%, La2O3 - 0.03wt%;

[0185] The density is 98.6%, the hardness is 209 HV, the electrical conductivity is 71% IACS, the thermal conductivity is 201 W / (m·K), and the interfacial thermal resistance is 3.2 × 10⁻⁶. -4 m 2 • K / W, porosity 0.7%.

[0186] Comparative Example 6

[0187] The difference between this comparative example and Example 1 is that basic copper carbonate is not used as the copper source to prepare the alloy, and the mass ratio of copper oxide, copper tungstate, and copper powder is 8.26:8.26:1.

[0188] All other steps are the same as in Example 1.

[0189] The tungsten-copper alloy prepared in Comparative Example 6 was tested, and the results showed that the alloy composition was W-70.1wt%, Cu-29.781wt%, Ag-0.09wt%, and La2O3-0.029wt%.

[0190] The density is 98.8% (due to the CO2 produced during the decomposition of basic copper carbonate, which acts as a drainage channel, the infiltration channels close prematurely, further hindering the infiltration of the copper phase into the alloy and resulting in insufficient copper phase filling), the hardness is 218 HV, the electrical conductivity is 75% IACS, the thermal conductivity is 216 W / (m·K), and the interfacial thermal resistance is 2.4 × 10⁻⁶. -4 m 2 K / W, porosity 0.5%.

[0191] As can be seen from the above embodiments and comparative examples: Embodiment 1, combined with Comparative Example 1, shows that the combination scheme of "composite copper source + mixed tungsten source + four-stage integrated process + gradient dynamic pressure melting infiltration" adopted in this application can improve the alloy density and reduce the interfacial thermal resistance compared with traditional tungsten-copper alloys without silver source and without rare earth oxide reinforcement. Embodiment 1, combined with Comparative Example 2, shows that pressure melting infiltration can effectively improve the uniformity of the pore dispersion of the billet, promote the entry of the copper phase into the interior of the alloy, improve the alloy density, and thus improve the mechanical and thermal properties. Embodiment 1, combined with Comparative Example 3, shows that copper tungstate, as a dual component of composite copper source and mixed tungsten source, contains copper that can induce the reduction of elemental copper to coat the tungsten matrix, promote interfacial bonding, and the absence of copper significantly reduces the alloy density, hardness, and thermal and electrical conductivity, confirming its important regulatory role in microstructure and properties. Embodiment 1, combined with Comparative Example 4, shows that the addition of trace amounts of silver... The key to improving the electrical and thermal conductivity of tungsten-copper alloys lies in the silver-free system. The reduced electrical and thermal conductivity of the alloy highlights the reinforcing effect of the composite silver system. Example 1, combined with Comparative Example 5, shows that the composite powder prepared using the four-stage integrated reduction method is prone to sandwich formation and insufficient reduction, leading to a sharp decline in performance during subsequent alloy preparation. Example 1, combined with Comparative Example 6, shows that the use of basic copper carbonate, due to the unblocking effect of CO2, provides a connecting channel for copper phase melting and infiltration, improving the alloy's thermal properties. Combining the above examples and comparative examples, this application proposes a high thermal conductivity tungsten-copper alloy and its preparation method. Through an innovative technical approach, a superior microstructure of "tungsten core-copper-silver solid solution shell-rare earth transition layer" is constructed, enabling the alloy to possess a high density of 99.5% or higher, a high thermal conductivity of 235 W / (m·K) or higher, a high electrical conductivity of 78% IACS or higher, and a thermal conductivity of 1.8 × 10⁻⁶. -4 m 2 With a low interfacial thermal resistance of K / W and below, its overall performance is significantly better than that of tungsten-copper alloys prepared by traditional processes, fully meeting the heat dissipation requirements of cutting-edge fields such as aerospace and electronic packaging.

[0192] This application proposes a high thermal conductivity tungsten-copper alloy and its preparation method. Ammonium paratungstate and copper tungstate are used as a mixed tungsten source, while copper oxide, copper tungstate, and basic copper carbonate are used as a composite copper source. An organic / low-toxicity inorganic silver-containing compound-organic ligand composite silver system (preferably silver isooctanoate, alternatively silver carbonate) is added, and trace amounts of rare earth oxides are introduced to regulate the interface. This improves the alloy's electrical and thermal conductivity, powder coating uniformity, and interfacial bonding strength while avoiding harmful gas emissions. A tungsten-copper-silver composite powder is prepared, and this composite powder is used to prepare a silver-reinforced tungsten-copper alloy. The tungsten-copper alloy exhibits excellent thermal and electrical conductivity, high strength, and extremely low interfacial heat. The process involves using ammonium paratungstate and copper tungstate as a mixed tungsten source, with copper in copper tungstate inducing the reduction of elemental copper to coat the tungsten matrix; a composite copper source (copper oxide + copper tungstate + basic copper carbonate) provides a portion of the copper in the tungsten-copper alloy, and the calcination and decomposition of basic copper carbonate produces CO2, achieving "in-situ pore creation and copper replenishment" to fill the micropores in the tungsten skeleton; in the composite silver system, organic ligands control the low-temperature decomposition rate of silver-containing compounds, allowing silver to be uniformly dispersed in the copper phase in the form of nanoparticles / short fibers; rare earth oxides preferentially accumulate at the tungsten-copper interface, forming a 1-5 nm thick rare earth doped transition layer to reduce interfacial thermal resistance; the remaining copper is obtained by copper powder melt infiltration.

[0193] The technological innovations of this application are as follows:

[0194] (1) Synergistic dispersion of “composite silver system + organic ligand”: Silver isooctanoate / silver carbonate is used instead of silver nitrate, decomposition without harmful gas, and organic ligand controls the uniform dispersion of silver in nano-form, which is superior to the dispersion effect of existing silver-containing compounds.

[0195] (2) "Composite copper source + in-situ hole making" design: Basic copper carbonate, copper oxide and copper tungstate work together to decompose and generate CO2 to clear the powder channels, and the copper interconnection rate is increased by more than 10%, solving the problem of insufficient filling of traditional copper sources;

[0196] (3) Four-stage integrated process: Low-temperature silver dispersion-deep reduction-homogenization-passivation are carried out in a continuous manner, reducing energy consumption by 15% and avoiding powder oxidation, so as to achieve precise and controllable composite powder structure;

[0197] (4) Gradient copper layer + dynamic pressure melting and infiltration: The upper thick copper layer utilizes gravity-assisted infiltration and dynamic pressure control to achieve complete filling of the copper phase, increasing the density to 99.5%-99.9% and reducing the interface thermal resistance by more than 30%.

[0198] The above description is only a preferred embodiment of this application and does not limit the patent scope of this application. All equivalent structural transformations made using the content of this application's specification under the inventive concept of this application, or direct / indirect applications in other related technical fields, are included within the patent protection scope of this application.

Claims

1. A method for producing a high thermal conductivity tungsten copper alloy, characterized by, The method comprises the following steps: S1, obtaining ammonium paratungstate, copper oxide, cupric tungstate, basic copper carbonate, silver-containing compound, organic complexing agent, rare earth oxide and copper powder as raw materials; the content of copper in the raw materials is 9.85-39.95wt%, the content of tungsten in the raw materials is 60-90wt%, the content of silver in the raw materials is 0.05-0.15wt%, the content of rare earth oxide in the raw materials is 0.01-0.05wt%, and the content of organic complexing agent in the raw materials is 0.015-0.12wt%; S2, ball milling the ammonium paratungstate, the copper oxide, the cupric tungstate, the basic copper carbonate, the silver-containing compound, the organic complexing agent and the rare earth oxide to obtain a composite sol, drying the composite sol to obtain a precursor powder, and heat treating the precursor powder to obtain a composite powder; S3, layering and pressing the composite powder and the copper powder according to the structure of bottom copper powder-composite powder-top copper powder to obtain a composite green compact, and sintering the composite green compact by infiltration to obtain a tungsten-copper alloy; In the step S1, the copper in the raw materials is derived from the copper oxide, the cupric tungstate, the basic copper carbonate and the copper powder, wherein the mass ratio of the copper oxide, the cupric tungstate, the basic copper carbonate and the copper powder is (7-9):(4-10):(0.5-1.5):1; The tungsten in the raw materials is derived from the ammonium paratungstate and the cupric tungstate, wherein the mass ratio of the ammonium paratungstate and the cupric tungstate is (2.5-7):1; The silver in the raw materials is derived from the silver-containing compound, the silver-containing compound comprising at least one of silver iso-octoate or silver carbonate; the organic complexing agent comprising at least one of disodium ethylenediaminetetraacetate or citric acid; and the rare earth oxide comprising at least one of La2O3 or CeO2; In the step S2, the heat treatment is specifically as follows: calcining the precursor powder at 450-550℃ in air for 1-2h to decompose the metal salt into an oxide and obtain a WO3-CuO-CuWO4-Ag-rare earth oxide composite oxide spherical powder; after calcination, nitrogen gas is introduced to exhaust air and CO2, and the duration is 20-30min; and then hydrogen reduction and passivation treatment are performed, specifically as follows: First stage: temperature is 350-450℃, hydrogen flow is 10-15m 3 / h, holding time is 1-2h; powder laying height is not more than 1 / 2 of the height of powder loading ceramic boat Second stage: temperature 750-800°C, hydrogen flow rate 15-25 m 3 / h, holding time 1-2 h; Third stage: temperature is 850-950℃, hydrogen flow is 20-30m 3 / h, holding time is 1-2h; In the fourth stage, the cooling rate is 5-10℃ / min, the passivation temperature is 300-350℃, the atmosphere is 5-8% O2-N2 mixed gas by volume fraction, and the holding time is 30-60min.

2. The method of claim 1, wherein the high thermal conductivity tungsten copper alloy is prepared by the steps of: providing a tungsten copper alloy; and annealing the tungsten copper alloy at a temperature of 800°C to 1200°C for 1 to 10 hours. The ammonium paratungstate in the step S1 is single-crystal ammonium paratungstate, which is smooth in surface and has no cracks, and the tungsten content is greater than 68%; the copper oxide is spherical, the particle size of the copper oxide is 0.5-2 μm; the purity of the cupric tungstate is ≥99.9%; the purity of the basic copper carbonate is ≥99.5%, and the particle size of the basic copper carbonate is 1-3 μm; the purity of the copper powder is ≥99.95%, and the particle size of the copper powder is 1-3 μm; the purity of the rare earth oxide is ≥99.9%, and the particle size of the rare earth oxide is 50-100 nm; the purity of the organic complexing agent is ≥99%.

3. The method of claim 1, wherein the high thermal conductivity tungsten copper alloy is prepared by the steps of: providing a tungsten copper alloy; and annealing the tungsten copper alloy at a temperature of 800°C to 1200°C for 1 to 10 hours. In the step S2, the ball milling method is specifically as follows: the ammonium paratungstate, the copper oxide, the cupric tungstate, the basic copper carbonate, the silver-containing compound, the organic complexing agent and the rare earth oxide are mixed and loaded into a high-energy mixer, and are dispersed at a fly-knife rotating speed of 2500-3000 r / min and a main shaft rotating speed of 50-60 r / min for 1-1.5 h to sufficiently disperse the components; Then, the mixture is placed in a high-energy ball mill, anhydrous ethanol and polyvinyl alcohol dispersant are added, and ball milling is carried out at a ball-to-material ratio of (5-6):1 and a frequency of 40-50 Hz for 4-5 h to obtain the composite sol. The drying method is specifically as follows: the composite sol is delivered to a spray drying tower by a peristaltic pump, and a centrifugal spraying+side pressure atomization composite method is adopted; the inlet temperature is 210-225 DEG C, the outlet temperature is 88-92 DEG C, the spraying disc rotating speed is 14000-16000 r / min, the side atomization pressure is 0.2-0.4 MPa, and the feeding speed is 700-800 mL / min; after the slurry is atomized into tiny droplets, the tiny droplets are dried instantaneously by countercurrent contact with hot air, and the precursor powder with sphericity ≥95%, D50=5-18 μm and loose bulk density of 1.95-2.1 g / cm 3 .

4. The method of claim 1, wherein the high thermal conductivity tungsten copper alloy is prepared by the steps of: providing a tungsten copper alloy; and annealing the tungsten copper alloy at a temperature of 800°C to 1200°C for 1 to 10 hours. The step S3 is specifically: the composite powder and the copper powder are laid according to the structure of bottom copper powder-composite powder-top copper powder: the mass ratio of the bottom copper powder and the top copper powder is 1:(1.2-1.5); the pressing is specifically: first, the pre-compacted blank is obtained under the pressure of 80-100 MPa of the oil press for 15-20 seconds, and then the pre-compacted blank is cold isostatic pressed under the pressure of 180-230 MPa for 30-50 seconds to obtain the composite compact with the density of 12.8-13.2 g / cm 3 .

5. The method of claim 1, wherein the high thermal conductivity tungsten copper alloy is prepared by the steps of: providing a tungsten copper alloy; and annealing the tungsten copper alloy at a temperature of 800°C to 1200°C for 1 to 10 hours. In the step S3, the sintering method is specifically as follows: the composite compact is placed in an alumina boat with a matching size, a pure tungsten weight block is placed on the top, and they are placed in a hydrogen furnace and sintered according to the following process: The exhaust stage: 1000-1100℃ for 1-2 h, hydrogen flow rate is 3-8 L / min, and residual gas of the compact is removed; The primary infiltration: the temperature is increased to 1200-1300℃ at a rate of 3-5℃ / min, a pressure of 0.5-1.5 MPa is applied for 1-2 h, the hydrogen flow rate is 2-5 L / min, and the copper phase is preliminarily infiltrated into the tungsten skeleton; The deep infiltration: the temperature is continuously increased to 1300-1400℃, the pressure is increased to 1-1.5 MPa for 0.5-2 h, the hydrogen flow rate is 3-8 L / min, and the copper phase is completely filled in the pores; Cooling: cooling to room temperature in the furnace to obtain the tungsten-copper alloy.

6. A high thermal conductivity tungsten copper alloy characterized by, The tungsten-copper alloy is prepared by the method of any one of claims 1-5.

7. The high thermal conductivity tungsten copper alloy of claim 6, wherein, The tungsten-copper alloy forms a tungsten core-copper-silver solid solution shell-rare earth transition layer three-level core-shell structure, the size of the tungsten core is 1-3 μm, the size of the copper-silver solid solution shell is 50-100 nm, the size of the rare earth transition layer is 1-5 nm, the CV value of the tungsten particles of the tungsten-copper alloy is ≤12%, the tungsten-copper alloy forms a silver nano-phase and a copper phase, the silver nano-phase penetrates through the copper phase to form a continuous heat conduction channel in the tungsten-copper alloy, and the porosity of the tungsten-copper alloy is ≤0.3%.

8. The high thermal conductivity tungsten copper alloy of claim 6, wherein, The tungsten copper alloy has a density ≥ 99.5%, the tungsten copper alloy has an electrical conductivity ≥ 78% IACS, the tungsten copper alloy has a thermal conductivity ≥ 235 W / (m·K), the tungsten copper alloy has a hardness ≥ 235 HV, and the tungsten copper alloy has an interface thermal resistance ≤ 1.8×10 -4 m 2 K / W.

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