Vacuum-sintered high-purity beryllium material with high elongation and preparation method of vacuum-sintered high-purity beryllium material

Abstract

The invention discloses a high-elongation vacuum-sintered high-purity beryllium material and a preparation method thereof, and belongs to the technical field of beryllium materials. The preparation method comprises the following steps: S1, distilling and purifying a crude beryllium material in a vacuum state, and crushing under the protection of inert gas to obtain beryllium powder with the particle size of 1-100 microns; s2, the beryllium powder is subjected to cold press forming in a hydraulic machine provided with a vacuum glove box, and a beryllium cold-pressed biscuit is obtained; and S3, the beryllium cold-pressed biscuit is sequentially subjected to cold isostatic pressing, vacuum sintering, cooling and surface machining treatment, and the high-purity beryllium material is obtained. The prepared high-purity beryllium material is large in relative density, high in ductility, low in impurity content, short in preparation technological process and high in direct recovery rate, and the requirements of rolling, forging and machining are met.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of beryllium materials, and particularly relates to high-purity beryllium material with high elongation rate prepared by vacuum sintering and a preparation method thereof. BACKGROUND

[0002] Beryllium is a scarce strategic resource, has the characteristics of small density, high strength, high melting point, good dimensional stability, etc., and is widely used in atomic energy reactor materials, aerospace engineering materials, X-ray transmission windows and other fields. At the same time, the nuclear, thermal, optical, acoustic and other physical properties of beryllium are also very excellent, and it occupies a very important position in the fields of weapons, navigation and space telescopes, infrared optical systems and high-energy physics.

[0003] However, the beryllium has low ductility at room temperature, usually only 2-5%, and must be prepared by powder metallurgy process. When machining, it is easy to suddenly break, resulting in high manufacturing cost of beryllium products. Moreover, the low ductility also limits its wide application as a lightweight structural material. Therefore, whether the ductility of beryllium is improved becomes the most important symbol of whether the physical metallurgy of beryllium makes a major progress.

[0004] At present, the existing high-purity beryllium and high-elongation beryllium material includes refining beryllium by molten salt electrolysis and processing beryllium by forging process. For example, a method for preparing high-purity beryllium by electrochemical purification of primary beryllium is disclosed in Chinese patent CN116837421A. The method first constructs a beryllium-containing molten salt system, then performs electrochemical refining under a protective gas atmosphere with primary beryllium as an anode to obtain a cathode product, and finally removes the salt inclusions in the cathode product to obtain high-purity beryllium metal. However, the process is complicated, and it is difficult to remove chlorides and fluorides in the high-purity beryllium metal, which leads to the failure of subsequent product process. A method for preparing beryllium material with high micro-yield strength and high elongation rate, and the product and application thereof are disclosed in Chinese patent CN113652620A. The method sequentially performs pre-forging high-temperature annealing, four-stage dynamic recrystallization forging, and post-forging stabilization treatment on isostatic pressing beryllium material to obtain beryllium material with high micro-yield strength and high elongation rate. However, the forging process has certain effect, low overall efficiency, long process flow, high cost, and great harm to human body due to the toxicity of beryllium. In addition, the process introduces a large amount of impurities, which is not conducive to the use of subsequent products. Furthermore, although the beryllium material prepared by forging has high elongation rate, the strength is too high to be used for beryllium material rolling, and it is easy to break during the machining process. SUMMARY

[0005] One of the purposes of the present application is to provide a preparation method of high-purity beryllium material with high elongation rate by vacuum sintering. The high-purity beryllium material prepared by the method has high relative density, high elongation rate, low impurity content, short preparation process flow, and high direct yield, and meets the requirements of rolling, forging and machining.

[0006] In order to achieve one of the above purposes, the present application adopts the following technical solutions:

[0007] A method for preparing high-purity beryllium material with high elongation rate by vacuum sintering, comprising the following steps:

[0008] Step S1, distilling and purifying the crude beryllium material under vacuum, and then crushing the material under the protection of inert gas to obtain beryllium powder with a particle size of 1-100 um;

[0009] Step S2, cold-pressing the beryllium powder in a hydraulic press equipped with a vacuum glove box to obtain a beryllium cold-pressed green compact;

[0010] In the step S2, the specific process of cold-pressing is as follows:

[0011] Under the atmosphere of inert gas and at room temperature, the beryllium powder is pressed at a pressure of 60-120 MPa for 3-5 minutes;

[0012] Step S3, sequentially performing cold isostatic pressing, vacuum sintering, cooling and surface processing on the beryllium cold-pressed green compact to obtain high-purity beryllium material.

[0013] Further, in the step S1, the crude beryllium material comprises beryllium powder, beryllium blocks and beryllium particles;

[0014] In the step S1, the metallic impurities in the crude beryllium material and their mass percentages are as follows:

[0015] Fe < 0.2%; Al < 0.5%; Mg < 1%; Cu < 0.1%; Zn < 0.1%;

[0016] The non-metallic impurities in the crude beryllium material and their mass percentages are as follows:

[0017] O < 3%; C < 2%.

[0018] Further, in the step S1, the vacuum degree under vacuum is 1.0 x 10 -5 pa-1 x 10 - 2 pa.

[0019] Further, in the step S1, the specific process of distillation and purification comprises:

[0020] Raising the temperature of the crude beryllium material from room temperature to 250-350℃, and distilling and purifying for 3-5 hours;

[0021] Continuing to raise the temperature to 550-650℃, and distilling and purifying for 3-5 hours;

[0022] Continuing to raise the temperature to 750-950℃, and distilling and purifying for 2-4 hours;

[0023] Continuously heating to 1050-1150 DEG C, distillation purification 2-10 hours;

[0024] Finally, heating to 1200-1350 DEG C, distillation purification 10-40 hours, and cooling to room temperature.

[0025] Further, the inert gas is high-purity argon or helium.

[0026] Further, in the step S2, O < 5ppm, H < 1ppm and H2O < 1ppm in the inert gas environment in the vacuum glove box.

[0027] The relative density of the beryllium cold compact is 40-60%.

[0028] Further, in the step S3, the pressure of the cold isostatic pressing is 80-150Mpa, and the time is 10-30min.

[0029] Further, in the step S3, the specific process of the vacuum sintering is as follows:

[0030] Under the vacuum degree of 1.0*10 -4 pa-5*10 -2 pa, the beryllium cold compact after the cold isostatic pressing is heated from room temperature to 180-320 DEG C, sintered for 4-10h, then continuously heated to 650-850 DEG C, sintered for 8-18h, and then heated to 1100-1190 DEG C and kept for 8-24h.

[0031] In order to achieve the above-mentioned second purpose, the application adopts the following technical scheme:

[0032] A high-purity beryllium material with high elongation rate is prepared by the high-purity beryllium material preparation method.

[0033] Further, the purity of the high-purity beryllium material is ≥99.9%, the relative density is >99.5%, and the elongation rate is >8.5%.

[0034] In summary, the scheme provided by the application has the following technical effects:

[0035] The high-purity beryllium material has high purity (≥99.9%), high relative density (>99.5%), high elongation rate (>8.5%), O < 800ppm, Fe < 100ppm, and other impurity content < 100ppm; the process flow is short, the direct yield is high (>90%), the operation is simple, safe and pollution-free, and the material can be rolled, forged and processed. DETAILED DESCRIPTION

[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] This embodiment provides a method for preparing high-purity beryllium material by vacuum sintering with high elongation. The method includes the following steps:

[0038] Step S1: After distilling and purifying the crude beryllium material under vacuum, it is then crushed under the protection of an inert gas to obtain beryllium powder with a particle size of 1-100 μm.

[0039] The crude beryllium feedstock in this embodiment includes beryllium powder, beryllium blocks, and beryllium particles. The metallic impurities in the crude beryllium feedstock and their mass percentages are as follows: Fe < 0.2%; Al < 0.5%; Mg < 1%; Cu < 0.1%; Zn < 0.1%; and other metallic impurities < 0.1%. The non-metallic impurities in the crude beryllium feedstock and their mass percentages are as follows: O < 3%; C < 2%. The non-metallic impurity O in the crude beryllium feedstock includes free oxygen and oxygen from beryllium oxide.

[0040] To remove metallic impurities Fe and Cu from the crude beryllium feedstock, this embodiment employs a vacuum of 1.0 × 10⁻⁶. -5 pa~1×10 -2 Distillation purification is performed under vacuum conditions (Pa) to prevent metallic impurities Fe and Cu from evaporating along with Be, thus ensuring the purity of the beryllium material after distillation purification. The specific distillation purification process in this embodiment includes:

[0041] The crude beryllium material is heated from room temperature to 250-350°C and distilled for 3-5 hours to remove moisture and prevent the beryllium from being oxidized due to excessively high water temperature.

[0042] Continue heating to 550–650℃ and distill for 3–5 hours to remove Mg and Zn metal impurities from the impurities;

[0043] Continue heating to 750–950°C and distill for 2–4 hours to remove Al metal impurities from the impurities;

[0044] Continue heating to 1050℃~1150℃ and distill for 2~10 hours to remove the remaining metal impurities with lower melting points from the impurities;

[0045] Finally, the temperature is raised to 1200℃~1350℃, and the distillation is carried out for 10~40 hours. The mixture is then cooled to room temperature in the furnace, and the evaporated beryllium is collected to remove carbon and oxygen from the impurities (wherein, carbon and oxygen remain in the crucible as beryllium carbide and beryllium oxide, respectively).

[0046] In this embodiment, the gas is crushed into powder in an inert atmosphere crusher. The inert gas is generally selected as high-purity argon (99.999% purity) or high-purity helium (99.999% purity).

[0047] Step S2: The beryllium powder is cold-pressed in a hydraulic press equipped with a vacuum glove box to obtain a beryllium cold-pressed preform.

[0048] In this embodiment, the inert gas environment within the vacuum glove box contains O < 5 ppm, H < 1 ppm, and H₂O < 1 ppm, resulting in a relative density of 40-60% for the beryllium cold-pressed preform. To ensure the formability and strength of the cold-pressed preform, preventing deformation and cracking after isostatic pressing, and to reduce the oxygen content of the beryllium cold-pressed preform, thus minimizing BeO formation during subsequent sintering, the specific cold-pressing process in this embodiment is as follows:

[0049] The beryllium powder was pressed for 3 to 5 minutes under an inert gas atmosphere and at room temperature using a pressure of 60 to 120 MPa.

[0050] Step S3: The beryllium cold-pressed blank is subjected to cold isostatic pressing, vacuum sintering, cooling and surface processing in sequence to obtain high-purity beryllium material.

[0051] To increase the relative density of the cold-pressed beryllium preform, this embodiment employs cold isostatic pressing (COP) to achieve this density. To ensure the beryllium material can be well-formed and possesses sufficient strength, the beryllium preform is free from cracking. In this embodiment, the COP pressure is 80–150 MPa, and the time is 10–30 minutes.

[0052] To effectively reduce the oxidation of Be at high temperatures, decrease the precipitation of BeO at the boundary, and increase the plasticity of the material, vacuum sintering is employed in this embodiment. The specific process of vacuum sintering is as follows:

[0053] At 1.0×10 -4 pa~5×10 -2 Under a vacuum of Pa, the cold-pressed beryllium blank was heated from room temperature to 180–320°C and sintered for 4–10 hours. Then, the temperature was further increased to 650–850°C and sintered for 8–18 hours. After that, the temperature was increased to 1100–1190°C and held for 8–24 hours.

[0054] The high-purity beryllium material in this embodiment has a purity ≥99.9%, a relative density >99.5%, O <800ppm, Fe <100ppm, other impurity content <100ppm, and elongation >8.5%.

[0055] The technical solution of this embodiment is illustrated below through specific examples:

[0056] Example 1:

[0057] Step S1: Weigh 700g of beryllium powder (impurity content as shown in Table 1 before treatment) and place it in a beryllium oxide crucible. Place the crucible in a vacuum distillation furnace and evacuate to 5.0 × 10⁻⁶. -4 The beryllium was purified by distillation at 280°C from room temperature for 3.5 hours. The temperature was then increased to 580°C and distilled for 4.5 hours; further increased to 920°C and distilled for 4 hours; then increased to 1100°C and distilled for 6 hours; finally, the temperature was increased to 1200°C and distilled for 35 hours. The mixture was then cooled to room temperature in the furnace, and the evaporated beryllium was collected. It was then crushed under a high-purity helium atmosphere to obtain beryllium powder with a D90 of 20 μm.

[0058] Step S2: In a hydraulic press equipped with a vacuum glove box, beryllium powder is pressed for 4 minutes at a pressure of 90 MPa under high-purity helium and room temperature to obtain a cold-pressed beryllium preform with a relative density of 55%.

[0059] Step S3: Hold the beryllium cold-pressed billet at 130 MPa for 25 minutes to obtain the beryllium billet body.

[0060] At 5.0×10 -3 Under a vacuum of Pa, the cold-pressed beryllium blank was heated from room temperature to 200°C and sintered for 6 hours. Then, the temperature was increased to 800°C and sintered for 12 hours. Finally, the temperature was increased to 1150°C and held for 16 hours. After cooling, the sintered body was surface-processed to obtain 650g of high-purity beryllium material with a purity greater than 99.91%.

[0061] The impurity content of beryllium powder and high-purity beryllium material in this embodiment is shown in Table 1. The relative density, elongation and direct yield of high-purity beryllium material in this embodiment are also shown in Table 1.

[0062] Example 2:

[0063] Step S1: Weigh 700g of beryllium powder and place it in a beryllium oxide crucible. Place the crucible in a vacuum distillation furnace and evacuate to a vacuum level of 1.0 × 10⁻⁶. - 2 Pa was heated from room temperature to 250°C and distilled for 3 hours. The temperature was then increased to 550°C and distilled for 5 hours; further increased to 950°C and distilled for 4 hours; then increased to 1050°C and distilled for 10 hours; finally, the temperature was increased to 1250°C and distilled for 40 hours. The mixture was then cooled to room temperature in the furnace, and the evaporated beryllium was collected. It was then crushed under a high-purity helium atmosphere to obtain beryllium powder with a D90 of 1 μm.

[0064] Step S2: In a hydraulic press equipped with a vacuum glove box, beryllium powder is pressed for 5 minutes at a pressure of 60 MPa under high-purity helium and room temperature to obtain a cold-pressed beryllium preform with a relative density of 40%.

[0065] Step S3: Hold the beryllium cold-pressed billet at 150 MPa for 30 minutes to obtain the beryllium billet body.

[0066] At 5.0×10 -2 Under a vacuum of Pa, the cold-pressed beryllium blank was heated from room temperature to 320°C and sintered for 10 hours. The temperature was then increased to 850°C and sintered for 18 hours. Finally, the temperature was increased to 1190°C and held for 24 hours. After cooling, the sintered body underwent surface processing to obtain 632g of high-purity beryllium material with a purity greater than 99.94%.

[0067] The impurity content of beryllium powder and high-purity beryllium material in this embodiment is shown in Table 1. The relative density, elongation and direct yield of high-purity beryllium material in this embodiment are also shown in Table 1.

[0068] Example 3:

[0069] Step S1: Weigh 700g of beryllium block and place it in a beryllium oxide crucible. Place the crucible in a vacuum distillation furnace and evacuate to a vacuum level of 2.0 × 10⁻⁶. - 3 The beryllium was purified by distillation at 350°C from room temperature for 4 hours; then at 650°C for 3 hours; then at 900°C for 3 hours; then at 1150°C for 6 hours; and finally at 1350°C for 25 hours. The purified beryllium was then cooled to room temperature in the furnace, and the evaporated beryllium blocks were collected. These blocks were then crushed under a high-purity argon atmosphere to obtain beryllium powder with a D90 of 20 μm.

[0070] Step S2: In a hydraulic press equipped with a vacuum glove box, beryllium powder is pressed for 3 minutes at a pressure of 120 MPa under a high-purity argon atmosphere and at room temperature to obtain a cold-pressed beryllium preform with a relative density of 60%.

[0071] Step S3: Hold the beryllium cold-pressed billet at 120 MPa for 15 minutes to obtain the beryllium billet body.

[0072] Then at 1.0×10 -4 Under a vacuum of Pa, the beryllium billet was heated from room temperature to 300°C and sintered for 4 hours. Then, the temperature was increased to 750°C and sintered for 8 hours. Finally, the temperature was increased to 1150°C and held for 15 hours. After cooling, the sintered body was surface-processed to obtain 660g of high-purity beryllium material with a purity greater than 99.93%.

[0073] The impurity content of the beryllium block and high-purity beryllium material in this embodiment is shown in Table 1. The relative density, elongation and direct yield of the high-purity beryllium material in this embodiment are also shown in Table 1.

[0074] Example 4:

[0075] Step S1: Weigh 700g of beryllium granules and place them in a beryllium oxide crucible. Place the crucible in a vacuum distillation furnace and evacuate to a vacuum level of 1.0 × 10⁻⁶. - 5 The beryllium was heated from room temperature to 300°C and distilled for 5 hours. The temperature was then increased to 600°C and distilled for 4 hours; further increased to 750°C and distilled for 2 hours; then increased to 1100°C and distilled for 2 hours; finally, the temperature was increased to 1300°C and distilled for 10 hours. The mixture was then cooled to room temperature in the furnace, and the evaporated beryllium particles were collected. These particles were then crushed under a high-purity helium atmosphere to obtain beryllium powder with a D90 of 100 μm.

[0076] Step S2: In a hydraulic press equipped with a vacuum glove box, beryllium powder is pressed for 4 minutes at a pressure of 90 MPa under an inert gas atmosphere and at room temperature to obtain a cold-pressed beryllium preform with a relative density of 50%.

[0077] Step S3: Hold the beryllium cold-pressed billet at 80 MPa for 10 minutes to obtain the beryllium billet body.

[0078] At 2.0×10 -3 Under a vacuum of Pa, the cold-pressed beryllium blank was heated from room temperature to 180°C and sintered for 8 hours. The temperature was then increased to 650°C and sintered for 14 hours. Finally, the temperature was increased to 1100°C and held for 8 hours. After cooling, the sintered body underwent surface processing to obtain 640g of high-purity beryllium material with a purity greater than 99.93%.

[0079] The impurity content of the beryllium particles and high-purity beryllium material in this embodiment is shown in Table 1. The relative density, elongation, and direct yield of the high-purity beryllium material in this embodiment are also shown in Table 1.

[0080] Table 1. Impurity content of crude beryllium feedstock and high-purity beryllium material in Examples 1-4, and relative density, elongation, and direct yield of the high-purity beryllium material.

[0081]

[0082] The above embodiments merely illustrate several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A method for preparing high-purity beryllium material by vacuum sintering with high elongation, characterized in that, The method for preparing the high-purity beryllium material includes the following steps: Step S1: After distilling and purifying the crude beryllium material under vacuum, it is then crushed under the protection of an inert gas to obtain beryllium powder with a particle size of 1-100 μm. Step S2: The beryllium powder is cold-pressed in a hydraulic press equipped with a vacuum glove box to obtain a beryllium cold-pressed preform; In step S2, the specific process of cold pressing is as follows: The beryllium powder was pressed for 3-5 minutes under an inert gas atmosphere and at room temperature using a pressure of 60-120 MPa. Step S3: The beryllium cold-pressed blank is subjected to cold isostatic pressing, vacuum sintering, cooling and surface processing in sequence to obtain high-purity beryllium material.

2. The method for preparing high-purity beryllium material according to claim 1, characterized in that, In step S1, the crude beryllium material includes beryllium powder, beryllium blocks, and beryllium particles; In step S1, the metallic impurities and their mass percentages in the crude beryllium material are as follows: Fe<0.2%; Al<0.5%; Mg<1%; Cu<0.1%; Zn<0.1%; The non-metallic impurities and their mass percentages in the crude beryllium feedstock are as follows: O < 3%; C < 2%.

3. The method for preparing high-purity beryllium material according to claim 2, characterized in that, In step S1, the vacuum level under the vacuum condition is 1.0 × 10⁻⁶. -5 ~1×10 -2 Pa.

4. The method for preparing high-purity beryllium material according to claim 3, characterized in that, In step S1, the specific process of distillation and purification includes: The crude beryllium material is heated from room temperature to 250–350°C and purified by distillation for 3–5 hours. Continue heating to 550–650℃ and distill for 3–5 hours; Continue heating to 750–950°C and distill for 2–4 hours; Continue heating to 1050℃~1150℃ and distill for 2~10 hours; Finally, the temperature is raised to 1200℃~1350℃, and the distillation and purification takes 10~40 hours. The mixture is then cooled to room temperature in the furnace.

5. The method for preparing high-purity beryllium material according to claim 4, characterized in that, The inert gas is high-purity argon or helium.

6. The method for preparing high-purity beryllium material according to claim 5, characterized in that, In step S2, the inert gas environment in the vacuum glove box contains O < 5 ppm, H < 1 ppm and H2O < 1 ppm. The relative density of the beryllium cold-pressed preform is 40-60%.

7. The method for preparing high-purity beryllium material according to claim 6, characterized in that, In step S3, the pressure of the cold isostatic pressing is 80-150 MPa, and the time is 10-30 min.

8. The method for preparing high-purity beryllium material according to claim 7, characterized in that, In step S3, the specific process of vacuum sintering is as follows: At 1.0×10 -4 ~5×10 -2 Under a vacuum of Pa, the cold-pressed beryllium blank was heated from room temperature to 180–320°C and sintered for 4–10 hours. Then, the temperature was further increased to 650–850°C and sintered for 8–18 hours. After that, the temperature was increased to 1100–1190°C and held for 8–24 hours.

9. A high-purity beryllium material with high elongation sintered under vacuum, characterized in that, The high-purity beryllium material is prepared using the high-purity beryllium material preparation method described in any one of claims 1 to 8.

10. The high-purity beryllium material according to claim 9, characterized in that, The high-purity beryllium material has a purity of ≥99.9%, a relative density of >99.5%, and an elongation of >8.5%.

Images