A high-purity molybdenum ingot, its preparation method and preparation system

Abstract

This invention provides a high-purity molybdenum ingot, its preparation method, and its preparation system. First, high-purity molybdenum billets are sintered under vacuum to remove adsorbed gaseous impurities and some low-boiling-point volatile impurities from the metal surface. Then, sintering under a high-temperature hydrogen reducing atmosphere removes oxide impurities and non-metallic impurities (carbon, sulfur, etc.). Finally, electron beam vacuum melting technology is used to efficiently remove most metallic impurities (such as potassium, sodium, iron, etc.) through vapor pressure difference in a high-vacuum environment, yielding a molybdenum ingot with a purity of 5N or higher (99.999 wt.%). This method features simple processing and high batch-to-batch product stability, making it suitable for preparing high-purity molybdenum for high-end electronic devices, semiconductors, and aerospace applications.

Description

Technical Field

[0001] This application relates to the field of metal purification technology, and more specifically, to a high-purity molybdenum ingot, its preparation method, and its preparation system. Background Technology

[0002] Molybdenum metal, due to its unique physicochemical properties such as high melting point, high strength, and good thermal and electrical conductivity, has wide applications in semiconductors, aerospace, electronic components, and new energy fields. However, these high-end fields have extremely demanding requirements for molybdenum materials, requiring both ultra-high purity of 5N level (99.999%) and near-theoretical density and extremely high quality stability to meet the needs of use and processing under complex conditions.

[0003] Currently, high-purity metallic molybdenum is generally produced using a combined chemical-physical purification process. Among these processes, hydrometallurgy is the primary method for preparing high-purity metallic molybdenum. However, hydrometallurgy has low efficiency in removing alkali metals such as potassium and sodium, and it also causes secondary pollution, with the large amount of waste liquid generated easily burdening the environment. While physical metallurgical methods such as high-temperature sintering have advantages in removing some oxides and volatile impurities, their removal effect is difficult to meet the purity requirements of 5N and above. The density usually only reaches 90% to 95% of the theoretical density, and there are defects in the microstructure. Summary of the Invention

[0004] To address the aforementioned issues, this invention provides a high-purity molybdenum ingot, its preparation method, and its preparation system. The method employs a combined process of vacuum sintering, hydrogen atmosphere reduction sintering, and electron beam vacuum melting to prepare 5N-grade high-purity molybdenum ingots. This process efficiently removes high-saturation vapor pressure, volatile impurities, and gaseous impurities such as C, O, and N from the metal. It significantly improves the purity and density of the high-purity molybdenum material, shortens the purification time, and increases purification efficiency. Simultaneously, it reduces the use of chemical reagents in the wet purification process, lowers environmental pollution, and aligns with green development requirements.

[0005] In a first aspect, the present invention provides a method for preparing high-purity metallic molybdenum ingots, the method comprising: S1, pressing an appropriate amount of metallic molybdenum powder into a billet;

[0006] S2. The billet is vacuum sintered at a temperature of 900 ℃~1500 ℃ to obtain the first material;

[0007] S3. The first material is sintered at high temperature in a hydrogen atmosphere to obtain the second material;

[0008] S4. After the second material is cooled to room temperature, it is bundled up. The bundled second material is then subjected to electron beam vacuum melting and cooled to obtain high-purity molybdenum ingots.

[0009] The power of the electron beam vacuum melting is 50 kW to 100 kW, and the melting time is 20 min to 40 min.

[0010] Optionally, in step S2, the vacuum degree of the vacuum sintering is 10. -2 Pa~10 -4 Pa;

[0011] The heating rate is 8 ℃ / min to 15 ℃ / min.

[0012] Optionally, in step S3, the flow rate of the hydrogen gas is 0.5 L / min to 5 L / min.

[0013] Optionally, in step S3, during the high-temperature sintering process, the heating rate is 5 ℃ / min~10 ℃ / min, the temperature is 1800 ℃~2600 ℃, and the high-temperature sintering time is 2 h~5 h.

[0014] Optionally, in step S1, the appropriate amount of the metallic molybdenum powder is composed of a mixture of 100-mesh and 200-mesh metallic molybdenum powder;

[0015] The mass ratio of the 100-mesh molybdenum powder to the 200-mesh molybdenum powder is (3~5):(5~7).

[0016] Optionally, in step S1, the pressure during pressing is 600 MPa to 1200 MPa.

[0017] Optionally, in step S4, the cooling rate is 8 ℃ / min to 15 ℃ / min.

[0018] Optionally, the preparation method further includes:

[0019] In step S3, when the second material is cooled to 800 ℃~1200 ℃, the hydrogen is replaced with an inert gas, and then the second material is subjected to high-temperature vacuum dehydrogenation treatment, and taken out after cooling;

[0020] The vacuum degree during the high-temperature vacuum dehydrogenation process is 10. -2 Pa~10 -4 Pa, temperature is 800 ℃~1200℃.

[0021] In a second aspect, the present invention provides a high-purity molybdenum ingot, which is prepared by the preparation method described in the first aspect above; the purity of the high-purity molybdenum ingot is 99.999%.

[0022] Thirdly, the present invention provides a system for preparing high-purity molybdenum ingots, the system being used to perform the preparation method described in the first aspect, the system comprising:

[0023] The vacuum sintering device, the hydrogen sintering device, and the electron beam vacuum melting device are connected in sequence.

[0024] The vacuum sintering device is used to vacuum sinter the billet to obtain the first material;

[0025] The hydrogen sintering apparatus is used to sinter the first material at high temperature in a hydrogen atmosphere to obtain the second material.

[0026] The electron beam vacuum melting device is used to perform electron beam vacuum melting on the bundled second material, and after cooling, obtain high-purity molybdenum ingots.

[0027] Beneficial technical effects:

[0028] 1. This invention provides a method for preparing high-purity molybdenum ingots. By setting up a multi-step process of vacuum sintering, hydrogen sintering, and electron beam vacuum melting, impurities in the molybdenum metal, especially alkali metals (such as potassium and sodium) and oxides, are effectively removed, enabling the molybdenum metal to achieve an ultra-high purity of 5N level (99.999%) or higher, meeting the stringent purity requirements of high-end fields. By setting up multi-step sintering and melting processes, the use and processing of the molybdenum metal material under complex conditions are more stable, reducing structural defects and improving the mechanical properties and thermal stability of the molybdenum metal. Among them, electron beam vacuum melting is carried out in a high-temperature and high-vacuum environment, which can effectively remove pores and defects in the second material, making the density of the final molybdenum ingot close to the theoretical density, significantly higher than the 90%~95% density of traditional high-temperature sintering processes. Compared with hydrometallurgical processes, the method provided by this invention avoids the generation of a large amount of waste liquid, greatly reducing secondary pollution problems and meeting environmental protection requirements.

[0029] 2. This invention provides a high-purity metallic molybdenum ingot, prepared using the method of this invention. The molybdenum ingot has a density close to the theoretical density, with fewer pores and defects, and possesses high strength, good thermal conductivity, and electrical conductivity, making it suitable for use and processing under complex conditions. The purity of this high-purity metallic molybdenum ingot reaches 99.999% (5N grade), with potassium and sodium impurity content ≤0.3ppm, iron impurity content ≤0.5ppm, and total impurity content ≤10ppm. It can meet the extreme requirements for material purity in high-end fields such as semiconductors, aerospace, and electronic components, especially exhibiting excellent performance stability under extreme environments such as high temperature, high pressure, and strong corrosion.

[0030] 3. This invention provides a system for preparing high-purity molybdenum ingots. This system integrates a vacuum sintering device, a hydrogen sintering device, and an electron beam vacuum melting device, enabling integrated preparation from billet to high-purity molybdenum ingots, improving production efficiency and process controllability. When producing molybdenum ingots using this system, a multi-step process of vacuum sintering, hydrogen sintering, and electron beam melting can be achieved, thereby efficiently removing alkali metals, oxides, and other volatile impurities from the molybdenum material, ensuring the high purity and high density of the final product, avoiding the waste liquid discharge problem in hydrometallurgical processes, reducing environmental pollution, and meeting the requirements of green manufacturing. Attached Figure Description

[0031] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments of this application 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 these drawings without creative effort.

[0032] Figure 1 A flowchart illustrating a method for preparing high-purity molybdenum ingots according to an embodiment of this application is shown.

[0033] Figure 2 A schematic diagram of a high-purity molybdenum ingot preparation system proposed in an embodiment of this application is shown.

[0034] Explanation of reference numerals in the attached figures:

[0035] 1. Vacuum sintering apparatus; 2. Hydrogen sintering apparatus; 3. Electron beam vacuum melting apparatus. Detailed Implementation

[0036] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0037] In the accompanying drawings, the size of constituent elements, the thickness of layers, or areas may sometimes be exaggerated for clarity. Therefore, any implementation of this disclosure is not necessarily limited to the dimensions shown in the drawings, and the shapes and sizes of the components in the drawings do not reflect true proportions. Furthermore, the drawings schematically illustrate ideal examples, and any implementation of this disclosure is not limited to the shapes or values ​​shown in the drawings.

[0038] In related technologies, molybdenum metal, due to its unique physicochemical properties such as high melting point (2623 ℃), high strength, and good thermal and electrical conductivity, has wide applications in semiconductors, aerospace, electronic components, and new energy fields. Particularly in semiconductor manufacturing, molybdenum is used to manufacture high-power devices and interconnect materials for integrated circuits; in aerospace, molybdenum alloys are used to manufacture high-temperature structural components; and in new energy, molybdenum plays a crucial role as a catalyst support in hydrogen energy technology. However, these high-end fields place extremely stringent requirements on molybdenum materials, demanding both ultra-high purity (above 5N grade, 99.999%) and near-theoretical density and extremely high quality stability to meet the demands of use and processing under complex conditions. For example, in semiconductor manufacturing, even trace impurities can severely affect device performance and reliability; in aerospace, the density and uniformity of the material directly affect the service life and safety of components.

[0039] Currently, high-purity molybdenum metal is generally purified using a combined chemical-physical process. Traditional processes require multiple purification steps, are complex, time-consuming, and have high equipment maintenance costs, making it difficult to guarantee the purity and quality stability of molybdenum materials. Therefore, they are gradually being replaced by combined processes. Hydrometallurgical processes have low removal efficiency for alkali metals such as potassium and sodium, and pose secondary pollution problems, generating large amounts of waste liquid that can burden the environment. While physical metallurgical methods such as high-temperature sintering have advantages in removing some oxides and volatile impurities, their removal effect is insufficient to meet the purity requirements above 5N, with density typically only reaching 90%–95% of the theoretical density, and structural defects remaining. For example, during high-temperature sintering, uneven temperature gradients and pressure distribution can easily lead to porosity and grain boundary segregation within the material, affecting its mechanical properties and thermal stability. Furthermore, the reducing agents and solvents used in traditional processes may introduce new impurities, further affecting the purity of the material.

[0040] To overcome these challenges, a series of novel purification technologies have been developed in recent years. For example, electron beam melting can effectively remove volatile impurities and improve material purity; plasma melting can achieve efficient purification at lower temperatures, reducing energy consumption and pollution. Meanwhile, advanced powder metallurgy technologies, such as hot isostatic pressing (HIP) and spark plasma sintering (SPS), can significantly improve the density and microstructure uniformity of materials, bringing them closer to their theoretical density. The application of these new technologies not only improves the purity and quality stability of molybdenum materials but also reduces production costs and environmental burden, providing strong support for the application of molybdenum materials in high-end fields.

[0041] Regarding the relevant technical content, this invention employs a combined process technology of vacuum sintering, hydrogen atmosphere reduction sintering, and electron beam vacuum melting to prepare 5N-grade high-purity metallic molybdenum ingots. This not only efficiently removes volatile impurities and gaseous impurities such as C, O, and N from the metal, but also significantly improves the purity and density of the high-purity metallic molybdenum material, shortens the purification time, increases purification efficiency, and reduces the use of chemical reagents in the wet purification process, thereby reducing environmental pollution.

[0042] See Figure 1 This invention provides a method for preparing high-purity molybdenum ingots, the method comprising:

[0043] Step S1: Press an appropriate amount of molybdenum powder into a billet;

[0044] Step S2: The billet is vacuum sintered at a temperature of 900 ℃~1500 ℃ to obtain the first material;

[0045] Step S3: The first material is sintered at high temperature in a hydrogen atmosphere to obtain the second material;

[0046] Step S4: After the second material is cooled to room temperature, it is bundled up, and the bundled second material is subjected to electron beam vacuum melting. After cooling, high-purity molybdenum ingots are obtained.

[0047] The power of the electron beam vacuum melting is 50 kW to 100 kW, and the melting time is 20 min to 40 min.

[0048] It should be noted that the billet can be vacuum sintered at temperatures of 900 ℃, 950 ℃, 1000 ℃, 1100 ℃, 1200 ℃, 1300 ℃, 1400 ℃, and 1500 ℃. By setting the vacuum sintering temperature, it is possible to sinter the molybdenum powder billet at high temperatures while avoiding excessive sintering or grain coarsening caused by excessively high temperatures.

[0049] The vacuum sintering time can be 2 h to 5 h; for example, the vacuum sintering time can be 2 h, 3 h, 4 h, or 5 h.

[0050] The power of electron beam vacuum melting can be 50 kW, 55 kW, 60 kW, 65 kW, 70 kW, 75 kW, 80 kW, 85 kW, 90 kW, 95 kW, or 100 kW; the melting time can be 20 min, 22 min, 25 min, 27 min, 30 min, 32 min, 35 min, 37 min, or 40 min. By setting the process parameters of electron beam melting, it is possible to ensure the high purity and high density of the second material while avoiding over-melting that would lead to energy waste or a decline in the performance of the second material.

[0051] In this invention, after pressing an appropriate amount of molybdenum powder into a billet, the billet is pre-sintered in a vacuum environment. This step effectively removes some volatile impurities (such as moisture and gases), and vacuum sintering also pre-densifies the molybdenum powder billet, providing a foundation for subsequent hydrogen sintering and electron beam melting. The first material is then sintered at high temperature in a hydrogen atmosphere. Hydrogen reduces oxides in the first material, further improving its purity. Hydrogen sintering also helps remove some volatile impurities, providing a higher purity material for subsequent electron beam melting. Finally, electron beam vacuum melting is performed. A high-energy electron beam heats the second material in a vacuum environment, causing it to melt and resolidify, thereby eliminating pores and defects and making the density of the second material close to the theoretical density. In a vacuum environment, remaining volatile impurities (such as alkali metals and oxides) can also be effectively evaporated and removed, ultimately yielding a high-purity molybdenum ingot.

[0052] In summary, the preparation method provided by this invention has a higher removal efficiency for alkali metals such as potassium and sodium compared to traditional hydrometallurgical processes. Furthermore, this invention employs a dry process (vacuum sintering, hydrogen sintering, and electron beam melting) to prepare molybdenum ingots, avoiding waste liquid discharge and reducing environmental pollution. By combining a multi-step process of vacuum sintering, hydrogen sintering, and electron beam vacuum melting, alkali metals, oxides, and other volatile impurities are efficiently removed, solving the problem of incomplete impurity removal in traditional processes. This improves the purity of molybdenum ingots to above 5N level, meeting the stringent purity requirements of high-end applications. Moreover, the densification of traditional high-temperature sintering processes typically only reaches 90%–95% of the theoretical density and suffers from structural defects. This invention, by coupling electron beam vacuum melting, can eliminate porosity and defects under high vacuum and high temperature environments, making the density of molybdenum ingots approach the theoretical density, solving the problem of insufficient density, and thus improving the mechanical properties and thermal stability of the secondary material.

[0053] In some embodiments, in step S2, the vacuum degree of the vacuum sintering is 10. -2 Pa~10 -4 Pa;

[0054] The heating rate is 8 ℃ / min to 15 ℃ / min.

[0055] It should be noted that the vacuum degree of vacuum sintering can be 10. -2 Pa, 10 -3 Pa, 10 -4 Pa;

[0056] The heating rate can be 8 ℃ / min, 9 ℃ / min, 10 ℃ / min, 11 ℃ / min, 12 ℃ / min, 13 ℃ / min, 14 ℃ / min, or 15 ℃ / min.

[0057] In this invention, under this vacuum level, volatile impurities (such as moisture, gases, alkali metals, etc.) in the billet can be evaporated and removed more effectively. The high vacuum environment also reduces the contact between impurities and the billet, avoiding secondary contamination and further improving the purity of the billet. Compared with traditional hydrometallurgical processes, vacuum sintering solves the problem of low alkali metal removal efficiency in hydrometallurgical processes. Combined with the heating rate, it ensures that the molybdenum powder billet is heated uniformly during sintering, avoiding local overheating or thermal stress concentration caused by excessively rapid heating. Uniform heating also helps to gradually release and remove volatile impurities, preventing impurities from remaining in the billet. Furthermore, this heating rate can avoid internal stress concentration or grain coarsening of the billet caused by excessively rapid heating, thereby reducing structural defects and improving the quality of the first material.

[0058] In some embodiments, in step S3, the flow rate of hydrogen is 0.5 L / min to 5 L / min.

[0059] It should be noted that the hydrogen flow rate can be 0.5 L / min, 1 L / min, 1.5 L / min, 2 L / min, 2.5 L / min, 3 L / min, 3.5 L / min, 4 L / min, 4.5 L / min, or 5 L / min.

[0060] In this invention, hydrogen gas has strong reducing properties at high temperatures, effectively reducing oxides (such as MoO2, MoO3, etc.) in the first material, further improving the purity of the first material. At high temperatures, hydrogen gas also promotes the diffusion and bonding between molybdenum particles, increasing the density of the first material and providing a higher purity material for subsequent electron beam vacuum melting, resulting in a final product with a density close to the theoretical density.

[0061] In practical implementation, by setting the hydrogen flow rate within the aforementioned range, it is possible to ensure sufficient contact between the hydrogen and the first material, promoting the reduction reaction, while avoiding hydrogen waste due to excessive flow rate or insufficient reduction due to insufficient flow rate. Furthermore, the hydrogen flow rate within this range also ensures uniform heating of the first material during sintering, preventing localized overheating due to excessive flow rate or uneven sintering due to insufficient flow rate. In this invention, the hydrogen participates in the reaction during sintering to generate water vapor, ensuring that the reaction does not produce harmful gases, thus meeting the requirements of green manufacturing.

[0062] In some embodiments, during step S3, the heating rate is 5 ℃ / min to 10 ℃ / min, the temperature is 1800 ℃ to 2600 ℃, and the high-temperature sintering time is 2 h to 5 h.

[0063] It should be noted that the heating rate can be 5 ℃ / min, 6 ℃ / min, 7 ℃ / min, 8 ℃ / min, 9 ℃ / min, or 10 ℃ / min;

[0064] The temperature can be 1800 ℃, 1900 ℃, 2000 ℃, 2200 ℃, 2400 ℃, or 2600 ℃;

[0065] The high-temperature sintering time can be 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h, or 5 h.

[0066] In this invention, volatile impurities (such as alkali metals, oxides, carbides, etc.) in the first material can be effectively evaporated and removed at a temperature of 1800 ℃ ~ 2600 ℃. Furthermore, oxides (such as MoO2, MoO3, etc.) in the first material are reduced, thereby improving the purity of the first material. The diffusion and bonding ability between molybdenum particles are also significantly enhanced, improving the compactness of the first material.

[0067] A heating rate of 5 ℃ / min ~ 10 ℃ / min ensures uniform heating of the first material during sintering, avoiding localized overheating, thermal stress concentration, or grain coarsening caused by excessively rapid heating, thereby reducing structural defects and improving production efficiency. Uniform heating also helps to gradually release and remove volatile impurities, preventing impurities from remaining in the first material.

[0068] A sintering time of 2 to 5 hours ensures that impurities are fully volatilized and removed, while avoiding impurity residue due to too short a time or energy waste due to too long a time, as well as avoiding insufficient density due to too short a time or excessive grain growth due to too long a time.

[0069] In summary, the high-temperature sintering process provided by this invention is a dry process, which avoids the waste liquid discharge problem in wet metallurgical processes and reduces environmental pollution. Volatile impurities generated during high-temperature sintering can also be effectively collected and treated, meeting the requirements of green manufacturing.

[0070] In some embodiments, in step S1, an appropriate amount of the metallic molybdenum powder is composed of a mixture of 100-mesh and 200-mesh metallic molybdenum powder;

[0071] The mass ratio of the 100-mesh molybdenum powder to the 200-mesh molybdenum powder is (3~5):(5~7).

[0072] It should be noted that the mass ratio of 100-mesh molybdenum powder to 200-mesh molybdenum powder can be 3:5, 3:6, 3:7, 4:5, 4:6, 4:7, 5:5, 5:6, or 5:7.

[0073] In this invention, the mixing of 100-mesh and 200-mesh molybdenum powders creates a favorable particle size distribution, thereby improving the formability of the billet. The coarser 100-mesh molybdenum powder acts as a skeleton, providing structural support, while the finer 200-mesh molybdenum powder fills the gaps between the coarse particles, resulting in increased compactness of the billet after pressing. By adjusting the mass ratio of the two powders, insufficient compactness due to excessive coarse particles or difficulties in forming the billet due to excessive fine particles can be avoided.

[0074] A billet made from a mixture of 100-mesh and 200-mesh molybdenum powders can form a more uniform microstructure during sintering, promoting diffusion and bonding between particles. The finer 200-mesh molybdenum powder has a higher specific surface area, enabling faster diffusion and densification during sintering. Combined with the set mass ratio, this ensures uniform shrinkage of the billet during sintering, avoiding localized stress concentrations or defects caused by uneven particle size distribution.

[0075] In some embodiments, in step S1, the raw material is selected as 99.95% high-purity metallic molybdenum powder, which is then classified by particle size. 100-mesh and 200-mesh metallic molybdenum powders are mixed in a ratio of (3~5):(5~7).

[0076] In some embodiments, in step S1, the pressure during pressing is 600 MPa to 1200 MPa.

[0077] It should be noted that the pressing pressure can be 600 MPa, 650 MPa, 700 MPa, 750 MPa, 800 MPa, 850 MPa, 900 MPa, 950 MPa, 1000 MPa, 1100 MPa, or 1200 MPa.

[0078] In this invention, setting a higher pressing pressure enables the molybdenum powder particles to bond tightly together, reducing porosity and voids in the billet, thereby improving the billet's density. It also ensures that the billet is subjected to uniform stress during pressing, avoiding insufficient density due to too low pressure or cracking or deformation due to too high pressure. The pressed billet is more likely to achieve high density during sintering, reducing sintering time and energy consumption. Furthermore, the billet shrinks more uniformly during sintering, avoiding localized stress concentrations or defects caused by uneven pressure, and reducing porosity and defects.

[0079] In some embodiments, pressing can be performed by molding or isostatic pressing to press an appropriate amount of molybdenum powder into a billet.

[0080] In some embodiments, the pressed blank can be in the shape of a strip, a round bar, etc.;

[0081] When the billet is long and narrow, the billet size can be (20~40)*(20~40)*(200~600) mm; when the billet is round and cylindrical, the billet size can be φ(30~50)*(300~800) mm.

[0082] In this invention, no additives or binders are added during the pressing process to avoid introducing impurities and contamination, resulting in higher purity molybdenum ingots.

[0083] In some embodiments, in step S4, the cooling rate is 8 ℃ / min to 15 ℃ / min.

[0084] It should be noted that the cooling rate can be 8 ℃ / min, 9 ℃ / min, 10 ℃ / min, 11 ℃ / min, 12 ℃ / min, 13 ℃ / min, 14 ℃ / min, or 15 ℃ / min.

[0085] In this invention, by setting a cooling rate, the second material can shrink uniformly during cooling, reducing internal stress concentration caused by temperature gradients. Within a cooling rate of 8 ℃ / min to 15 ℃ / min, the second material can form a uniform microstructure during cooling, thereby reducing grain coarsening or local defects and improving product quality. Uniform cooling also helps the second material maintain high density, avoiding porosity or defects caused by uneven cooling, thus improving the strength, toughness, and thermal stability of the final product.

[0086] In some embodiments, the preparation method further includes:

[0087] In step S3, when the second material is cooled to 800 ℃~1200 ℃, the hydrogen is replaced with an inert gas, and then the second material is subjected to high-temperature vacuum dehydrogenation treatment, and taken out after cooling;

[0088] The vacuum degree during the high-temperature vacuum dehydrogenation process is 10. -2 Pa~10 -4 Pa, temperature is 800 ℃~1200℃.

[0089] It should be noted that the second material can be cooled to 800 ℃, 850 ℃, 900 ℃, 950 ℃, 1000 ℃, 1100 ℃, or 1200 ℃;

[0090] Inert gases can be argon, nitrogen, etc.

[0091] In this invention, during hydrogen sintering, a very small amount of hydrogen can easily remain in the second material, affecting the purity of the final product. By performing vacuum dehydrogenation treatment at a high temperature of 800℃~1200℃, the residual hydrogen in the second material can be effectively removed, thereby eliminating porosity and defects caused by hydrogen residue, making the material density close to the theoretical density, and further improving the material purity. And 10 -2 Pa ~ 10 -4 The high vacuum environment of Pa can accelerate the escape of hydrogen and ensure the dehydrogenation effect.

[0092] In practice, the hydrogen produced during the dehydrogenation process can be effectively collected and treated to avoid environmental pollution.

[0093] The present invention also provides a high-purity molybdenum ingot, which is prepared by the preparation method described above;

[0094] The purity of the high-purity molybdenum ingot is 99.999%.

[0095] The high-purity molybdenum ingots prepared by the method of this invention can be widely used in semiconductor, aerospace, electronic components and new energy fields, especially in extreme environments such as high temperature, high pressure and strong corrosion, where they exhibit excellent performance stability.

[0096] This invention also provides a system for preparing high-purity molybdenum ingots, see [link to documentation]. Figure 2 The system is used to perform the above preparation method to prepare the high-purity molybdenum ingot, and the system includes:

[0097] Vacuum sintering device 1, hydrogen sintering device 2 and electron beam vacuum melting device 3 are connected in sequence;

[0098] The vacuum sintering device 1 is used to vacuum sinter the billet to obtain the first material;

[0099] The hydrogen sintering device 2 is used to sinter the first material at high temperature in a hydrogen atmosphere to obtain the second material.

[0100] The electron beam vacuum melting device 3 is used to perform electron beam vacuum melting on the bundled second material, and obtain high-purity molybdenum ingots after cooling.

[0101] In practice, an appropriate amount of molybdenum powder is pressed into a billet, which is then placed in a vacuum sintering apparatus 1. The internal pressure of the vacuum sintering apparatus 1 is adjusted to 10. -2 Pa~10 -4 Pa, with its heating rate set at 8 ℃ / min~15 ℃ / min, until the temperature reaches 900 ℃~1500 ℃, so that the billet is subjected to high-temperature sintering treatment in vacuum sintering device 1 to obtain the first material;

[0102] The first material is then transferred to the hydrogen sintering apparatus 2, and hydrogen is introduced into the hydrogen sintering apparatus 2 at a rate of 0.5 L / min to 5 L / min. The heating rate of the hydrogen sintering apparatus 2 is set to 5 ℃ / min to 10 ℃ / min until the temperature rises to 1800 ℃ to 2600 ℃. The first material is then sintered in the hydrogen sintering apparatus 2 for 2 h to 5 h to obtain the second material.

[0103] After the second material is cooled to room temperature, it is bundled and then placed into the electron beam vacuum melting device 3. The melting power in the electron beam vacuum melting device 3 is set to 50 kW to 100 kW, and the second material is melted in the electron beam vacuum melting device 3 for 20 min to 40 min. After the material is cooled, it is taken out to obtain high-purity molybdenum ingots.

[0104] In this invention, the system integrates three process steps: vacuum sintering, hydrogen sintering, and electron beam vacuum melting, achieving integrated preparation from raw material to high-purity molybdenum ingot. Sintering in a vacuum environment effectively removes volatile impurities such as moisture, gases, and alkali metals, providing high-purity intermediate materials for subsequent processes. High-temperature sintering in a hydrogen atmosphere reduces oxides in the molybdenum material and removes some volatile impurities (such as carbon and sulfur). Under the influence of high vacuum and a high-energy electron beam, residual impurities (such as alkali metals and oxides) are further removed, ensuring the final product achieves an ultra-high purity of 5N level (99.999%) or higher, meeting the stringent material requirements of semiconductors, aerospace, electronic components, and new energy fields.

[0105] The system employs a dry process (vacuum sintering, hydrogen sintering, and electron beam melting), avoiding the waste liquid discharge problems associated with hydrometallurgical processes and reducing environmental pollution. Furthermore, the waste gases (hydrogen, etc.) generated during hydrogen sintering and electron beam melting can be effectively collected and treated, meeting the requirements of green manufacturing. This system is not only suitable for the preparation of high-purity molybdenum ingots, but can also be adapted to the preparation of other high-purity metal materials (such as tungsten and tantalum) by adjusting process parameters.

[0106] In some embodiments, the material racks in the vacuum sintering apparatus 1 and the hydrogen sintering apparatus 2 can adopt a multi-layer horizontal structure to increase the amount of billet placed and improve production efficiency.

[0107] In some embodiments, the vacuum sintering apparatus 1 and the hydrogen sintering apparatus 2 may be housed in the same sintering furnace;

[0108] For example, a vacuum / hydrogen dual-purpose sintering furnace can perform vacuum sintering on one side and hydrogen sintering on the other side; or, in a sintering furnace, vacuum sintering can be performed first, followed by hydrogen atmosphere sintering, which can prevent the first material from coming into contact with other impurities during the movement of the first material and ensure the purity of the first material.

[0109] In some embodiments, in step S3, when the second material cools down to 800 ℃~1200 ℃, inert gas can be introduced into the hydrogen sintering device 2 to replace the hydrogen in the device, and then the vacuum degree of the hydrogen sintering device 2 is adjusted to 10. -2 Pa~10 -4 The second material is subjected to high-temperature vacuum dehydrogenation treatment at a temperature of 800 ℃~1200 ℃, and then removed after cooling.

[0110] To enable those skilled in the art to more clearly understand the present invention, the following embodiments will be used to provide a detailed description of a high-purity molybdenum ingot, its preparation method, and its preparation system.

[0111] The following examples all use Figure 2 The system shown is used to prepare high-purity molybdenum ingots.

[0112] Example 1

[0113] (1) The raw material is 99.95% high-purity metallic molybdenum powder. The particle size is classified and 100 mesh and 200 mesh metallic molybdenum powder are mixed in a ratio of 3:7. The blank is pressed into a blank by molding. The pressing pressure is set to 600 MPa. The blank is pressed into a long strip with a size of 20*20*200 mm.

[0114] (2) The pressed molybdenum billet is placed in a vacuum / hydrogen dual-purpose sintering furnace for vacuum sintering. The material rack adopts a multi-layer horizontal structure, and the vacuum degree is set to 1×10 -2 Pa, heating rate set to 8 °C / min, sintering temperature set to 900 °C, sintering time set to 5 h, and first material obtained after sintering;

[0115] (3) After vacuum sintering, high-purity hydrogen is injected into the furnace and the first material is sintered in a high-temperature hydrogen atmosphere under a reducing atmosphere. The heating rate is set to 5 °C / min, the temperature is set to 1800 °C, the sintering time is 5 h, and the hydrogen flow rate is controlled at 0.5 L / min. The second material is obtained after sintering.

[0116] (4) After sintering in a hydrogen atmosphere, cooling begins at a rate of 8 °C / min. When the temperature drops to 1200 °C, high-purity argon is injected into the furnace to replace the hydrogen. After the hydrogen replacement is complete, the second material undergoes high-temperature vacuum dehydrogenation, with the vacuum level controlled at 5 × 10⁻⁶.-4 Pa, the dehydrogenation time is set to 3 h, and after the dehydrogenation is completed, the second material is taken out after cooling to room temperature;

[0117] (5) The second material assembly is bundled together by welding or binding. After bundling, it is placed in an electron beam vacuum melting furnace for electron beam vacuum refining. The melting power is set to 50 kW and the vacuum degree is set to 2×10. -3 Pa, the melting time was set to 20 min, and a high-purity molybdenum ingot was obtained after melting. After melting, the ingot was slowly cooled to room temperature and taken out. The purity of the high-purity molybdenum ingot was 99.999%.

[0118] Example 2

[0119] (1) The raw material is 99.95% high-purity metallic molybdenum powder. The particle size is classified and 100 mesh and 200 mesh metallic molybdenum powder are mixed in a 5:5 ratio. The blank is pressed into a billet by isostatic pressing. The pressing pressure is set to 1000 MPa. The billet is pressed into a round bar with a size of φ40*600 mm.

[0120] (2) The pressed molybdenum billet is placed in a vacuum / hydrogen dual-purpose sintering furnace for vacuum sintering, with the vacuum level set to 5×10⁻⁶. -4 Pa, heating rate set to 15 °C / min, sintering temperature set to 1500 °C, sintering time set to 2 h, and first material obtained after sintering;

[0121] (3) After vacuum sintering is completed, high-purity hydrogen is injected into the furnace and the first material is sintered in a high-temperature hydrogen atmosphere under a reducing atmosphere. The heating rate is set to 10 °C / min, the temperature is set to 2600 °C, the sintering time is set to 2 h, and the hydrogen flow rate is controlled at 5 L / min. The second material is obtained after sintering.

[0122] (4) After sintering in a hydrogen atmosphere, cooling begins at a rate of 15 °C / min. When the temperature drops to 800 °C, high-purity argon is injected into the furnace to replace the hydrogen. After the hydrogen replacement is complete, the second material undergoes high-temperature vacuum dehydrogenation, with the vacuum level controlled at 1 × 10⁻⁶. -2 Pa, the dehydrogenation time is set to 10 h, and after the dehydrogenation is completed, the second material is taken out after cooling to room temperature;

[0123] (5) The second material combination is bundled together by welding or binding, and then placed in an electron beam vacuum melting furnace for electron beam vacuum refining. The melting power is set to 100 kW and the vacuum degree is set to 2×10 -4Pa, the melting time was set to 40 min to obtain high-purity molybdenum ingots. After melting, the ingots were slowly cooled to room temperature and removed. The purity of the high-purity molybdenum ingots was 99.999%.

[0124] Example 3

[0125] (1) The raw material is 99.95% high-purity metallic molybdenum powder. The particle size is classified and 100 mesh and 200 mesh powder are mixed in a ratio of 4:6. The blank is pressed into a billet by isostatic pressing. The pressing pressure is set to 1200 MPa. The billet is pressed into a round bar with a size of φ50*800 mm.

[0126] (2) The pressed molybdenum billet is placed in a vacuum / hydrogen dual-purpose sintering furnace for vacuum sintering, with the vacuum level controlled at 3×10⁻⁶. -3 Pa, heating rate set to 10 °C / min, sintering temperature set to 1300 °C, sintering time set to 3 h, and first material obtained after sintering;

[0127] 3. After vacuum sintering is completed, high-purity hydrogen is injected into the furnace, and the first material is sintered in a high-temperature hydrogen atmosphere under a reducing atmosphere. The heating rate is set to 8 °C / min, the temperature is set to 2200 °C, the sintering time is set to 3 h, and the hydrogen flow rate is set to 3 L / min. The second material is obtained after sintering.

[0128] 4. After sintering in the hydrogen atmosphere is complete, cooling begins at a rate of 10 °C / min. When the temperature drops to 1000 °C, high-purity argon is injected into the furnace to replace the hydrogen. After hydrogen replacement is complete, the second material undergoes high-temperature vacuum dehydrogenation, with the vacuum level controlled at 1 × 10⁻⁶. -3 Pa, the dehydrogenation time is set to 6 h, and after the dehydrogenation is completed, the second material is taken out after cooling to room temperature;

[0129] 5. The second material assembly is bundled together using welding or binding methods. After bundling, it is placed in an electron beam vacuum melting furnace for electron beam vacuum refining. The melting power is set to 80 kW, and the vacuum degree is set to 6×10⁻⁶. -4 Pa, the melting time was set to 30 min to obtain high-purity molybdenum ingots. After melting, the ingots were slowly cooled to room temperature and removed. The purity of the high-purity molybdenum ingots was 99.999%.

[0130] In summary, this invention employs a combined purification technology of vacuum sintering, hydrogen atmosphere sintering, and electron beam vacuum melting to produce 5N-grade high-purity molybdenum ingots with a purity ≥99.999% (5N grade). The density of the molybdenum ingots is significantly improved, approaching 100% of the theoretical value, resulting in a significant enhancement in processing performance. Furthermore, the efficient heating through electron beam melting greatly improves production efficiency.

[0131] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0132] Although preferred embodiments of the present application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the embodiments of the present application.

[0133] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or terminal device. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or terminal device that includes said element.

[0134] The above provides a detailed description of a high-purity molybdenum ingot, its preparation method, and its preparation system. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this application. At the same time, those skilled in the art will recognize that there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A method for preparing high-purity molybdenum ingots, characterized in that, The method includes: S1. Press an appropriate amount of molybdenum powder into a billet; S2. The billet is vacuum sintered at a temperature of 900 ℃~1500 ℃ to obtain the first material; S3. The first material is sintered at high temperature in a hydrogen atmosphere to obtain the second material; S4. After the second material is cooled to room temperature, it is bundled up. The bundled second material is then subjected to electron beam vacuum melting and cooled to obtain high-purity molybdenum ingots. The cooling rate is 8 ℃ / min to 15 ℃ / min; the electron beam vacuum melting power is 50 kW to 100 kW, and the melting time is 20 min to 40 min. In step S1, the appropriate amount of metallic molybdenum powder is composed of a mixture of 100-mesh and 200-mesh metallic molybdenum powder; the mass ratio of the 100-mesh metallic molybdenum powder to the 200-mesh metallic molybdenum powder is (3~5):(5~7). In step S2, the vacuum degree of the vacuum sintering is 10. -2 Pa~10 -4 Pa; heating rate is 8 ℃ / min~15 ℃ / min.

2. The method for preparing high-purity molybdenum ingots according to claim 1, characterized in that, In step S3, the flow rate of the hydrogen gas is 0.5 L / min to 5 L / min.

3. The method for preparing high-purity molybdenum ingots according to claim 1, characterized in that, In step S3, during the high-temperature sintering process, the heating rate is 5 ℃ / min~10 ℃ / min, the temperature is 1800 ℃~2600 ℃, and the high-temperature sintering time is 2 h~5 h.

4. The method for preparing high-purity molybdenum ingots according to claim 1, characterized in that, In step S1, the pressure during pressing is 600 MPa to 1200 MPa.

5. The method for preparing high-purity molybdenum ingots according to any one of claims 1 to 4, characterized in that, The preparation method further includes: In step S3, when the second material is cooled to 800 ℃~1200 ℃, the hydrogen is replaced with an inert gas, and then the second material is subjected to high-temperature vacuum dehydrogenation treatment, and taken out after cooling; The vacuum degree during the high-temperature vacuum dehydrogenation process is 10. -2 Pa~10 -4 Pa, temperature is 800 ℃~1200 ℃.

6. A high-purity molybdenum ingot, characterized in that, The high-purity molybdenum ingot is prepared by the preparation method according to any one of claims 1 to 5; The purity of the high-purity molybdenum ingot is 99.999%.

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