Method for preparing high-purity beryllium based on vacuum solid-state electromigration

Abstract

The invention discloses a method for preparing high-purity beryllium based on vacuum solid-state electromigration, and relates to the technical field of high-purity beryllium, and the method comprises the following steps: (1) carrying out electrolytic polishing on a beryllium rod; and (2) in an ultrahigh vacuum environment, a composite electric field is applied to the beryllium rod treated in the step (1), the electric field comprises an axial direct current component and a radial pulse component, an axial temperature gradient is established to drive directional migration of impurities, electric heating parameters are adjusted in real time through in-situ spectrum monitoring, and high-purity beryllium is obtained. According to the method, the impurities can be effectively induced to move in the beryllium rod through the composite electric field, so that the beryllium rod is purified, and the purity of the beryllium rod can reach 99.995% or above.

Description

Technical Field

[0001] The present invention relates to the technical field of high-purity beryllium, and particularly relates to a method for preparing high-purity beryllium based on vacuum solid-state electromigration. Background Art

[0002] High-purity beryllium (purity ≥ 99.995%) is irreplaceable in precision devices such as synchrotron radiation source windows and inertial navigation gyroscopes, and requires the content of specific impurities (such as Fe, C, O) to be less than 50 ppm. The directional migration characteristics of impurity atoms in the metal lattice under the action of current can be utilized, and the impurity enrichment can be realized by combining with the temperature gradient. However, when treating beryllium rods by the traditional solid-state electromigration method, due to the high melting point of beryllium (1287 °C), high-temperature operation (1200 - 1300 °C) is required, which easily causes grain boundary cracking; the high vapor pressure of beryllium results in a metal loss rate > 3% in a vacuum environment, and the impurity removal efficiency is low (the purity after purification is usually < 99.99%). Therefore, there is an urgent need for a method for efficiently removing impurities to prepare high-purity beryllium. Summary of the Invention

[0003] In order to solve the above technical problems, the purpose of the present invention is to provide a method for preparing high-purity beryllium based on vacuum solid-state electromigration. This method can effectively induce the movement of impurities in the beryllium rod through a composite electric field, and then achieve the purification of the beryllium rod, so that the purity of the beryllium rod can reach more than 99.995%.

[0004] The technical solution for the present invention to solve the above technical problems is as follows: Provide a method for preparing high-purity beryllium based on vacuum solid-state electromigration, including the following steps:

[0005] (1) Electrolytically polish the beryllium rod;

[0006] (2) In an ultra-high vacuum environment, apply a composite electric field to the beryllium rod processed in step (1). The electric field includes a DC component in the axial direction and a pulse component in the radial direction, establish an axial temperature gradient to drive the directional migration of impurities, and adjust the electrothermal parameters in real time through in-situ spectroscopy to obtain high-purity beryllium.

[0007] Further, in step (1), the pressure of the ultra-high vacuum environment is less than 10 -7 Pa.

[0008] Further, in step (1), the beryllium rod is an industrial-grade beryllium rod with a purity ≥ 99.9%.

[0009] Further, in step (1), the size of the beryllium rod raw material is Φ15mm × 150mm, the initial Fe content is 100 - 200 ppm, and the C content is 200 - 300 ppm.

[0010] Further, in step (1), the surface roughness Ra of the polished beryllium rod ≤ 0.2 μm. Preferably, Ra ≤ 0.15 μm

[0011] Further, in step (2), the current density of the DC component wherein, σ(T) is the conductivity of beryllium at temperature T, α is the thermoelectric potential coefficient, is the temperature gradient, Z is the effective charge number, e is the elementary charge, and E is the electric field strength.

[0012] Further, in step (2), the electric field frequency of the pulse component matches the vibration frequency of the beryllium lattice, and the frequency range is 0.5 - 15 kHz; the peak current density of the pulse component is 30 - 80% of the DC component.

[0013] Further, the duty cycle of the pulsed electric field is 10 - 30%.

[0014] Further, in step (2), a staged current increase strategy is adopted, and the current density increase amplitude in each stage is ≤ 20%, and zero-current annealing for 5 - 15 minutes is inserted between adjacent stages.

[0015] Further, in step (2), the temperature in the high-temperature region of the temperature gradient is 900 - 1000 °C, and the temperature in the low-temperature region is 700 - 800 °C. The heat source is a two-zone temperature-controlled vacuum chamber.

[0016] Further, in step (2), the treatment time is 100 - 160 h.

[0017] The present invention has the following beneficial effects:

[0018] The method of the present invention can effectively induce the movement of impurities in the beryllium rod through the composite electric field, and further realize the purification of the beryllium rod, so that the purity of the beryllium rod can reach more than 99.995%. Detailed implementation mode

[0019] The principles and features of the present invention are described below. The examples given are only used to explain the present invention and are not intended to limit the scope of the present invention. For those not specified in the examples, the conventional conditions or the conditions recommended by the manufacturer are followed. For the reagents or instruments not specified by the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0020] Example 1

[0021] A method for preparing high-purity beryllium based on vacuum solid-state electromigration includes the following steps:

[0022] (1) The initial Fe content of the industrial-grade beryllium rod (purity ≥ 99.9%) is 150 ppm, the C content is 280 ppm, and the size is Φ15 mm × 150 mm; the beryllium rod is electrolytically polished until the surface roughness is reduced to 0.15 μm;

[0023] (2) In an ultra-high vacuum environment, a composite electric field is applied to the beryllium rod processed in step (1). The electric field includes a DC component in the axial direction and a pulsed component in the radial direction. The current density of the axial electric field is 120 A / cm 2 , and the radial electric field is 5 kHz / 20% duty cycle. An axial temperature gradient is established to drive the directional migration of impurities. The electrothermal parameters are adjusted in real time through in-situ spectroscopy monitoring. After processing for 120 h, high-purity beryllium is obtained.

[0024] In this example, the head purity of the obtained high-purity beryllium is 99.9963%, the Fe content is reduced to 18 ppm, the C content is 35 ppm, and the mass loss is 0.32%.

[0025] Example 2

[0026] A method for preparing high-purity beryllium based on vacuum solid-state electromigration includes the following steps:

[0027] (1) The initial O content of an industrial-grade beryllium rod (purity ≥ 99.9%) is 650 ppm, and the size is Φ30 mm × 150 mm; the beryllium rod is electrolytically polished until the surface roughness is reduced to 0.1 μm;

[0028] (2) In an ultra-high vacuum environment, a composite electric field is applied to the beryllium rod processed in step (1). The electric field includes a DC component in the axial direction and a pulsed component in the radial direction. The current density of the axial electric field is 180 A / cm 2 , and the radial electric field is 8 kHz / 20% duty cycle. An axial temperature gradient is established to drive the directional migration of impurities. The electrothermal parameters are adjusted in real time through in-situ spectroscopy monitoring. After processing for 160 h, high-purity beryllium is obtained.

[0029] In this example, the head purity of the obtained high-purity beryllium is 99.997%, and the O content is reduced to 72 ppm.

[0030] Example 3

[0031] A method for preparing high-purity beryllium based on vacuum solid-state electromigration includes the following steps:

[0032] (1) The initial Fe content of an industrial-grade beryllium rod (purity ≥ 99.9%) is 120 ppm, the C content is 260 ppm, and the size is Φ15 mm × 150 mm; the beryllium rod is electrolytically polished until the surface roughness is reduced to 0.2 μm;

[0033] (2) In an ultra-high vacuum environment, a composite electric field is applied to the beryllium rod processed in step (1). The electric field includes a DC component in the axial direction and a pulsed component in the radial direction. The current density of the axial electric field is 120 A / cm 2 , and the radial electric field is 15 kHz / 30% duty cycle. An axial temperature gradient is established to drive the directional migration of impurities. The electrothermal parameters are adjusted in real time through in-situ spectroscopy monitoring. After processing for 100 h, high-purity beryllium is obtained.

[0034] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing high-purity beryllium based on vacuum solid-state electromigration, characterized in that, It includes the following steps: (1) Electrolytically polish the beryllium rod; (2) In an ultra-high vacuum environment, apply a composite electric field to the beryllium rod processed in step (1). The electric field includes a DC component in the axial direction and a pulsed component in the radial direction. Establish an axial temperature gradient to drive the directional migration of impurities, and adjust the electrothermal parameters in real time through in-situ spectroscopy to obtain high-purity beryllium.

2. The method for preparing high-purity beryllium based on vacuum solid-state electromigration according to claim 1, wherein In step (1), the beryllium rod is an industrial-grade beryllium rod with a purity of ≥99.9%.

3. The method for preparing high-purity beryllium based on vacuum solid-state electromigration according to claim 1, wherein, In step (1), the surface roughness Ra of the beryllium rod after polishing is ≤0.2 μm.

4. The method for preparing high-purity beryllium based on vacuum solid-state electromigration according to claim 1, characterized in that, In step (2), the current density of the DC component where σ(T) is the conductivity of beryllium at temperature T, and α is the thermoelectric potential coefficient, is the temperature gradient, Z is the effective charge number, e is the elementary charge, and E is the electric field strength.

5. The method for preparing high-purity beryllium based on vacuum solid-state electromigration according to claim 1, wherein, In step (2), the electric field frequency of the pulsed component matches the beryllium lattice vibration frequency, and the frequency range is 0.5 - 15 kHz; the peak current density of the pulsed component is 30 - 80% of the DC component.

6. The method for preparing high-purity beryllium based on vacuum solid-state electromigration according to claim 1, characterized in that, In step (2), a stepwise current increase strategy is adopted, and the current density increase in each stage is ≤20%. Zero-current annealing for 5 - 15 minutes is inserted between adjacent stages.

7. The method for preparing high-purity beryllium based on vacuum solid-state electromigration according to claim 1, wherein In step (2), the temperature in the high-temperature region of the temperature gradient is 900 - 1000 °C, and the temperature in the low-temperature region is 700 - 800 °C.

8. The method for preparing high-purity beryllium based on vacuum solid-state electromigration according to claim 1, wherein, In step (2), the processing time is 100 - 160 h.