424 results about "Remanence" patented technology

The invention discloses a neodymium-iron-boron magnet with double main phases and light rare earth diffusion based on asymmetric cerium distribution and a preparation method, and relates to the technical field of neodymium-iron-boron magnets. The method comprises the steps that a diffusion matrix is prepared through a double-main-phase technology, in the double-main-phase technology, the components of a main-phase alloy and an auxiliary-phase alloy are RaCebFe100-a-b-c-dMcBd, R is PrNd alloy or Nd metal, M is at least one of Cu, Al, Zr, Co and Ga, the content of Ce in the main-phase alloy is larger than that of Ce in the auxiliary-phase alloy, then the upper surface and the lower surface of the diffusion matrix are coated with a diffusion source solution, and the diffusion matrix is obtained through heat treatment. Carrying out heat treatment and aging treatment to obtain a neodymium-iron-boron magnet; the diffusion source solution is formed by mixing a diffusion source and a solvent, and the diffusion source is (PrmNdn) aAlbCucZrdCoeMgf. The neodymium-iron-boron magnet obtained through the method has high residual magnetism and high coercive force at the same time, the diffusion efficiency of the diffusion source is high, and the rare earth utilization rate is increased.

The invention discloses a reweighted inversion method and system for a magnetic anomaly modulus under a residual magnetism condition and a storage medium, and belongs to the technical field of magnetic exploration, and the method comprises the following steps: converting the magnetic anomaly modulus to obtain the magnetic anomaly modulus; carrying out nonlinear forward modeling on the magnetic anomaly modulus; and linearizing a forward modeling formula of the magnetic anomaly modulus, constructing a reweighted minimum model objective function, solving the reweighted minimum model objective function, finally obtaining the magnetization intensity of an inversion space, and delineating a target geologic body. According to the scheme, the nonlinear forward modeling formula of the magnetic anomaly modulus is subjected to linear representation, and the sensitivity matrix serving as depth weighting is further updated by utilizing the magnetic anomaly modulus kernel function matrix updated along with iteration, so that the reweighting minimum model objective function is constructed, the precision of magnetic anomaly modulus inversion under the residual magnetism condition is improved, and the accuracy of the magnetic anomaly modulus inversion under the residual magnetism condition is improved. And a more reliable inversion result is provided for more accurate depiction of a deep magnetic structure, mineral resource exploration and the like.

The invention discloses a neodymium iron boron magnet with a protective film and a manufacturing method thereof, and the manufacturing method specifically comprises the following steps: S1, pretreating a plurality of raw materials to ensure the purity and cleanliness of the raw materials; s2, the pretreated materials are mixed in proportion and smelted to prepare uniform neodymium-iron-boron alloy; s3, the smelted alloy is crushed, and particle powder meeting the requirement is prepared through jet mill equipment; s4, the powder is put into a mold, forming orientation is conducted through a magnetic field press, and the maximum residual magnetism is obtained; s5, performing high-temperature sintering on the molded magnet to improve the density and the magnetic performance of the molded magnet; s6, the sintered magnet is machined, and the needed size and shape are obtained; s7, carrying out pretreatment on the surface of the magnet, and carrying out aftertreatment after chemical nickel plating to ensure the quality of a plating layer; according to the method, the surface of the neodymium-iron-boron magnet is coated with a high-phosphorus chemical nickel layer in a plating mode, the magnet can be effectively prevented from being corroded by the external environment, and the service life of the magnet is prolonged.

The invention provides a cement-based material residual magnetism intensity detection device, a detection method and an evaluation method. The cement-based material residual magnetism intensity detection device comprises a magnetic shielding cylinder, a fluxgate magnetometer and a test tool, the magnetic shielding cylinder is used for shielding a magnetic field to ensure stable test environment magnetic field; the fluxgate magnetometer comprises a fluxgate probe and a fluxgate digital display meter, the fluxgate probe is used for measuring a vector value of space magnetic induction intensity at a position corresponding to the fluxgate probe, and the fluxgate digital display meter is used for displaying a residual magnetism intensity measured value measured by the fluxgate probe; the test tool is arranged in the magnetic shielding cylinder and is used for placing a sample to be tested and fixing a fluxgate probe; according to the invention, a fluxgate magnetometer and a magnetic shielding cylinder are adopted to detect the residual magnetism intensity of the cement-based material, a standardized detection process and a test method are provided for solid components, a liquid mixture and a molded test block, and quantitative characterization of the distribution rule of the residual magnetism intensity of the cement-based material is realized through fewer detection points.

The invention belongs to the technical field of neodymium iron boron rare earth permanent magnets, and relates to a cerium-containing neodymium iron boron magnet with high coercivity and high stability and a preparation method thereof. According to the preparation method, the cerium-containing copper auxiliary alloy and the neodymium iron boron magnetic powder are ingeniously combined, the whole preparation process is optimized, and remarkable technical progress and economic benefits are achieved. Firstly, in the aspect of magnetic performance, Ce in a specific proportion is added into the cerium-containing copper auxiliary alloy, the cerium-containing copper auxiliary alloy is used, the coercive force of a magnet is effectively improved, high residual magnetism is kept to a certain degree, and introduction of Cu is beneficial to refining of grains and improvement of a grain boundary phase structure; therefore, the reverse magnetization resistance in the magnet is enhanced, and the magnet can maintain stable performance in a wider temperature range.

The invention discloses a fault signal dual-mode output method of a magnetic latching relay, particularly relates to the technical field of relay control, and is used for solving the problem of low mode switching efficiency caused by an existing physical jumper mechanism. The current mechanical state of the relay is detected by receiving a remote dual-mode switching instruction; applying a driving voltage sequence corresponding to the target mode according to the state; based on the iron core residual magnetism intensity and the dynamic margin of a target mode nominal value, judging and generating a driving enabling or degaussing trigger signal; when a driving enable signal is responded, the lag time difference between the voltage rising edge and the magnetic flux jump starting point is captured in real time, and the eddy current loss characterization quantity is generated by combining the product integration of the current differential and the temperature rise; adjusting the rising slope and the duty ratio of the driving voltage sequence according to the lag time difference and the over-limit condition of the eddy-current loss characterization quantity; and finally, the matching between an execution result and a target mode identifier is verified by controlling a coil current response waveform, and the continuous holding mode and the instantaneous pulse mode are remotely and reliably switched.

The present invention provides a flywheel energy storage flux adjustable induction motor and its magnetic adjustment method, wherein the motor comprises two permanent magnets with different coercive forces and a DC magnetic adjustment winding. A square wave pulse is input into the DC magnetic adjustment winding to generate a magnetic adjustment magnetic field, so that the residual magnetism of the low-coercive force permanent magnet changes in magnitude or direction, thereby realizing rapid adjustment of the motor air gap flux. When the motor is working, the DC magnetic adjustment winding is disconnected, and the residual magnetic flux generated by the high-coercive force permanent magnet and the low-coercive force permanent magnet enters the air gap in parallel to provide excitation flux for the motor; when the motor is on standby, a negative square wave pulse is input into the DC magnetic adjustment winding to generate a magnetic adjustment magnetic field that can reversely saturate magnetize the low-coercive force permanent magnet, so that the low-coercive force permanent magnet is reversely magnetized, and the residual magnetic flux of the high-coercive force and low-coercive force permanent magnets is equal in magnitude and opposite in direction, so that the air gap flux is reduced to 0, thereby eliminating standby iron loss. In addition, the DC magnetic adjustment winding can also be used as a backup excitation source to prevent the risk of permanent magnet demagnetization.

The invention relates to a method for dynamically eliminating residual magnetism of an iron core of a converter transformer, and belongs to the field of transformer demagnetization. According to the method, a capacitance energy storage and release device is connected to the two ends of a transformer winding, capacitance energy storage causes RLC oscillation of the transformer, a magnetic field is generated through current caused by the RLC oscillation, and magnetic domains of iron core ferromagnetic materials are rearranged through the changed magnetic field, so that the demagnetization effect on residual magnetism of the transformer is achieved. The method comprises the following steps: drawing a hysteresis loop in the demagnetization process of a transformer by collecting voltage and current data in the demagnetization process, translating an end point of the hysteresis loop to an original point, and judging the residual magnetism direction and size of initial demagnetization according to the area of each quadrant of the hysteresis loop; and then transformer demagnetization is carried out again, the residual magnetism direction and size of the first demagnetization are evaluated according to the hysteresis loop of the second demagnetization, and whether the residual magnetism is smaller than a threshold value is judged. According to the method, the direction and size of residual magnetism in the demagnetization process can be evaluated in real time, the demagnetization energy is dynamically adjusted, and sufficient demagnetization of the converter transformer is ensured.

The invention discloses a zero magnetic shielding device and a use method thereof, and the device comprises a magnetic shielding cylinder which is composed of a shielding cylinder body and a shielding cover detachably connected with the shielding cylinder body. And the non-magnetic multifunctional test frame is arranged in the magnetic shielding cylinder and consists of an arc-shaped seat, a lifting mechanism, a test bedplate, a track, a storage rack, a Helmholtz coil and a folding nylon magnetic sensing assembly. When the magnetic flux and residual magnetism switching test is carried out on the object to be tested in the magnetic shielding cylinder, the non-magnetic multifunctional test frame does not need to be replaced, the efficiency of the magnetic flux and residual magnetism switching test on the object to be tested in the magnetic shielding cylinder is improved, and the advantage of convenient switching test is achieved. And the method has the advantages of high measurement precision and wide application range.

The invention provides a magnetic code disc film material and a preparation method and application thereof. By introducing the TiN layer, a proper amount of nitrogen atoms can enter lattice gaps of iron, electron cloud distribution of iron atoms is changed, and the magnetic moment of the iron atoms is changed; the magnetic moment of Fe atoms can be influenced by N atoms and crystal structures, an alpha-Fe8N phase is formed in FeCoCr through introduction of N ions, the average magnetic moment of each Fe atom in the alpha-Fe8N phase is 2.4 mu B, alpha-Fe8N is a metastable phase, a sample can finally form stable gamma '-Fe4N through annealing, and the magnetic moment of the stable gamma'-Fe4N is generally about 2.5 mu B-2. 7 mu B and is higher than the magnetic moment 2.2 mu B of the Fe atoms in metal Fe; besides, Ti forms a Ti-Fe weak magnetic phase pinning magnetic domain wall in the FeCoCr thin film, and the coercive force and residual magnetism of the FeCoCr layer can be effectively improved at the same time through the method.

The invention relates to the technical field of magnetic shielding, and discloses a self-adaptive active adjustment type magnetic shielding device demagnetization circuit and device, and a control acquisition system, which are used for comparing a residual magnetism state with a preset expected value and generating a control instruction; the energy output identification system is used for outputting an alternating current degaussing signal according to the control instruction to perform degaussing, outputting an excitation pulse signal to perform residual magnetism detection, identifying a zero crossing point of the alternating current degaussing signal and realizing mode switching of degaussing and residual magnetism detection; and the magnetic shielding device is used for demagnetizing under the action of the alternating current demagnetizing signal and feeding back the residual magnetism state of the preset feature point under the action of the excitation pulse signal. The demagnetization is interrupted at the preset feature points in the demagnetization process, the real-time residual magnetism state is collected, and the demagnetization parameter at the next moment is adjusted after the real-time residual magnetism state is compared with the preset residual magnetism expected value, so that the problem of low efficiency due to the fact that the demagnetization parameter needs to be reset after the process is finished is solved, and the demagnetization efficiency and accuracy are greatly improved.

The invention relates to the technical field of magnet materials, and discloses a high-temperature-resistant neodymium-iron-boron magnet and a preparation method of the high-temperature-resistant neodymium-iron-boron magnet. The high-temperature-resistant neodymium-iron-boron magnet comprises the following components in parts by weight: 25-30 parts of neodymium, 60-65 parts of iron, 1.0-2.0 parts of boron, 3.0-5.0 parts of lanthanum, 0.5-2.0 parts of zirconium, 0.5-1.0 part of molybdenum and 0.1-0.5 part of nano ceramic particles, and the invention further provides a preparation method of the high-temperature-resistant neodymium-iron-boron magnet. S1, preparing and mixing alloy raw materials; s2, nano ceramic coating treatment is carried out; s3, magnetic field assisted pressing forming; and S4, rapid induction sintering. Through the magnetic field assisted directional pressing process, effective control over grain orientation in the pressing forming stage is achieved, magnetic domain arrangement is more ordered, and the residual magnetism and the energy product are improved. Different from a forming mode with disordered grain directions and poor magnetic anisotropy in an existing common cold pressing process, the technical defect that the utilization rate of magnetic performance is low due to poor orientation is overcome.

The invention discloses a method for measuring and analyzing residual magnetism characteristics of an iron core. According to the method, a to-be-detected iron core is demagnetized, preset residual magnetism is set, direct-current voltage excitation with opposite polarities, the same amplitude and the same duration is applied to a primary winding of the to-be-detected iron core, and transient current response signals are synchronously collected; two groups of current under positive / negative polarity excitation are extracted, and the residual magnetism direction is judged by comparing the change rate of the current; a curve of equivalent resistance changing along with time is calculated based on forward current and voltage, a resistance value corresponding to a characteristic inflection point moment is selected, the resistance value is substituted into a pre-established residual magnetism-equivalent resistance empirical formula to deduce the magnitude of residual magnetism, and a matched iron core residual magnetism detection and demagnetization integrated system integrates information management, residual magnetism detection, demagnetization and display modules. And closed-loop automation of detection, analysis and demagnetization is realized. According to the method, a magnetic field sensor is not needed, the residual magnetism direction and size can be synchronously obtained in a high-precision and robust mode only through port electric signals, and the method is suitable for on-site off-line or live detection.

The invention discloses a circuit breaker contact structure integrated with a permanent magnet and a vacuum circuit breaker, and relates to the technical field of vacuum circuit breakers, the circuit breaker contact structure integrated with the permanent magnet comprises a contact piece, a contact cup, an insulation sleeve, a permanent magnet ring and a conducting rod, the contact piece and the conducting rod are arranged at the two ends of the contact cup respectively, the insulation sleeve is sleeved outside the contact cup, the permanent magnet ring is sleeved outside the insulation sleeve, and the contact cup is provided with a spiral slot. The vacuum circuit breaker adopts a circuit breaker contact structure integrated with a permanent magnet. Through innovative structural design and material application, the problems that in an existing vacuum circuit breaker contact structure, magnetic field phase lag and residual magnetism affect arc extinguishing are effectively solved, the longitudinal magnetic field control effect is enhanced at the current peak value, the residual magnetism is restrained at the current zero passage, coordination and cooperation of the two are achieved, and the service life of the vacuum circuit breaker is prolonged. The breaking performance and reliability of the vacuum circuit breaker are improved, and the breaking reliability of the vacuum circuit breaker is improved.

The invention provides a Y-rich rare earth permanent magnet and a preparation method and a magnetic performance improving method thereof, and the performance improving method comprises the steps: uniformly mixing to-be-diffused metal powder containing Dy and / or Tb elements with an organic solvent to obtain to-be-diffused alloy liquid; the alloy liquid to be diffused is attached to the surface of the Y-rich rare earth permanent magnet, and the Y-rich rare earth permanent magnet is placed in a vacuum sintering furnace; the Y-rich rare earth permanent magnet is subjected to grain boundary diffusion heat treatment through the vacuum sintering furnace, so that Dy and / or Tb elements are diffused into the surface layer of a main phase lattice of the Y-rich rare earth permanent magnet; and carrying out tempering treatment on the Y-rich rare earth permanent magnet. The problems that the coercive force of an existing Y-containing magnet is difficult to effectively improve, and residual magnetism is easily reduced can be effectively solved.

The invention belongs to the field of magnetic materials. The invention provides a preparation method of a rare earth permanent magnet, which comprises the following steps: weighing rare earth magnetic powder, adding a binder solution, uniformly mixing, and drying until a solvent is completely volatilized to obtain bonded magnetic powder; the bonded magnetic powder is placed in a die cavity of a constant-temperature die for heat preservation and preheating; an inner cavity of the constant-temperature mold is vacuumized to form a vacuum environment, and gas adhering to gaps of the magnetic powder is exhausted; applying a magnetic field to the mold, forming an oriented magnetic field in the mold cavity, arranging easy magnetization axes of the magnetic powder along the direction of the oriented magnetic field, and applying pressing force to obtain a mold pressing blank; and heating and curing the molded green body to obtain the rare earth permanent magnet. The rare earth permanent magnet prepared through the preparation method has high compactness, the residual magnetism and the maximum magnetic energy product capacity of the permanent magnet are improved, rare earth magnetic powder is prevented from being oxidized, and the coercive force of the permanent magnet is remarkably improved.

The invention discloses a high-magnetic-performance neodymium-iron-boron magnet and a preparation method thereof, and belongs to the technical field of magnetic materials. The technical problem that an existing magnet is low in magnetic performance is solved. The invention provides a preparation method of a high-magnetic-performance neodymium-iron-boron magnet. The preparation method comprises the following steps: S1, preparing neodymium-iron-boron powder A and neodymium-iron-boron powder B by adopting a vacuum melting method; s2, carrying out powder mixing and orientation compression treatment; s21, powder mixing treatment, wherein the neodymium-iron-boron powder A and the neodymium-iron-boron powder B are mixed, and evenly-mixed neodymium-iron-boron powder is obtained; s22, orientation treatment, wherein the evenly-mixed neodymium iron boron powder is placed in a magnetic field with the magnetic field intensity larger than 2.0 T to be subjected to orientation forming, and a neodymium iron boron blank is obtained; and S3, carrying out sintering treatment and two-stage aging treatment on the prepared neodymium-iron-boron blank to finally obtain the neodymium-iron-boron magnet with high magnetic performance. The residual magnetism of the neodymium-iron-boron magnet prepared by the method disclosed by the invention is 14.21 kGs or above.

[Object] To provide a Peltier element with an ultra-low thermal resistance heat flux sensor that is capable of detecting heat flow passing through the Peltier element at high speed and has negligible thermal resistance.[Solving Means] It has a structure in which an anomalous Nernst heat flux sensor 20 is formed directly on one or both of an upper part and a lower part of an insulating board that forms a Peltier element 10. The present invention is favorably characterized in that each fine line (22a) of a thermoelectric generator is formed of a magnetic material having residual magnetization even in absence of an external magnetic field and is magnetized in a direction orthogonal to a length direction of the fine line, and each fine line (23a) of a connector is formed of a ferromagnetic material that is magnetized in a direction opposite to a direction in which each fine line (22a) is magnetized, a magnetic material having a Nernst coefficient with an opposite sign to that of each fine line (22a), or a non-magnetic material.

Disclosed in the present invention are a neodymium-iron-boron magnet, a manufacturing method therefor, and the use thereof. In the neodymium-iron-boron magnet, a first easy-demagnetization zone, a second easy-demagnetization zone, a third easy-demagnetization zone and a fourth easy-demagnetization zone have the same heavy-rare-earth content; a first transition zone, a second transition zone, a third transition zone and a fourth transition zone have the same heavy-rare-earth content; the content ratio of Tb in a non-easy demagnetization zone to that in the first easy-demagnetization zone is (0-0.9):1; the content ratio of Dy in the first easy-demagnetization zone to that in the non-easy demagnetization zone is (0-0.9):1; the content ratio of Tb in the first transition zone to that in the first easy-demagnetization zone is (0.8-1):1. The neodymium-iron-boron magnet of the present invention can reduce the attenuation of a surface magnetic field strength and magnetic flux of the neodymium-iron-boron magnet while ensuring remanence, and has good anti-demagnetization performance.

The invention relates to the technical field of rare earth permanent magnet materials, in particular to a grain boundary diffusion magnet based on a hard magnetic 6: 14 phase and a preparation method of the grain boundary diffusion magnet. Preparing a diffusion source, and loading the diffusion source on the surface of the matrix magnet; carrying out heat preservation diffusion under the environment pressure of which the vacuum degree is less than or equal to 10 <-2 > Pa; and carrying out aging treatment to obtain the grain boundary diffusion magnet based on the hard magnetic 6: 14 phase. The grain boundary phase of the prepared grain boundary diffusion magnet based on the hard magnetism 6: 14 phase is mainly the continuous 6: 14 phase, the hard magnetism is presented, the coercive force is improved, meanwhile, the residual magnetism is prevented from being reduced, the problems that the coercive force of an existing neodymium-iron-boron magnet is improved in a limited mode, and the residual magnetism cannot be prevented from being reduced are solved, and the service life of the neodymium-iron-boron magnet is prolonged. The invention provides a low-cost high-comprehensive-magnetic-performance grain boundary diffusion magnet preparation method.

The invention relates to a high-temperature irreversible magnetic flux loss proportion and residual magnetism prediction method, belongs to the field of high-temperature-resistant permanent magnets, and is particularly suitable for predicting irreversible magnetic flux loss proportion and residual magnetism generated when high-temperature magnets such as SmCo and the like are subjected to high-temperature pre-stabilization treatment. The core of the method is as follows: the irreversible magnetic flux loss proportion and the residual magnetism of a magnet element subjected to high-temperature pre-stabilization treatment at a specific temperature can be accurately calculated only by inputting three key parameters of the geometric shape of the magnet, the knee-point magnetic field intensity with international standards and the residual magnetism, and the method is simple and efficient in calculation process; a reliable and easily-obtained magnetic parameter basis is provided for accurate design of a high-temperature permanent magnet magnetic circuit, and the design efficiency and reliability are remarkably improved.

The invention discloses a method for predicting the room-temperature magnetic performance of a neodymium iron boron permanent magnet, which is a prediction method based on practice and theoretical analysis, the prediction method deforms an existing residual magnetism and coercive force theoretical formula, and the form is changed into a form containing phase composition parameters based on actual deformation from a theoretical aesthetic form. According to the prediction method, a residual magnetism and coercive force calculation model is established by calculating the proportion of the main phase (NdFeB) to the non-magnetic phase (Non-magnetic Phase), simple, efficient and accurate prediction of the room-temperature magnetic performance of the neodymium-iron-boron permanent magnet is achieved, the non-magnetic phase composition and components which cannot be quantitatively analyzed can be bypassed, and the prediction accuracy of the room-temperature magnetic performance of the neodymium-iron-boron permanent magnet is improved. The influence of the components of the neodymium-iron-boron permanent magnet on the performance is simply and clearly displayed and calculated from a more macroscopic perspective, and a universal and quantitative rapid solution can be provided for component design and process design of various neodymium-iron-boron permanent magnets.

The invention relates to a cerium-iron-boron permanent magnet material with low content of a non-magnetic phase CeFe2 and a preparation method of the cerium-iron-boron permanent magnet material. The cerium-iron-boron permanent magnet material is composed of the following components in percentage by atom: 11%-17% of Ce, 70%-80% of Fe, 5%-10% of B, 0.1%-3% of Co, 0.1%-3% of Zr and 0.1%-5% of La. The preparation method comprises the following steps of S1, smelting, wherein Ce, La, Fe, Co, Zr and FeB are prepared into a CeLaFeCoZrB alloy cast ingot through electric arc smelting according to the atomic percent composition; s2, melt-spinning: crushing the CeLaFeCoZrB alloy ingot prepared in the S1, and then preparing an alloy strip by using a melt rapid quenching method; and S3, magnetic field annealing: performing vacuum annealing on the alloy strip prepared in S2, wherein the annealing temperature is 2-12K below the Curie temperature Tc of the alloy. Compared with the prior art, the method has the advantages that the phase volume fraction of the non-magnetic CeFe2 phase in the cerium-iron-boron permanent magnet material alloy is remarkably reduced, and the residual magnetism and the maximum magnetic energy product of the alloy are improved.

The invention discloses an acoustic magnetoelectric pipeline interior detection system and method, a storage medium and a product, and relates to the technical field of pipeline detection, and the system comprises an electromagnetic ultrasonic probe, a magnetoacoustic piezoelectric probe, a residual magnetic stress detection probe, a signal generation module and a signal acquisition module; the signal generation module is used for providing sine wave current excitation signals for the electromagnetic ultrasonic probe and the magnetoacoustic piezoelectric probe; the electromagnetic ultrasonic probe is used for generating a magnetic field voltage signal; the magnetoacoustic piezoelectric probe is used for generating a vibration signal; the residual magnetism stress detection probe is used for capturing magnetic field signals to obtain characteristic signals of stress areas and surface defects; the signal acquisition module is used for acquiring and storing a magnetic field voltage signal, a vibration signal and a characteristic signal. The system can effectively detect circumferential weld cracks and internal defects of pipelines, can detect low-flow, low-pressure, large-wall-thickness and weak-magnetic pipelines, and can improve the precision and efficiency of pipeline detection.

The invention relates to the technical field of preparation of neodymium-iron-boron materials, and discloses a high-performance neodymium-iron-boron material and a preparation method thereof, and the high-performance neodymium-iron-boron material realizes efficient permeation of heavy rare earth elements along a specific path through a grain boundary network pre-construction and gradient diffusion technology in combination with a hydrogen decrepitation and surface activation process, so that the coercive force and thermal stability of a magnet are remarkably improved. An alternating magnetic field assisted sintering and dynamic tempering process is innovatively adopted, and a magnetic field-lattice coupling effect is utilized to release microscopic stress, so that magnetic performance attenuation in a high-temperature environment is effectively inhibited. A surface protection system is fused with a grain boundary modification and composite coating technology, a multistage corrosion-resistant barrier is constructed through the synergistic effect of an intermetallic compound layer and a nano coating, and the service life of the magnet in a severe environment is greatly prolonged. According to the method, the bottleneck of mutual restriction of performance indexes in a traditional process is broken through, and collaborative optimization of coercive force strengthening, temperature stability improving and corrosion resistance is achieved on the basis of keeping the high residual magnetism characteristic.

The application discloses a large-size rare earth permanent magnet material and a preparation method thereof. The preparation method of the large-size rare earth permanent magnet material comprises the following specific steps: pretreating a base magnet blank; performing sputtering treatment on the pretreated magnet; and performing heat treatment on the magnet after the sputtering treatment to obtain the required rare earth permanent magnet material. The application provides a batch preparation method suitable for large-size (width greater than 20 mm) sintered neodymium-iron-boron permeation. The application is used to improve the magnet performance, on one hand, the product performance can be effectively improved (compared with the base magnet blank, the coercive force is increased by 6930Oe-9990Oe, and the remanence is reduced by 220Gs-340Gs), on the other hand, the batch product with qualified appearance and meeting the performance requirements can be output, and the burr defects of the large-size product can be avoided.

This invention discloses neodymium iron boron (NdFeB) magnets, their preparation methods, and applications. In the NdFeB magnets: the content of heavy rare earth elements (Tb) in the first, second, third, and fourth easily demagnetized regions is the same; the content of heavy rare earth elements in the first, second, third, and fourth transition regions is the same; the Tb content ratio of the non-easily demagnetized region to the first easily demagnetized region is (0-0.9):1; the Dy content ratio of the first easily demagnetized region to the non-easily demagnetized region is (0-0.9):1; and the Tb content ratio of the first transition region to the first easily demagnetized region is (0.8-1):1. The NdFeB magnets of this invention can reduce the attenuation of surface magnetism and magnetic flux while maintaining remanence, exhibiting good anti-demagnetization performance.

The invention discloses a sintered neodymium-iron-boron permanent magnet material with a low coercive force temperature coefficient for a new energy automobile, and relates to the technical field of sintered neodymium-iron-boron permanent magnet materials. Collaborative optimization of high residual magnetism and high coercive force is realized through preparation of the sintered neodymium-iron-boron permanent magnet material; the performance bottleneck of a traditional sintered neodymium-iron-boron magnet material is broken through, and the energy density and the demagnetization resistance of the magnet are doubly improved, so that the magnet is excellent in high-temperature and high-intensity magnetic field environments.

The invention discloses a preparation method of a neodymium-iron-boron magnet. The preparation method comprises the following steps: (1) coating a film on the surface of neodymium iron boron rapid quenching magnetic powder to obtain coated magnetic powder; the neodymium iron boron rapid quenching magnetic powder is composed of elements shown in the formula (I): RE B M < c > Fe < 100 wt%-a-b-c (I), wherein the coating film has an element composition as shown in a formula (II): Re < 100 wt%-x > M < x > (II), the thickness of the coating film is 1-20 [mu] m; (2) carrying out cold pressing on the coated magnetic powder to obtain a cold-pressed blank; performing hot pressing on the cold-pressed blank to obtain a hot-pressed precursor; (3) performing thermal deformation treatment on the hot-pressed precursor to obtain a thermal deformation magnet; and (4) carrying out heat treatment on the thermally deformed magnet at 620-720 DEG C to obtain the neodymium iron boron magnet. According to the preparation method, the coercive force of the neodymium-iron-boron magnet can be improved, and the influence on residual magnetism and the maximum magnetic energy product is small.

The application relates to the technical field of magnetic materials, in particular to a preparation method of high-performance heavy-rare-earth-free neodymium iron boron magnets; the preparation method comprises the following steps: rapidly quenching a main phase alloy into a flake, obtaining coarse powder after hydrogen breaking; immersing the coarse powder in an ethanol mixed solution containing lanthanum nitrate and cerium nitrate, drying the pretreated coarse powder after ultrasonic-magnetic stirring cooperative treatment; adding an antioxidant and a lubricant into the pretreated coarse powder, preparing fine powder with an average particle size of 2-3.5 microns through airflow milling; performing magnetic field orientation compression molding on the fine powder under nitrogen protection, improving the density through cold isostatic pressing; finally, performing vacuum sintering and step-by-step tempering treatment to obtain the high-performance heavy-rare-earth-free neodymium iron boron magnets; wherein the main phase alloy is composed of the following components with mass percentage: 28-31wt.% Pr25Nd75, 0.88-1.2wt.% B, 0-0.1wt.% Al, 0.05-0.3wt.% Ti, 0.05-0.4wt.% Cu, 0.5-1.4wt.% Co, 0.1-0.4wt.% Ga, and the balance is Fe; the prepared neodymium iron boron magnet has the dual characteristics of high coercivity and high remanence, and effectively guarantees the performance and quality.