Preparation method of high-purity superfine diboride powder

Abstract

The application provides a preparation method of high-purity superfine diboride powder and relates to the field of metal borides. The preparation method comprises the following steps: introducing BCl3 and H2 into a vacuum environment to obtain a mixed gas; mixing the mixed gas and metal wires and performing electric explosion treatment to obtain a reaction powder; and performing passivation ball milling treatment on the reaction powder in a mixed atmosphere of argon and oxygen to obtain the high-purity superfine diboride powder; and the metal wires comprise at least one of titanium wires, magnesium wires and aluminum wires. The method does not introduce by-products and impurities in the whole process, the obtained diboride powder is small in particle size, uniform in distribution and free of agglomeration, the preparation method is short in process and high in efficiency, and the method has a good industrialization prospect.

Description

Technical Field

[0001] This application relates to the field of metal borides, and more particularly to a method for preparing high-purity ultrafine diboride powder. Background Technology

[0002] High-purity, ultrafine boride powders such as titanium diboride, magnesium diboride, and aluminum diboride have irreplaceable strategic application value in nuclear fusion, superconducting power, aerospace, advanced ceramics, and lightweight composite materials. However, existing preparation methods generally suffer from problems such as coarse powder particle size and low purity, which restricts their application in high-end fields. Therefore, the controllable preparation of high-purity, ultrafine diboride powders has become a current research focus.

[0003] Currently, the main methods for preparing high-purity ultrafine diboride powders include ball milling and molten salt method. Ball milling achieves particle size refinement by adjusting the ball milling process, but the resulting powder has a wide particle size distribution and still contains many large particles; the molten salt method can obtain finer powders, but the product purity is lower, making it difficult to simultaneously meet the requirements of high purity and ultrafineness. Summary of the Invention

[0004] The purpose of this application is to provide a method for preparing high-purity ultrafine diboride powder to solve the above-mentioned problems.

[0005] To achieve the above objectives, this application provides a method for preparing high-purity ultrafine diboride powder, comprising: BCl3 and H2 are introduced into a vacuum environment to obtain a mixed gas; a metal wire is subjected to an electrical explosion in the mixed gas to obtain a reaction powder. Under a mixed atmosphere of argon and oxygen, the reaction powder was subjected to passivation ball milling to obtain high-purity ultrafine diboride powder. The metal wire includes at least one of titanium wire, magnesium wire, and aluminum wire.

[0006] Optionally, the vacuum degree in the vacuum environment is ≤-0.095MPa; And / or, the pressure of the mixed gas is ≥0.4 MPa; And / or, the molar ratio of Cl in BCl3 to H in H2 is 0.5-1.5:0.5-1.5.

[0007] Optionally, the diameter of the metal wire is 0.2-0.7 mm; And / or, the wire feeding rate of the metal wire is 5cm / s-15cm / s; And / or, the purity of the metal wire is ≥99.99%.

[0008] Optionally, the electrical explosion process includes sequentially performing a first-level pulse process, a second-level pulse process, and a third-level pulse process; The voltage of the first-level pulse processing is 500-1200V, the current amplitude is 50-150A, and the pulse width is 5-20μs; The voltage of the secondary pulse processing is 15000-30000V, the current amplitude is 1000-5000A, and the pulse width is 0.5-3μs; The voltage of the three-stage pulse processing is 3000-8000V, the current amplitude is 500-2000A, and the pulse width is 0.1-0.5μs.

[0009] Optionally, the interval between the secondary pulse processing and the primary pulse processing is 1-10 μs; And / or, the interval between the third-level pulse processing and the second-level pulse processing is 0.1-1 μs.

[0010] Optionally, the temperature of the first-stage pulse processing is 1500-1900K; And / or, the temperature of the secondary pulse processing is ≥8000K; And / or, the temperature of the three-stage pulse processing is 800-1000K.

[0011] Optionally, cooling is performed after the three-stage pulse processing is completed, and the cooling rate is ≥10. 6 K / s.

[0012] Optionally, in the mixed atmosphere of argon and oxygen, the volume of oxygen is 2-5% of the volume of argon. And / or, the pressure of the argon and oxygen mixed atmosphere is ≥0.2MPa; And / or, the passivation ball milling treatment time is ≥10h.

[0013] Optionally, the apparatus for performing the electro-explosion treatment further includes a circulating fan, a gas cooler, and a cyclone collector fan; The speed of the circulating fan is 15-40Hz, and the cooling temperature of the gas cooler is 5-15℃.

[0014] Optionally, the high-purity ultrafine diboride powder includes at least one of titanium diboride, magnesium diboride, and aluminum diboride; And / or, the high-purity ultrafine diboride powder has a particle size of 20-100 nm and a purity of ≥99.9%.

[0015] Compared with the prior art, the beneficial effects of this application include: The method for preparing high-purity, ultrafine diboride powder provided in this application combines electro-explosion technology with gas-phase synthesis to achieve efficient preparation of nano-diborides. This method uses the localized high temperature generated during the electro-explosion process as a heat source, and replaces the conventional protective inert gas with a reactive gas (a mixture of BCl3 and H2). Under pulsed input conditions, the electro-explosion instantaneously generates a high-temperature plasma zone, where the metal vapor generated by the metal wire reacts with the mixed gas within the cavity, thereby producing nano-sized diborides. This method introduces no byproducts or impurities throughout the process, resulting in diborides with high purity, fine particle size, uniform distribution, and no agglomeration. The preparation method is short, efficient, and has good prospects for industrialization. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation on the scope of this application.

[0017] Figure 1 Scanning electron microscope image of the high-purity ultrafine diboride powder provided in Example 1. Detailed Implementation

[0018] First, the solution provided in this application will be explained in more detail as follows: This application provides a method for preparing high-purity ultrafine diboride powder, including: BCl3 and H2 are introduced into a vacuum environment to obtain a mixed gas; a metal wire is subjected to an electrical explosion in the mixed gas to obtain a reaction powder. It is important to note that the electro-explosion treatment is carried out in an electro-explosion device. The device cavity is evacuated, and a mixture of BCl3 and H2 gas is introduced. Then, a high voltage is applied to the device. After the voltage is applied, the wire feeding mechanism of the device will feed the metal wire towards the high-voltage plate. When the metal wire is close to the high-voltage plate, the high voltage is introduced. Under the action of the extremely high temperature generated by the high voltage of the electro-explosion treatment, the metal wire vaporizes and forms metal vapor. A momentary high temperature is formed around the metal vapor. The momentary high temperature will cause the metal gas, boron trichloride gas, and hydrogen to react and produce ultrafine nano diborides. Under a mixed atmosphere of argon and oxygen, the reaction powder was subjected to passivation ball milling to obtain high-purity ultrafine diboride powder. It is important to note that passivation ball milling can prevent the reaction powder from growing further. This is mainly because, during the ball milling passivation process, a stable passivation layer is generated on the particle surface, reducing the surface energy and blocking atomic migration and grain boundary movement, thereby fundamentally inhibiting grain growth during subsequent storage.

[0019] The metal wire includes at least one of titanium wire, magnesium wire, and aluminum wire.

[0020] In some embodiments, the vacuum level in the vacuum environment is ≤-0.095MPa; Optionally, the vacuum level in the vacuum environment can be any value of -0.095 MPa, -0.096 MPa, -0.097 MPa, -0.098 MPa, -0.099 MPa, -0.1 MPa, -0.15 MPa or ≤-0.095 MPa; And / or, the pressure of the mixed gas is ≥0.4 MPa; Optionally, the pressure of the mixed gas can be any value of 0.4 MPa, 0.5 MPa, 1 MPa or ≥0.4 MPa; It should be noted that the pressure of the mixed gas must be ≥0.4MPa to ensure the concentration of reactants in the electro-explosion treatment, thereby meeting the thermodynamic conditions for the electro-explosion treatment reaction to occur. And / or, the molar ratio of Cl in BCl3 to H in H2 is 0.5-1.5:0.5-1.5.

[0021] Optionally, the molar ratio of Cl in BCl3 to H in H2 can be any value between 0.5:0.6, 0.5:1, 0.5:1.5, 1:0.5, 1:1, 1:1.5 or 0.5-1.5:0.5-1.5.

[0022] In some embodiments, the diameter of the metal wire is 0.2-0.7 mm; Optionally, the diameter of the metal wire can be any value between 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, or 0.2-0.7 mm; It should be noted that if the diameter of the metal wire is too thin, it cannot be fed continuously and stably, and the wire is prone to breakage; if the diameter of the metal wire is too thick, the resulting powder particles will be too coarse. And / or, the wire feeding rate of the metal wire is 5cm / s-15cm / s; Optionally, the wire feeding rate can be any value between 5 cm / s, 6 cm / s, 7 cm / s, 8 cm / s, 9 cm / s, 10 cm / s, 11 cm / s, 12 cm / s, 13 cm / s, 14 cm / s, 15 cm / s, or 5-15 cm / s. It is important to note that the wire feeding speed and discharge voltage must be kept within a certain range to ensure that the reaction requires a sufficient amount of metal vapor without generating too much metal powder byproduct. If the wire feeding speed is too low, the efficiency will be too low; if the wire feeding speed is too high, the vapor concentration will be too high, resulting in a large amount of metal powder byproduct. If the discharge voltage is too low, the metal wire will not be able to electro-explode and vaporize. And / or, the purity of the metal wire is ≥99.99%.

[0023] Optionally, the purity of the metal wire can be any value of 99.99%, 99.995%, 99.999%, or ≥99.99%.

[0024] In some embodiments, the electrical explosion process includes sequentially performing a first-level pulse process, a second-level pulse process, and a third-level pulse process; The voltage of the first-level pulse processing is 500-1200V, the current amplitude is 50-150A, and the pulse width is 5-20μs; Optionally, the voltage of the first-level pulse processing can be any value between 500V, 600V, 700V, 800V, 900V, 1000V, 1100V, 1200V or 500-1200V, the current amplitude can be any value between 50A, 100A, 150A or 50-150A, and the pulse width can be any value between 5μs, 10μs, 15μs, 20μs or 5-20μs; The voltage of the secondary pulse processing is 15000-30000V, the current amplitude is 1000-5000A, and the pulse width is 0.5-3μs; Optionally, the voltage for the secondary pulse processing can be any value between 15000V, 20000V, 25000V, 30000V, or 15000-30000V; the current amplitude can be any value between 1000A, 2000A, 3000A, 4000A, 5000A, or 1000-5000A; and the pulse width can be any value between 0.5μs, 1μs, 1.5μs, 2μs, 2.5μs, 3μs, or 0.5-3μs. The voltage of the three-stage pulse processing is 3000-8000V, the current amplitude is 500-2000A, and the pulse width is 0.1-0.5μs.

[0025] Optionally, the voltage for the three-stage pulse processing can be any value between 3000V, 4000V, 5000V, 6000V, 7000V, 8000V, or 3000-8000V; the current amplitude can be any value between 500A, 1000A, 1500A, 2000A, or 500-2000A; and the pulse width can be any value between 0.1μs, 0.2μs, 0.3μs, 0.4μs, 0.5μs, or 0.1-0.5μs.

[0026] It is important to note that the first-stage pulse treatment is primarily for wire preheating. During this stage, the electro-explosion power supply applies a low-amplitude, long-pulse voltage to raise the temperature of the metal wire to near its melting point without vaporizing it. This avoids the plasma shock wave disturbance caused by instantaneous vaporization from a single-stage strong pulse, reduces particle agglomeration due to excessively high local metal vapor concentration, and improves the uniformity of subsequent vaporization. This provides a uniform and stable precursor state for subsequent stages, ensuring a more complete reaction between BCl3, H2, and metal vapor, thereby reducing impurity phases (Ti, TiO2) from the source. x The probability of formation of (B2O3, Mg, Al, Ti, etc.); The secondary pulse treatment is the high-energy pulsed filament vaporization reaction stage. After a microsecond interval between the primary pulses, the equipment power supply applies a high-amplitude, short-pulse-width secondary voltage, causing the preheated filament to rapidly cross the vaporization threshold, forming a high-density, highly uniform metal vapor plasma. Simultaneously, it reacts with BCl3 and H2 to generate diborides. The energy parameters in this stage directly determine the plasma temperature and density, which is crucial for controlling the powder particle size. The third-stage pulse processing is a short-pulse powder particle size refinement and uniform shaping stage. The equipment power supply applies a third-stage short-pulse voltage, which compresses the plasma cloud through electromagnetic force, accelerates the cooling and quenching rate of the vapor, and suppresses the collision, aggregation and Ostwald ripening effect of nanoparticles, thereby obtaining nanoparticles with more uniform and dispersed particle size.

[0027] It should also be noted that conventional electro-explosion methods use single-stage pulse voltage. Traditional single-stage pulse energy is a physical reaction under single-stage pulse input voltage conditions. Under inert gas protection, the filament is atomized and condensed to prepare nanoparticles of the corresponding filament composition. However, this method still has the following drawbacks: the energy injection is too concentrated, which can easily lead to local overheating, uncontrolled plasma expansion, and uneven particle size distribution of the product (more large particles than nanoparticles), agglomeration, or component segregation. The multi-stage pulse method provided in this application can solve the above problems. It uses the local high temperature of the electro-explosion process as a heat source, and replaces the conventional protective inert gas with a reactive gas (a mixture of BCl3 and H2). Under multi-stage pulse input conditions, a high-temperature plasma zone is generated. The metal vapor generated by the metal filament reacts with the mixed gas in the cavity to produce nano-boronides. By precisely controlling the reaction process parameters, the particle size of the diboronides is made finer, more uniform, and better dispersed.

[0028] In some embodiments, the interval between the secondary pulse processing and the primary pulse processing is 1-10 μs; Optionally, the interval between the second-level pulse processing and the first-level pulse processing can be any value between 1μs, 2μs, 3μs, 4μs, 5μs, 6μs, 7μs, 8μs, 9μs, 10μs or 1-10μs; It should be noted that when the interval between the second-level pulse processing and the first-level pulse processing is in the range of 1-10μs, it is a microsecond-level delay to ensure that the metal wire is still in the pre-melted high-temperature state. And / or, the interval between the third-level pulse processing and the second-level pulse processing is 0.1-1 μs.

[0029] Optionally, the interval between the third-level pulse processing and the second-level pulse processing can be any value between 0.1μs, 0.2μs, 0.3μs, 0.4μs, 0.5μs, 0.6μs, 0.7μs, 0.8μs, 0.9μs, 1μs, or 0.1-1μs.

[0030] In some embodiments, the temperature of the primary pulse processing is 1500-1900K; Optionally, the temperature for the first-stage pulse processing can be any value between 1500K, 1600K, 1700K, 1800K, 1900K, or 1500-1900K; And / or, the temperature of the secondary pulse processing is ≥8000K; Optionally, the temperature for the secondary pulse processing can be any value of 8000K, 8100 K, 8200 K, 8300 K, 8400 K, 8500K or ≥8000K; It is important to note that when the temperature of the secondary pulse treatment is ≥8000K, the gas-phase reaction of the metal wire, BCl3, and H2 must be complete to generate high-purity diborides. If the temperature is too low, the reaction will be incomplete, leaving residual Ti and BCl3. x The intermediate phase; when the temperature is too high, the plasma density is too high, which causes the particles to collide and grow rapidly, and the particle size becomes uncontrolled and coarser. And / or, the temperature of the three-stage pulse processing is 800-1000K.

[0031] Optionally, the temperature for the three-stage pulse processing can be any value between 800K, 850K, 900K, 950K, 1000K, or 800-1000K.

[0032] In some embodiments, cooling is performed after the three-stage pulse processing is completed, and the cooling rate is ≥10. 6 K / s.

[0033] Optionally, the cooling rate can be 10. 6 K / s, 2×10 6 K / s, 3×10 6 K / s, 4×10 6 K / s, 5×10 6 K / s, 6×10 6 K / s, 7×10 6 K / s, 8×10 6 K / s, 9×10 6 K / s, 10 7 K / s or ≥10 6 Any value of K / s.

[0034] It should be noted that the quenching rate is ≥10 6 K / s can maximally suppress particle collision, aggregation and Ostwald ripening, thereby obtaining finer and more dispersed powders.

[0035] In some embodiments, in the mixed atmosphere of argon and oxygen, the volume of oxygen is 2-5% of the volume of argon. Optionally, the volume of oxygen is any value between 2%, 3%, 4%, 5% or 2-5% of the volume of argon. It is important to note that ball milling and passivation of powder under an atmosphere of argon mixed with a small amount of oxygen (2-5%) results in the formation of a nano-oxide layer on the powder surface. The ultra-thin oxide layer film significantly reduces the surface energy of the powder, greatly weakens the driving force of the Kelvin effect, blocks the diffusion path of powder atoms between particles, inhibits Ostwald ripening from the root, and prevents the particles from growing further. And / or, the pressure of the argon and oxygen mixed atmosphere is ≥0.2MPa; Optionally, the pressure of the argon and oxygen mixture atmosphere can be any value of 0.2 MPa, 0.3 MPa, 0.4 MPa, 0.5 MPa, 0.6 MPa, 0.7 MPa, 0.8 MPa, 0.9 MPa, 1 MPa or ≥0.2 MPa; It should be noted that the pressure of the mixed atmosphere of argon and oxygen must be ≥0.2MPa; if the pressure is too low, sufficient passivation cannot be achieved. And / or, the passivation ball milling treatment time is ≥10h.

[0036] Optionally, the passivation ball milling time can be any value of 10h, 11h, 12h, 13h, 14h, 15h, 20h or ≥10h.

[0037] It should be noted that the ball milling time should not be less than 10 hours. If the time is too short, the ball will not passivate sufficiently, and if the time is too long, the energy consumption will be too high.

[0038] In some embodiments, the apparatus for performing the electro-explosion treatment further includes a circulating fan, a gas cooler, and a cyclone collector fan; The speed of the circulating fan is 15-40Hz, and the cooling temperature of the gas cooler is 5-15℃.

[0039] Optionally, the rotational speed of the circulating fan can be any value between 15 Hz, 20 Hz, 25 Hz, 30 Hz, 35 Hz, 40 Hz or 15-40 Hz, and the cooling temperature of the gas cooler can be any value between 5℃, 10℃, 15℃ or 5-15℃.

[0040] In some embodiments, during cyclone collection, the rotation speed of the circulating motor needs to be precisely controlled, and the reaction products are separated into large-particle metal powder, micron-sized metal powder, and nano-sized diborides through a multi-stage classification system.

[0041] In some embodiments, the high-purity ultrafine diboride powder includes at least one of titanium diboride, magnesium diboride, and aluminum diboride; And / or, the high-purity ultrafine diboride powder has a particle size of 20-100 nm and a purity of ≥99.9%.

[0042] Optionally, the particle size of the high-purity ultrafine diboride powder can be any value between 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm or 20-100 nm, and the purity can be any value of 99.9%, 99.99%, 99.999%, 99.9999% or ≥99.9%.

[0043] The implementation schemes of this application will be described in detail below with reference to specific embodiments. However, those skilled in the art will understand that the following embodiments are only for illustrating this application and should not be regarded as limiting the scope of this application. Unless otherwise specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments used without specified manufacturers are all conventional products that can be purchased commercially.

[0044] Example 1 This embodiment provides a method for preparing high-purity ultrafine diboride powder, the specific preparation steps of which are as follows: S1; The electric explosion equipment is evacuated to -0.095MPa and filled with a mixture of BCl3 and H2 (the molar ratio of Cl in BCl3 to H in H2 is 1:1) until the pressure inside the equipment is 0.4MPa; S2: Turn on the equipment circulation fan, set the speed to 20Hz, turn on the gas cooler, set the temperature to 5℃, and turn on the cyclone collector fan at 15Hz. S3: After the gas inside the equipment stabilizes, turn on the boost module of the electric explosion equipment and connect it to the multi-stage pulse voltage system. Set it according to the multi-stage pulse energy cycle. The first-stage pulse voltage is 500V, current amplitude is 100A, pulse width is 10μs, and temperature is 1500-1900K. The second-stage pulse interval is 2μs, the second-stage pulse voltage is 17000V, current amplitude is 2kA, pulse width is 1μs, and temperature is ≥8000K. The third-stage pulse interval is 0.5μs, the third-stage pulse voltage is 4000V, current amplitude is 1.5kA, and pulse width is 100ns. After the third-stage pulse processing is completed, cooling is performed at a rate ≥10. 6 K / s; Open the wire feeding mechanism, the wire feeding speed is 8cm / s, the titanium wire diameter is 0.3mm, start running the equipment according to the above multi-level pulse energy cycle settings, after the equipment runs out, turn off the wire feeding structure, turn off the voltage module, turn off the cyclone collecting fan, turn off the cooling fan, and turn off the circulating fan in sequence. The generated nano-boron titanium enters the collection chamber under the action of cyclone collection. S4: The powder in the collection chamber is subjected to passivation ball milling treatment. Specifically, the vacuum is drawn to -0.095MPa, and then argon gas mixed with 2% oxygen by volume is introduced and the pressure is increased to 0.3MPa. The powder is then ball milled and passivated for 12 hours. After the ball milling is completed, the powder is discharged and sieved through a 45-mesh sieve to obtain high-purity ultrafine diboride powder.

[0045] The scanning electron microscope image of this high-purity ultrafine diboride powder is as follows: Figure 1 As shown.

[0046] Example 2 The differences from Example 1 are as follows: the first-stage pulse voltage is 1200V, the current amplitude is 150A, the pulse width is 20μs, and the temperature is 1500-1900K; the interval between the second-stage pulse and the previous-stage pulse is 8μs, the second-stage pulse voltage is 28000V, the current amplitude is 5kA, the pulse width is 3μs, and the temperature is ≥8000K; the interval between the third-stage pulse and the second-stage pulse is 0.1μs, the third-stage pulse voltage is 8000kV, the current amplitude is 2kA, and the pulse width is 500 ns; the wire feeding speed is 14cm / s.

[0047] Example 3 The difference from Example 1 is that in step S4, the vacuum is drawn to -0.095 MPa, and then argon gas mixed with 5% oxygen is introduced and the pressure is increased to 0.4 MPa for powder ball milling passivation. The ball milling time is 15 hours.

[0048] Example 4 The difference from Example 1 is that the titanium wire is replaced with a magnesium wire with a diameter of 0.3 mm and a purity of ≥99.9%.

[0049] Example 5 The difference from Example 1 is that the titanium wire is replaced with an aluminum wire with a diameter of 0.4 mm and a purity of ≥99.9%.

[0050] Comparative Example 1 The difference from Example 1 is that the passivation ball milling treatment in step S4 is not performed.

[0051] Comparative Example 2 The difference from Example 1 is that the first-level pulse processing in step S3 is not performed.

[0052] Comparative Example 3 The difference from Example 1 is that the secondary pulse treatment in step S3 is not performed, the main reaction cannot occur, and the corresponding boride nanoparticles are not generated.

[0053] Comparative Example 4 The difference from Example 1 is that the three-stage pulse processing in step S3 is not performed.

[0054] Comparative Example 5 The difference from Example 1 is that the first-level pulse processing and third-level pulse processing in step S3 are not performed.

[0055] Comparative Example 6 The difference from Example 1 is that the wire feeding speed is 4 cm / s. Although the product purity and particle size do not change significantly, the yield is reduced.

[0056] Comparative Example 7 The difference from Example 1 is that the wire feeding speed is 16 cm / s.

[0057] The high-purity ultrafine diboride powders provided in the above embodiments and comparative examples were subjected to particle size and purity testing. The specific test results are shown in Table 1.

[0058] The test method for particle size is GB / T 42208-2022.

[0059] The purity test method is XRD quantitative phase analysis.

[0060] Table 1 Particle size and purity

[0061] analyze: The above tests show that, as seen in Example 1 and Comparative Example 1, the powder without ball milling passivation treatment has a larger particle size; as seen in Example 1 and Comparative Example 2, the powder without first-stage pulse treatment, due to the lack of a preheating stage, suffers from particle agglomeration caused by excessively high local metal vapor concentration, and the generation of impurities during the reaction process, ultimately resulting in larger particles and lower purity; as seen in Example 1 and Comparative Example 3, the main reaction cannot occur without second-stage pulse treatment; as seen in Example 1 and Comparative Example 4, the powder without third-stage pulse treatment has larger particles due to the lack of refining and uniform shaping; as seen in Example 1 and Comparative Example 5, the powder directly subjected to conventional electro-explosion without first and third-stage pulse treatment has a larger particle size and lower purity; as seen in Example 1 and Comparative Example 6, a slow wire feeding speed affects preparation efficiency, resulting in lower efficiency; as seen in Example 1 and Comparative Example 7, a fast wire feeding speed leads to excessively high metal vapor concentration, resulting in impurity generation and lower purity.

[0062] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

[0063] Furthermore, those skilled in the art will understand that although some embodiments herein include certain features included in other embodiments but not others, combinations of features from different embodiments are intended to be within the scope of this application and form different embodiments. For example, any of the claimed embodiments can be used in any combination. The information disclosed in this background section is intended only to enhance the understanding of the general background of this application and should not be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

Claims

1. A method for preparing high-purity ultrafine diboride powder, characterized in that, include: BCl3 and H2 are introduced into a vacuum environment to obtain a mixed gas; a metal wire is subjected to an electrical explosion in the mixed gas to obtain a reaction powder. Under a mixed atmosphere of argon and oxygen, the reaction powder was subjected to passivation ball milling to obtain high-purity ultrafine diboride powder. The metal wire includes at least one of titanium wire, magnesium wire, and aluminum wire; The electrical explosion process includes sequentially performing a first-level pulse process, a second-level pulse process, and a third-level pulse process; The voltage of the first-level pulse processing is 500-1200V, the current amplitude is 50-150A, and the pulse width is 5-20μs; The voltage of the secondary pulse processing is 15000-30000V, the current amplitude is 1000-5000A, and the pulse width is 0.5-3μs; The voltage of the three-stage pulse processing is 3000-8000V, the current amplitude is 500-2000A, and the pulse width is 0.1-0.5μs; The wire feeding rate is 5cm / s-15cm / s; The molar ratio of Cl in BCl3 to H in H2 is 0.5-1.5:0.5-1.5; In the mixed atmosphere of argon and oxygen, the volume of oxygen is 2-5% of the volume of argon. The high-purity ultrafine diboride powder includes at least one of titanium diboride, magnesium diboride, and aluminum diboride.

2. The method for preparing high-purity ultrafine diboride powder according to claim 1, characterized in that, The vacuum level in the vacuum environment is ≤-0.095MPa; And / or, the pressure of the mixed gas is ≥0.4MPa.

3. The method for preparing high-purity ultrafine diboride powder according to claim 1, characterized in that, The diameter of the metal wire is 0.2-0.7 mm; And / or, the purity of the metal wire is ≥99.99%.

4. The method for preparing high-purity ultrafine diboride powder according to claim 1, characterized in that, The interval between the secondary pulse processing and the primary pulse processing is 1-10 μs; And / or, the interval between the third-level pulse processing and the second-level pulse processing is 0.1-1 μs.

5. The method for preparing high-purity ultrafine diboride powder according to claim 1, characterized in that, The temperature of the first-stage pulse processing is 1500-1900K; And / or, the temperature of the secondary pulse processing is ≥8000K; And / or, the temperature of the three-stage pulse processing is 800-1000K.

6. The method for preparing high-purity ultrafine diboride powder according to claim 1, characterized in that, After the three-stage pulse processing is completed, cooling is performed at a rate ≥10. 6 K / s.

7. The method for preparing high-purity ultrafine diboride powder according to claim 1, characterized in that, The pressure of the mixed atmosphere of argon and oxygen is ≥0.2 MPa; And / or, the passivation ball milling treatment time is ≥10h.

8. The method for preparing high-purity ultrafine diboride powder according to claim 1, characterized in that, The apparatus for performing the electro-explosion treatment also includes a circulating fan, a gas cooler, and a cyclone collector fan; The speed of the circulating fan is 15-40Hz, and the cooling temperature of the gas cooler is 5-15℃.

9. The method for preparing high-purity ultrafine diboride powder according to any one of claims 1-8, characterized in that, The high-purity ultrafine diboride powder has a particle size of 20-100 nm and a purity of ≥99.9%.

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