A method for preparing high-purity beryllium based on electron beam melting

Abstract

This invention provides a method for preparing high-purity beryllium based on electron beam melting, comprising the following steps: S1. Raw material pretreatment: beryllium raw material is subjected to vacuum induction melting to obtain beryllium ingots; S2. Multi-stage electron beam melting: beryllium ingots are placed in a water-cooled copper crucible of an electron beam melting furnace for multi-stage electron beam melting to obtain electron beam melted beryllium ingots; S3. Primary post-treatment: the surface and top impurity enrichment areas of the electron beam melted beryllium ingots are removed by wire cutting or lathe machining, and then processed into cylindrical beryllium ingots required for zone melting; S4. Multi-stage zone melting: the cylindrical beryllium ingots are placed in a zone melting device for multi-stage zone melting to obtain melted beryllium ingots; S5. Secondary post-treatment: the ingot head and tail of the melted beryllium ingots are removed to obtain high-purity beryllium. This invention combines vacuum induction melting, electron beam melting, and zone melting. By precisely controlling process parameters, it achieves efficient and synergistic removal of multiple impurities while significantly reducing beryllium volatilization loss, ultimately obtaining high-purity beryllium with a purity higher than 99.99%.

Description

Technical Field

[0001] This invention relates to a method for preparing high-purity beryllium, and more particularly to a method for preparing high-purity beryllium based on electron beam melting. Background Technology

[0002] Beryllium and its alloys are widely used in high-end fields such as aerospace, nuclear industry, and electronic components due to their low density, high specific strength, high specific stiffness, good dimensional stability, and excellent thermal properties. However, impurity elements in beryllium, such as oxygen, carbon, nitrogen, iron, aluminum, and silicon, can severely degrade its mechanical, thermal, and nuclear properties. Therefore, the preparation of high-purity beryllium is crucial for expanding its application range and improving device performance.

[0003] Currently, the main industrial methods for preparing metallic beryllium include the magnesothermic reduction method to produce beryllium beads, which are then vacuum-cast into beryllium ingots. However, the beryllium ingots produced by this method have very limited purity (95-98%) and high impurity content, making it difficult to meet the requirements of high-end applications. Electron beam melting (EBM), a technology that uses high-speed electrons to bombard materials in a high-vacuum environment to melt them, features high melting temperature, high vacuum, and long molten pool maintenance time. It can effectively remove volatile impurities and some non-volatile impurities, making it an effective means of preparing high-purity refractory metals.

[0004] However, the method of directly melting crude beryllium or commercially pure beryllium in a single high-power electron beam has the following problems:

[0005] 1) Incomplete removal of impurities: For some impurities that have a strong binding force with beryllium (such as some metallic impurities), or impurities with a vapor pressure close to that of beryllium, it is difficult to remove them effectively in a single melting process.

[0006] 2) Beryllium volatilization loss: Beryllium itself has a high vapor pressure at high temperatures, which will cause a large amount of beryllium to volatilize during long-term smelting. This not only reduces the yield, but the volatilized beryllium will also contaminate the smelting chamber and electron gun.

[0007] 3) High energy consumption and low efficiency: The pursuit of high purity through excessively long smelting time will lead to a sharp increase in energy consumption and poor economic efficiency. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to provide a method for preparing high-purity beryllium based on electron beam melting. This method combines vacuum induction melting, electron beam melting and zone melting. By precisely controlling the process parameters, it achieves efficient and synergistic removal of multiple impurities, while significantly reducing the volatilization loss of beryllium, and finally obtains high-purity beryllium with a purity higher than 99.99%.

[0009] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0010] A method for preparing high-purity beryllium based on electron beam melting includes the following steps:

[0011] S1. Raw material pretreatment:

[0012] Beryllium ingots are obtained by vacuum induction melting of beryllium raw materials;

[0013] S2. Multi-stage electron beam melting:

[0014] The beryllium ingot obtained in step S1 is placed into a water-cooled copper crucible in an electron beam melting furnace for multi-stage electron beam melting to obtain electron beam melted beryllium ingot. After each stage of electron beam melting, the beryllium ingot is flipped before the next stage of electron beam melting. The maximum melting power used during electron beam melting is gradually reduced.

[0015] S3. Post-processing:

[0016] The electron beam melted beryllium ingot obtained in step S2 is processed by wire cutting or lathe to remove the surface and top impurity enrichment areas, and then processed into cylindrical beryllium ingots required for zone melting;

[0017] S4. Multi-level zone smelting:

[0018] The cylindrical beryllium ingot obtained in step S3 is placed into a zone melting device for multi-stage zone melting to obtain smelted beryllium ingots. The width of the melting zone used in the zone melting process is gradually reduced.

[0019] S5. Secondary post-processing:

[0020] The smelted beryllium ingot obtained in step S4 is partially cut off at the ingot head and tail to obtain high-purity beryllium.

[0021] Furthermore, in step S1 of the present invention, the beryllium raw material is beryllium beads or flake beryllium with a purity ≤98% obtained by magnesothermic reduction or vacuum casting.

[0022] Furthermore, in step S1 of this invention, the temperature of vacuum induction melting is 1300-1400℃, and the vacuum degree is 10. -2 -10 Pa for 10-20 minutes. Vacuum induction melting can remove some volatile impurities.

[0023] Furthermore, in step S2 of this invention, the power of each stage of electron beam melting is 40-200kW, and the vacuum degree is 10. -4 -10 -1 Pa, time is 10-60 minutes. Step S2 suppresses the volatilization of beryllium by gradually reducing the electron beam melting power. In the initial stage, a large amount of volatile impurities are removed by high power melting. Then, low-speed electron beam stirring promotes the diffusion and flotation of impurity elements in the molten pool, so that they are vacuum-drawn away or enriched to the top of the ingot. Then, step S3 removes the top enriched area.

[0024] Furthermore, in step S3 of the present invention, the diameter of the cylindrical beryllium ingot is 40-100mm and the length is 40-100mm.

[0025] Furthermore, in step S4 of the present invention, the width of the melting zone in each stage of regional melting is 5-30 mm, and the melting zone moving speed is 0.1-5 mm / min.

[0026] Furthermore, in step S5 of the present invention, the removal ratio of both the ingot head and the ingot tail is 5%. Step S5 removes the portion with a higher impurity content.

[0027] Furthermore, in step S5 of the present invention, the purity of the high-purity beryllium is ≥99.99%.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1) The present invention employs a multi-stage electron beam melting process with progressively decreasing melting power to effectively control beryllium volatilization and improve material utilization. Each stage of electron beam melting sets different process parameters for impurities with different characteristics, thereby achieving directional, efficient, and synergistic removal of impurities.

[0030] 2) The regional refining method used in this invention can further remove trace impurity elements, ensuring that the purity of the final product reaches 99.99%. The process is highly controllable and easy to industrialize. Moreover, the process flow of this invention is clear, the parameters of each step are well-defined, and it is easy to achieve automated control, providing a reliable technical solution for the large-scale and stable production of high-purity beryllium. Detailed Implementation

[0031] The present invention will now be described in detail with reference to specific embodiments. The illustrative embodiments and descriptions of the present invention are used to explain the present invention, but are not intended to limit the present invention.

[0032] Example 1

[0033] High-purity beryllium was prepared according to the following steps:

[0034] S1. Raw material pretreatment:

[0035] Beryllium ingots were obtained by vacuum induction melting of beryllium raw materials, which were 98% pure beryllium beads prepared by magnesian reduction. The vacuum induction melting temperature was 1300℃ and the vacuum degree was 5×10⁻⁶. -2 Pa, the time is 15 minutes;

[0036] S2.1. Primary electron beam melting:

[0037] The beryllium ingot obtained in step S1 is placed into a water-cooled copper crucible in an electron beam melting furnace, and a vacuum of 5 × 10⁻⁶ is applied. -2Pa, start the electron gun, preheat to 1000℃ at a rate of 80℃ / min to completely melt the beryllium ingot, adjust to the focusing mode, set the power to 100kW and melt for 40 minutes to obtain the first-stage electron beam melted beryllium ingot;

[0038] S2.2. Secondary electron beam melting:

[0039] The first-stage electron beam melted beryllium ingot obtained in step S2.1 is flipped, reloaded into the furnace, and evacuated to a vacuum of 3×10⁻⁶. -3 Pa, with a power set at 80kW and a frequency of 10Hz, using rectangular scanning, and melting for 20 minutes to obtain a two-stage electron beam melted beryllium ingot;

[0040] S2.3. Three-stage electron beam melting:

[0041] The secondary electron beam melted beryllium ingot obtained in step S2.2 is flipped, reloaded into the furnace, and evacuated to a vacuum of 5×10⁻⁶. -4 Pa, with a power set at 60kW and a circular scanning method, electron beam-melted beryllium ingots were obtained after melting for 20 minutes;

[0042] S3. Post-processing:

[0043] The electron beam melted beryllium ingot obtained in step S2.3 is machined by a lathe to remove the surface layer of 2mm and the top impurity enrichment area of ​​10mm, and then processed into a cylindrical beryllium ingot required for zone melting. The cylindrical beryllium ingot has a diameter of 50mm and a length of 50mm.

[0044] S4.1. Level 1 Zone Smelting:

[0045] The cylindrical beryllium ingot obtained in step S3 is placed into a zone melting device, the width of the melting zone is controlled to be 30 mm, and the melting zone is moved unidirectionally at a moving speed of 1 mm / min. After two cycles, a first-stage zone-melted cylindrical beryllium ingot is obtained.

[0046] S4.2. Level 1 Zone Smelting:

[0047] The cylindrical beryllium ingot obtained in step S4.1 and the zone-melted cylindrical beryllium ingot are placed into the zone-melting device. The width of the melting zone is controlled to be 5 mm. The melting zone is moved unidirectionally at a moving speed of 1 mm / min. After 3 cycles, the molten beryllium ingot is obtained.

[0048] S5. Secondary post-processing:

[0049] The smelted beryllium ingot obtained in step S4.2 is partially cut off at the ingot head and tail to obtain high-purity beryllium, with the cutting ratio of the ingot head and tail being 5% each.

[0050] The final product, high-purity beryllium, was analyzed by GDMS (glow discharge mass spectrometry), and its purity reached 99.993%. The contents of the main impurities are shown in Table 1, and the beryllium yield was 92.5%.

[0051] Table 1. Content of main impurity elements in purified beryllium ingots

[0052] content 42ppm 25ppm 18ppm 12ppm 15ppm 50ppm

[0053] Comparative example:

[0054] Using the same raw materials as in Example 1, but only one electron beam melting was performed at a melting power of 100kW for 120 minutes. The remaining steps were the same as in Example 1. The purity of the final product was 99.85%, and the beryllium yield was 78%. The results show that although a single long-duration melting can remove some impurities, the purification effect is far inferior to that of this invention, and the beryllium volatilization loss is severe.

[0055] Example 2

[0056] High-purity beryllium was prepared according to the following steps:

[0057] S1. Raw material pretreatment:

[0058] Beryllium ingots were obtained by vacuum induction melting of beryllium raw materials, which were 98% pure beryllium beads produced by vacuum casting. The vacuum induction melting temperature was 1400℃ and the vacuum degree was 10. -2 Pa, the time is 10 minutes;

[0059] S2.1. Primary electron beam melting:

[0060] The beryllium ingot obtained in step S1 is placed into a water-cooled copper crucible in an electron beam melting furnace, and a vacuum of 5 × 10⁻⁶ is applied. -2 Pa, start the electron gun, preheat to 1000℃ at a rate of 80℃ / min to completely melt the beryllium ingot, adjust to the focusing mode, set the power to 100kW, and melt for 60 minutes to obtain a first-stage electron beam melted beryllium ingot;

[0061] S2.2. Secondary electron beam melting:

[0062] The first-stage electron beam melted beryllium ingot obtained in step S2.1 is flipped, reloaded into the furnace, and evacuated to a vacuum of 3×10⁻⁶. -3 Pa, with a power set at 80kW and a frequency of 10Hz, using rectangular scanning, and melting for 20 minutes to obtain a two-stage electron beam melted beryllium ingot;

[0063] S2.3. Three-stage electron beam melting:

[0064] The secondary electron beam melted beryllium ingot obtained in step S2.2 is flipped, reloaded into the furnace, and evacuated to 10°C. -4 Pa, with a power set at 40kW and a circular scanning method, electron beam-melted beryllium ingots were obtained after 20 minutes of melting;

[0065] S3. Post-processing:

[0066] The electron beam melted beryllium ingot obtained in step S2.3 is desecrated by wire cutting to remove the surface layer of 2 mm and the top impurity enrichment area of ​​10 mm, and then processed into a cylindrical beryllium ingot required for zone melting. The cylindrical beryllium ingot has a diameter of 40 mm and a length of 40 mm.

[0067] S4.1. Level 1 Zone Smelting:

[0068] The cylindrical beryllium ingot obtained in step S3 is placed into a zone melting device, the width of the melting zone is controlled to be 15mm, and the melting zone is moved unidirectionally at a moving speed of 1mm / min. After two cycles, a first-stage zone-melted cylindrical beryllium ingot is obtained.

[0069] S4.2. Level 1 Zone Smelting:

[0070] The cylindrical beryllium ingot obtained in step S4.1 and the zone-melted cylindrical beryllium ingot are placed into the zone-melting device. The width of the melting zone is controlled to be 5 mm. The melting zone is moved unidirectionally at a moving speed of 0.1 mm / min. After 3 cycles, the molten beryllium ingot is obtained.

[0071] S5. Secondary post-processing:

[0072] The smelted beryllium ingot obtained in step S4.2 is partially cut off at the ingot head and tail to obtain high-purity beryllium, with the cutting ratio of the ingot head and tail being 5% each.

[0073] Example 3

[0074] High-purity beryllium was prepared according to the following steps:

[0075] S1. Raw material pretreatment:

[0076] Beryllium ingots were obtained by vacuum induction melting of beryllium raw materials. The beryllium raw materials were flake beryllium with a purity of 97% obtained by magnesothermic reduction. The vacuum induction melting temperature was 1350℃, the vacuum degree was 10Pa, and the time was 20 minutes.

[0077] S2.1. Primary electron beam melting:

[0078] The beryllium ingot obtained in step S1 is placed into a water-cooled copper crucible in an electron beam melting furnace, and a vacuum is drawn to 10. -1 Pa, start the electron gun, preheat to 1000℃ at a rate of 80℃ / min to completely melt the beryllium ingot, adjust to the focusing mode, set the power to 200kW and melt for 10 minutes to obtain the first-stage electron beam melted beryllium ingot;

[0079] S2.2. Secondary electron beam melting:

[0080] The first-stage electron beam melted beryllium ingot obtained in step S2.1 is flipped, reloaded into the furnace, and evacuated to a vacuum of 3×10⁻⁶. -3Pa, with a power set at 80kW and a frequency of 10Hz, using rectangular scanning, and melting for 20 minutes to obtain a two-stage electron beam melted beryllium ingot;

[0081] S2.3. Three-stage electron beam melting:

[0082] The secondary electron beam melted beryllium ingot obtained in step S2.2 is flipped, reloaded into the furnace, and evacuated to 10°C. -4 Pa, with a power set at 40kW and a circular scanning method, electron beam-melted beryllium ingots were obtained after 20 minutes of melting;

[0083] S3. Post-processing:

[0084] The electron beam melted beryllium ingot obtained in step S2.3 is machined by a lathe to remove the surface layer of 2mm and the top impurity enrichment area of ​​10mm, and then processed into a cylindrical beryllium ingot required for zone melting. The cylindrical beryllium ingot has a diameter of 100mm and a length of 100mm.

[0085] S4.1. Level 1 Zone Smelting:

[0086] The cylindrical beryllium ingot obtained in step S3 is placed into a zone melting device, the width of the melting zone is controlled to be 30 mm, and the melting zone is moved unidirectionally at a moving speed of 5 mm / min. After two cycles, a first-stage zone-melted cylindrical beryllium ingot is obtained.

[0087] S4.2. Level 1 Zone Smelting:

[0088] The cylindrical beryllium ingot obtained in step S4.1 and the zone-melted cylindrical beryllium ingot are placed into the zone-melting device. The width of the melting zone is controlled to be 5 mm. The melting zone is moved unidirectionally at a moving speed of 0.1 mm / min. After 3 cycles, the molten beryllium ingot is obtained.

[0089] S5. Secondary post-processing:

[0090] The smelted beryllium ingot obtained in step S4.2 is partially cut off at the ingot head and tail to obtain high-purity beryllium, with the cutting ratio of the ingot head and tail being 5% each.

[0091] Example 4

[0092] High-purity beryllium was prepared according to the following steps:

[0093] S1. Raw material pretreatment:

[0094] Beryllium ingots were obtained by vacuum induction melting of beryllium raw materials, which were beryllium beads with a purity of 97.5% produced by magnesothermic reduction. The vacuum induction melting temperature was 1300℃ and the vacuum degree was 10. -1 Pa, the time is 15 minutes;

[0095] S2.1. Primary electron beam melting:

[0096] The beryllium ingot obtained in step S1 is placed into a water-cooled copper crucible in an electron beam melting furnace, and a vacuum of 5 × 10⁻⁶ is applied. -2 Pa, start the electron gun, preheat to 1000℃ at a rate of 80℃ / min to completely melt the beryllium ingot, adjust to the focusing mode, set the power to 100kW and melt for 30 minutes to obtain the first-stage electron beam melted beryllium ingot;

[0097] S2.2. Secondary electron beam melting:

[0098] The first-stage electron beam melted beryllium ingot obtained in step S2.1 is flipped, reloaded into the furnace, and evacuated to a vacuum of 3×10⁻⁶. -3 Pa, with a power set at 60kW and a frequency of 10Hz, using rectangular scanning, and melting for 30 minutes to obtain a two-stage electron beam melted beryllium ingot;

[0099] S2.3. Three-stage electron beam melting:

[0100] The secondary electron beam melted beryllium ingot obtained in step S2.2 is flipped, reloaded into the furnace, and evacuated to a vacuum of 5×10⁻⁶. -4 Pa, with a power set at 40kW and using circular scanning, electron beam melting of beryllium ingots was obtained after 30 minutes;

[0101] S3. Post-processing:

[0102] The electron beam melted beryllium ingot obtained in step S2.3 is desecrated by wire cutting to remove the surface layer of 2 mm and the top impurity enrichment area of ​​10 mm, and then processed into a cylindrical beryllium ingot required for zone melting. The cylindrical beryllium ingot has a diameter of 80 mm and a length of 80 mm.

[0103] S4.1. Level 1 Zone Smelting:

[0104] The cylindrical beryllium ingot obtained in step S3 is placed into a zone melting device, the width of the melting zone is controlled to be 20 mm, and the melting zone is moved unidirectionally at a moving speed of 0.5 mm / min. After two cycles, a first-stage zone-melted cylindrical beryllium ingot is obtained.

[0105] S4.2. Level 1 Zone Smelting:

[0106] The cylindrical beryllium ingot obtained in step S4.1 and the zone-melted cylindrical beryllium ingot are placed into the zone-melting device. The width of the melting zone is controlled to be 10 mm. The melting zone is moved unidirectionally at a moving speed of 0.5 mm / min. After 3 cycles, the molten beryllium ingot is obtained.

[0107] S5. Secondary post-processing:

[0108] The smelted beryllium ingot obtained in step S4.2 is partially cut off at the ingot head and tail to obtain high-purity beryllium, with the cutting ratio of the ingot head and tail being 5% each.

[0109] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method for preparing high-purity beryllium based on electron beam melting, characterized in that: Includes the following steps: S1. Raw material pretreatment: Beryllium ingots are obtained by vacuum induction melting of beryllium raw materials; S2. Multi-stage electron beam melting: The beryllium ingot obtained in step S1 is placed into a water-cooled copper crucible in an electron beam melting furnace for multi-stage electron beam melting to obtain electron beam melted beryllium ingot. After each stage of electron beam melting, the beryllium ingot is flipped before the next stage of electron beam melting. The maximum melting power used during electron beam melting is gradually reduced. S3. Post-processing: The electron beam melted beryllium ingot obtained in step S2 is processed by wire cutting or lathe to remove the surface and top impurity enrichment areas, and then processed into cylindrical beryllium ingots required for zone melting; S4. Multi-level zone smelting: The cylindrical beryllium ingot obtained in step S3 is placed into a zone melting device for multi-stage zone melting to obtain smelted beryllium ingots. The width of the melting zone used in the zone melting process is gradually reduced. S5. Secondary post-processing: The smelted beryllium ingot obtained in step S4 is partially cut off at the ingot head and tail to obtain high-purity beryllium.

2. The method for preparing high-purity beryllium based on electron beam melting according to claim 1, characterized in that: In step S1, the beryllium raw material is beryllium beads or flake beryllium with a purity of ≤98% obtained by magnesothermic reduction or vacuum casting.

3. The method for preparing high-purity beryllium based on electron beam melting according to claim 1, characterized in that: In step S1, the temperature of vacuum induction melting is 1300-1400℃, and the vacuum degree is 10. -2 -10Pa, for 10-20 minutes.

4. The method for preparing high-purity beryllium based on electron beam melting according to claim 1, characterized in that: In step S2, the power of each stage of electron beam melting is 40-200kW, and the vacuum degree is 10. -4 -10 -1 Pa, time is 10-60 minutes.

5. The method for preparing high-purity beryllium based on electron beam melting according to claim 1, characterized in that: In step S3, the diameter of the cylindrical beryllium ingot is 40-100mm and the length is 40-100mm.

6. The method for preparing high-purity beryllium based on electron beam melting according to claim 1, characterized in that: In step S4, the width of the melting zone in each melting zone is 5-30 mm, and the moving speed of the melting zone is 0.1-5 mm / min.

7. The method for preparing high-purity beryllium based on electron beam melting according to claim 1, characterized in that: In step S5, the removal ratio of both the spindle head and spindle tail is 5%.

8. The method for preparing high-purity beryllium based on electron beam melting according to claim 1, characterized in that: In step S5, the purity of the high-purity beryllium is ≥99.99%.