Tungsten-copper alloy, method for preparing the same, and electronic device
By using ammonium metatungstate and dispersants during the preparation process to form a uniform tungsten skeleton, the problem of uneven pore distribution in tungsten-copper alloys was solved, achieving uniform thermal stress distribution and improved high-temperature service performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- JIANGXI COPPER TECHNOLOGY RESEARCH INSTITUTE CO LTD
- Filing Date
- 2025-08-13
- Publication Date
- 2026-08-04
AI Technical Summary
The existing tungsten-copper alloy manufacturing process suffers from uneven pore distribution and large fluctuations in pore size gradient, leading to thermal stress concentration and easy crack propagation during high-temperature service.
A pore-forming agent solution was prepared using ammonium metatungstate, a dispersant, and ammonia. A uniform tungsten skeleton was formed through solid-liquid mixing and multi-stage heat treatment to control the air gap distribution. Subsequently, it was melt-infiltrated with copper to form a tungsten-copper alloy.
This method achieves uniform thermal stress distribution in tungsten-copper alloys, improves high-temperature service performance, prevents crack propagation, and ensures the stability and electrical and thermal conductivity of the alloy.
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Figure CN121006456B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of metal matrix composite technology, specifically to a tungsten-copper alloy, its preparation method, and electronic devices. Background Technology
[0002] Tungsten-copper alloy (W-Cu) is widely used in electronic packaging, electrical contacts, and high-temperature electrodes due to its high melting point, high thermal conductivity, and low coefficient of thermal expansion. Currently, W-Cu alloys are mainly prepared using an infiltration process. The main preparation method involves first preparing a porous tungsten framework, then infiltrating molten copper into the tungsten framework to ultimately form the tungsten-copper alloy.
[0003] Currently, the tungsten framework prepared by existing processes has problems such as uneven pore distribution, large fluctuations in pore size gradient, and high randomness of permeation path. As a result, the tungsten-copper alloy obtained after copper infiltration has problems such as local thermal stress concentration and easy crack propagation during high-temperature service. Summary of the Invention
[0004] The purpose of this application is to overcome the shortcomings of the prior art and provide a tungsten-copper alloy, its preparation method, and electronic devices.
[0005] To achieve the above objectives, the technical solution adopted in this application is as follows: The first aspect of this application provides a method for preparing a tungsten-copper alloy, comprising the following steps:
[0006] The dispersant was added to a saturated aqueous solution of ammonium metatungstate and stirred until homogeneous. Then ammonia was added to obtain a pore-forming agent solution with a pH ≥ 7.8.
[0007] The tungsten powder and the pore-forming agent solution are mixed and homogenized to obtain a mixed slurry.
[0008] The mixed slurry is dried at a temperature of 20-60℃ to obtain composite powder;
[0009] The composite powder is subjected to decomposition heat treatment, reduction heat treatment and sintering treatment in sequence to obtain a tungsten framework; the temperature of the decomposition heat treatment is less than the temperature of the reduction heat treatment and the temperature of the sintering treatment.
[0010] The tungsten framework and copper are subjected to melt infiltration treatment to obtain a tungsten-copper alloy.
[0011] In some embodiments, the temperature of the decomposition heat treatment is 350-450°C.
[0012] In some embodiments, the decomposition heat treatment time is 0.5-2 hours.
[0013] In some embodiments, the heating rate of the decomposition heat treatment is 8-10 °C / min.
[0014] In some embodiments, the temperature of the reduction heat treatment is 550-600°C.
[0015] In some embodiments, the reduction heat treatment time is 0.5-1 hour.
[0016] In some embodiments, the heating rate of the reduction heat treatment is 3-5°C / min.
[0017] In some embodiments, the atmosphere of the reduction heat treatment is a hydrogen-argon mixed atmosphere; preferably, the volume flow ratio of hydrogen to argon in the hydrogen-argon mixed atmosphere is (1:3)-(1:5).
[0018] In some embodiments, the sintering temperature is 1600-2100°C.
[0019] In some embodiments, the sintering process takes 1-4 hours.
[0020] In some embodiments, the heating rate of the sintering process is 10-20 °C / min.
[0021] In some embodiments, the atmosphere for the decomposition heat treatment, reduction heat treatment and sintering treatment is a reducing atmosphere; preferably, the atmosphere for the reduction heat treatment is a hydrogen-argon mixture, wherein the volume flow ratio of hydrogen to argon in the hydrogen-argon mixture is (1:3)-(1:5).
[0022] In some embodiments, the dispersant is at least one selected from polyvinylpyrrolidone, polyethylene glycol, and sodium polyacrylate;
[0023] In some embodiments, the mass of the dispersant is 0.5-1% of the mass of the saturated aqueous solution of ammonium metatungstate.
[0024] In some embodiments, the drying process is carried out at a temperature of 40-60°C and a vacuum degree of 1-10 Pa.
[0025] In some embodiments, the specific steps of mixing and homogenizing the tungsten powder and the pore-forming agent solution to obtain the mixed slurry are as follows:
[0026] Tungsten powder and the pore-forming agent are premixed and then subjected to ultrasonic treatment at a frequency of 40-120 Hz for 1-2 hours.
[0027] In some embodiments, the parameters of the melt infiltration treatment satisfy at least one of the following:
[0028] (a) The mass ratio of the tungsten skeleton to copper is (15:1)-(1:1);
[0029] (b) The temperature of the melt infiltration treatment is 1300-1500℃;
[0030] (c) The vacuum degree of the infiltration treatment is 0.1 × 10⁻⁶. 5 -0.5×10 5 Pa;
[0031] (d) The melting and infiltration treatment lasts for 2-4 hours.
[0032] In some embodiments, the vacuum degree of the drying process is 1-10 Pa.
[0033] A second aspect of this application provides a tungsten-copper alloy, which is prepared by the method for preparing tungsten-copper alloys.
[0034] A third aspect of this application provides an electronic device comprising the aforementioned tungsten-copper alloy.
[0035] Compared with the prior art, the beneficial effects of this application are as follows:
[0036] In the preparation method of the tungsten-copper alloy provided in this application, firstly, a pore-forming agent solution meeting the pH requirements is prepared by using ammonium metatungstate, a dispersant, ammonia, and deionized water. Then, solid tungsten powder and the pore-forming agent solution are mixed and homogenized through solid-liquid mixing to obtain a mixed slurry. Next, the mixed slurry is dried to form a composite powder. During the drying process, ammonium metatungstate crystals in the pore-forming agent solution precipitate and adhere to adjacent tungsten particles, and the size of the ammonium metatungstate crystals is controlled within an ideal nanoscale range. Then, the composite powder is subjected to multi-stage heat treatment at different temperatures (decomposition heat treatment temperature < reduction heat treatment temperature < sintering temperature). During the decomposition heat treatment and reduction heat treatment processes, the NH4+ in the ammonium metatungstate crystals... + H2O is released in gaseous form in steps, creating air gaps. WO3 is reduced to tungsten microparticles that adhere to the surface of the tungsten particles. During the sintering process, the tungsten microparticles, tungsten particles, and air gaps work together to form a tungsten skeleton. The air gaps in the tungsten skeleton are evenly distributed, and the pore size gradient of the air gaps fluctuates little. When the tungsten skeleton is infiltrated with pure copper, the infiltration path of the pure copper is easy to control, avoiding the formation of micron-sized copper pools in the larger air gaps in the tungsten skeleton. This results in a uniform distribution of thermal stress in the tungsten-copper alloy, stable performance under high-temperature service, and less susceptibility to crack propagation. Attached Figure Description
[0037] Figure 1 Here is a SEM image of the composite powder from Example 1;
[0038] Figure 2 Metallographic image of the tungsten-copper alloy of Example 1;
[0039] Figure 3 Metallographic diagram of the tungsten-copper alloy in Comparative Example 1;
[0040] Figure 4 The image shows the metallographic diagram of the tungsten-copper alloy in Comparative Example 2. Detailed Implementation
[0041] To facilitate understanding of this application, a more complete description will be provided below. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.
[0042] As used in this article:
[0043] "Prepared from" is synonymous with "comprising". The terms "comprising", "including", "having", "containing", or any other variations thereof as used herein are intended to cover non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that includes the listed elements is not necessarily limited to those elements, but may include other elements not expressly listed or elements inherent to such composition, step, method, article, or apparatus.
[0044] The conjunction "composed of..." excludes any unspecified elements, steps, or components. If used in a claim, this phrase makes the claim closed, excluding materials other than those described, except for associated conventional impurities. When the phrase "composed of..." appears in a clause of the body of a claim rather than immediately following it, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.
[0045] When a quantity, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pair of any upper or preferred value with any lower or preferred value, regardless of whether the range is disclosed individually. For example, when the range “1-5” is disclosed, the described range should be interpreted as including ranges “1-4”, “1-3”, “1-2”, “1-2 and 4-5”, “1-3 and 5”, etc. When numerical ranges are described herein, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within that range.
[0046] In these embodiments, unless otherwise specified, the portions and percentages are all by weight.
[0047] "Parts by mass" refers to the basic unit of measurement that expresses the mass ratio of multiple components. One part can represent any unit mass, such as 1g or 2.689g. If we say that component A has 'a' parts by mass and component B has 'b' parts by mass, it means that the mass ratio of component A to component B is a:b. It is important to understand that, unlike mass percentage content, the sum of the mass parts of all components is not limited to 100 parts.
[0048] "And / or" is used to indicate that one or both of the described situations may occur, for example, A and / or B includes (A and B) and (A or B).
[0049] In order to solve the problems of localized thermal stress concentration, crack propagation under high temperature service, interface delamination or thermal failure in existing tungsten-copper alloys.
[0050] The first aspect of this application provides a method for preparing a tungsten-copper alloy, comprising the following steps:
[0051] S1: Add the dispersant to a saturated aqueous solution of ammonium metatungstate, stir until homogeneous, and then add ammonia to obtain a pore-forming agent solution with pH ≥ 7.8.
[0052] Ammonium metatungstate has a solubility of approximately 300-400 g / 100 mL in water at room temperature (20-25°C), indicating its high solubility and ease of complete dissolution in water. Using ammonium metatungstate, with its high solubility, in solid-liquid mixing and solute precipitation offers the advantage of not requiring excessive water addition as a solvent, thus reducing the time and cost of subsequent evaporation and drying. Furthermore, compared to other pore-forming agents (such as urea and ammonium bicarbonate), ammonium metatungstate has a wider decomposition temperature range. This application uses ammonium metatungstate as the main component of the pore-forming agent solution. During subsequent heat treatment, as the temperature gradually increases, ammonium metatungstate decomposes stepwise, resulting in the formation of small, relatively uniformly dispersed air gaps around the tungsten particles. This avoids the situation where other pore-forming agents completely decompose and release gas within a narrow decomposition temperature range, releasing a large amount of gas in a short time. This can lead to uncontrollable air gap morphology and size within the tungsten framework, potentially resulting in air gaps of tens of micrometers in size and causing large copper pools within the tungsten-copper alloy during the melting and infiltration process.
[0053] Specifically, the dispersant can adsorb onto the surface of the solute particles (ammonium metatungstate) through long-chain adsorption, forming a physical barrier around the ammonium metatungstate particles and hindering the van der Waals forces between them, thus allowing the particles to be uniformly dispersed. Simultaneously, when the pore-forming agent solution including the dispersant and ammonium metatungstate is mixed with tungsten powder, the dispersant can effectively reduce the agglomeration rate of the precipitated crystals (ammonium metatungstate crystals) during the drying process. According to experimental data, compared to the pore-forming agent solution without the dispersant, the agglomeration rate of ammonium metatungstate crystals decreased by 30% after adding the dispersant.
[0054] Specifically, the preparation method of the pore-forming agent solution includes the following steps:
[0055] First, ammonium metatungstate is added to deionized water to obtain a saturated aqueous solution of ammonium metatungstate.
[0056] Next, the dispersant is added to the saturated aqueous solution of ammonium metatungstate and stirred until homogeneous. Then, ammonia is added dropwise while stirring to adjust the pH of the pore-forming agent solution to ≥7.8.
[0057] Specifically, the pH of the pore-forming agent solution can be one or any two of 7.8, 8.0, 8.3, 8.5, 9.0, 9.5, 10.0, 10.5, and 11.0; preferably 7.8-8.5.
[0058] The reason for controlling the pH of the pore-forming agent solution during its preparation is twofold. Firstly, to stabilize the solution and maintain an alkaline environment, thus preventing premature decomposition of ammonium metatungstate. Since ammonium metatungstate dissolves in water to form a weakly acidic solution, if the solution is in an acidic environment, ammonium metatungstate will undergo hydrolysis, releasing ammonium ions. Premature release of ammonium ions reduces gas escape during subsequent heat treatment, decreasing the amount of gas escape and weakening the pore-forming effect. On the other hand, by controlling the pH of the pore-forming agent solution within a suitable range, fine ammonium metatungstate crystals can precipitate during the subsequent drying process. The size of the ammonium metatungstate crystals can be controlled within the range of 10-50 nm, which is beneficial for the decomposition of ammonium metatungstate crystals during the decomposition heat treatment process. This results in the formation of smaller and more numerous air gaps around the tungsten particles, forming a tungsten skeleton with uniformly distributed pores. Consequently, the copper infiltration effect during the melting and infiltration process is better, achieving a synergistic effect of low thermal expansion and high electrical and thermal conductivity in the tungsten-copper alloy. When the pH exceeds 8.5, crystal precipitation reaches a plateau and has no further significant effect on the precipitation of nanocrystals. Based on cost considerations, a pH of 7.8-8.5 for the pore-forming agent solution is preferred. Therefore, pH control during the preparation of the pore-forming agent solution plays a crucial role in the subsequent multi-stage heat treatment.
[0059] In some embodiments, the dispersant is at least one selected from polyvinylpyrrolidone, polyethylene glycol, and sodium polyacrylate;
[0060] In some embodiments, the mass of the dispersant is 0.5-1% of the mass of the saturated aqueous solution of ammonium metatungstate; for example, it can be a range of one or any two of 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, 0.95%, 1%.
[0061] A mass fraction of dispersant within the above range is beneficial for the uniform dispersion of ammonium metatungstate in the pore-forming agent solution.
[0062] S2: Mix tungsten powder and the pore-forming agent solution to obtain a premixed slurry, and then subject the premixed slurry to ultrasonic treatment to obtain a mixed slurry.
[0063] In this application, the tungsten powder is composed of tungsten particles. The tungsten powder and a pore-forming agent solution are mixed in a solid-liquid manner, allowing the tungsten particles to be immersed in the pore-forming agent solution. The solute (ammonium metatungstate) in the pore-forming agent solution can uniformly adhere to the surface of the tungsten particles. During the subsequent drying process, the uniformly adhered ammonium metatungstate crystallizes and precipitates, forming uniformly distributed ammonium metatungstate crystals on the surface of the tungsten particles. This effectively avoids the agglomeration of the pore-forming agent. The uniformly distributed ammonium metatungstate crystals ensure that the air gaps generated during the decomposition and reduction heat treatment processes are small and dispersed, preventing the formation of large air gaps due to pore-forming agent agglomeration, and consequently resulting in copper pools of tens of micrometers in size after melt infiltration treatment.
[0064] In some embodiments, the frequency of the ultrasonic treatment is 40-120Hz, for example, it can be one or any two of 40Hz, 50Hz, 60Hz, 70Hz, 80Hz, 90Hz, 100Hz, 110Hz, 120Hz; the ultrasonic treatment time is 1-2h, for example, it can be one or any two of 1h, 1.2h, 1.5h, 1.8h, 2h.
[0065] In this application, ultrasonic treatment of the premixed slurry serves two purposes. First, it induces the formation of numerous transient nucleation sites for the solute (ammonium metatungstate) in the pore-forming agent solution, inhibiting Ostwald ripening and facilitating the refinement of ammonium metatungstate crystals during subsequent low-temperature drying. Second, ultrasonic treatment enhances convection of the pore-forming agent solution, increasing the mass transfer rate of solute molecules to the tungsten particle surface, preventing excessive local supersaturation, and reducing defect formation. Simultaneously, the shear force generated by the vibration during ultrasonic treatment disrupts the van der Waals forces between tungsten particles, inhibiting particle agglomeration. Specifically, after ultrasonic treatment at 100 Hz for 1 hour, the agglomeration rate of ammonium metatungstate crystals dispersed on the tungsten particle surface was reduced by 70% in the resulting composite powder after drying.
[0066] S3: The mixed slurry is dried at a temperature of 20-60℃ to obtain composite powder.
[0067] Specifically, the composite powder includes tungsten particles and ammonium metatungstate crystals attached to the tungsten particles.
[0068] Specifically, the drying temperature can be one or any two of the following: 20°C, 25°C, 30°C, 40°C, 42°C, 44°C, 46°C, 48°C, 50°C, 52°C, 54°C, 56°C, 58°C, and 60°C; preferably 40-60°C.
[0069] During the drying process, a temperature of 20-60℃ can prevent material decomposition, denaturation, or structural damage caused by high temperatures, while also effectively removing solvents or moisture. On one hand, a temperature of 20-60℃ can slow down the thermal motion of solvent molecules (deionized water) in the pore-forming agent solution, preventing a sudden increase in local supersaturation, allowing the solute (ammonium metatungstate) more time for uniform nucleation, resulting in the precipitation of fine-sized ammonium metatungstate crystals. On the other hand, a temperature of 20-60℃ can inhibit Ostwald ripening, preventing larger crystal particles in the ammonium metatungstate crystals from engulfing smaller crystal particles, thereby maintaining the uniformity of the precipitated ammonium metatungstate crystal size.
[0070] It is worth noting that this application achieves the synergistic effect of controlling the pH of the pore-forming agent solution (7.8-8.5) and the drying temperature (20-60℃) to regulate the crystal size of ammonium metatungstate. Specifically, according to group tests, drying at 20-60℃ within the pH range of 7.8-8.5 can control the crystal size within the range of 10-30 nm. The precipitation of fine ammonium metatungstate crystals can form smaller and more numerous primary air gaps around the tungsten particles during subsequent decomposition. This structure is beneficial for exhibiting the synergistic effect of low thermal expansion and high electrical and thermal conductivity in tungsten-copper alloys.
[0071] This application does not impose specific restrictions on the vacuum degree and time of the drying process, as long as the composite powder can be dried to a constant weight.
[0072] Specifically, the vacuum degree of the drying process is 1-10 Pa, for example, it can be one or any two of 1 Pa, 2 Pa, 3 Pa, 4 Pa, 5 Pa, 6 Pa, 7 Pa, 8 Pa, 9 Pa, 10 Pa.
[0073] S4: The composite powder is subjected to decomposition heat treatment, reduction heat treatment and sintering treatment in sequence to obtain a tungsten skeleton; the temperature of the decomposition heat treatment is less than the temperature of the reduction heat treatment and the temperature of the sintering treatment.
[0074] Specifically, during the decomposition heat treatment process, as the temperature rises, the water of crystallization in the ammonium metatungstate crystals is first removed and then evaporated and released in the form of water vapor. Next, some of the ammonium ions in the ammonium metatungstate are decomposed into NH3 and released in the form of ammonia. During the dissipation of the gases (water vapor and ammonia), air gaps are formed around the tungsten particles, thus creating pores. In other words, after the composite powder undergoes decomposition heat treatment, the ammonium metatungstate crystals decompose to form the first air gap and tungsten trioxide.
[0075] Specifically, during the reduction heat treatment process, the tungsten trioxide product obtained from the decomposition heat treatment is reduced to tungsten microparticles under a hydrogen-containing reducing atmosphere. Water vapor is also generated during this process. Similarly, during the escape of the water vapor, a second air gap is formed around the tungsten particles and tungsten microparticles as the water vapor is released. For example... Figure 1 As shown, the surface of the larger tungsten particles is covered with smaller tungsten microparticles, and there are many air gaps between the tungsten particles and the microparticles, which are used for the infiltration of copper liquid during the melting and infiltration process.
[0076] Specifically, during the sintering process, tungsten particles and microparticles serve as raw materials for the formation of the tungsten skeleton. The air gaps (first air gap and second air gap) formed by the decomposition heat treatment and reduction heat treatment can serve as pores in the tungsten skeleton. As the sintering temperature increases, sintering necks are formed between tungsten particles, between tungsten microparticles, or between tungsten particles and tungsten microparticles through solid-phase diffusion. As the degree of solid-phase diffusion deepens, the sintering necks continue to grow. After sintering, the tungsten particles and microparticles will connect with each other through the sintering necks to form a network structure, thereby sintering into a porous tungsten skeleton.
[0077] In some embodiments, the temperature of the decomposition heat treatment is 350-450°C; for example, it can be a range of one or any two of 350°C, 370°C, 390°C, 410°C, 430°C, and 450°C.
[0078] The chemical formula involved in the decomposition heat treatment process is: (NH4)6[H2W 12 O 40 ]·xH2O→6NH3(g)+12WO3+(x+1)H2O(g);
[0079] Specifically, the decomposition process of ammonium metatungstate involves the following stages: dehydration occurs between room temperature and 200°C, where water of crystallization is removed first and then released as water vapor. The ammonium decomposition stage occurs between 300-500°C, producing decomposition products of NH3, H2O, and WO3. This application, by incorporating a decomposition heat treatment process, effectively removes the water of crystallization from ammonium metatungstate, preventing residual water of crystallization from reacting with the transitional reduction product WO2 from the subsequent reduction heat treatment process to form WO2(OH)2. This avoids the coarsening of tungsten particles caused by WO2(OH)2's gas-phase transport and redeposition via the CVT mechanism, which would otherwise significantly reduce the high-temperature mechanical properties of the tungsten framework and even the tungsten-copper alloy.
[0080] In some embodiments, the decomposition heat treatment time is 0.5-2 hours; for example, it can be a range of one or any two of 0.5 hours, 0.7 hours, 1.0 hours, 1.3 hours, 1.5 hours, 1.8 hours, and 2 hours.
[0081] In some embodiments, the heating rate of the decomposition heat treatment is 8-10 °C / min; for example, it can be a range of one or any two of 8 °C / min, 8.2 °C / min, 8.5 °C / min, 8.7 °C / min, 9 °C / min, 9.3 °C / min, 9.5 °C / min, 9.8 °C / min, and 10 °C / min.
[0082] By controlling the heating rate of the decomposition heat treatment within the above range, the water of crystallization in ammonium metatungstate can be fully removed in a short time. At the same time, it can also ensure that ammonium metatungstate can be fully decomposed during the ammonium decomposition stage, so that ammonia gas can escape and form the first gas gap around the tungsten particles.
[0083] In some embodiments, the temperature of the reduction heat treatment is 550-600°C; for example, it can be a range of one or any two of 550°C, 560°C, 570°C, 580°C, 590°C, and 600°C.
[0084] The chemical formula involved in the reduction heat treatment process is: WO3 + 3H2 → W + 3H2O(g).
[0085] This application sets the reduction temperature to 550-600℃, which can prevent WO3 from causing tungsten particles to coarsen due to Ostwald aging. The reduction temperature is lower than the lower limit of the Ostwald aging temperature, thereby achieving tungsten particle refinement and ensuring that the tungsten-copper alloy has excellent high-temperature mechanical properties.
[0086] In some embodiments, the reduction heat treatment time is 0.5-1h; for example, it can be a range of one or any two of 0.5h, 0.6h, 0.7h, 0.8h, 0.9h, and 1h.
[0087] In some embodiments, the heating rate of the reduction heat treatment is 3-5℃ / min; for example, it can be a range of one or any two of 3℃ / min, 3.2℃ / min, 3.5℃ / min, 3.7℃ / min, 4℃ / min, 4.3℃ / min, 4.5℃ / min, 4.8℃ / min, and 5℃ / min.
[0088] The heating rate during the reduction heat treatment is 3-5℃ / min. The slow heating is to allow the water of crystallization in ammonium metatungstate to evaporate further before reaching the lower limit of the Ostwald aging temperature, so as to avoid the reaction of the residual water of crystallization with the transitional reduction product WO2 during the reduction heat treatment, which would affect the mechanical properties of the tungsten skeleton and tungsten-copper alloy.
[0089] In some embodiments, the sintering temperature is 1600-2100°C; for example, it can be a range of one or any two of 1600°C, 1700°C, 1800°C, 1900°C, 2000°C, and 2100°C.
[0090] This application sets the sintering temperature within a suitable range of 1600-2100℃, which ensures the formation of the sintering neck and the formation of metallurgical bonds between particles (tungsten particles and tungsten microparticles), so that the tungsten skeleton exhibits good mechanical properties and provides support for the melting and infiltration process. At the same time, it can also avoid abnormal growth of tungsten particles and tungsten microparticles due to high temperature overheating, and ensure that the tungsten skeleton has stable high temperature mechanical properties.
[0091] In some embodiments, the sintering treatment time is 1-4 hours; for example, it can be one or any two of 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours, and 4 hours.
[0092] In some embodiments, the heating rate of the sintering process is 10-20°C / min; for example, it can be a range of one or any two of 10°C / min, 11°C / min, 12°C / min, 13°C / min, 14°C / min, 15°C / min, 16°C / min, 17°C / min, 18°C / min, 19°C / min, and 20°C / min.
[0093] Within the above-mentioned temperature rise rate range, the high-temperature heat treatment time can be shortened as much as possible, avoiding grain coarsening caused by prolonged heat treatment of tungsten particles and microparticles. A sintering time of 1-4 hours is taken to minimize the sintering time while ensuring sufficient sintering.
[0094] In some embodiments, the atmosphere for the decomposition heat treatment, reduction heat treatment, and sintering treatment is a reducing atmosphere.
[0095] Specifically, the reducing atmosphere is at least one of hydrogen, ammonia, or a mixture of hydrogen and argon.
[0096] During the decomposition heat treatment, reduction heat treatment, and sintering process, a reducing atmosphere is used to effectively prevent the oxidation of tungsten particles and microparticles, ensure sintering performance, ensure that the tungsten particles and microparticles are fully sintered to form a tungsten skeleton with good load-bearing capacity, ensure that the tungsten skeleton can withstand the surface tension of copper melt during the melting and infiltration process, ensure the structural stability of the tungsten skeleton, and prevent the tungsten skeleton from collapsing.
[0097] In some embodiments, the atmosphere of the reduction heat treatment is a hydrogen-argon mixture, wherein the volume flow ratio of hydrogen to argon in the hydrogen-argon mixture is (1:3)-(1:5), for example, it can be one of 1:3, 1:3.5, 1:4, 1:4.5, 1:5 or any value between two of them.
[0098] It is worth noting that in order to mitigate the adverse effects of Ostwald curing, the reduction heat treatment time should be shortened as much as possible. Therefore, the heat treatment strategy adopts the method of increasing the heating rate and reducing the holding time.
[0099] To shorten the reduction heat treatment time and ensure more complete reduction of tungsten particles, a hydrogen-argon mixed atmosphere is used during the reduction heat treatment process. The introduction of argon can effectively increase the overall flow rate of the reducing atmosphere, allowing hydrogen to fully contact tungsten oxide within a limited time to generate tungsten particles and microparticles.
[0100] When the volume flow ratio of hydrogen to argon is (1:3) to (1:5), the tungsten oxide is completely reduced, and the grain size of tungsten particles and microparticles does not coarsen.
[0101] S5: The tungsten skeleton and copper are subjected to melt infiltration treatment to obtain a tungsten-copper alloy.
[0102] like Figure 2 As shown, molten pure copper and tungsten skeletons are placed in a melting furnace, allowing the flowing copper liquid to seep into the pores inside the tungsten skeleton, achieving phase composite between the tungsten skeleton and copper, and obtaining a tungsten-copper alloy (bright white is tungsten, and red metallic luster is copper).
[0103] In some embodiments, the parameters of the melt infiltration treatment satisfy at least one of the following:
[0104] (a) The mass ratio of the tungsten skeleton to copper is (15:1) to (1:1); for example, it can be one of 15:1, 13:1, 11:1, 9:1, 7:1, 5:1, 3:1, 1:1 or any value between the two.
[0105] (b) The temperature of the melt infiltration treatment is 1300-1500°C; for example, it can be one of 1300°C, 1350°C, 1400°C, 1450°C, 1500°C or any range between two of them.
[0106] (c) The vacuum degree of the infiltration treatment is 0.1 × 10⁻⁶. 5 -0.5×10 5 Pa; for example, it could be 0.1 × 10⁻⁶ Pa. 5 Pa, 0.2×10 5 Pa, 0.3×10 5 Pa, 0.4×10 5 Pa, 0.5×10 5 Pa is a range of values between one or both of them;
[0107] (d) The melting and infiltration treatment time is 2-4 hours; for example, it can be one of 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours or any value between two of them.
[0108] In this application, a melting furnace is used to infiltrate a tungsten framework and pure copper, and the vacuum level of the melting furnace is controlled to meet the requirement of 0.1 × 10⁻⁶. 5 -0.5×10 5 The pressure inside the melting furnace is negative, which allows the gas in the air gaps of the tungsten skeleton to be expelled. In other words, the pressure inside the melting furnace is higher than the pressure in the air gaps of the tungsten skeleton. Under this pressure, the pure copper liquid in the molten state will better penetrate into the interior of the tungsten skeleton, thereby improving the melting efficiency and the saturation of copper in the tungsten-copper alloy.
[0109] Furthermore, the molten infiltrated billet can be post-processed, such as by milling or turning, to treat the outer surface of the molten infiltrated billet and finally obtain a tungsten-copper alloy.
[0110] A second aspect of this application provides a tungsten-copper alloy, wherein the tungsten-copper is prepared by the method for preparing the tungsten-copper alloy.
[0111] A third aspect of this application provides an electronic device comprising the aforementioned tungsten-copper alloy.
[0112] It is worth noting that electronic devices can include electronic packaging devices, electrical contacts, high-temperature electrodes, heat sinks, etc.
[0113] Example 1
[0114] This embodiment provides a method for preparing a tungsten-copper alloy, including the following steps:
[0115] S1: Add ammonium metatungstate to deionized water to obtain a saturated aqueous solution of ammonium metatungstate; add a dispersant to the saturated aqueous solution of ammonium metatungstate, stir evenly, and then add ammonia dropwise while stirring to obtain a pore-forming agent solution with pH=8.0; wherein, the dispersant is polyethylene glycol, and the mass of the dispersant is 1.0% of the mass of the saturated aqueous solution of ammonium metatungstate;
[0116] S2: Mix tungsten powder and the pore-forming agent solution obtained in step S1 to obtain a premixed slurry. Perform ultrasonic treatment on the premixed slurry to obtain a mixed slurry. The ultrasonic treatment frequency is 100 Hz and the time is 1 h.
[0117] S3: The mixed slurry obtained in step S2 is dried at a temperature of 50℃ and a vacuum of 10Pa for 6 hours to obtain composite powder;
[0118] S4: The composite powder obtained in step S3 is subjected to decomposition heat treatment, reduction heat treatment and sintering treatment in sequence to obtain a tungsten skeleton;
[0119] The decomposition heat treatment was carried out at a temperature of 400℃ for 1 hour, with a heating rate of 10℃ / min; the atmosphere was hydrogen.
[0120] The reduction heat treatment was performed at a temperature of 600℃ for 1 hour, with a heating rate of 5℃ / min. The atmosphere was a hydrogen-argon mixture with a volume flow ratio of 1:3 for hydrogen and argon.
[0121] The sintering temperature was 1800℃, the time was 3h, and the heating rate was 15℃ / min;
[0122] S5: The tungsten framework obtained in step S4 and copper are subjected to melt infiltration treatment at a mass ratio of 8:1 to obtain a tungsten-copper alloy; wherein the melt infiltration treatment temperature is 1400℃ and the vacuum degree is 1.0×10⁻⁶. 5 Pa, time is 3h.
[0123] Example 2
[0124] This embodiment provides a method for preparing a tungsten-copper alloy, including the following steps:
[0125] S1: Ammonium metatungstate is added to deionized water to obtain a saturated aqueous solution of ammonium metatungstate; a dispersant is added to the saturated aqueous solution of ammonium metatungstate, and after stirring evenly, ammonia water is added dropwise while stirring to obtain a pore-forming agent solution with pH=8.0; wherein, the dispersant is polyvinylpyrrolidone, and the mass of the dispersant is 1.0% of the mass of the saturated aqueous solution of ammonium metatungstate;
[0126] S2: Mix tungsten powder and the pore-forming agent solution obtained in step S1 to obtain a premixed slurry. Ultrasonically treat the premixed slurry to obtain a mixed slurry. The ultrasonic treatment frequency is 80 Hz and the time is 1 h.
[0127] S3: The mixed slurry obtained in step S2 is dried at a temperature of 40℃ and a vacuum of 10Pa for 8 hours to obtain composite powder;
[0128] S4: The composite powder obtained in step S3 is subjected to decomposition heat treatment, reduction heat treatment and sintering treatment in sequence to obtain a tungsten skeleton;
[0129] The decomposition heat treatment was carried out at a temperature of 350℃ for 1 hour, with a heating rate of 10℃ / min; the atmosphere was hydrogen.
[0130] The reduction heat treatment was performed at a temperature of 600℃ for 1 hour, with a heating rate of 5℃ / min. The atmosphere was a hydrogen-argon mixture with a volume flow ratio of 1:4 for hydrogen and argon.
[0131] The sintering temperature was 2000℃, the time was 2h, and the heating rate was 15℃ / min.
[0132] S5: The tungsten framework obtained in step S4 and copper are subjected to melt infiltration treatment at a mass ratio of 5:1 to obtain a tungsten-copper alloy; wherein the melt infiltration treatment temperature is 1400℃ and the vacuum degree is 1.0×10⁻⁶. 5 Pa, time is 2h.
[0133] Example 3
[0134] This embodiment provides a method for preparing a tungsten-copper alloy, including the following steps:
[0135] S1: Ammonium metatungstate is added to deionized water to obtain a saturated aqueous solution of ammonium metatungstate; a dispersant is added to the saturated aqueous solution of ammonium metatungstate, and after stirring evenly, ammonia water is added dropwise while stirring to obtain a pore-forming agent solution with pH=7.8; wherein, the dispersant is polyvinylpyrrolidone, and the mass of the dispersant is 0.5% of the mass of the saturated aqueous solution of ammonium metatungstate;
[0136] S2: Mix tungsten powder and the pore-forming agent solution obtained in step S1 to obtain a premixed slurry. Ultrasonically treat the premixed slurry to obtain a mixed slurry. The ultrasonic treatment frequency is 40 Hz and the time is 2 h.
[0137] S3: The mixed slurry obtained in step S2 is dried at a temperature of 20℃ and a vacuum degree of 10Pa for 10 hours to obtain composite powder;
[0138] S4: The composite powder obtained in step S3 is subjected to decomposition heat treatment, reduction heat treatment and sintering treatment in sequence to obtain a tungsten skeleton;
[0139] The decomposition heat treatment was carried out at a temperature of 350℃ for 1 hour, with a heating rate of 10℃ / min; the atmosphere was hydrogen.
[0140] The reduction heat treatment was performed at a temperature of 550℃ for 1 hour, with a heating rate of 5℃ / min. The atmosphere was a hydrogen-argon mixture with a volume flow ratio of 1:3 for hydrogen and argon.
[0141] The sintering temperature was 1600℃, the time was 4h, and the heating rate was 15℃ / min;
[0142] S5: The tungsten framework obtained in step S4 and copper are subjected to melt infiltration treatment at a mass ratio of 15:1 to obtain a tungsten-copper alloy; wherein the melt infiltration treatment temperature is 1300℃ and the vacuum degree is 1.0×10⁻⁶. 5 Pa, time is 4h.
[0143] Example 4
[0144] This embodiment provides a method for preparing a tungsten-copper alloy, including the following steps:
[0145] S1: Ammonium metatungstate is added to deionized water to obtain a saturated aqueous solution of ammonium metatungstate; a dispersant is added to the saturated aqueous solution of ammonium metatungstate, and after stirring evenly, ammonia water is added dropwise while stirring to obtain a pore-forming agent solution with pH=8.5; wherein, the dispersant is sodium polyacrylate, and the mass of the dispersant is 1.0% of the mass of the saturated aqueous solution of ammonium metatungstate;
[0146] S2: Mix tungsten powder and the pore-forming agent solution obtained in step S1 to obtain a premixed slurry. Ultrasonically treat the premixed slurry to obtain a mixed slurry. The ultrasonic treatment frequency is 120 Hz and the time is 1 h.
[0147] S3: The mixed slurry obtained in step S2 is dried at a temperature of 60℃ and a vacuum of 10Pa for 6 hours to obtain composite powder;
[0148] S4: The composite powder obtained in step S3 is subjected to decomposition heat treatment, reduction heat treatment and sintering treatment in sequence to obtain a tungsten skeleton;
[0149] The decomposition heat treatment was carried out at a temperature of 450℃ for 1 hour, with a heating rate of 10℃ / min; the atmosphere was hydrogen.
[0150] The reduction heat treatment was performed at a temperature of 600℃ for 1 hour, with a heating rate of 5℃ / min. The atmosphere was a hydrogen-argon mixture with a volume flow ratio of 1:5 for hydrogen to argon.
[0151] The sintering temperature was 2100℃, the time was 2h, and the heating rate was 15℃ / min.
[0152] S5: The tungsten framework obtained in step S4 and copper are subjected to melt infiltration treatment at a mass ratio of 1:1 to obtain a tungsten-copper alloy; wherein the melt infiltration treatment temperature is 1500℃ and the vacuum degree is 1.0×10⁻⁶. 5 Pa, time is 2h.
[0153] Example 5
[0154] This embodiment provides a method for preparing a tungsten-copper alloy, which differs from Embodiment 1 in that: in step S4, the heating rate of the decomposition heat treatment is 3℃ / min, and the heating rate of the reduction heat treatment is 8℃ / min.
[0155] Example 6
[0156] This embodiment provides a method for preparing a tungsten-copper alloy, which differs from Example 1 in that the pH of the pore-forming agent solution is 10.0.
[0157] Comparative Example 1
[0158] This comparative example provides a method for preparing a tungsten-copper alloy, which differs from Example 1 in that the preparation method of the composite powder is different. The preparation method of the composite powder in this comparative example is as follows: ammonium metatungstate and tungsten powder are mixed evenly to obtain the composite powder.
[0159] Comparative Example 2
[0160] This comparative example provides a method for preparing a tungsten-copper alloy, which differs from Example 1 in that: in step S1, urea is used instead of ammonium metatungstate.
[0161] Comparative Example 3
[0162] This comparative example provides a method for preparing a tungsten-copper alloy, which differs from Example 1 in that the pore-forming agent solution is a saturated aqueous solution of ammonium metatungstate.
[0163] Comparative Example 4
[0164] This comparative example provides a method for preparing a tungsten-copper alloy, which differs from Example 1 in that the pH of the pore-forming agent solution is 6.0.
[0165] Comparative Example 5
[0166] This comparative example provides a method for preparing a tungsten-copper alloy, which differs from Example 1 in that: this comparative example does not perform ultrasonic treatment, that is, this comparative example does not contain step S2.
[0167] Comparative Example 6
[0168] This comparative example provides a method for preparing a tungsten-copper alloy, which differs from Example 1 in that the drying temperature is 80°C.
[0169] Comparative Example 7
[0170] This comparative example provides a method for preparing a tungsten-copper alloy, which differs from Example 1 in that: in step S4, no decomposition heat treatment is performed.
[0171] Comparative Example 8
[0172] This comparative example provides a method for preparing a tungsten-copper alloy, which differs from Example 1 in that: in step S4, the reduction heat treatment temperature is 600℃, the time is 1h, the heating rate is 4℃ / min, and the atmosphere is hydrogen.
[0173] Performance testing
[0174] The tungsten-copper alloys obtained in the examples and comparative examples were subjected to performance tests, and the test methods are as follows:
[0175] (1) According to GB / T 28898-2012, the copper content of the core and edge of the tungsten copper alloy is tested by titration; where the core refers to the circular area from the center to 1 / 3R, and the edge refers to the annular area from 1 / 3R to the edge, where R is the radius of the tungsten copper alloy.
[0176] (2) The microstructure of the tungsten-copper alloy was analyzed and the copper pool size was measured using a laser confocal microscope;
[0177] (3) The average hardness of the tungsten-copper alloy was determined by Vickers hardness tester, and the average value of the hardness test results of any 5 locations of the sample was taken.
[0178] (4) The density of tungsten-copper alloy was determined by Archimedes method.
[0179] The test results are shown in Table 1 and Figure 2-4 As shown.
[0180] Table 1
[0181]
[0182]
[0183] As can be seen from the experimental data in Table 1, the copper content in the core and the copper content in the edge of the tungsten-copper alloy of this application are comparable, the average size of the copper pool is ≤1μm, and the average hardness is ≥260Hv; indicating that the copper in the tungsten-copper alloy of this application is uniformly distributed, the copper pool is small, and the hardness is high.
[0184] Figure 2 Metallographic image of the tungsten-copper alloy of Example 1; Figure 3 Metallographic diagram of the tungsten-copper alloy in Comparative Example 1; Figure 4 Metallographic image of the tungsten-copper alloy in Comparative Example 2; from Figure 2-4 As can be seen, in the tungsten-copper alloy prepared using the technical solution of Example 1, the copper is uniformly and finely distributed, with no copper pools larger than 1 μm, and the copper is distributed in a network pattern in the alloy; in the tungsten-copper alloy prepared using the technical solution of Comparative Example 1, the copper is distributed in several copper pools of 5-30 μm; in the tungsten-copper alloy prepared using the technical solution of Comparative Example 2, the size of the copper pools is further increased, with the largest copper pool reaching 100-200 μm, and the copper distribution in Comparative Examples 1 and 2 is an isolated island-like distribution.
[0185] Finally, it should be noted that the above embodiments are used to illustrate the technical solutions of this application and not to limit the scope of protection of this application. Although this application has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this application without departing from the substance and scope of the technical solutions of this application.
Claims
1. A method for preparing a tungsten-copper alloy, characterized in that, Includes the following steps: The dispersant was added to a saturated aqueous solution of ammonium metatungstate and stirred until homogeneous. Then ammonia was added to obtain a pore-forming agent solution with a pH ≥ 7.
8. Tungsten powder and the pore-forming agent solution are mixed to obtain a premixed slurry, and the premixed slurry is subjected to ultrasonic treatment to obtain a mixed slurry; The mixed slurry is dried at a temperature of 20-60℃ to obtain composite powder; The composite powder is subjected to decomposition heat treatment, reduction heat treatment and sintering treatment in sequence to obtain a tungsten framework; the temperature of the decomposition heat treatment is less than the temperature of the reduction heat treatment and the temperature of the sintering treatment. The atmosphere for the reduction heat treatment is a reducing atmosphere; the reducing atmosphere is a hydrogen-argon mixture. The tungsten framework and copper are subjected to melt infiltration treatment to obtain a tungsten-copper alloy.
2. The method for preparing the tungsten-copper alloy as described in claim 1, characterized in that, The temperature of the decomposition heat treatment is 350-450℃; And / or, the duration of the decomposition heat treatment is 0.5-2 hours; And / or, the heating rate of the decomposition heat treatment is 8-10℃ / min.
3. The method for preparing the tungsten-copper alloy as described in claim 1, characterized in that, The temperature of the reduction heat treatment is 550-600℃; And / or, the reduction heat treatment time is 0.5-1 h; And / or, the heating rate of the reduction heat treatment is 3-5℃ / min.
4. The method for preparing the tungsten-copper alloy as described in claim 1, characterized in that, The sintering temperature is 1600-2100℃; And / or, the sintering treatment time is 1-4 hours; And / or, the heating rate of the sintering process is 10-20℃ / min.
5. The method for preparing the tungsten-copper alloy as described in claim 1, characterized in that, The atmosphere for the decomposition heat treatment and sintering treatment is a reducing atmosphere.
6. The method for preparing the tungsten-copper alloy as described in claim 1, characterized in that, The volumetric flow rate ratio of hydrogen to argon in the hydrogen-argon mixture is (1:3) to (1:5).
7. The method for preparing the tungsten-copper alloy as described in claim 1, characterized in that, The dispersant is at least one of polyvinylpyrrolidone, polyethylene glycol, and sodium polyacrylate; And / or, the mass of the dispersant is 0.5-1% of the mass of the saturated aqueous solution of ammonium metatungstate; And / or, the drying process is carried out at a temperature of 40-60°C and a vacuum degree of 1-10 Pa.
8. The method for preparing the tungsten-copper alloy as described in claim 1, characterized in that, The ultrasonic treatment is performed at a frequency of 40-120 Hz for 1-2 hours.
9. The method for preparing the tungsten-copper alloy as described in claim 1, characterized in that, The parameters of the melt infiltration treatment satisfy at least one of the following: (a) The mass ratio of the tungsten skeleton to copper is (15:1) to (1:1). (b) The temperature of the melt infiltration treatment is 1300-1500 ℃; (c) The vacuum degree of the melt infiltration treatment is 0.1 × 10⁻⁶. 5 -0.5×10 5 Pa; (d) The melting and infiltration treatment time is 2-4 hours.
10. A tungsten-copper alloy, characterized in that, The tungsten-copper alloy is prepared by the method for preparing the tungsten-copper alloy according to any one of claims 1-9.
11. An electronic device, characterized in that, Including the tungsten-copper alloy as described in claim 10.