Preparation method of spherical REBCO powder

Abstract

The invention discloses a preparation method of spherical REBCO powder, and belongs to the field of superconducting materials. The preparation method specifically comprises the following steps: preparing a high-quality precursor at 800-1000 DEG C by adopting a solid-phase reaction method; the precursor is coarsely crushed and then placed in a vacuum gas atomization furnace for induction melting, the induction heating temperature ranges from 1400 DEG C to 1700 DEG C, and after a melt falls down, high-pressure inert gas is used for spraying to obtain spherical powder. The method has the advantages of high sphericity and uniformity, high purity and phase stability, improved process efficiency and wide applicability, is suitable for preparing REBCO powder of various rare earth elements (Y, Eu, Gd, Yb and the like), and has strong parameter adjustability.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of superconducting materials, and particularly relates to a preparation method of spherical REBCO powder. BACKGROUND

[0002] Copper oxide superconductor is the most widely used high-temperature superconducting material at present. It has excellent properties such as high superconducting transition temperature, high upper critical field and high current-carrying characteristics, and is a key basic material for realizing controllable nuclear fusion, developing the next generation of high-energy accelerators and super-high-field whole-body magnetic resonance imaging systems. At present, the international community generally uses the pulsed laser deposition method (PLD) to prepare copper oxide superconducting tapes, and the core material of the PLD method is a target material prepared by pressing powder. Therefore, the development process of practical high-temperature superconducting wires must be based on high-performance powder materials.

[0003] The grains of high-temperature superconducting precursor powder prepared by solid-phase sintering are generally polygonal, with sizes ranging from sub-microns to hundreds of microns, and the preparation efficiency and yield are low. Vacuum gas atomization is an advanced process for preparing metal or alloy powder, which atomizes molten metal into fine droplets and rapidly solidifies in a vacuum or inert gas environment, obtaining high-purity, high-spherical, and controllable particle size distribution powder. This technology is widely used in additive manufacturing (3D printing), powder metallurgy, aerospace, medical implants and other fields. In addition, using gas atomization equipment to rapidly cool the solidification droplets of high-temperature superconductors (such as copper oxide superconductors) can obtain high-quality spherical powder particles containing nanometer and sub-micron grains. SUMMARY

[0004] In order to solve the technical problems in the background art, the application provides a preparation method of spherical REBCO powder, which belongs to the field of superconducting materials. The precursor is prepared by a solid-phase reaction method, the crushed blank is placed in a vacuum gas atomization furnace for induction melting, and then high-pressure argon gas is used to obtain near-spherical powder during the falling process of the melt.

[0005] The technical scheme of the application is as follows:

[0006] A preparation method of spherical REBCO powder, comprising the following steps:

[0007] (1) Preparation of precursor: high-purity oxide powders are mixed according to the stoichiometric ratio RE:Ba:Cu=1:2:3, ball milled, pressed, and then two-step sintered at 800-1000℃ to obtain a precursor;

[0008] (2) Gas atomization treatment: the precursor is broken and placed in a vacuum gas atomization furnace, vacuumed to below 1 Pa, inductively heated to 1400-1700 DEG C to melt, the melt is guided into an atomizing nozzle, 2-10 MPa high pressure inert gas is sprayed, the gas flow is 100-500 m3 / h, the melt flow rate is 0.5-3 kg / min, and spherical powder with D50 of 10-100 microns is obtained.

[0009] In the above technical solution, the two-step sintering in step (1) comprises:

[0010] The pre-sintering stage is sintering at 800-900 DEG C for 10-24 hours;

[0011] The main sintering stage is sintering at 900-1000 DEG C in flowing oxygen for 12-48 hours.

[0012] In the above technical solution, the inert gas is argon.

[0013] In the above technical solution, the material of the atomizing nozzle is alumina, zirconia, silicon nitride or boron nitride.

[0014] In the above technical solution, the smelting chamber crucible and the tundish are made of refractory material, and the material is alumina, zirconia, silicon nitride or boron nitride.

[0015] In the above technical solution, the high pressure inert gas pressure is 6-10 MPa, and the gas flow is 300-500 m3 / h.

[0016] In the above technical solution, the melt flow rate is 1.5-3 kg / min.

[0017] In the above technical solution, the powder particle size D50 is 25-53 microns.

[0018] In the above technical solution, the RE is one of Y, Eu, Gd or Yb.

[0019] In the above technical solution, the vacuum degree of the vacuum gas atomization furnace is ≤0.5 Pa.

[0020] Beneficial effects:

[0021] 1. High sphericity and uniformity: through the vacuum gas atomization process combined with high pressure inert gas spraying, the melt is rapidly solidified into spherical particles, the powder sphericity is ≥95%, the particle size distribution is concentrated (D50 10-100 microns), and the additive manufacturing and target material pressing requirements are met.

[0022] 2. High purity and phase stability: the vacuum environment (≤1 Pa) and inert gas protection avoid oxidation impurities, and the two-step sintering process ensures Phase formation is complete, and phase separation is reduced.

[0023] 3. Process efficiency is improved: the single treatment capacity of the gas atomization method can reach 3 kg / min, and the efficiency is improved by 3-5 times compared with the traditional solid phase method.

[0024] 4. Wide applicability: suitable for REBCO powder preparation of various rare earth elements (Y, Eu, Gd, Yb, etc.), and strong parameter adjustability. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 It is a schematic diagram of the structure of the gas atomization furnace.

[0026] Figure 2 It is a picture of the powder appearance.

[0027] Among them, 1 is a vacuum induction melting chamber, 2 is a crucible, 3 is a tundish, 4 is an atomizer, 5 is an atomizing gas source, 6 is an atomizing chamber, 7 is a material melt drop, and 8 is a vacuum system. DETAILED DESCRIPTION

[0028] The present application will be described in detail below in combination with the drawings and specific examples. However, the following examples are only for explaining the present application, and the protection scope of the present application should include the entire content of the claims, and through the description of the following examples, a person skilled in the art can fully realize the entire content of the claims of the present application.

[0029] Example 1

[0030] High-purity Y2O3, BaCO3, and CuO were used as raw materials, mixed according to the stoichiometric ratio (Y:Ba:Cu = 1:2:3), tabletted, and two-step sintered to obtain The precursor was coarsely broken and placed in the crucible of the vacuum gas atomization furnace melting chamber, the furnace body was closed, vacuum was drawn to 0.05 Pa, heating was started to 1500 ℃, and after the appearance of the melt, it was poured into the tundish, the melt was introduced into the atomizing nozzle from the tundish, the melt flow rate was 2 kg / min, the high-pressure argon pressure was 6 MPa, the gas flow was 300 m 3 / h, and the final powder particle size D50 = 35 μm.

[0031] Figure 1 The complete structure of the vacuum gas atomization furnace, which is the core equipment for preparing spherical REBCO powder, is shown, and the functions of the components with different reference numerals are as follows:

[0032] Vacuum induction melting chamber 1: closed cavity, maintaining a vacuum degree of ≤0.5 Pa inside, heating the crucible to 1400-1700 ℃ by an induction coil.

[0033] Crucible 2: made of alumina / zirconia / nitride refractory material, containing broken REBCO precursor, melting in the melting chamber.

[0034] Tundish 3: also made of refractory material, receiving molten metal and stably guiding to the atomizer, controlling the flow rate of the melt at 0.5-3 kg / min.

[0035] Atomizer 4: using high-temperature-resistant ceramic nozzle (alumina / zirconia / silicon nitride / boron nitride) to disperse the melt into micron-sized droplets.

[0036] Atomizing gas source 5: providing 2-10 MPa high-pressure inert gas (usually argon) to form a high-speed gas flow through the nozzle to crush the melt.

[0037] Atomizing chamber 6: inert gas environment cavity, where the droplets rapidly solidify into spherical powder, with a gas flow rate of 100-500 m³ / h.

[0038] Material melt 7: micron-sized droplets (10-100 μm in diameter) formed by atomization, forming nearly spherical particles under the action of surface tension.

[0039] Vacuum system 8: maintaining a vacuum environment throughout the device (vacuumed to ), preventing oxidation of the melt and ensuring process purity.

[0040] Workflow: precursor melting in crucible 2 → melt introduced into atomizer 4 through tundish 3 → atomizing gas source 5 sprays to crush the melt → material melt 7 solidifies in atomizing chamber 6 → vacuum system 8 maintains a low-pressure environment throughout. This design achieves efficient (single processing capacity of 3 kg / min), high-purity (no oxidized impurities), and high-sphericity (≥95%) powder preparation.

[0041] The appearance of the powder is shown in Figure 2 . Figure 2 The spherical powder real photo intuitively verifies the process effect: the powder presents uniform nearly spherical morphology; the particle size is concentrated in D50=25-53 μm, meeting the needs of additive manufacturing and target material pressing.

[0042] Example 2

[0043] High-purity Eu2O3, BaO, and CuO were used as raw materials, mixed according to the stoichiometric ratio (Eu:Ba:Cu = 1:2:3), tabletted, and two-step sintered to obtain the precursor. After coarse crushing, the precursor was placed in the vacuum gas atomization furnace melting chamber crucible, the furnace body was closed and vacuumed to 0.1 Pa, then heated to 1600 ℃, and after the appearance of the melt, it was poured into the tundish. The melt was introduced into the atomizing nozzle from the tundish, the melt flow rate was 3 kg / min, the high-pressure argon pressure was 10 MPa, and the gas flow rate was 500 m3 / h, final powder particle size D50 = 25 μm.

[0044] Example 3

[0045] High-purity Gd2O3, BaO, CuO were used as raw materials, mixed according to the stoichiometric ratio (Gd:Ba:Cu = 1:2:3), tabletting, two-step sintering to obtain The precursor was coarsely broken and placed in the crucible of the vacuum gas atomization furnace melting chamber, the furnace body was closed and vacuumed to 0.5 Pa, then heated to 1700 ℃, after the appearance of the melt, poured into the tundish, the melt was introduced into the atomizing nozzle from the tundish, the melt flow rate was 1.5 kg / min, the high-pressure argon pressure was 6 MPa, and the gas flow was 300 m 3 / h, final powder particle size D50 = 32 μm.

[0046] Example 4

[0047] High-purity Yb2O3, BaO, CuO were used as raw materials, mixed according to the stoichiometric ratio (Yb:Ba:Cu = 1:2:3), tabletting, two-step sintering to obtain The precursor was coarsely broken and placed in the crucible of the vacuum gas atomization furnace melting chamber, the furnace body was closed and vacuumed to 0.1 Pa, then heated to 1400 ℃, after the appearance of the melt, poured into the tundish, the melt was introduced into the atomizing nozzle from the tundish, the melt flow rate was 0.5 kg / min, the high-pressure argon pressure was 2 MPa, and the gas flow was 100 m 3 / h, final powder particle size D50 = 53 μm.

[0048] The above description is merely a specific implementation of the present application, enabling a person skilled in the art to understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing spherical REBCO powder, characterized in that: The following steps are involved: (1) Precursor preparation: Mix high-purity oxide powders according to the stoichiometric ratio of RE:Ba:Cu=1:2:3, ball mill and press, and then perform two-step sintering at 800-1000℃ to obtain Precursor; (2) Gas atomization treatment: The precursor is crushed and placed in a vacuum gas atomization furnace, evacuated to below 1 Pa, induction heated to 1400-1700 ° C for melting, and the melt is introduced into the atomization nozzle through the tundish, and 2-10 MPa high-pressure inert gas is used for injection. The gas flow rate is , melt flow rate 0.5-3 kg / min, and spherical powder with D50 of 10-100 μm was obtained.

2. The method according to claim 1, characterized in that The two-step sintering in step (1) includes: Pre-firing stage: sintering at 800-900℃ for 10-24 hours; Main sintering stage: sintering at 900-1000°C in flowing oxygen for 12-48 hours.

3. The method according to claim 1, characterized in that The inert gas is argon.

4. The method according to claim 1, wherein The atomizing nozzle is made of aluminum oxide, zirconium oxide, silicon nitride or boron nitride.

5. The method according to claim 1, wherein The crucible and tundish in the smelting chamber are made of refractory materials, such as alumina, zirconia, silicon nitride or boron nitride.

6. The method according to claim 1, characterized in that The high-pressure inert gas pressure is 6-10 MPa, and the gas flow rate is .

7. The method according to claim 1, characterized in that The melt flow rate is 1.5-3 kg / min.

8. The method according to claim 1, characterized in that The powder particle size D50 is 25-53 μm.

9. The method according to claim 1, characterized in that The RE is one of Y, Eu, Gd or Yb.

10. The method according to claim 1, characterized in that The vacuum degree of the vacuum air atomization furnace is ≤0.5 Pa.

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