High-purity metal molybdenum ingot, preparation method and preparation system thereof

Abstract

The invention provides a high-purity metal molybdenum ingot, a preparation method and a preparation system thereof. The preparation method comprises the following steps: firstly, performing vacuum sintering on a high-purity molybdenum blank to remove gas impurities and part of low-boiling-point volatile impurities adsorbed on the metal surface; sintering in a hydrogen reducing atmosphere under a high-temperature condition to remove oxide impurities and non-metal impurities (carbon, sulfur and the like); and finally, most metal impurities (such as potassium, sodium, iron and the like) are efficiently removed through vapor pressure difference in a high-vacuum environment by adopting an electron beam vacuum melting technology, and the metal molybdenum ingot with the purity reaching 5N grade or above (99.999 wt.%) is prepared. The method has the characteristics of simple process and high product batch stability, and is suitable for preparing high-purity metal molybdenum used in the fields of high-end electronic devices, semiconductors and aerospace.

Description

Technical Field

[0001] The present application relates to the technical field of metal purification, and in particular to a high-purity metal molybdenum ingot, a preparation method and a preparation system thereof. Background Art

[0002] Metallic molybdenum is widely used in semiconductors, aerospace, electronic components, new energy and other fields due to its unique physical and chemical properties, such as high melting point, high strength, good thermal conductivity and electrical conductivity. However, these high-end fields have extremely stringent requirements for molybdenum materials, requiring ultra-high purity of 5N level (99.999%) or above, and requiring the material to have a density close to the theoretical density and extremely high quality stability to meet the needs of use and processing under complex conditions.

[0003] At present, high-purity metallic molybdenum generally adopts chemical-physical combined purification process, among which hydrometallurgical process is the main method for preparing high-purity metallic molybdenum. However, the hydrometallurgical process has low removal efficiency for alkali metals such as potassium and sodium, and there is a secondary pollution problem. The large amount of waste liquid generated is likely to burden the environment. Although 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 above 5N level. The density usually only reaches 90%~95% of the theoretical density, and there are defects in the organization. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a high-purity metal molybdenum ingot, a preparation method and a preparation system thereof, which adopts a combined process of vacuum sintering, hydrogen atmosphere reduction sintering and electron beam vacuum melting to prepare 5N grade high-purity metal molybdenum ingots, which can efficiently remove high saturated vapor pressure, volatile impurities and gas impurities such as C, O, and N in the metal, and can significantly improve the purity and density of high-purity metal molybdenum materials, shorten the purification time, and improve the purification efficiency. At the same time, the use of chemical reagents in the wet purification process is reduced, environmental pollution is reduced, and the requirements of green development are met.

[0005] In a first aspect, the present invention provides a method for preparing a high-purity metal molybdenum ingot, the method comprising: S1, pressing an appropriate amount of metal molybdenum powder into a blank; S2, the blank is vacuum sintered at a temperature of 900°C to 1500°C to obtain a first material; S3, sintering the first material at high temperature in a hydrogen atmosphere to obtain a second material; S4, the second material is bundled after cooling to room temperature, and the bundled second material is subjected to electron beam vacuum melting, and a high-purity metal molybdenum ingot is obtained after cooling; The power of the electron beam vacuum melting is 50 kw~100 kw, and the melting time is 20 min~40 min.

[0006] Optionally, in step S2, the vacuum degree of the vacuum sintering is 10 -2 Pa~10 -4 Pa; The heating rate is 8 ℃ / min~15 ℃ / min.

[0007] Optionally, in step S3, the flow rate of hydrogen is 0.5 L / min~5 L / min.

[0008] Optionally, in step S3, during the high temperature sintering treatment, the heating rate is 5°C / min-10°C / min, the temperature is 1800°C-2600°C, and the high temperature sintering time is 2 h-5 h.

[0009] Optionally, in step S1, the appropriate amount of the metal molybdenum powder is composed of a mixture of 100-mesh and 200-mesh metal molybdenum powders; Wherein, the mass ratio of the 100-mesh metal molybdenum powder to the 200-mesh metal molybdenum powder is (3-5): (5-7).

[0010] Optionally, in step S1, the pressure during pressing is 600 MPa~1200 MPa.

[0011] Optionally, in step S4, the cooling rate is 8°C / min to 15°C / min.

[0012] Optionally, the preparation method further comprises: In step S3, when the temperature of the second material is reduced to 800°C-1200°C, the hydrogen is replaced by an inert gas, and the second material is subjected to a high-temperature vacuum dehydrogenation treatment, and then taken out after cooling; The vacuum degree during the high temperature vacuum dehydrogenation treatment is 10 -2 Pa~10 -4 Pa, temperature is 800℃~1200℃.

[0013] In a second aspect, the present invention provides a high-purity metal molybdenum ingot, which is prepared by the preparation method described in the first aspect; the purity of the high-purity metal molybdenum ingot is 99.999%.

[0014] In a third aspect, the present invention provides a system for preparing a high-purity metal molybdenum ingot, the system being used to perform the preparation method described in the first aspect, the system comprising: A vacuum sintering device, a hydrogen sintering device and an electron beam vacuum melting device connected in sequence; The vacuum sintering device is used to vacuum sinter the blank to obtain the first material; The hydrogen sintering device is used to sinter the first material at high temperature in a hydrogen atmosphere to obtain a second material; The electron beam vacuum melting device is used to perform electron beam vacuum melting on the bundled second material to obtain a high-purity metal molybdenum ingot after cooling.

[0015] Beneficial technical effects: 1. The present invention provides a method for preparing a high-purity metal molybdenum ingot. By setting a multi-step process of vacuum sintering, hydrogen sintering and electron beam vacuum melting, impurities in metal molybdenum, especially alkali metals (such as potassium, sodium) and oxides, etc., are effectively removed, so that the metal molybdenum reaches an ultra-high purity of 5N level (99.999%) or above, meeting the stringent requirements of high-end fields for material purity; by setting a multi-step sintering and melting process, the use and processing of metal molybdenum materials under complex conditions are more stable, the tissue defects are reduced, and the mechanical properties and thermal stability of metal molybdenum are improved; wherein, the electron beam vacuum melting is carried out under high temperature and high vacuum environment, which can effectively remove pores and defects in the second material, so that the density of the final molybdenum ingot is close to the theoretical density, which is significantly higher than the 90% to 95% density of the traditional high-temperature sintering process, and compared with the hydrometallurgical process, the method provided by the present invention avoids the generation of a large amount of waste liquid, greatly reduces the secondary pollution problem, and meets environmental protection requirements; 2. The present invention provides a high-purity metal molybdenum ingot, which is made by the preparation method of the present invention. The molybdenum ingot has a compactness close to the theoretical density, less pores and defects, high strength, good thermal conductivity and electrical conductivity, and is suitable for use and processing under complex conditions; the purity of the high-purity metal molybdenum ingot reaches 99.999% (5N grade), the potassium and sodium impurity contents in the high-purity molybdenum ingot are ≤0.3ppm, the iron impurity content is ≤0.5ppm, and the total impurity content is ≤10ppm, which can meet the extreme requirements of high-end fields such as semiconductors, aerospace, and electronic components for material purity, especially in extreme environments such as high temperature, high pressure, and strong corrosion, and exhibits excellent performance stability; 3. The present invention provides a preparation system for high-purity metal molybdenum ingots, which integrates a vacuum sintering device, a hydrogen sintering device and an electron beam vacuum melting device, and can realize the integrated preparation from blanks to high-purity molybdenum ingots, thereby improving production efficiency and process controllability; when using the system to produce molybdenum ingots, a multi-step process of vacuum sintering, hydrogen sintering and electron beam melting can be realized, thereby efficiently removing alkali metals, oxides and other volatile impurities in the molybdenum material, ensuring the high purity and high density of the final product, avoiding the problem of waste liquid discharge in the hydrometallurgical process, reducing environmental pollution, and meeting the requirements of green manufacturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the description of the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0017] Figure 1 A flow chart of a method for preparing a high-purity metal molybdenum ingot proposed in an embodiment of the present application is shown; Figure 2 A schematic diagram of the structure of a preparation system for a high-purity metal molybdenum ingot proposed in an embodiment of the present application is shown.

[0018] Description of reference numerals: 1. Vacuum sintering device; 2. Hydrogen sintering device; 3. Electron beam vacuum melting device. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0020] In the drawings, the size of the constituent elements, the thickness of the layer or the area may be exaggerated for the sake of clarity. Therefore, any implementation of the present disclosure is not necessarily limited to the size shown in the drawings, and the shapes and sizes of the components in the drawings do not reflect the true proportions. In addition, the drawings schematically show ideal examples, and any implementation of the present disclosure is not limited to the shapes or values ​​shown in the drawings.

[0021] In the related technologies, metallic molybdenum is widely used in semiconductors, aerospace, electronic components and new energy fields due to its unique physical and chemical properties, such as high melting point (2623 ℃), high strength, good thermal conductivity and electrical conductivity. In particular, in semiconductor manufacturing, molybdenum is used to manufacture interconnect materials for high-power devices and integrated circuits; in the aerospace field, molybdenum alloys are used to manufacture high-temperature structural parts; in the new energy field, molybdenum plays an important role in hydrogen energy technology as a catalyst carrier. However, these high-end fields have extremely demanding requirements for molybdenum materials. They need to achieve ultra-high purity above 5N level (99.999%), and require the material to have a density close to the theoretical density and extremely high quality stability to meet the needs of use and processing under complex conditions. For example, in semiconductor manufacturing, even trace amounts of impurities can seriously affect the performance and reliability of the device; in the aerospace field, the density and organizational uniformity of the material are directly related to the service life and safety of the components.

[0022] At present, high-purity molybdenum metal generally adopts chemical-physical combined purification process, because the traditional process requires multi-step purification, the process is complex, time-consuming, and the equipment maintenance cost is high, which makes it difficult to ensure the purity and quality stability of molybdenum metal materials. Therefore, it is gradually replaced by combined process. Among them, the hydrometallurgical process has low removal efficiency for alkali metals such as potassium and sodium, and there is a secondary pollution problem. The large amount of waste liquid generated is easy to burden the environment; physical metallurgical methods such as high-temperature sintering have advantages in removing some oxides and volatile impurities, but their removal effect is difficult to meet the requirements of purity above 5N level, and the density usually only reaches 90%~95% of the theoretical density, and there are defects in the organization. For example, during high-temperature sintering, due to uneven temperature gradient and pressure distribution, pores and grain boundary segregation are easily caused inside the material, affecting the mechanical properties and thermal stability of the material. In addition, the reducing agents and solvents used in traditional processes may introduce new impurities, further affecting the purity of the material.

[0023] In order to overcome these challenges, a series of new purification technologies have been developed in recent years. For example, electron beam melting technology can effectively remove volatile impurities and improve the purity of materials; plasma melting technology can achieve efficient purification at lower temperatures, reducing energy consumption and pollution. At the same time, the use of advanced powder metallurgy technologies such as hot isostatic pressing (HIP) and spark plasma sintering (SPS) can significantly improve the density and organizational uniformity of materials, making them close to the 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 burdens, providing strong support for the application of molybdenum materials in high-end fields.

[0024] In view of the content of the related technology, the present invention adopts the combined process technology of vacuum sintering, hydrogen atmosphere reduction sintering and electron beam vacuum melting to prepare 5N grade high-purity metal molybdenum ingots, which can not only efficiently remove volatile impurities and gas impurities such as C, O, N in the metal, but also significantly improve the purity and density of high-purity metal molybdenum materials, shorten the purification time, improve the purification efficiency, and at the same time reduce the use of chemical reagents in the wet purification process and reduce environmental pollution.

[0025] See also Figure 1 The present invention provides a method for preparing a high-purity metal molybdenum ingot, the method comprising: Step S1: pressing an appropriate amount of metal molybdenum powder into a blank; Step S2: the blank is vacuum sintered at a temperature of 900° C. to 1500° C. to obtain a first material; Step S3: sintering the first material at high temperature in a hydrogen atmosphere to obtain a second material; Step S4: the second material is bundled after being cooled to room temperature, and the bundled second material is subjected to electron beam vacuum melting, and a high-purity metal molybdenum ingot is obtained after cooling; The power of the electron beam vacuum melting is 50 kw~100 kw, and the melting time is 20 min~40 min.

[0026] It should be noted that the blank can be vacuum sintered at 900°C, 950°C, 1000°C, 1100°C, 1200°C, 1300°C, 1400°C, and 1500°C; by setting the temperature of vacuum sintering, the molybdenum powder blank can be sintered at high temperature while avoiding excessive sintering or grain coarsening of the blank due to excessively high temperature; The vacuum sintering time may be 2 h to 5 h; for example, the vacuum sintering time may be 2 h, 3 h, 4 h, or 5 h; 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, and 100 kw; the melting time can be 20 min, 22 min, 25 min, 27 min, 30 min, 32 min, 35 min, 37 min, and 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 energy waste or degradation of the performance of the second material caused by excessive melting.

[0027] In the present invention, after pressing an appropriate amount of metal molybdenum powder into a blank, the molybdenum powder blank is preliminarily sintered under a vacuum environment. This step can effectively remove some volatile impurities (such as moisture, gas, etc.). Vacuum sintering can also make the molybdenum powder blank preliminarily dense, providing a basis for subsequent hydrogen sintering and electron beam melting. Then, the first material is sintered at high temperature in a hydrogen atmosphere. Hydrogen can reduce the oxides in the first material, further improving the purity of the first material. Hydrogen sintering also helps to remove some volatile impurities, providing higher purity materials for subsequent electron beam melting. Finally, electron beam vacuum melting is performed, and the second material is heated by a high-energy electron beam in a vacuum environment to melt and re-solidify, thereby eliminating pores and defects, and making the density of the second material close to the theoretical density. In a vacuum environment, the remaining volatile impurities (such as alkali metals, oxides, etc.) can also be effectively evaporated and removed, and finally a high-purity metal molybdenum ingot is obtained.

[0028] In summary, the preparation method provided by the present invention has a higher removal efficiency for alkali metals such as potassium and sodium than the traditional hydrometallurgical process, and the present invention adopts a dry process (vacuum sintering, hydrogen sintering and electron beam melting) to prepare molybdenum ingots, avoiding waste liquid discharge and reducing pollution to the environment. By combining the multi-step process of vacuum sintering, hydrogen sintering and electron beam vacuum melting, alkali metals, oxides and other volatile impurities are efficiently removed, the problem of incomplete impurity removal in the traditional process is solved, and the purity of the molybdenum ingot is increased to above 5N level, meeting the stringent requirements of the purity of metal molybdenum ingots in the high-end field. In addition, the density of the traditional high-temperature sintering process can usually only reach 90%~95% of the theoretical density, and there are organizational defects. The present invention can eliminate pores and defects in a high vacuum and high temperature environment by coupling the electron beam vacuum melting process, so that the density of the molybdenum ingot is close to the theoretical density, solving the problem of insufficient density, and then improving the mechanical properties and thermal stability of the second material.

[0029] In some embodiments, in step S2, the vacuum degree of the vacuum sintering is 10 -2 Pa~10 -4 Pa; The heating rate is 8 ℃ / min~15 ℃ / min.

[0030] It should be noted that the vacuum degree of vacuum sintering can be 10 -2 Pa, 10 -3 Pa, 10 -4 Pa; The heating rate may be 8°C / min, 9°C / min, 10°C / min, 11°C / min, 12°C / min, 13°C / min, 14°C / min, or 15°C / min.

[0031] In the present invention, under this vacuum degree, volatile impurities (such as water, gas, alkali metals, etc.) in the blank can be evaporated and removed more effectively. The high vacuum environment can also reduce the contact between impurities and the blank, avoid secondary pollution, and further improve the purity of the blank. Compared with the traditional hydrometallurgical process, vacuum sintering solves the problem of low efficiency of alkali metal removal in the wet process. Combined with the heating rate, it can ensure that the molybdenum powder blank is evenly heated during the sintering process, avoiding local overheating or thermal stress concentration caused by too fast heating. The uniform heating also helps to gradually release and remove volatile impurities, avoiding impurities from remaining in the blank. In addition, the heating rate can avoid stress concentration or grain coarsening inside the blank caused by too fast heating, thereby reducing tissue defects and improving the quality of the first material.

[0032] In some embodiments, in step S3, the flow rate of hydrogen is 0.5 L / min~5 L / min.

[0033] It should be noted that the flow rate of hydrogen 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, and 5 L / min.

[0034] In the present invention, hydrogen has strong reducing properties at high temperatures and can effectively reduce oxides (such as MoO2, MoO3, etc.) in the first material, further improving the purity of the first material. Hydrogen can also promote diffusion and bonding between molybdenum particles at high temperatures to improve the compactness of the first material, provide higher purity materials for subsequent electron beam vacuum melting, and make the final product close to the theoretical density.

[0035] In specific implementation, by setting the hydrogen flow rate within the above range, hydrogen can be fully contacted with the first material to promote the reduction reaction, and hydrogen waste caused by too high a flow rate or insufficient reduction caused by too low a flow rate can be avoided. In addition, the hydrogen flow rate within this range can also ensure that the first material is evenly heated during the sintering process, avoiding local overheating caused by too high a flow rate or uneven sintering caused by too low a flow rate. In the present invention, hydrogen generates water vapor after participating in the reaction during the sintering process, so that the reaction does not produce harmful gases, meeting the requirements of green manufacturing.

[0036] In some embodiments, in step S3, during the high temperature sintering treatment, the heating rate is 5°C / min-10°C / min, the temperature is 1800°C-2600°C, and the high temperature sintering time is 2 h-5 h.

[0037] It should be noted that the heating rate can be 5 ℃ / min, 6 ℃ / min, 7 ℃ / min, 8 ℃ / min, 9 ℃ / min, 10 ℃ / min; The temperature can be 1800°C, 1900°C, 2000°C, 2200°C, 2400°C, 2600°C; 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.

[0038] In the present invention, at a temperature of 1800°C to 2600°C, volatile impurities (such as alkali metals, oxides, carbides, etc.) in the first material can be effectively evaporated and removed. Also, the oxides (such as MoO2, MoO3, etc.) in the first material are reduced, thereby improving the purity of the first material. The diffusion and bonding capabilities between molybdenum particles are also significantly enhanced, thereby improving the compactness of the first material; At a heating rate of 5 ℃ / min to 10 ℃ / min, the first material can be heated evenly during the sintering process to avoid local overheating, thermal stress concentration or grain coarsening caused by too fast heating, thereby reducing organizational defects and improving production efficiency. Uniform heating also helps to gradually release and remove volatile impurities, avoiding impurities remaining in the first material.

[0039] Within the sintering time of 2 h to 5 h, it can ensure that impurities are fully volatilized and removed, while avoiding impurity residues caused by too short a time or energy waste caused by too long a time, as well as avoiding insufficient density caused by too short a time or excessive grain growth caused by too long a time.

[0040] In summary, the high temperature sintering process provided by the present invention is a dry process, which avoids the problem of waste liquid discharge in the hydrometallurgical process and reduces the pollution to the environment. The volatile impurities generated during the high temperature sintering process can also be effectively collected and treated, meeting the requirements of green manufacturing.

[0041] In some embodiments, in step S1, the appropriate amount of the metal molybdenum powder is composed of a mixture of 100 mesh and 200 mesh metal molybdenum powder; Wherein, the mass ratio of the 100-mesh metal molybdenum powder to the 200-mesh metal molybdenum powder is (3-5): (5-7).

[0042] It should be noted that the mass ratio of 100-mesh metal molybdenum powder to 200-mesh metal molybdenum powder can be 3:5, 3:6, 3:7, 4:5, 4:6, 4:7, 5:5, 5:6, 5:7.

[0043] In the present invention, the 100-mesh and 200-mesh metal molybdenum powders are mixed and used to form a good particle size distribution, thereby improving the formability of the blank. Among them, the coarser 100-mesh molybdenum powder is used as a skeleton to provide structural support, and the finer 200-mesh molybdenum powder is used to fill the gaps between the coarse particles, which can improve the compactness of the blank after pressing. By setting the mass ratio of the two, it is possible to avoid insufficient compactness of the blank due to too many coarse particles, or difficulty in blank forming due to too many fine particles.

[0044] The blank made of a mixture of 100 mesh and 200 mesh molybdenum powder can form a more uniform microstructure during the sintering process, promoting diffusion and bonding between particles. Among them, the finer 200 mesh molybdenum powder has a higher specific surface area and can diffuse and densify faster during the sintering process. Combined with the set mass ratio, it can ensure that the blank shrinks evenly during the sintering process, avoiding local stress concentration or defects caused by uneven particle size distribution.

[0045] In some embodiments, in step S1, the raw material is 99.95% high-purity metal molybdenum powder, which is subjected to particle size classification, and the 100-mesh and 200-mesh metal molybdenum powders are mixed in a ratio of (3-5): (5-7).

[0046] In some embodiments, in step S1, the pressing pressure is 600 MPa to 1200 MPa.

[0047] It should be noted that the pressure during pressing 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.

[0048] In the present invention, by setting a higher pressing pressure, the metal molybdenum powder particles can be tightly combined, the pores and gaps in the blank can be reduced, and the compactness of the blank can be improved. Also, it is ensured that the blank is uniformly stressed during the pressing process, avoiding insufficient compactness of the blank due to too low pressure, or cracking or deformation of the blank due to too high pressure. The pressed blank is easier to achieve high compactness during the sintering process, reducing the sintering time and energy consumption, and the blank can shrink more evenly during the sintering process, avoiding local stress concentration or defects caused by uneven pressure, and reducing pores and defects.

[0049] In some embodiments, the pressing may be performed by pressing a proper amount of metallic molybdenum powder into a blank by die pressing or isostatic pressing.

[0050] In some embodiments, the pressed blank may be in the shape of a long strip, a round bar, etc.; When the blank is in the shape of a long strip, the size of the blank can be (20~40)*(20~40)*(200~600) mm; when the blank is in the shape of a round bar, the size of the blank can be φ(30~50)*(300~800) mm.

[0051] In the present invention, no additives or binders are added during the pressing process to avoid contamination by impurities, thereby making the obtained metal molybdenum ingots have a higher purity.

[0052] In some embodiments, in step S4, the cooling rate is 8°C / min to 15°C / min.

[0053] It should be noted that the cooling rate can be 8 ℃ / min, 9 ℃ / min, 10 ℃ / min, 11 ℃ / min, 12 ℃ / min, 13 ℃ / min, 14 ℃ / min, and 15 ℃ / min.

[0054] In the present invention, by setting the cooling rate, the second material can shrink uniformly during the cooling process, reducing the internal stress concentration caused by the temperature gradient. Within the cooling rate of 8°C / min to 15°C / min, the second material can form a uniform microstructure during the cooling process, thereby reducing grain coarsening or local defects and improving product quality. Uniform cooling also helps the second material to always maintain high density, avoid pores or defects caused by uneven cooling, thereby improving the strength, toughness and thermal stability of the final product.

[0055] In some embodiments, the preparation method further comprises: In step S3, when the temperature of the second material is reduced to 800°C-1200°C, the hydrogen is replaced by an inert gas, and the second material is subjected to a high-temperature vacuum dehydrogenation treatment, and then taken out after cooling; The vacuum degree during the high temperature vacuum dehydrogenation treatment is 10 -2 Pa~10 -4 Pa, temperature is 800℃~1200℃.

[0056] It should be noted that the second material can be cooled to 800°C, 850°C, 900°C, 950°C, 1000°C, 1100°C, 1200°C; The inert gas can be argon, nitrogen, etc. In the present invention, during the hydrogen sintering process, a very small amount of hydrogen is likely to remain in the second material, affecting the purity of the final product. By performing vacuum dehydrogenation treatment at a high temperature of 800°C to 1200°C, the residual hydrogen in the second material can be effectively removed, thereby eliminating the pores and defects caused by the residual hydrogen, making the material density close to the theoretical density, and further improving the material purity. -2 Pa ~ 10 -4 The high vacuum environment of Pa can accelerate the escape of hydrogen and ensure the dehydrogenation effect.

[0057] In specific implementation, the hydrogen generated during the dehydrogenation process can be effectively collected and processed to avoid pollution to the environment.

[0058] The present invention also provides a high-purity metal molybdenum ingot, which is prepared by the above-mentioned preparation method; The purity of the high-purity metal molybdenum ingot is 99.999%.

[0059] The high-purity molybdenum ingots prepared by the preparation method of the present invention can be widely used in the fields of semiconductors, aerospace, electronic components and new energy, especially in extreme environments such as high temperature, high pressure and strong corrosion, and show excellent performance stability.

[0060] The present invention also provides a system for preparing high-purity metal molybdenum ingots. Figure 2 , the system is used to perform the above-mentioned preparation method to prepare the high-purity metal molybdenum ingot, and the system comprises: A vacuum sintering device 1, a hydrogen sintering device 2 and an electron beam vacuum melting device 3 connected in sequence; The vacuum sintering device 1 is used to vacuum sinter the blank to obtain a first material; The hydrogen sintering device 2 is used to sinter the first material at high temperature in a hydrogen atmosphere to obtain a second material; The electron beam vacuum melting device 3 is used to perform electron beam vacuum melting on the bundled second material to obtain a high-purity metal molybdenum ingot after cooling.

[0061] In the specific implementation, a proper amount of metal molybdenum powder is pressed into a blank, and then the blank is placed in a vacuum sintering device 1, and the internal pressure of the vacuum sintering device 1 is adjusted to 10 -2 Pa~10 -4 Pa, setting the heating rate to 8 ℃ / min~15 ℃ / min, until the temperature is raised to 900 ℃~1500 ℃, so that the blank is subjected to high-temperature sintering treatment in the vacuum sintering device 1 to obtain the first material; Then, the first material is transferred to the hydrogen sintering device 2, hydrogen is introduced into the hydrogen sintering device 2 at a rate of 0.5 L / min to 5 L / min, and the heating rate of the hydrogen sintering device 2 is set to 5°C / min to 10°C / min until the temperature rises to 1800°C to 2600°C, and the first material is sintered in the hydrogen sintering device 2 for 2 h to 5 h to obtain the second material; The second material is bundled after being cooled to room temperature, and the bundled second material is placed in the electron beam vacuum melting device 3, and the melting power in the electron beam vacuum melting device 3 is set to 50 kw~100 kw, so that the second material is melted in the electron beam vacuum melting device 3 for 20 min~40 min, and the obtained material is taken out after being cooled to obtain a high-purity metal molybdenum ingot.

[0062] In the present invention, the system integrates three process steps of vacuum sintering, hydrogen sintering and electron beam vacuum melting, realizing the integrated preparation from blank to high-purity molybdenum ingot. Among them, sintering in a vacuum environment is to effectively remove volatile impurities such as moisture, gas, alkali metals, etc., and provide high-purity intermediate materials for subsequent processes; high-temperature sintering in a hydrogen atmosphere is to reduce the oxides in the molybdenum material and remove some volatile impurities (such as carbon, sulfur, etc.); under the action of high vacuum and high-energy electron beam, it is to further remove residual impurities (such as alkali metals, oxides, etc.), ensuring that the final product reaches an ultra-high purity of 5N level (99.999%) or above, which can meet the stringent requirements for materials in the fields of semiconductors, aerospace, electronic components and new energy.

[0063] The system adopts dry process (vacuum sintering, hydrogen sintering and electron beam melting) as a whole, avoiding the problem of waste liquid discharge in hydrometallurgical process and reducing pollution to the environment. In addition, the waste gas (hydrogen, etc.) generated during hydrogen sintering and electron beam melting can be effectively collected and treated, meeting the requirements of green manufacturing. The system is not only suitable for the preparation of high-purity metal molybdenum ingots, but also can be used for the preparation of other high-purity metal materials (such as tungsten, tantalum, etc.) by adjusting the process parameters.

[0064] In some embodiments, the material racks in the vacuum sintering device 1 and the hydrogen sintering device 2 may adopt a multi-layer horizontal structure to increase the amount of blanks placed and improve production efficiency.

[0065] In some embodiments, the vacuum sintering device 1 and the hydrogen sintering device 2 can be arranged in the same sintering furnace; 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 is performed first and then hydrogen atmosphere sintering is performed, which can prevent the first material from contacting other impurities during the movement process and ensure the purity of the first material.

[0066] In some embodiments, in step S3, when the temperature of the second material drops to 800°C-1200°C, an inert gas may be filled 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 Pa, the temperature is 800 ℃ ~ 1200 ℃, so as to perform high-temperature vacuum dehydrogenation treatment on the second material, and then take it out after cooling.

[0067] In order to enable those skilled in the art to more clearly understand the present invention, a high-purity metal molybdenum ingot, a preparation method and a preparation system thereof described in the present invention are now described in detail through the following examples.

[0068] The following embodiments all adopt Figure 2 The system shown is used to prepare high-purity molybdenum metal ingots.

[0069] Example 1 (1) The raw material is 99.95% high-purity metal molybdenum powder, which is graded. The 100-mesh and 200-mesh metal molybdenum powders are mixed in a ratio of 3:7 and 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. (2) The pressed metal molybdenum blank 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, the heating rate is set to 8 °C / min, the sintering temperature is 900 °C, the sintering time is 5 h, and the first material is obtained after sintering; (3) After the vacuum sintering is completed, high-purity hydrogen is injected into the furnace to perform high-temperature hydrogen atmosphere sintering on the first material 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. After sintering, the second material is obtained; (4) After sintering in hydrogen atmosphere, the temperature is lowered and the cooling rate is set to 8 °C / min. When the temperature drops to 1200 °C, high-purity argon gas is injected into the furnace to replace the hydrogen in the furnace. After the hydrogen replacement is completed, the second material is subjected to high-temperature vacuum dehydrogenation and the vacuum degree is controlled at 5×10 -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; (5) The second material is bundled by welding or bundling, and then 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 -3Pa, the smelting time is set to 20min, and a high-purity metal molybdenum ingot is obtained after smelting. After the smelting is completed, it is slowly cooled to room temperature and the high-purity metal molybdenum ingot is taken out. The purity of the high-purity metal molybdenum ingot is 99.999%.

[0070] Example 2 (1) The raw material is 99.95% high-purity metal molybdenum powder, which is graded and the 100-mesh and 200-mesh metal molybdenum powders are mixed in a ratio of 5:5. The powders are pressed into billets by isostatic pressing at a pressure of 1000 MPa. The billets are pressed into round rods with a size of φ40*600 mm. (2) The pressed metal molybdenum billet is placed in a vacuum / hydrogen dual-purpose sintering furnace for vacuum sintering. The vacuum degree is set to 5×10 -4 Pa, the heating rate is set to 15 °C / min, the sintering temperature is set to 1500 °C, the sintering time is set to 2 h, and the first material is obtained after sintering; (3) After the vacuum sintering is completed, high-purity hydrogen is injected into the furnace to perform high-temperature hydrogen atmosphere sintering on the first material 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. After sintering, the second material is obtained; (4) After sintering in hydrogen atmosphere is completed, the temperature is lowered, and the cooling rate is set to 15 °C / min. When the temperature drops to 800 °C, high-purity argon gas is injected into the furnace to replace the hydrogen in the furnace. After the hydrogen replacement is completed, the second material is subjected to high-temperature vacuum dehydrogenation, and the vacuum degree is controlled at 1×10 -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; (5) The second material is bundled by welding or bundling, and the bundle is 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 -4 Pa, the smelting time is set to 40min, and a high-purity metal molybdenum ingot is obtained. After the smelting is completed, it is slowly cooled to room temperature and the high-purity metal molybdenum ingot is taken out. The purity of the high-purity metal molybdenum ingot is 99.999%.

[0071] Example 3 (1) The raw material is 99.95% high-purity metal molybdenum powder, which is graded and the 100-mesh and 200-mesh powders are mixed in a ratio of 4:6. The powders are pressed into billets by isostatic pressing at a pressure of 1200 MPa. The billets are pressed into round rods with a size of φ50*800 mm. (2) The pressed metal molybdenum blank is placed in a vacuum / hydrogen dual-purpose sintering furnace for vacuum sintering, and the vacuum degree is controlled at 3×10-3 Pa, the heating rate is set to 10 °C / min, the sintering temperature is set to 1300 °C, the sintering time is set to 3 h, and the first material is obtained after sintering; 3. After the 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. After sintering, the second material is obtained; 4. After the sintering in hydrogen atmosphere is completed, the temperature is lowered, and the cooling rate is set to 10 ℃ / min. When the temperature drops to 1000 ℃, high-purity argon gas is injected into the furnace to replace the hydrogen in the furnace. After the hydrogen replacement is completed, the second material is subjected to high-temperature vacuum dehydrogenation, and the vacuum degree is controlled at 1×10 -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; 5. The second material is bundled by welding or bundling, and then 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 -4 Pa, the smelting time is set to 30min, and a high-purity metal molybdenum ingot is obtained. After the smelting is completed, it is slowly cooled to room temperature and the high-purity metal molybdenum ingot is taken out. The purity of the high-purity metal molybdenum ingot is 99.999%.

[0072] In summary, the present invention adopts vacuum sintering, hydrogen atmosphere sintering and electron beam vacuum melting combined purification technology to prepare 5N grade high-purity metal molybdenum ingots. The purity of metal molybdenum is ≥99.999% (5N grade), the density of the molybdenum ingot is greatly improved, close to 100% of the theoretical value, the processing performance is significantly improved, and the production efficiency is greatly improved through the efficient heating of electron beam melting.

[0073] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0074] Although the preferred embodiments of the present application have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the embodiments of the present application.

[0075] Finally, it should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or terminal device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or terminal device. In the absence of further restrictions, the elements defined by the sentence "including one..." do not exclude the existence of other identical elements in the process, method, article or terminal device including the elements.

[0076] The above is a detailed introduction to a high-purity metal molybdenum ingot, a preparation method and a preparation system provided by the present application. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method of the present application and its core idea; at the same time, for general technical personnel in this field, according to the idea of ​​the present application, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A method for preparing a high-purity metal molybdenum ingot, characterized in that: The method comprises: S1. Pressing an appropriate amount of metal molybdenum powder into a blank; S2, the blank is vacuum sintered at a temperature of 900°C to 1500°C to obtain a first material; S3, sintering the first material at high temperature in a hydrogen atmosphere to obtain a second material; S4, the second material is bundled after cooling to room temperature, and the bundled second material is subjected to electron beam vacuum melting, and a high-purity metal molybdenum ingot is obtained after cooling; The power of the electron beam vacuum melting is 50 kw~100 kw, and the melting time is 20 min~40 min.

2. The method for preparing a high-purity metal molybdenum ingot according to claim 1, characterized in that: In step S2, the vacuum degree of the vacuum sintering is 10 -2 Pa~10 -4 Pa; The heating rate is 8 ℃ / min~15 ℃ / min.

3. The method for preparing a high-purity metal molybdenum ingot according to claim 1, characterized in that: In step S3, the flow rate of hydrogen is 0.5 L / min~5 L / min.

4. The method for preparing a high-purity metal molybdenum ingot according to claim 1, characterized in that: In step S3, during the high temperature sintering treatment, the heating rate is 5°C / min-10°C / min, the temperature is 1800°C-2600°C, and the high temperature sintering time is 2 h-5 h.

5. The method for preparing high-purity metal molybdenum ingot according to claim 1, characterized in that: In step S1, an appropriate amount of the metal molybdenum powder is composed of a mixture of 100-mesh and 200-mesh metal molybdenum powders; Wherein, the mass ratio of the 100-mesh metal molybdenum powder to the 200-mesh metal molybdenum powder is (3-5): (5-7).

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

7. The method for preparing high-purity metal molybdenum ingot according to claim 1, characterized in that: In step S4, the cooling rate is 8°C / min to 15°C / min.

8. The method for preparing a high-purity metal molybdenum ingot according to any one of claims 1 to 7, characterized in that: The preparation method further comprises: In step S3, when the temperature of the second material is reduced to 800°C-1200°C, the hydrogen is replaced by an inert gas, and the second material is subjected to a high-temperature vacuum dehydrogenation treatment, and then taken out after cooling; The vacuum degree during the high temperature vacuum dehydrogenation treatment is 10 -2 Pa~10 -4 Pa, temperature is 800 ℃ ~ 1200 ℃.

9. A high-purity metal molybdenum ingot, characterized in that: The high-purity metal molybdenum ingot is prepared by the preparation method according to any one of claims 1 to 8; The purity of the high-purity metal molybdenum ingot is 99.999%.

10. A system for preparing high-purity metal molybdenum ingots, characterized in that: The system is suitable for executing the preparation method according to any one of claims 1 to 8, and the system comprises: A vacuum sintering device, a hydrogen sintering device and an electron beam vacuum melting device connected in sequence; The vacuum sintering device is used to vacuum sinter the blank to obtain the first material; The hydrogen sintering device is used to sinter the first material at high temperature in a hydrogen atmosphere to obtain a second material; The electron beam vacuum melting device is used to perform electron beam vacuum melting on the bundled second material to obtain a high-purity metal molybdenum ingot after cooling.

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