A method for depositing a Gd-Fe-based metal compound on a surface

Abstract

The application belongs to the field of rare earth intermetallic compound preparation, and discloses a Gd-Fe system metal compound surface deposition method, CaO and Gd2O3 are added into molten GdF3-LiF-KF-NaF mixed molten salt, and constant temperature is kept; a pure Fe electrode is inserted into the molten salt and connected to a positive pole of a power supply, a glass carbon electrode is inserted into the molten salt and connected to a negative pole of the power supply, and continuous oxidation is carried out; the Fe electrode is switched to the negative pole of the power supply, the glass carbon electrode is switched to the positive pole of the power supply, and pulsed direct current signal electrodeposition is applied; during the electrodeposition operation process, the Fe cathode is loaded with ultrasonic oscillation every certain time interval, the products on the electrode surface are collected by a tungsten crucible, and the obtained Gd m Fe n The secondary phase alloy is cast in an argon protection casting system and cooled to normal temperature, and after the dross on the surface of the alloy is removed, the alloy is stored in a vacuum sealed tank. The obtained Gd m Fe n The impurities in the secondary phase alloy are not higher than 500 ppm, and no toxic and harmful gas is generated in the production process.

Description

Technical Field

[0001] This invention belongs to the field of rare earth intermetallic compound preparation technology, specifically relating to a method for surface deposition of Gd-Fe based metal compounds. Background Technology

[0002] Rare earth-iron group metal compounds (RE-IG IMs) have demonstrated exceptional properties in functional materials fields such as optics and electromagnetism. Rare earth element Gd has four shell electrons. f 7 5 d 1 6 s 2 Configuration, ionic radius follows the lanthanide contraction law and has a stable oxidation state Gd 3+ (4 f 7 Theoretically, Gd-Fe intermetallic compounds with high magnetic moments and magnetocaloric effects are readily formed. Studies have shown that Gd... m Fe n Metal compounds possess near-room-temperature magnetic refrigeration performance with a second-order magnetic phase transition, exhibiting higher Curie temperatures and a wider refrigeration temperature range, and have broad application prospects in the field of room-temperature magnetic refrigeration cycles. Summary of the Invention

[0003] The purpose of this invention is to develop a surface deposition method for Gd-Fe based metal compounds to prepare Gd with higher purity. m Fe n Intermetallic compounds.

[0004] To achieve the above-mentioned objectives, the present invention provides the following technical solution: A method for surface deposition of Gd-Fe based metal compounds includes the following steps: (1) Raw material pretreatment Anhydrous GdF3, LiF, KF, NaF, CaO, and Gd2O3 were dried under argon atmosphere. The dried GdF3, LiF, KF, and NaF were uniformly mixed in a molar ratio of 2:6:1:1 and filled into a high-purity boron nitride tank and heated until fully melted. Then, 4.8-5.2% by mass of mixed CaO and Gd2O3 were added to the melted GdF3-LiF-KF-NaF mixed molten salt. After stirring with argon atmosphere, the mixture was kept at a constant temperature and allowed to stand. The molar ratio of CaO to Gd2O3 was 3:1. (2) Oxidation of iron electrode Insert the pure Fe electrode into the molten salt treated in step (1) and connect it to the positive terminal of the power supply. At the same time, insert the glassy carbon electrode into the molten salt and connect it to the negative terminal of the power supply. Set the potential difference between the electrodes to 1.2-2.4V and continue the oxidation for 2-3 hours. (3) Pulsating DC electrodeposition Under argon protection, the Fe electrode after step (2) is transferred to the negative terminal of the power supply to form an electrodeposition cathode system, and the glassy carbon electrode is transferred to the positive terminal of the power supply to form an electrodeposition anode system; a pulsating DC signal is applied for electrodeposition for 2-3 hours, and the temperature is controlled at 1050-1150℃, wherein the pulsating DC signal is controlled at a potential of 4.0-4.6V, a duty cycle of 70-90%, and a frequency of 10-20Hz; (4) Secondary phase product stripping During the electrodeposition step (3), at regular intervals, the Fe cathode is subjected to ultrasonic vibration, and the products detached from the electrode surface are collected in a tungsten crucible. The resulting Gd m Fe n The secondary phase alloy is cast into ingots in an argon-protected casting system and cooled to room temperature. After removing the slag from the alloy surface, it is stored in a vacuum-sealed storage tank.

[0005] Preferably, in step (1), the product is dried at 300-350°C for 48-60 hours.

[0006] Preferably, in step (1), GdF3, LiF, KF and NaF are filled into a high-purity boron nitride tank and heated to 950°C to fully melt.

[0007] Preferably, in step (1), 5% by mass of a mixture of CaO and Gd2O3 is added to the molten GdF3-LiF-KF-NaF mixed molten salt.

[0008] Preferably, in step (3), the frequency of the ultrasound is 35-55 Hz and the sound intensity is 1.9-2.5 W / cm². 2 Oscillation for 5-11 minutes.

[0009] Preferably, in step (4), the Fe cathode is subjected to ultrasonic oscillation every 30 minutes.

[0010] Preferably, the purity of anhydrous GdF3, LiF, KF, NaF, CaO, and Gd2O3 is not less than 99.99%, the purity of argon is not less than 99.99%, and the purity of pure Fe electrode is not less than 99.99%.

[0011] The Gd obtained in this invention m Fe n Impurities in secondary phase alloy products are no higher than 500 ppm, Gd m Fe n The purity of the secondary phase alloy can reach 99.98%, and there are no toxic or harmful gases during the production process, which meets environmental protection requirements. In addition, the alloy composition is uniform, the production cost and energy consumption are low, the process is simple, and the production cycle is short. Detailed Implementation

[0012] The method provided by the present invention will be described in detail below with reference to the embodiments, but it should not be construed as limiting the scope of protection of the present invention.

[0013] In Examples 1-7, anhydrous GdF3, LiF, KF, NaF, CaO, and Gd2O3 were dried at 300-350℃ for 48-60 hours under argon atmosphere. The molar ratio of GdF3, LiF, KF, and NaF in the GdF3-LiF-KF-NaF molten salt was 2:6:1:1.

[0014] Example 1: Dry GdF3, LiF, KF, and NaF were filled into a high-purity boron nitride crucible and heated to 950°C under argon protection until fully melted. Then, 5% (by mass) of a mixed CaO-Gd2O3 (molar ratio 3:1) was added, and the mixture was stirred with argon gas and allowed to stand at a constant temperature of 950°C for 2 hours. A pure Fe electrode (by mass not less than 99.99%) was inserted into the molten GdF3-LiF-KF-NaF-CaO-Gd2O3 system and connected to the positive terminal of a power supply. A glassy carbon electrode was then used. Molten salt was inserted into the negative terminal of the power supply, with an inter-electrode potential difference of 1.2V, and oxidation was continued for 2 hours. The system temperature was then raised to 1050℃, and the Fe electrode was switched to the negative terminal of the power supply to form an electrodeposition cathode system, while the high-purity glassy carbon electrode was switched to the positive terminal of the power supply to form an electrodeposition anode system. Electrodeposition was performed for 2 hours under a pulsating DC signal (potential 4.0V, duty cycle 70%, frequency 10Hz). During the electrodeposition process, the Fe cathode was subjected to ultrasound (frequency 35Hz, sound intensity 1.9W / cm²) every 30 minutes. 2 After shaking for 5 minutes, the product detached from the electrode surface was collected in a tungsten crucible; the Gd obtained in the tungsten crucible was then... m Fe n The secondary phase alloy was cast into ingots in an argon-protected casting system and cooled to room temperature. After removing the slag from the alloy surface, it was stored in a vacuum-sealed storage tank. (Gd) m Fe n The purity of intermetallic compounds can reach 99.95%.

[0015] Example 2: Dry GdF3, LiF, KF, and NaF were filled into a high-purity boron nitride crucible and heated to 950°C under argon protection until fully melted. Then, 5% (by mass) of a mixed CaO-Gd2O3 (molar ratio 3:1) was added, and the mixture was stirred with argon gas and allowed to stand at a constant temperature of 950°C for 2 hours. A pure Fe electrode (by mass not less than 99.99%) was inserted into the molten GdF3-LiF-KF-NaF-CaO-Gd2O3 system and connected to the positive terminal of a power supply. A glassy carbon electrode was inserted... Molten salt was connected to the negative electrode of the power supply, with an inter-electrode potential difference of 1.4V, and oxidation was carried out for 2.2 hours. The system temperature was then raised to 1070℃, and the Fe electrode was switched to the negative electrode to form an electrodeposition cathode system, while the high-purity glassy carbon electrode was switched to the positive electrode to form an electrodeposition anode system. Electrolysis was performed for 2.2 hours under a pulsating DC signal (potential 4.1V, duty cycle 73%, frequency 12Hz). During the electrodeposition process, the Fe cathode was subjected to ultrasound (frequency 38Hz, sound intensity 2.0W / cm²) every 30 minutes. 2 After oscillation for 6 minutes, the product detached from the electrode surface was collected in a tungsten crucible; the Gd obtained in the tungsten crucible was then... m Fe n The secondary phase alloy was cast into ingots in an argon-protected casting system and cooled to room temperature. After removing the slag from the alloy surface, it was stored in a vacuum-sealed storage tank. (Gd) m Fe n The purity of intermetallic compounds can reach 99.96%.

[0016] Example 3: Dry GdF3, LiF, KF, and NaF were filled into a high-purity boron nitride crucible and heated to 950°C under argon protection until fully melted. Then, 5% (by mass) of a mixed CaO-Gd2O3 (molar ratio 3:1) was added, and the mixture was stirred with argon gas and allowed to stand at a constant temperature of 950°C for 2 hours. A pure Fe electrode (by mass not less than 99.99%) was inserted into the molten GdF3-LiF-KF-NaF-CaO-Gd2O3 system and connected to the positive terminal of a power supply. A glassy carbon electrode was inserted... Molten salt was connected to the negative electrode of the power supply, with an inter-electrode potential difference of 1.6V, and oxidation was carried out for 2.3 hours. The system temperature was then raised to 1090℃, and the Fe electrode was switched to the negative electrode to form an electrodeposition cathode system, while high-purity glassy carbon was switched to the positive electrode to form an electrodeposition anode system. Electrolysis was performed for 2.4 hours under a pulsating DC signal (potential 4.2V, duty cycle 77%, frequency 13Hz). During the electrodeposition process, the Fe cathode was subjected to ultrasound (frequency 42Hz, sound intensity 2.1W / cm²) every 30 minutes. 2 After oscillation for 7 minutes, the product detached from the electrode surface was collected in a tungsten crucible; the Gd obtained in the tungsten crucible was then... m Fe nThe secondary phase alloy was cast into ingots in an argon-protected casting system and cooled to room temperature. After removing the slag from the alloy surface, it was stored in a vacuum-sealed storage tank. (Gd) m Fe n The purity of intermetallic compounds can reach 99.97%.

[0017] Example 4: Dry GdF3, LiF, KF, and NaF were filled into a high-purity boron nitride crucible and heated to 950°C under argon protection until fully melted. Then, 5% (by mass) of a mixed CaO-Gd2O3 (molar ratio 3:1) was added, and the mixture was stirred with argon gas and allowed to stand at a constant temperature of 950°C for 2 hours. A pure Fe electrode (by mass not less than 99.99%) was inserted into the molten GdF3-LiF-KF-NaF-CaO-Gd2O3 system and connected to the positive terminal of a power supply. A glassy carbon electrode was inserted... Molten salt was connected to the negative electrode of the power supply, with an inter-electrode potential difference of 1.8V, and oxidation was carried out for 2.5 hours. The system temperature was then raised to 1100℃, and the Fe electrode was switched to the negative electrode to form an electrodeposition cathode system, while high-purity glassy carbon was switched to the positive electrode to form an electrodeposition anode system. Electrolysis was performed for 2.5 hours under a pulsating DC signal (potential 4.3V, duty cycle 80%, frequency 15Hz). During the electrodeposition process, the Fe cathode was subjected to ultrasound (frequency 45Hz, sound intensity 2.2W / cm²) every 30 minutes. 2 After oscillation for 8 min, the product detached from the electrode surface was collected in a tungsten crucible; the Gd obtained in the tungsten crucible was then... m Fe n The secondary phase alloy was cast into ingots in an argon-protected casting system and cooled to room temperature. After removing the slag from the alloy surface, it was stored in a vacuum-sealed storage tank. (Gd) m Fe n The purity of intermetallic compounds can reach 99.98%.

[0018] Example 5: Dry GdF3, LiF, KF, and NaF were filled into a high-purity boron nitride crucible and heated to 950°C under argon protection until fully melted. Then, 5% (by mass) of a mixed CaO-Gd2O3 (molar ratio 3:1) was added, and the mixture was stirred with argon gas and allowed to stand at a constant temperature of 950°C for 2 hours. A pure Fe electrode (by mass not less than 99.99%) was inserted into the molten GdF3-LiF-KF-NaF-CaO-Gd2O3 system and connected to the positive terminal of a power supply. A glassy carbon electrode was inserted... Molten salt was connected to the negative electrode of the power supply, with an inter-electrode potential difference of 2.0V, and oxidation was carried out for 2.6 hours. The system temperature was then raised to 1120℃, and the Fe electrode was switched to the negative electrode to form an electrodeposition cathode system, while high-purity glassy carbon was switched to the positive electrode to form an electrodeposition anode system. Electrolysis was performed for 2.7 hours under a pulsating DC signal (potential 4.4V, duty cycle 83%, frequency 17Hz). During the electrodeposition process, the Fe cathode was subjected to ultrasound (frequency 48Hz, sound intensity 2.3W / cm²) every 30 minutes. 2 After oscillation for 9 minutes, the product detached from the electrode surface was collected in a tungsten crucible; the Gd obtained in the tungsten crucible was then... m Fe n The secondary phase alloy was cast into ingots in an argon-protected casting system and cooled to room temperature. After removing the slag from the alloy surface, it was stored in a vacuum-sealed storage tank. (Gd) m Fe n The purity of intermetallic compounds can reach 99.96%.

[0019] Example 6: Dry GdF3, LiF, KF, and NaF were filled into a high-purity boron nitride crucible and heated to 950℃ under argon protection until fully melted. Then, 5% (w / w) of a mixed CaO-Gd2O3 (molar ratio 3:1) was added, and the mixture was stirred with argon gas and allowed to stand at a constant temperature of 950℃ for 2 hours. A pure Fe electrode (w / w not less than 99.99% by mass) was inserted into the molten GdF3-LiF-KF-NaF-CaO-Gd2O3 system and connected to the positive terminal of a power supply. A glassy carbon electrode was inserted into the molten salt and connected to the negative terminal of the power supply. The potential difference between the electrodes was set to 2.2 V, and the oxidation time was 2.8 hours. The system temperature was raised to 1140℃, the Fe electrode was switched to the negative terminal to form an electrodeposition cathode system, and the high-purity glassy carbon electrode was switched to the positive terminal to form an electrodeposition anode system. Electrolysis was performed for 2.9 hours under a pulsating DC signal (potential 4.5V, duty cycle 86%, frequency 19Hz). During the electrodeposition process, the Fe cathode was subjected to ultrasonic waves (frequency 52 Hz, sound intensity 2.4 W / cm²) every 30 minutes. 2 After shaking for 10 min, the product detached from the electrode surface was collected in a tungsten crucible; the Gd obtained in the tungsten crucible was then... m Fe nThe secondary phase alloy was cast into ingots in an argon-protected casting system and cooled to room temperature. After removing the slag from the alloy surface, it was stored in a vacuum-sealed storage tank. (Gd) m Fe n The purity of intermetallic compounds can reach 99.97%.

[0020] Example 7: Dry GdF3, LiF, KF, and NaF were filled into a high-purity boron nitride crucible and heated to 950℃ under argon protection until fully melted. Then, 5% (w / w) of a mixed CaO-Gd2O3 (molar ratio 3:1) was added, and the mixture was stirred with argon gas and kept at a constant temperature of 950℃ for 2 hours. A pure Fe electrode (w / w not less than 99.99% by mass) was inserted into the molten GdF3-LiF-KF-NaF-CaO-Gd2O3 system and connected to the positive terminal of a power supply. A glassy carbon electrode was inserted into the molten salt and connected to the negative terminal of the power supply. The potential difference between the electrodes was set to 2.4V, and the oxidation time was 3.0 hours. The system temperature was raised to 1150℃, the Fe electrode was switched to the negative terminal to form an electrodeposition cathode system, and the high-purity glassy carbon electrode was switched to the positive terminal to form an electrodeposition anode system. Electrolysis was performed under a pulsating DC signal (potential 4.6V, duty cycle 90%, frequency 20Hz) for 3 hours. During the electrodeposition process, the Fe cathode was subjected to ultrasonic waves (frequency 55 Hz, sound intensity 2.5 W / cm²) every 30 minutes. 2 After oscillation for 11 min, the product detached from the electrode surface was collected in a tungsten crucible; the Gd obtained in the tungsten crucible was then... m Fe n The secondary phase alloy was cast into ingots in an argon-protected casting system and cooled to room temperature. After removing the slag from the alloy surface, it was stored in a vacuum-sealed storage tank. (Gd) m Fe n The purity of intermetallic compounds can reach 99.96%.

[0021] Comparative Example 1: Based on Example 1, the molar ratio of GdF3, LiF, KF, and NaF was adjusted to 2.1:6.1:1.1:1.1, while other processes and conditions remained unchanged. After implementation, GdF3 was obtained. m Fe n The purity of the intermetallic compound was only 98.38%; if the molar ratio of GdF3, LiF, KF, and NaF was adjusted to 1.9:5.9:0.9:0.9, while keeping other processes and conditions unchanged, Gd was obtained after implementation. m Fe n The purity of the intermetallic compound was only 97.56%, and the oxygen impurities were higher than 1500 ppm.

[0022] Comparative Example 2: Based on Example 2, keeping other implementation conditions unchanged, the mass percentage of the added mixed CaO-Gd2O3 (molar ratio 3:1) was adjusted to 4.7%, resulting in Gd m Fe n The purity of the intermetallic compound was only 98.56%; with other experimental conditions unchanged, adjusting the mass percentage of the added mixed CaO-Gd2O3 (molar ratio 3:1) to 5.3% yielded Gd m Fe n The purity of the intermetallic compound was only 98.71%, and the oxygen impurities were all above 1000 ppm.

[0023] Comparative Example 3: Based on Example 3, keeping other implementation conditions unchanged, the molar ratio of the added mixed CaO-Gd2O3 was adjusted to 3.1:1, resulting in Gd m Fe n The purity of the intermetallic compound was only 99.01%; with other experimental conditions unchanged, adjusting the molar ratio of the added mixed CaO-Gd₂O₃ to 2.9:1 yielded Gd m Fe n The purity of the intermetallic compound was only 99.08%, and the oxygen impurities were all above 500 ppm.

[0024] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for surface deposition of Gd-Fe based metal compounds, characterized in that, Includes the following steps: (1) Raw material pretreatment Anhydrous GdF3, LiF, KF, NaF, CaO, and Gd2O3 were dried under argon atmosphere. The dried GdF3, LiF, KF, and NaF were uniformly mixed in a molar ratio of 2:6:1:1 and filled into a high-purity boron nitride tank and heated until fully melted. Then, 4.8-5.2% by mass of mixed CaO and Gd2O3 were added to the melted GdF3-LiF-KF-NaF mixed molten salt. After stirring with argon atmosphere, the mixture was kept at a constant temperature and allowed to stand. The molar ratio of CaO to Gd2O3 was 3:

1. (2) Oxidation of iron electrode Insert the pure Fe electrode into the molten salt treated in step (1) and connect it to the positive terminal of the power supply. At the same time, insert the glassy carbon electrode into the molten salt and connect it to the negative terminal of the power supply. Set the potential difference between the electrodes to 1.2-2.4V and continue the oxidation for 2-3 hours. (3) Pulsating DC electrodeposition Under argon protection, the Fe electrode after step (2) is transferred to the negative terminal of the power supply to form an electrodeposition cathode system, and the glassy carbon electrode is transferred to the positive terminal of the power supply to form an electrodeposition anode system; a pulsating DC signal is applied for electrodeposition for 2-3 hours, and the temperature is controlled at 1050-1150℃, wherein the pulsating DC signal is controlled at a potential of 4.0-4.6V, a duty cycle of 70-90%, and a frequency of 10-20Hz; (4) Secondary phase product stripping During the electrodeposition step (3), at regular intervals, the Fe cathode is subjected to ultrasonic vibration, and the products detached from the electrode surface are collected in a tungsten crucible. The resulting Gd m Fe n The secondary phase alloy is cast into ingots in an argon-protected casting system and cooled to room temperature. After removing the slag from the alloy surface, it is stored in a vacuum-sealed storage tank.

2. The method according to claim 1, characterized in that, In step (1), the product is dried at 300-350℃ for 48-60 hours.

3. The method according to claim 1, characterized in that, In step (1), GdF3, LiF, KF and NaF are filled into a high-purity boron nitride tank and heated to 950°C to fully melt.

4. The method according to claim 1, characterized in that, In step (1), 5% by mass of a mixture of CaO and Gd2O3 is added to the molten GdF3-LiF-KF-NaF mixed molten salt.

5. The method according to claim 1, characterized in that, In step (3), the frequency of the ultrasound is 35-55 Hz, and the sound intensity is 1.9-2.5 W / cm². 2 Oscillation for 5-11 minutes.

6. The method according to claim 1, characterized in that, In step (4), the Fe cathode is subjected to ultrasonic oscillation every 30 minutes.

7. The method according to claim 1, characterized in that, The purity of anhydrous GdF3, LiF, KF, NaF, CaO, and Gd2O3 is not less than 99.99%, the purity of argon is not less than 99.99%, and the purity of pure Fe electrode is not less than 99.99%.