Primary phase change magnetocaloric alloy material as well as preparation method and application thereof

Abstract

The invention relates to a primary phase change magnetocaloric alloy material and a preparation method and application thereof. The chemical general formula of the primary phase change magnetocaloric alloy material is La1-xRExFe13-y-z-aCoySizCa, RE is selected from one of Ce, Pr and Nd, 0.01 < = x < = 0.2, 0.1 < = y < = 0.8, 1.2 < = z + a < = 1.6, and 0.05 < = a < = 0.15. The material is high in saturation magnetization and high in heating value, can adjust the Curie temperature around 0 DEG C, is applied to deicing and ice melting of power transmission lines, and has an excellent ice melting and coating effect.

Description

Technical Field

[0001] The present invention relates to the field of magnetocaloric ice melting technology, and in particular to a primary phase-change magnetocaloric alloy material, a preparation method thereof, and applications thereof. Background Art

[0002] Icing disasters pose a serious threat to the safe operation of power transmission lines. To address the problem of de-icing transmission lines, various de-icing methods have been developed, including hydrophobic anti-icing layers, heating wire wrapping, utilizing the high-resistance steel core of steel-cored aluminum stranded conductors to heat and melt, adding specialized insulation cores to heat and melt, overcurrent and short-circuit current methods, mechanical de-icing, thermal radiation, external heat sources, and magnetocaloric methods. The magnetocaloric method involves attaching a magnetic coating to the outer surface of the transmission conductor. This coating has a Curie temperature near zero degrees Celsius. When the ambient temperature is below the Curie temperature, the ferromagnetic material becomes strongly ferromagnetic, generating high magnetic induction intensity, large hysteresis losses, and eddy current losses, which in turn releases intense heat, effectively preventing and melting ice and protecting the line.

[0003] Magnetocaloric materials (MCMs) have attracted considerable attention due to their efficient and environmentally friendly energy conversion properties, showing promising applications in magnetic refrigeration systems, magnetic heat pumps, and thermomagnetic generators. Beyond energy conversion, these materials may also provide solutions to practical engineering challenges. For example, the magnetocaloric effect (MCE) could be a novel de-icing method for high-voltage transmission line icing. Its physical mechanism is that when an external magnetic field acts on MCMs, the magnetic moments within the material align along the magnetic field, resulting in an increase in magnetic order and a decrease in magnetic entropy. Under adiabatic conditions, this entropy reduction must be compensated by an increase in lattice or electronic entropy, which in turn causes a temperature rise in the material. Notably, according to Maxwell's equations and Ampere's law, time-varying currents in transmission lines spontaneously generate oscillating magnetic fields. This synergistic effect of intrinsic magnetic field generation and magnetocaloric response opens up possibilities for de-icing applications.

[0004] The core evaluation index of magnetocaloric effect is the isothermal magnetic entropy change (ΔS M ). High-performance MCMs with first-order phase transition characteristics, such as La(Fe,Si) 13 , (Mn,Fe)2(P,X)(X=As,Ge,Si) and NiMnX Heusler alloys (X=Ga,In,Sn,Sb), due to their large magnetic entropy change Among them, La(Fe,Si) 13 The base compound can achieve 27.8 J·kg under a magnetic field of μ0ΔH=5T. -1 ·K -1 of It is an ideal candidate for commercial de-icing material for transmission lines.

[0005] La(Fe,Si) 13The compound has a cubic NaZn 13 type structure (space group ): The La atoms occupy the 8a Wyckoff site, the Si atoms are located at the 96i site, and the Fe atoms are distributed at the 8b and 96i sites. Its giant magnetocaloric effect stems from the synergistic effect of magnetoelastic coupling and itinerant electron metamagnetism (IEM) transition. At the electronic level, the density of states of Fe-3d electrons dominates these magnetic transitions. Research shows that by changing the Si content or doping, the number of valence electrons can be regulated, thereby changing the density of states, the phase transition order, and the IEM transition behavior, and ultimately achieving precise regulation of the MCE. Currently, systematic research has been carried out on the substitution of rare earth (RE) at the La site (RE = Ce, Er, Nd, Pr, Gd): For example, in La 1-y Ce y (Fe 0.86 Si 0.14 ) 13 , the substitution of Ce induces a second-order to first-order phase transition and simultaneously reduces the Curie temperature T C by about 30 K; the doping of Er leads to a second-order phase transition and weakens the MCE; the introduction of Nd in La 1-y Nd y (Fe 0.88 Si 0.12 ) 13 (0 < y < 0.3) causes a linear lattice contraction, making drop from 13 to 10 J·kg -1 ·K -1 (0 - 5 T); while in La 0.5 Pr 0.5 (Fe 0.88 Si 0.12 ) 13 , although the substitution of Pr increases by 37%, the T C drops by 10 K. These findings confirm that rare earth substitution can achieve precise regulation of the MCE through the synergistic changes in electronic structure, crystal parameters, and thermodynamic properties. However, existing materials cannot meet the requirements of magnetic thermal ice melting, where the Curie temperature of the alloy is adjusted to near 0 degrees and has a large heat release. Summary of the Invention

[0006] To solve the above technical problems, the present invention provides a first-order phase change magnetocaloric alloy material, its preparation method, and application. The first-order phase change magnetocaloric alloy material provided by the present invention is prepared by multiple component composite addition, has a high saturation magnetization intensity and a high calorific value, can achieve the Curie temperature of the alloy near 0 °C, and has good magnetic thermal ice melting characteristics.

[0007] In the first aspect, the present invention provides a first-order phase change magnetocaloric alloy material, and the chemical general formula of the first-order phase change magnetocaloric alloy material is La 1-xRE x Fe 13-y-z-a Co y Si z C a , wherein RE is selected from one of Ce, Pr, and Nd, and 0.01≤x≤0.2, 0≤y≤0.8, 1.2≤z+a≤1.6, and 0.05≤a≤0.15.

[0008] In a second aspect, the present invention provides a method for preparing the primary phase-change magnetocaloric alloy material according to the first aspect, the method comprising the following steps:

[0009] (1) La source, RE source, Fe source, Co source, Si source, and C source are mixed in proportion, smelted uniformly in a protective atmosphere, and cast into an ingot to obtain a master alloy;

[0010] (2) The master alloy is placed in a vacuum rapid quenching strip spinning device to be melted uniformly, and the strip is spun for rapid quenching to obtain a rapid quenching thin strip, that is, a first-level phase change magnetocaloric alloy material is obtained.

[0011] In some embodiments of the present invention, the smelting method is to place the raw materials in a vacuum induction melting furnace, evacuate the vacuum, introduce a protective atmosphere, supply electricity for melting, and then use electromagnetic force for stirring and refining. The smelting temperature is 1300-1450°C, for example, 1300°C, 1350°C, 1400°C, 1450°C, etc., and the smelting time is 10-15 minutes, for example, 10 minutes, 11 minutes, 12 minutes, 13 minutes, 14 minutes, 15 minutes, etc.

[0012] In some embodiments of the present invention, the vacuum degree of the vacuum induction melting furnace after evacuation is 5×10 -1 ~5×10 -2 Pa, for example 6×10 -2 Pa, 8×10 -2 Pa, 1×10 -1 Pa, 3×10 -1 Pa et al.

[0013] In some embodiments of the present invention, the protective atmosphere in the vacuum induction melting furnace is selected from one or more of argon, helium, nitrogen, and neon.

[0014] In some embodiments of the present invention, after the protective atmosphere is introduced, the pressure in the vacuum induction melting furnace is 40-80 kPa, for example, 40 kPa, 50 kPa, 60 kPa, 70 kPa, 80 kPa, etc.

[0015] In some embodiments of the present invention, the step (2) includes: placing the master alloy in the induction coil in the cavity of the single-roller rapid quenching strip-spinning machine, and the vacuum degree of the cavity and the gas storage bottle is ≤3×10-3 Pa, fill with protective atmosphere, so that the air pressure of the cavity and the gas cylinder are 100-200 mbar (for example, 100 mbar, 140 mbar, 180 mbar, 200 mbar, etc.) and 400-600 mbar (for example, 400 mbar, 450 mbar, 500 mbar, 550 mbar, 600 mbar, etc.), respectively, supply power to melt the master alloy and then open the air pressure valve to allow the uniformly melted master alloy to sputter onto the surface of the rotating copper roller to obtain a rapidly quenched thin strip, and the linear speed of the copper roller surface is 25-40 m / s, for example, 25 m / s, 30 m / s, 35 m / s, 40 m / s, etc.

[0016] In some embodiments of the present invention, the preparation method further comprises placing the rapidly quenched thin strip obtained in step (2) in a protective atmosphere for heat treatment, and then performing hydrogen absorption treatment, thereby obtaining a primary phase change magnetocaloric alloy material.

[0017] In some embodiments of the present invention, the heat treatment method is to place the rapidly quenched thin strip in a vacuum furnace, introduce a protective atmosphere after vacuuming, and keep it at 900-1100°C (for example, 900°C, 950°C, 1000°C, 1050°C, 1100°C, etc.) for 5-15 hours, for example, 5 hours, 8 hours, 10 hours, 12 hours, 15 hours, etc.

[0018] In some embodiments of the present invention, the method of hydrogen absorption treatment is to place the quick-quenched thin strip after heat treatment in a hydrogen absorption furnace with a hydrogen pressure of 0.1 to 2 MPa (for example, 0.5 MPa, 1 MPa, 1.5 MPa, 2 MPa, etc.), and keep it at 200 to 400°C (for example, 200°C, 250°C, 300°C, 350°C, 400°C, etc.) for 2 to 12 hours (for example, 2 hours, 4 hours, 6 hours, 8 hours, 10 hours, 12 hours, etc.).

[0019] In some embodiments of the present invention, the vacuum degree of the high vacuum furnace after evacuation is 5×10 -4 ~8×10 - 3 Pa, for example 6×10 -4 Pa, 8×10 -4 Pa, 1×10 -3 Pa, 3×10 -3 Pa, 5×10 -3 Pa et al.

[0020] In some embodiments of the present invention, the protective atmosphere in the high vacuum furnace is selected from one or more of argon, helium, nitrogen, and neon.

[0021] Unless otherwise specified, the purity of the alloy elements selected from the raw materials for preparation in the present invention is higher than 99.9%, and the protective atmosphere introduced is high-purity gas (purity>99.99%).

[0022] In some embodiments of the present invention, after the protective atmosphere is introduced, the pressure in the high vacuum furnace is 0.8 to 1.1 atm, for example, 0.8 atm, 0.9 atm, 1 atm, 1.1 atm, etc.

[0023] In some embodiments of the present invention, before preparing the primary phase change magnetocaloric alloy material, the structural formula of the alloy is designed by a first-principles design calculation method. The calculation method is based on the VASP software package, and uses density functional theory (DFT) to calculate the electronic structure, band structure, density distribution, and magnetism of the material. The Projector Augmented Wave (PAW) method is adopted, and the generalized gradient approximation (GGA) of the Perdew-Burke-Ernzerh (PBE) function is used to approximate the exchange correlation potential, comprising the following steps:

[0024] Select La(Fe,Si) with lattice constant a=1.1440nm 13 The unit cell is used as the initial structure. The unit cell contains 112 atoms, of which La, Ce, Pr, and Nd atoms occupy the 8a crystal site, Fe and Co atoms occupy the 8b and 96i crystal sites, Co atoms occupy the 96i crystal site, Si atoms occupy the 96i crystal site of Fe, and C atoms are inserted as interstitial atoms in the 24d interstitial crystal site. The convergence criterion for electronic self-consistency is 10 -7 eV, the convergence criterion for ion relaxation is The cutoff energy is 600eV and the K-point grid is 5×5×5. The "Hubbard U" method is used to treat the 4f orbitals of rare earth atoms. After structural optimization, static calculations are performed to obtain the electronic structure, band structure, density distribution characteristics, and magnetic properties. The La 1-x RE x Fe 13-y-z-a Co y Si z C a The composition and structural formula of the alloy. Through the above calculations, La 1-x RE x Fe 13-y-z-a Co y Si z C a The Curie temperature of the alloy is near 0°C and it has good magnetocaloric ice-melting properties.

[0025] In the present invention, the interstitial atom C hybridizes with the electron orbitals of Fe-3s and Fe-3p through the C-2s and C-2p orbitals, making NaZn 13 Type La 1-x RE x Fe 13-y-z-a Co y Si z C a The stability of the alloy is improved, which facilitates the formation of this phase and can also adjust the Curie temperature. The total atomic content of Si and C is 1.2-1.6, which can adjust the alloy into a primary phase transition material, ensuring the alloy has a high magnetic entropy change value and heat release. The Co content is 0.1≤y≤1, which is used to increase the Curie temperature and magnetization of the alloy. RE is used to further adjust the Curie temperature and simultaneously adjust the "spike" of the spin-down state near the Fermi level at the Fermi level, improving the stability of the ferromagnetic state, thereby increasing the phase transition rate and magnetic entropy change value.

[0026] In a third aspect, the present invention provides an application of the primary phase-change magnetocaloric alloy material described in the first aspect or the primary phase-change magnetocaloric alloy material prepared by the preparation method described in the second aspect, wherein the primary phase-change magnetocaloric alloy material is used for deicing and melting transmission lines.

[0027] In a fourth aspect, the present invention provides a method for magnetic thermal ice melting, which comprises crushing the primary phase-change magnetocaloric alloy material described in the first aspect or the primary phase-change magnetocaloric alloy material prepared by the preparation method described in the second aspect into powder with a size of ≤1 mm and encapsulating the powder in a thin-walled copper tube, replacing a transmission conductor in a transmission line with the thin-walled copper tube, or spirally winding the thin-walled copper tube around the conductor of the transmission line to perform de-icing and ice melting.

[0028] The technical solution provided by the embodiment of the present invention has the following advantages compared with the existing technology:

[0029] (1) The present invention obtains La by first-principles theoretical calculation design 1-x RE x Fe 13-y-z-a Co y Si z C a The alloy composition theoretically ensures that the Curie temperature of the high entropy alloy is around 0°C.

[0030] (2) The crystal phase of the first-order phase change magnetocaloric alloy material obtained by the preparation method provided by the present invention is a single first-order phase change face-centered cubic NaZn 13 Type La(Fe,Si) 13 Phase, the phase transition rate of this phase is large, the Curie temperature can be adjusted to near 0℃, the saturation magnetization intensity is high, and the calorific value is high.

[0031] (3) The present invention is the first to use a primary phase change magnetocaloric material for de-icing and anti-icing of power transmission lines. It is also the first to propose using a quick-quenched thin strip or a quick-quenched thin strip powder after hydrogen absorption to be encapsulated in a thin-walled copper tube, replacing a transmission wire in the power transmission circuit with the thin-walled copper tube, or spirally winding the thin-walled copper tube around the wire of the power transmission circuit to de-icing and anti-icing, and achieving an excellent de-icing effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0034] Figure 1 is La in Example 5 of the present invention 0.99 Nd 0.01 Fe 11.3 Co 0.1 Si 1.45 C 0.15 Temperature evolution of the finished powder during controlled de-icing tests in a large artificial climate simulation system. DETAILED DESCRIPTION

[0035] In order to more clearly understand the above-mentioned objectives, features and advantages of the present invention, the scheme of the present invention will be further described below. It should be noted that, in the absence of conflict, the embodiments of the present invention and the features therein can be combined with each other.

[0036] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein; it is obvious that the embodiments in the specification are only part of the embodiments of the present invention, rather than all the embodiments.

[0037] Example 1

[0038] This embodiment provides La 0.8 Ce 0.2 Fe 10.6 Co 0.8 Si 1.45 C 0.15 The composition design and preparation method of the magnetic thermal ice melting alloy include the following steps:

[0039] (1) Theoretical calculation

[0040] La(Fe,Si) 13 The lattice constant of the initial unit cell structure is chosen to be a = 1.1440 nm. The unit cell contains 112 atoms, with La and Ce atoms occupying the 8a site, Fe and Co atoms occupying the 8b and 96i sites; Co atoms occupy the 96i site, Si atoms occupy the 96i site of Fe, and C atoms are inserted as interstitial atoms in the 24d interstitial site. The convergence criterion for electronic self-consistency is 10 -7 The convergence criteria for eV and ion relaxation are The cutoff energy is 600 eV and the K-point grid is 5 × 5 × 5. The “Hubbard U” method is used to treat the 4f orbitals of rare earth atoms.

[0041] Select four alloy components La 0.8 Ce 0.2 Fe 11.3 Co 0.1 Si 1.45 C 0.15 、La 0.8 Ce 0.2 Fe 11 Co 0.4 Si 1.45 C 0.15 、La 0.8 Ce 0.2 Fe 10.6 Co 0.8 Si 1.45 C 0.15 、La 0.8 Ce 0.2 Fe 10.4 Co1Si 1.45 C 0.15 Structural optimization and static calculations were performed to obtain the structural parameters, formation energy, magnetic properties, and electronic structure of the alloy, thereby obtaining the optimal Co content. The calculation results show that La 0.8 Ce 0.2 Fe 10.6 Co 0.8 Si 1.45 C 0.15 The alloy has good comprehensive properties.

[0042] (2)La 0.8 Ce 0.2 Fe 10.6 Co 0.8 Si 1.45 C 0.15 The preparation of the alloy includes the following steps:

[0043] The raw materials of La, Ce, Fe, Co, Si and C with purity higher than 99.9% are divided into two groups according to the composition ratio of La 0.8 Ce 0.2 Fe10.6 Co 0. 8Si 1.45 C 0.15 Placed in a crucible in a vacuum induction melting furnace, 15 wt% of rare earth element Ce was added. Then vacuum was drawn to a vacuum degree of 5×10 -2 After the raw materials are completely melted, high-purity argon gas is introduced to bring the pressure in the furnace to 80 kPa. After power is supplied to completely melt the raw materials, the liquid is automatically stirred by electromagnetic force for refining. The temperature of the alloy liquid is 1300°C and kept warm for 15 minutes. The uniformly molten alloy liquid is cast into a water-cooled copper mold to obtain a molten alloy ingot. The smelted mother alloy is placed in a quartz tube with a small hole at the bottom, which is then placed in the induction coil in the single-roller rapid quenching strip spinning machine cavity. The cavity and gas storage cylinder are evacuated to 3×10 -3 Pa, high-purity argon is filled to a pressure of 100 mbar in the chamber and 500 mbar in the gas cylinder. A high-frequency voltage is then applied to the induction coil to uniformly melt the master alloy. The pressure valve between the gas cylinder and the quartz tube is opened, allowing the uniformly melted master alloy to sputter onto the surface of a high-speed rotating copper roller under the action of the pressure difference, thereby obtaining a rapidly quenched thin strip. The linear speed of the copper roller surface is 40 m / s. The rapidly quenched thin strip is evacuated to 8 × 10 -3 Pa, and then filled with high-purity argon (>99.99%) for heat treatment. The gas pressure in the furnace is maintained at 1.1atm during heat treatment. The heat treatment temperature is 1100℃, and the temperature is kept for 5h. After the heat treatment, it is quickly cooled to room temperature. The heat-treated sample is placed in a hydrogen absorption furnace for hydrogen absorption. The hydrogen absorption temperature is 200℃, the hydrogen absorption time is 12h, the hydrogen pressure is 0.1MPa, and the hydrogen purity is ≥99.999%. The rapidly quenched thin strip after hydrogen absorption is crushed into powder with a diameter of less than 1mm, and the powder is sealed in a thin-walled Cu tube. The thin-walled copper tube is spirally wound on the wire of the transmission circuit for magnetic thermal ice melting.

[0044] Example 2

[0045] This embodiment provides La 0.8 Ce 0.2 Fe 10.6 Co 0.8 Si 1.45 C 0.15 The composition design and preparation method of the magnetocaloric alloy include the following steps:

[0046] (1) The theoretical calculation is the same as that in Example 1.

[0047] (2)La 0.8 Ce 0.2 Fe 10.6 Co 0.8 Si 1.45 C 0.15 The preparation of the alloy includes the following steps:

[0048] The raw materials of La, Ce, Fe, Co, Si and C with purity higher than 99.9% are divided into two groups according to the composition ratio of La 0.8 Ce 0.2 Fe 10.6 Co 0. 8Si 1.45 C 0.15 Placed in a crucible in a vacuum induction melting furnace, 15 wt% of rare earth element Ce was added. Then vacuum was drawn to a vacuum degree of 5×10 -1 After the furnace is heated to 40 kPa, high-purity argon gas is introduced to bring the pressure inside the furnace to 40 kPa. After the raw materials are completely melted by electricity, the liquid is automatically stirred by electromagnetic force for refining. The temperature of the alloy liquid is 1450°C and kept warm for 10 minutes. The uniformly molten alloy liquid is cast into a water-cooled copper mold to obtain a molten alloy ingot. The smelted mother alloy is placed in a quartz tube with a small hole at the bottom, which is then placed in the induction coil in the cavity of the single-roller rapid quenching strip spinning machine. The cavity and the gas storage bottle are vacuumed to 3×10 -3 Pa, high-purity argon is filled to a pressure of 100 mbar in the chamber and 500 mbar in the gas cylinder. A high-frequency voltage is then applied to the induction coil to uniformly melt the master alloy. The pressure valve between the gas cylinder and the quartz tube is opened, allowing the uniformly melted master alloy to sputter onto the surface of a high-speed rotating copper roller under the action of the pressure difference, thereby obtaining a rapidly quenched thin strip. The linear speed of the copper roller surface is 25 m / s. The rapidly quenched thin strip is evacuated to 5×10 -4 Pa, and then filled with high-purity argon (>99.99%) for heat treatment. During the heat treatment, the gas pressure in the furnace is maintained at 0.8atm. The heat treatment temperature is 900℃, and the temperature is kept for 15h. After the heat treatment, it is quickly cooled to room temperature. The heat-treated sample is placed in a hydrogen absorption furnace for hydrogen absorption. The hydrogen absorption temperature is 400℃, the hydrogen absorption time is 2h, the hydrogen pressure is 2MPa, and the hydrogen purity is ≥99.999%. The rapidly quenched thin strip after hydrogen absorption is crushed into powder with a diameter of less than 1mm, and the powder is sealed in a thin-walled Cu tube. The thin-walled copper tube is spirally wound on the wire of the transmission circuit for magnetic thermal ice melting.

[0049] Example 3

[0050] This embodiment provides La 0.8 Pr 0.2 Fe 11.7 Co 0.1 Si 1.15 C 0.05 The composition design and preparation method of the magnetocaloric alloy include the following steps:

[0051] (1) Theoretical calculation

[0052] La(Fe,Si) 13The lattice constant of the initial unit cell structure is chosen to be a = 1.1440 nm. The unit cell contains 112 atoms, with La and Pr atoms occupying the 8a site, Fe and Co atoms occupying the 8b and 96i sites, Co atoms occupying the 96i site, Si atoms occupying the 96i site of Fe, and C atoms inserted as interstitial atoms in the 24d interstitial site. The convergence criterion for electronic self-consistency is 10 -7 The convergence criteria for eV and ion relaxation are The cutoff energy is 600 eV and the K-point grid is 5 × 5 × 5. The “Hubbard U” method is used to treat the 4f orbitals of rare earth atoms. 0.95 Pr 0.05 Fe 11.7 Co 0.1 Si 1.15 C 0.05 、La 0.9 Pr 0.1 Fe 11.7 Co 0.1 Si 1.15 C 0.05 、La 0.85 Pr 0.15 Fe 11.7 Co 0.1 Si 1.15 C 0.05 、La 0.8 Pr 0.2 Fe 11.7 Co 0.1 Si 1.15 C 0.05 Structural optimization and static calculations were performed to obtain the structural parameters, formation energy, magnetic properties, and electronic structure of the alloy, thereby obtaining the optimal Pr content. 0.9 Pr 0.1 Fe 11.7 Co 0.1 Si 1.15 C 0.05 The alloy has good comprehensive properties.

[0053] (2)La 0.9 Pr 0.1 Fe 11.7 Co 0.1 Si 1.15 C 0.05 The preparation of the alloy includes the following steps:

[0054] The raw materials such as La, Pr, Fe, Co, Si, C, etc. with purity higher than 99.9% are divided into the following proportions: La 0.9 Pr 0.1 Fe 11.7 Co 0.1 Si1.15 C 0.05 The crucible was placed in a vacuum induction melting furnace and 8 wt% of rare earth element Pr was added. Then the vacuum was evacuated to a vacuum degree of 3×10 -2 After the raw materials are completely melted, high-purity argon gas is introduced to bring the pressure in the furnace to 70 kPa. After power is supplied to completely melt the raw materials, the liquid is automatically stirred by electromagnetic force for refining. The temperature of the alloy liquid is 1400°C and kept warm for 15 minutes. The uniformly molten alloy liquid is cast into a water-cooled copper mold to obtain a molten alloy ingot. The smelted mother alloy is placed in a quartz tube with a small hole at the bottom, which is then placed in the induction coil in the single-roller rapid quenching strip spinning machine cavity. The cavity and gas storage bottle are vacuumed to 3×10 - 3 Pa, high-purity argon is filled to a pressure of 200 mbar in the chamber and 400 mbar in the gas cylinder. A high-frequency voltage is then applied to the induction coil to uniformly melt the master alloy. The pressure valve between the gas cylinder and the quartz tube is opened, allowing the uniformly melted master alloy to sputter onto the surface of a high-speed rotating copper roller under the action of the pressure difference, thereby obtaining a rapidly quenched thin strip. The linear speed of the copper roller surface is 40 m / s. The rapidly quenched thin strip is evacuated to 5×10 -3 Pa, then filled with high-purity argon (>99.99%) for heat treatment. During heat treatment, the furnace pressure is maintained at 1.0 atm. The heat treatment temperature is 1100°C for 8 hours. After heat treatment, the rapidly quenched ribbon is crushed into a powder with a diameter of less than 1 mm. The powder is sealed in a thin-walled copper tube, which is spirally wrapped around the conductors of the power transmission circuit for magnetic thermal ice melting.

[0055] Example 4

[0056] This embodiment provides La 0.99 Nd 0.01 Fe 11.3 Co 0.1 Si 1.45 C 0.15 The composition design and preparation method of the magnetocaloric alloy include the following steps:

[0057] (1) Theoretical calculation

[0058] La(Fe,Si) 13 The lattice constant of the initial unit cell structure is chosen to be a = 1.1440 nm. The unit cell contains 112 atoms, with La and Nd atoms occupying the 8a site, Fe and Co atoms occupying the 8b and 96i sites, Co atoms occupying the 96i site, Si atoms occupying the 96i site of Fe, and C atoms inserted as interstitial atoms in the 24d interstitial site. The convergence criterion for electronic self-consistency is 10 -7 The convergence criteria for eV and ion relaxation are The cutoff energy is 600 eV and the K-point grid is 5 × 5 × 5. The “Hubbard U” method is used to treat the 4f orbitals of rare earth atoms. 0.99 Nd 0.01 Fe 11.4 Co 0.1 Si 1.45 C 0.05 、La 0.99 Nd 0.01 Fe 11.35 Co 0.1 Si 1.45 C 0.1 、La 0.99 Nd 0.01 Fe 11.3 Co 0.1 Si 1.45 C 0.15 、La 0.99 Nd 0.01 Fe 11.25 Co 0.1 Si 1.45 C 0.2 Structural optimization and static calculations were performed to obtain the structural parameters, formation energy, magnetic properties, and electronic structure of the alloy, thereby obtaining the optimal Pr content. 0.99 Nd 0.01 Fe 11.3 Co 0.1 Si 1.45 C 0.15 The alloy has good comprehensive properties.

[0059] (2)La 0.99 Nd 0.01 Fe 11.3 Co 0.1 Si 1.45 C 0.15 Alloy preparation process

[0060] The raw materials such as La, Nd, Fe, Co, Si, C, etc. with purity higher than 99.9% are divided into the following proportions: La 0.99 Nd 0.01 Fe 11.3 Co 0.1 Si 1.45 C 0.15 Placed in a crucible in a vacuum induction melting furnace, additional 10wt.% of rare earth element Nd was added. Then vacuum was drawn to a vacuum degree of 3×10 -2After the raw materials are completely melted, high-purity argon gas is introduced to bring the pressure in the furnace to 70 kPa. After power is supplied to completely melt the raw materials, the liquid is automatically stirred by electromagnetic force for refining. The temperature of the alloy liquid is 1400°C and kept warm for 15 minutes. The uniformly molten alloy liquid is cast into a water-cooled copper mold to obtain a molten alloy ingot. The smelted mother alloy is placed in a quartz tube with a small hole at the bottom, which is then placed in the induction coil in the single-roller rapid quenching strip spinning machine cavity. The cavity and gas storage bottle are vacuumed to 3×10 - 3 Pa, high-purity argon is filled to a pressure of 100 mbar in the chamber and 500 mbar in the gas cylinder. A high-frequency voltage is then applied to the induction coil to uniformly melt the master alloy. The pressure valve between the gas cylinder and the quartz tube is opened, allowing the uniformly melted master alloy to sputter onto the surface of a high-speed rotating copper roller under the action of the pressure difference, thereby obtaining a rapidly quenched thin strip. The linear speed of the copper roller surface is 40 m / s. The rapidly quenched thin strip is evacuated to 5×10 -3 Pa, then filled with high-purity argon (>99.99%) for heat treatment. During heat treatment, the furnace pressure is maintained at 1.0 atm. The heat treatment temperature is 1100°C for 8 hours. After heat treatment, the rapidly quenched ribbon is crushed into a powder with a diameter of less than 1 mm. The powder is sealed in a thin-walled copper tube, which is spirally wrapped around the conductors of the power transmission circuit for magnetic thermal ice melting.

[0061] Example 5

[0062] This embodiment provides La 0.99 Nd 0.01 Fe 11.3 Co 0.1 Si 1.45 C 0.15 The composition design and preparation method of the magnetic thermal ice melting alloy include the following steps:

[0063] (1) Theoretical calculation

[0064] La(Fe,Si) 13 The lattice constant of the initial unit cell structure is a = 1.1440 nm. The unit cell contains 112 atoms, with La and Ce atoms occupying the 8a site, Fe atoms occupying the 8b and 96i sites, Co atoms occupying the 96i site, and Si atoms occupying the 96i site of Fe. The convergence criterion for electronic self-consistency is 10 -7 The convergence criteria for eV and ion relaxation are The cutoff energy is 600 eV and the K-point grid is 5 × 5 × 5. The “Hubbard U” method is used to treat the 4f orbitals of rare earth atoms.

[0065] Select four alloy components La 0.99 Nd 0.01 Fe11.3 Co 0.1 Si 1.55 C 0.05 、La 0.99 Nd 0.01 Fe 11.3 Co 0.1 Si 1.5 C 0.1 、La 0.99 Nd 0.01 Fe 11.3 Co 0.1 Si 1.45 C 0.15 、La 0.99 Nd 0.01 Fe 11.3 Co 0.1 Si 1.4 C 0.2 Structural optimization and static calculations were performed to obtain the structural parameters, formation energy, magnetic properties, and electronic structure of the alloy, thereby obtaining the optimal Co content. The calculation results show that La 0.99 Nd 0.01 Fe 11.3 Co 0.1 Si 1.45 C 0.15 The alloy has good comprehensive properties.

[0066] (2)La 0.99 Nd 0.01 Fe 11.3 Co 0.1 Si 1.45 C 0.15 The preparation of the alloy includes the following steps:

[0067] The raw materials of La, Ce, Fe and Si with purity higher than 99.9% are divided into two groups according to the composition ratio of La 0.99 Nd 0.01 Fe 11.3 Co 0.1 Si 1.45 C 0.15 Placed in a crucible in a vacuum induction melting furnace, 15 wt% of rare earth element Ce was added. Then vacuum was drawn to a vacuum degree of 5×10 -2 After the raw materials are completely melted, high-purity argon gas is introduced to bring the pressure in the furnace to 80 kPa. After power is supplied to completely melt the raw materials, the liquid is automatically stirred by electromagnetic force for refining. The temperature of the alloy liquid is 1300°C and kept warm for 15 minutes. The uniformly molten alloy liquid is cast into a water-cooled copper mold to obtain a molten alloy ingot. The smelted mother alloy is placed in a quartz tube with a small hole at the bottom, which is then placed in the induction coil in the single-roller rapid quenching strip spinning machine cavity. The cavity and gas storage cylinder are evacuated to 3×10 -3Pa, high-purity argon is filled to a pressure of 200 mbar in the chamber and 600 mbar in the gas cylinder. A high-frequency voltage is then applied to the induction coil to uniformly melt the master alloy. The pressure valve between the gas cylinder and the quartz tube is opened, allowing the uniformly melted master alloy to sputter onto the surface of a high-speed rotating copper roller under the action of the pressure difference, thereby obtaining a rapidly quenched thin strip. The linear speed of the copper roller surface is 40 m / s. The rapidly quenched thin strip is evacuated to 8 × 10 -3 Pa, and then filled with high-purity argon (>99.99%) for heat treatment. The gas pressure in the furnace is maintained at 1.1atm during heat treatment. The heat treatment temperature is 1100℃, and the temperature is kept for 5h. After the heat treatment, it is quickly cooled to room temperature. The heat-treated sample is placed in a hydrogen absorption furnace for hydrogen absorption. The hydrogen absorption temperature is 200℃, the hydrogen absorption time is 12h, the hydrogen pressure is 0.1MPa, and the hydrogen purity is ≥99.999%. The rapidly quenched thin strip after hydrogen absorption is crushed into powder with a diameter of less than 1mm, and the powder is sealed in a thin-walled Cu tube. The thin-walled copper tube is spirally wound on the wire of the transmission circuit for magnetic thermal ice melting.

[0068] Comparative Example 1

[0069] This comparative example provides La(Fe,Si) 13 The preparation method of the magnetocaloric alloy is different from that of Example 1 only in the alloy composition.

[0070] Performance Testing

[0071] Performance tests were performed on the embodiments of the present invention and comparative examples, and the main phase structure was measured by X-ray diffraction; the Curie temperature was measured by a comprehensive physical property measurement system (PPMS); the saturation magnetization was tested by a vibrating sample magnetometer (VSM); and the heat release was measured by differential scanning calorimetry (DSC).

[0072] The test results of Example 1 show that La 0.8 Ce 0.2 Fe 10.6 Co 0.8 Si 1.45 C 0.15 The finished powder is a single first-order phase transition face-centered cubic NaZn 13 Type La(Fe,Si) 13 Phase, Curie temperature is 278K, and the saturation magnetization intensity is 110Am when the test magnetic field is 5T 2 / kg, the heat release near the Curie temperature measured by DSC can reach 3.1W / g. The finished powder is used to melt ice on transmission lines. 0.8 Ce 0.2 Fe 10.6 Co 0.8 Si 1.45 C 0.15The Curie temperature of the first-order phase change magnetocaloric alloy material is close to zero and releases a large amount of heat.

[0073] The test results of Example 2 show that La 0.8 Ce 0.2 Fe 10.6 Co 0.8 Si 1.45 C 0.15 The finished powder is a single rhombohedral Th2Zn 17 The 2:17R phase structure of the type has a Curie temperature of 275K. The saturation magnetization intensity is 110.5emu / g when the test magnetic field is 5T. The heat release near the Curie temperature measured by DSC can reach 3.5W / g. The finished powder is used to melt ice on transmission lines. 0.8 Ce 0.2 Fe 10.6 Co 0.8 Si 1.45 C 0.15 The Curie temperature of the first-order phase change magnetocaloric alloy material is close to zero and releases a large amount of heat.

[0074] The test results of Example 3 show that La 0.8 Pr 0.2 Fe 11.7 Co 0.1 Si 1.15 C 0.05 The finished powder is a single first-order phase transition face-centered cubic NaZn 13 Type La(Fe,Si) 13 Phase, Curie temperature is 278K, and the saturation magnetization intensity is 120Am when the test magnetic field is 5T 2 / kg, the heat release near the Curie temperature measured by DSC can reach 3.5W / g. The finished powder is used to melt ice on transmission lines. 0.8 Pr 0.2 Fe 11.7 Co 0.1 Si 1.15 C 0.05 The Curie temperature of the first-order phase change magnetocaloric alloy material is close to zero and releases a large amount of heat.

[0075] The test results of Example 4 show that La 0.99 Nd 0.01 Fe 11.3 Co 0.1 Si 1.45 C 0.15 The finished powder is a single first-order phase transition face-centered cubic NaZn 13 Type La(Fe,Si) 13 Phase, Curie temperature is 274K, and the saturation magnetization intensity is 130Am when the test magnetic field is 5T2 / kg, the heat release near the Curie temperature measured by DSC can reach 4.2W / g. The finished powder is used to melt ice on transmission lines. 0.99 Nd 0.01 Fe 11.3 Co 0.1 Si 1.45 C 0.15 The Curie temperature of the first-order phase change magnetocaloric alloy material is close to zero and releases a large amount of heat.

[0076] The test results of Example 5 show that La 0.99 Nd 0.01 Fe 11.3 Co 0.1 Si 1.45 C 0.15 The finished powder is a single first-order phase transition face-centered cubic NaZn 13 Type La(Fe,Si) 13 Phase, Curie temperature is 274K, and the saturation magnetization intensity is 150Am when the test magnetic field is 5T 2 / kg, the heat release near the Curie temperature measured by DSC can reach 4.2W / g. The finished powder is used to melt ice on transmission lines after absorbing hydrogen. The Curie temperature is close to zero degrees and the heat release is large. Figure 1 shown.

[0077] Figure 1 is La in Example 5 0.99 Nd 0.01 Fe 11.3 Co 0.1 Si 1.45 C 0.15 Temperature evolution curve of the finished powder during controlled deicing test in a large artificial climate simulation system. The experimental process consists of four different stages: power-on start-up, rain and snow combination (-10°C), pure freezing (-10°C) and system shutdown. test ) and reference tube (T ref ) showed a Joule rapid heating phenomenon. In the 90-minute rain and snow combined stage, T ref Ice accumulation is achieved stably in the range of -1 to 1°C, while T test Maintaining 5±2℃ effectively inhibits freezing; then a 20-minute pure freezing phase, T ref Dropped to around -2℃, T test The temperature rose to 5-10°C and remained stable, demonstrating sustained heat output. Comparative analysis showed that while the reference conductors formed significant ice, the test conductors only showed slight ice coverage and typical melting characteristics, confirming the material's effective de-icing performance for transmission lines under freezing conditions. This systematic verification confirmed the material's operational reliability for de-icing overhead lines in extreme weather conditions.

[0078] The test results of Comparative Example 1 show that La(Fe,Si) 13 The finished powder is a single first-order phase transition face-centered cubic NaZn 13 Type La(Fe,Si) 13 Phase, the Curie temperature is 185K, which cannot meet the use requirements of the material near 0 degrees temperature.

[0079] In summary, the first-order phase-change magnetocaloric alloy material prepared by the preparation method provided by the present invention has high saturation magnetization intensity and high calorific value, can achieve a Curie temperature of the alloy near 0°C, and has significant effect in melting and de-icing transmission lines.

[0080] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or device comprising the element.

[0081] The foregoing description is intended only to provide specific embodiments of the present invention, which will enable those skilled in the art to understand and implement the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not intended to be limited to the embodiments described herein, but is to be construed in the widest manner consistent with the principles and novel features disclosed herein.

Claims

1. A primary phase change magnetocaloric alloy material, characterized in that: The chemical formula of the primary phase change magnetocaloric alloy material is La 1-x RE x Fe 13-y-z-a Co y Si z C a , wherein RE is selected from one of Ce, Pr, and Nd, and 0.01≤x≤0.2, 0.1≤y≤0.8, 1.2≤z+a≤1.6, and 0.05≤a≤0.

15.

2. The method for preparing a primary phase change magnetocaloric alloy material according to claim 1, characterized in that: The method comprises the following steps: (1) La source, RE source, Fe source, Co source, Si source, and C source are mixed in proportion, smelted uniformly in a protective atmosphere, and cast into an ingot to obtain a master alloy; (2) The master alloy is placed in a vacuum rapid quenching strip spinning device to be melted uniformly, and the strip is spun for rapid quenching to obtain a rapid quenching thin strip, that is, a first-level phase change magnetocaloric alloy material is obtained.

3. The preparation method according to claim 2, characterized in that The smelting method comprises placing the raw materials in a vacuum induction melting furnace, evacuating the vacuum, introducing a protective atmosphere, supplying electricity for melting, and then stirring and refining with electromagnetic force. The smelting temperature is 1300-1450° C., and the smelting time is 10-15 minutes.

4. The preparation method according to claim 3, characterized in that The vacuum degree of the vacuum induction melting furnace after evacuation is 5×10 -1 ~5×10 -2 Pa; Preferably, the protective atmosphere in the vacuum induction melting furnace is one or more of argon, helium, nitrogen and neon; Preferably, after the protective atmosphere is introduced, the pressure in the vacuum induction melting furnace is 40-80 kPa.

5. The preparation method according to claim 2, characterized in that The step (2) comprises: placing the master alloy in the induction coil in the cavity of the single-roller rapid quenching strip-spinning machine, and drawing the vacuum degree of the cavity and the gas storage bottle to ≤3×10 -3 Pa, fill with protective atmosphere, so that the air pressure of the cavity and the gas cylinder are 100-200mbar and 400-600mbar respectively, after supplying power to melt the master alloy, open the air pressure valve, so that the uniformly melted master alloy is sputtered onto the surface of the rotating copper roller to obtain a rapidly quenched thin strip, and the linear speed of the copper roller surface is 25-40m / s.

6. The preparation method according to claim 2, characterized in that The preparation method further comprises placing the rapidly quenched thin strip obtained in step (2) in a protective atmosphere for heat treatment, and then performing hydrogen absorption treatment, thereby obtaining a first-level phase change magnetocaloric alloy material.

7. The preparation method according to claim 6, characterized in that The heat treatment method is to place the rapidly quenched thin strip in a high vacuum furnace, introduce a protective atmosphere after vacuuming, and keep it warm at 900-1100°C for 5-15 hours; the hydrogen absorption treatment method is to place the rapidly quenched thin strip after heat treatment in a hydrogen absorption furnace with a hydrogen pressure of 0.1-2MPa, and keep it warm at 200-400°C for 2-12 hours.

8. The preparation method according to claim 7, characterized in that The vacuum degree of the high vacuum furnace after evacuation is 5×10 -4 ~8×10 -3 Pa; Preferably, the protective atmosphere in the high vacuum furnace is selected from one or more of argon, helium, nitrogen and neon; Preferably, after the protective atmosphere is introduced, the gas pressure in the high vacuum furnace is 0.8 to 1.1 atm.

9. Use of the primary phase-change magnetocaloric alloy material according to claim 1 or the primary phase-change magnetocaloric alloy material prepared by the preparation method according to any one of claims 2 to 8, characterized in that: The primary phase-change magnetocaloric alloy material is used for deicing and melting ice on power transmission lines.

10. A method for melting ice by magnetic heat, characterized in that: The method comprises crushing the primary phase-change magnetocaloric alloy material according to claim 1 or the primary phase-change magnetocaloric alloy material prepared by the preparation method according to any one of claims 2 to 8 into powder with a size of ≤1 mm and encapsulating the powder in a thin-walled copper tube, replacing a transmission conductor in a transmission line with the thin-walled copper tube, or spirally winding the thin-walled copper tube around a conductor of the transmission line to perform deicing and ice melting.

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