A production process for high-purity aviation-grade rhenium rods

Abstract

The invention discloses a production process of high-purity aviation-grade rhenium bars, including: grinding ammonium perrhenate, and screening the ground material to form ammonium rhenate powder; setting a plurality of temperature zones in a reduction furnace in sequence according to a preset temperature rise curve, and setting the insulation time of each temperature zone respectively, loading ammonium rhenate powder and introducing hydrogen to obtain rhenium powder; grinding rhenium powder, and screening out rhenium powder that meets the preset particle size to complete grinding and grading; loading the screened rhenium powder into a bar mold, pressing according to preset parameters to obtain rhenium bar blanks; setting a plurality of temperature zones in a high-temperature sintering furnace according to the temperature curve, loading rhenium bar blanks and performing high-temperature sintering under a vacuum atmosphere; polishing the surface of the high-purity rhenium bar obtained by high-temperature sintering to avoid unevenness, forming a finished rhenium bar, and completing vacuum packaging. The invention has a short process, simple operation, a high degree of control over the entire process, high product purity and stable quality, low energy consumption, and energy saving and environmental protection.

Description

Technical Field

[0001] The invention belongs to the technical field of rhenium particle preparation, and in particular relates to a production process of high-purity aviation-grade rhenium bars. Background Art

[0002] Rhenium is a rare refractory metal with many excellent properties, including high melting point, high resistivity, high strength, corrosion resistance, good plasticity and arc ablation resistance. It is widely used in aerospace, petrochemical, electronics and other industries. Therefore, high-purity aviation-grade metal is an important strategic resource.

[0003] In order to respond to storage needs, namely: 1. Appearance specifications: width × height × length: (15±1.5) × (15±1.5) × (500±25) mm; 2. The mass fraction of the main element of rhenium is required to reach 99.99%, and the 31 trace elements must meet the impurity content requirements of the contract (the content of 28 non-gaseous impurity elements does not exceed 5ppm).

[0004] In order to meet the above requirements, the difficulties are: 1. Control of appearance specifications. Rhenium powders of different particle sizes will experience mechanical shrinkage when pressed into billets. The pressed rhenium bar billets will also experience high-temperature shrinkage during the sintering process. How to determine the shrinkage ratio of the two times is the key to controlling the final appearance specifications of the rhenium bars. 2. The main grade of the rhenium bars reaches 99.99%, and 31 trace elements meet the impurity content requirements of the contract. Among them, the contents of 28 non-gaseous impurity elements do not exceed 5ppm, and C, H, O, and N are less than 300ppm, 10ppm, 10ppm, and 10ppm, respectively. Summary of the invention

[0005] The purpose of the present invention is to overcome the above problems existing in the prior art and provide a production process for high-purity aviation-grade rhenium bars.

[0006] In order to achieve the above technical objectives and the above technical effects, the present invention is implemented through the following technical solutions:

[0007] A production process for high-purity aviation-grade rhenium bars, comprising:

[0008] Grinding ammonium perrhenate and screening the ground material to form ammonium rhenate powder to complete the pretreatment;

[0009] According to the preset temperature rise curve, several temperature zones are sequentially set in the reduction furnace, and the insulation time of each temperature zone is respectively set, and ammonium rhenate powder is loaded and hydrogen is introduced to obtain rhenium powder to complete high-temperature reduction;

[0010] Grind rhenium powder and select rhenium powder that meets the preset particle size to complete grinding and classification;

[0011] The sieved rhenium powder is loaded into a bar mold and pressed according to preset parameters to obtain a rhenium bar blank to complete the pressing molding;

[0012] According to the temperature curve, several temperature zones are set in the high temperature sintering furnace, and the maximum temperature and corresponding time of each temperature zone are set respectively. Rhenium bar blanks are loaded and sintered at high temperature in a vacuum atmosphere so that the rhenium bar blanks are fully shrunk and densified to form high-purity rhenium bars;

[0013] The high-purity rhenium bar obtained by high-temperature sintering is surface-polished to avoid unevenness, forming a finished rhenium bar and completing vacuum packaging.

[0014] Furthermore, after the ammonium perrhenate is ground, it is screened using a vibrating screen with 80-120 meshes.

[0015] Furthermore, before the ammonium rhenate powder is loaded into the reduction furnace, the boat is loaded, specifically including: the ammonium rhenate powder is evenly spread in the rhenium boat, and the thickness is controlled to be 2-6 mm.

[0016] Furthermore, the reduction furnace includes five temperature zones, the temperature of the first temperature zone is controlled to be greater than or equal to 400°C, and the temperature of the last temperature zone is controlled to be less than or equal to 990°C; the temperature gradient of the five temperature zones is maintained at 80-120°C.

[0017] Furthermore, the preset parameters specifically include:

[0018] The particle size of rhenium powder is controlled at 80-120 mesh;

[0019] The size of rhenium bar billet is controlled at 490-510mm in length and 15.5-16.5 in width;

[0020] The weight of rhenium bar blank is controlled at 1130-1170g;

[0021] The pressing pressure is controlled at 200-300KN.

[0022] Furthermore, the pressing is performed using a 500T hydraulic press, and the pressing is performed in a horizontal direction, with a pressing surface area of ​​about 75cm 2 .

[0023] Furthermore, nitrogen is first passed through the high temperature sintering furnace to remove air, and then hydrogen is passed through for protection.

[0024] Furthermore, the maximum temperature in the high temperature sintering furnace is controlled at 2200-2450° C., and the time is controlled at 30-50 hours.

[0025] Further, the high temperature sintering furnace is heated to 1700-1750°C at a heating rate of 5-10°C / min, kept warm for 9-17h, and then heated to 2000-2050°C at a heating rate of 5-10°C / min, kept warm for 9-17h, and then heated to 2200-2450°C at a heating rate of 5-10°C / min, kept warm for 9-17h.

[0026] Furthermore, the rhenium powder is ground using a sieve of 80-120 meshes to screen out rhenium powder that meets a preset particle size.

[0027] The beneficial effects of the present invention are:

[0028] The present invention manufactures high-purity aviation-grade metal rhenium bars through processes such as ammonium perrhenate pretreatment, high-temperature reduction, grinding and grading, pressing and molding, high-temperature sintering, and surface treatment. The process is short and simple to operate. The entire process is highly controlled, the product is high in purity and stable in quality, the energy consumption is low, and it is energy-saving and environmentally friendly. Through the process flow of the present invention, not only can the external specifications be reasonably controlled, but also the impurity content can be controlled to meet the storage requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0030] Figure 1 It is a flow chart of the method of the present invention. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] like Figure 1 The production process of a high-purity aviation-grade rhenium bar shown in the figure specifically comprises the following steps:

[0033] Step 1: Grind the ammonium perrhenate and screen the ground material to form ammonium rhenate powder to complete the pretreatment.

[0034] Ammonium perrhenate with a grade of 99.99% is put into a ball mill for grinding. The parts of the ball mill that contact the ammonium perrhenate are made of rhenium to avoid doping. The ground material is sieved using a vibrating screen with 80-120 meshes, and the ammonium perrhenate powder under the screen is used for the high-temperature reduction process.

[0035] Step 2: several temperature zones are sequentially set in the reduction furnace according to the preset temperature rise curve, and the insulation time of each temperature zone is set respectively, and ammonium rhenate powder is loaded and hydrogen is introduced to obtain rhenium powder to complete high-temperature reduction.

[0036] The specific operation method of high temperature reduction is as follows:

[0037] Boat loading: Screen the 80-120 mesh ammonium rhenate powder after grinding, and spread the ammonium rhenate powder with appropriate particle size in the rhenium boat. The powder must be spread evenly to ensure that there is no dead corner, and the thickness is controlled at 2-6mm.

[0038] Set the heating curve:

[0039] Temperature setting: The reduction furnace has five temperature zones. According to the explored temperature rise curve, the highest temperature values ​​of the five temperature zones are set in sequence. The temperature of the first temperature zone is controlled to be greater than or equal to 400°C, and the temperature of the last temperature zone is less than or equal to 990°C. The temperature gradient of the five temperature zones is maintained at 80-120°C.

[0040] Time setting: Set the insulation time according to the reaction occurring in each temperature zone.

[0041] Finally, the loaded rhenium boat is pushed into the reduction furnace, and hydrogen is introduced for reduction, while the hydrogen flow rate is controlled.

[0042] Step 3: Grind the rhenium powder and select the rhenium powder that meets the preset particle size to complete the grinding and grading.

[0043] The metal rhenium powder obtained in the reduction process is put into a ball mill for grinding. All parts of the ball mill that come into contact with the metal rhenium powder are made of rhenium products to avoid the introduction of impurities into the rhenium powder. The ground material is sieved through a 80-120 mesh screen to screen out rhenium powder with a suitable particle size for the pressing process.

[0044] Step 4: Load the sieved rhenium powder into a bar mold and press it according to preset parameters to obtain a rhenium bar blank to complete the pressing molding.

[0045] As a specific implementation of the present invention, the preset parameters specifically include:

[0046] The particle size of rhenium powder is controlled at 80-120 mesh. The smaller the particle size, the greater the compression shrinkage ratio, that is, when the length and width of the rhenium billet are constant, the smaller the height; if the particle size of rhenium powder is too large, bending and deformation may occur during the sintering process;

[0047] The size of the rhenium bar blank is controlled at 490-510mm in length and 15.5-16.5 in width. Since the rhenium blank will shrink to a certain extent during the pressing and sintering process, the larger the length and width of the mold cavity, the smaller the height after pressing.

[0048] The weight of the rhenium bar blank is controlled at 1130-1170g to meet the target weight range of the rhenium blank, taking into account the shrinkage ratio generated during the pressing and high-temperature sintering process to ensure that the size of the rhenium bar after sintering meets the requirements;

[0049] The pressing pressure is controlled at 200-300KN. The greater the pressure, the easier it is to form the rhenium billet. However, if the pressure is too high, on the one hand, the mechanical shrinkage ratio from rhenium powder to rhenium bar will increase accordingly; at the same time, the billet is not easy to demold, and the rhenium billet is too dense, which is not conducive to the removal of internal impurities during the sintering process.

[0050] The screened rhenium powder was loaded into a bar mold and pressed under different parameters such as rhenium powder particle size, rhenium billet length and width, and billet pressing pressure. A 500T hydraulic press was used, and the rhenium bar was pressed horizontally with a pressing surface area of ​​about 75cm 2 , and obtain a rectangular rhenium bar blank with appropriate density and specifications: length × width × height: (500±25)×(15±1.5)×(15±1.5)mm.

[0051] Step 5: Set up several temperature zones in the high-temperature sintering furnace according to the temperature curve, set the maximum temperature and corresponding time of each temperature zone, load the rhenium bar blank and perform high-temperature sintering in a vacuum atmosphere to form a high-purity rhenium bar. The high-temperature sintering furnace can first pass nitrogen to remove the air, and then pass hydrogen for protection. High-temperature sintering of high-purity rhenium in a vacuum atmosphere will cause the high-purity rhenium to fully shrink and densify. The gas impurities in the high-purity rhenium, such as C, N, and O, will be removed from the inside of the rhenium body due to the presence of H2 in a vacuum and high-temperature environment, greatly reducing the impurity content in the sintering vacuum atmosphere. In the cooling stage, argon is passed to further reduce the H content in the rhenium bar. At the same time, the low-melting-point metal impurities in the furnace will also be extracted after evaporation under a negative pressure environment, thereby significantly improving the purity of the rhenium bar.

[0052] As a specific embodiment of the present invention, the maximum temperature in the high-temperature sintering furnace is controlled at 2200-2450°C, and the time is controlled at 30-50h. The longer the sintering time, the more complete the impurity removal, but the energy consumption will increase accordingly; at the same time, it will affect the service life of the equipment. The temperature rise curve is controlled to reduce the phase change shrinkage ratio (secondary shrinkage) during the sintering process, thereby reducing the cracking of the rhenium bar. After the sintering is completed, the temperature is lowered, the material is taken out, and finally sintered into a high-purity 4N grade rhenium bar.

[0053] Specifically, the high temperature sintering furnace is heated to 1700-1750°C at a heating rate of 5-10°C / min, kept warm for 9-17 hours, and then heated to 2000-2050°C at a heating rate of 5-10°C / min, kept warm for 9-17 hours, and then heated to 2200-2450°C at a heating rate of 5-10°C / min, kept warm for 9-17 hours.

[0054] Step 6: Polish the surface of the high-purity rhenium bar obtained by high-temperature sintering to avoid unevenness, form a finished rhenium bar, and complete vacuum packaging.

[0055] The quality of the rhenium bars produced by the present invention meets the requirements of the Q / 6S 3691-2023 industry standard, and the external dimensions meet the appearance requirements specified by the State Administration of Refinery.

[0056] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0057] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A production process for high-purity aviation-grade rhenium bars, characterized in that: include: Grinding ammonium perrhenate and screening the ground material to form ammonium rhenate powder to complete the pretreatment; According to the preset temperature rise curve, several temperature zones are sequentially set in the reduction furnace, and the insulation time of each temperature zone is respectively set, and ammonium rhenate powder is loaded and hydrogen is introduced to obtain rhenium powder to complete high-temperature reduction; Grind rhenium powder and select rhenium powder that meets the preset particle size to complete grinding and classification; The sieved rhenium powder is loaded into a bar mold and pressed according to preset parameters to obtain a rhenium bar blank to complete the pressing molding; According to the temperature curve, several temperature zones are set in the high temperature sintering furnace, and the maximum temperature and corresponding time of each temperature zone are set respectively. Rhenium bar blanks are loaded and sintered at high temperature in a vacuum atmosphere so that the rhenium bar blanks are fully shrunk and densified to form high-purity rhenium bars; The high-purity rhenium bar obtained by high-temperature sintering is surface-polished to avoid unevenness, forming a finished rhenium bar and completing vacuum packaging.

2. The production process of a high-purity aviation-grade rhenium bar according to claim 1, characterized in that: After the ammonium perrhenate is ground, it is screened using a vibrating screen of 80-120 mesh.

3. The production process of a high-purity aviation-grade rhenium bar according to claim 1, characterized in that: Before loading the ammonium rhenate powder into the reduction furnace, the boat loading is completed, specifically including: evenly spreading the ammonium rhenate powder in the rhenium boat, and the thickness is controlled at 2-6 mm.

4. The production process of a high-purity aviation-grade rhenium bar according to claim 1, characterized in that: The reduction furnace includes five temperature zones, the temperature of the first temperature zone is controlled to be greater than or equal to 400°C, and the temperature of the last temperature zone is controlled to be less than or equal to 990°C; the temperature gradient of the five temperature zones is maintained at 80-120°C.

5. The production process of a high-purity aviation-grade rhenium bar according to claim 1, characterized in that: The preset parameters include: The particle size of rhenium powder is controlled at 80-120 mesh; The size of rhenium bar blank is controlled at 490-510mm in length and 15.5-16.5 in width; The weight of rhenium bar blank is controlled at 1130-1170g; The pressing pressure is controlled at 200-300KN.

6. The production process of a high-purity aviation-grade rhenium bar according to claim 5, characterized in that: The pressing is done with a 500T hydraulic press, and the pressing is done horizontally, with a pressing surface area of ​​about 75cm 2 .

7. The production process of a high-purity aviation-grade rhenium bar according to claim 1, characterized in that: Nitrogen is first passed into the high-temperature sintering furnace to remove the air, and then hydrogen is passed for protection.

8. The production process of a high-purity aviation-grade rhenium bar according to claim 7, characterized in that: The maximum temperature in the high temperature sintering furnace is controlled at 2200-2450°C, and the time is controlled at 30-50h.

9. The production process of a high-purity aviation-grade rhenium bar according to claim 8, characterized in that: The high temperature sintering furnace is heated to 1700-1750°C at a heating rate of 5-10°C / min, and kept warm for 9-17 hours. The temperature is then raised to 2000-2050°C at a heating rate of 5-10°C / min, and kept warm for 9-17 hours. The temperature is then raised to 2200-2450°C at a heating rate of 5-10°C / min, and kept warm for 9-17 hours.

10. A process for producing high-purity aviation-grade rhenium rods according to any one of claims 1 to 9, characterized in that: The rhenium powder is ground using a 80-120 mesh screen to screen out the rhenium powder that meets the preset particle size.

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