767 results about "Saturation (magnetic)" patented technology

The invention belongs to the technical field of magnetic functional materials, and particularly relates to a nanocrystalline magnetically soft alloy and a preparation method and application thereof. The invention provides a nanocrystalline soft magnetic alloy which comprises the following chemical components: Fe, Si, B, Nb, Cu, P and rare earth metal, and the rare earth metal is selected from at least one of Nd and Sm. According to the nanocrystalline magnetically soft alloy, a proper amount of rare earth metal is added, the ferromagnetic coupling exchange effect between ordered phases of the nanocrystalline magnetically soft alloy is improved, so that the magnetic induction intensity and the high-frequency magnetic conductivity of the nanocrystalline magnetically soft alloy are both improved, the magnetic conductivity of the nanocrystalline magnetically soft alloy at 100 kHz can reach 42000 or above, and the high-frequency magnetic conductivity of the nanocrystalline magnetically soft alloy at 100 kHz can reach 42000 or above. Meanwhile, the saturation flux density reaches up to 1.75 T or above, and the coercive force is as low as 0.8 A / m.

The invention relates to a Fe-Si-Nb-B-Cu-Er amorphous alloy and a preparation method and application thereof, and belongs to the technical field of metal materials. The atomic percent expression of the Fe-Si-Nb-B-Cu-Er amorphous alloy disclosed by the invention is (Fe < 83 > Si < 3 > Nb < 4 > B < 9 > Cu < 1 >) < 100-x > Er < x >, wherein x is equal to 3.5 to 4.5. The rare earth element Er is added to optimize the soft magnetic performance of a Fe-Si-Nb-B-Cu amorphous alloy system, the coercive force of the Fe-Si-Nb-B-Cu amorphous alloy system is reduced, the preparation method is simple and easy to implement, and the Fe-based amorphous alloy with the excellent soft magnetization performance is obtained. The magnetization intensity of the amorphous alloy is sharply increased along with increase of a magnetic field under a low magnetic field and then gradually reaches saturation, typical soft magnetic performance is presented, and the amorphous alloy has wide application space in the field of magnetic materials.

The invention discloses an iron-based nanocrystalline soft magnetic alloy and a preparation method thereof. A magnetically soft alloy strip is prepared through smelting and a single-roller melt-spinning method, stress relief annealing is carried out on the magnetically soft alloy strip through assistance of a magnetic field, and then crystallization annealing treatment is carried out. Different from a traditional method for regulating and controlling the magnetic performance of the alloy through precipitation of a large number of nanocrystals, the method only induces precipitation of a very small number of nanocrystals, and high saturation flux density and low coercive force can be obtained while the toughness of the strip is ensured; the iron-based nanocrystalline soft magnetic alloy with high saturation flux density and low coercive force can be prepared by taking Fe as a main element, Co element with the atomic fraction lower than 8%, Cu element with the atomic fraction lower than 1% and at least one of oxygen, sulfur, phosphorus, carbon, silicon, boron and the like as other trace elements.

The invention discloses a stator assembly, a compressor and refrigeration equipment, and relates to the technical field of motors. The stator assembly comprises a stator core formed by stacking a plurality of amorphous alloy sheets, the stator core comprises a yoke part, a tooth part and a shoe part, and the stator core is formed by stacking a plurality of amorphous alloy sheets, so that the iron loss of the stator assembly can be reduced. For a motor, the area of a stator slot is expected to be as large as possible to increase the winding wire diameter so as to reduce copper loss, and the smaller the minimum width of a tooth part is, the better is, but the smaller the width of the tooth part is, the more likely to cause magnetic field saturation. In order to reasonably design the minimum tooth width of the tooth part so as to reduce the problem of magnetic voltage drop increase caused by magnetic field saturation, the minimum tooth width Wt of the tooth part is set in a range of 2piD / 9Q to 2piD / 3Q, so that the area of the stator slot can be effectively increased, the problem of magnetic voltage drop increase caused by magnetic field saturation can be improved, the magnitude of current can be reduced, and the service life of the stator slot can be prolonged. The working efficiency of the motor is improved.

The invention relates to a magnetic saturation evaluation method and system for a magnetic component in a strong magnetic field environment, and the method comprises the steps: constructing a target component model of a to-be-tested magnetic component according to a target geometric parameter and a target material parameter, and respectively setting excitation and boundary conditions of the target component model according to the target working current parameter and the target working environment magnetic field parameter, and performing simulation. The method comprises the following steps: acquiring simulated BH data of a target position in a target component model and corresponding simulated working environment magnetic induction intensity, and determining that the target component model reaches a magnetic saturation state according to the simulated BH data of the target position; and taking the corresponding simulated working environment magnetic induction intensity as a simulated saturated external magnetic field threshold value of the to-be-tested magnetic component. According to the embodiment of the invention, analog simulation of the saturation external magnetic field threshold of the to-be-tested magnetic component in the magnetic field environment is realized, and important support can be provided for model selection application and design optimization of the magnetic component in the high-intensity magnetic field environment.

A smart variable inductor based on magnetorheological materials comprises an "EE"-shaped iron core, two DC control coils, one AC coil, and a magnetorheological material gap. The magnetorheological material gap is located on the central column of the "EE"-shaped iron core. The two DC control coils and the AC coil are wound around the two side columns and the central column of the "EE"-shaped iron core, respectively. By controlling the DC current in the DC control coil, the magnetic saturation of the side columns can be changed, thus achieving intelligent wide-range adjustment of the inductance of the AC coil. The beneficial effects of this patent are: the provided smart variable inductor based on magnetorheological materials, due to the higher permeability of magnetorheological materials than air, which decreases with increasing magnetic field strength, has advantages such as a wide inductance adjustment range and low diffusion flux. When used in LLC resonant converters, it can achieve intelligent wide-range adjustment of input / output voltage and load, as well as intelligent current sharing control in multi-parallel converters.

Magnetic saturation detectors for power converters are presented herein. An energy transfer element has an input power winding wrapped around a center post. Single or multiple transverse windings are positioned perpendicular to the input power winding and coupled to receive a transverse current that provides a transverse magnetic flux density within the energy transfer element. The transverse magnetic flux density produces a transverse voltage waveform. A voltage detection circuit is configured to receive the transverse voltage waveform and detect a change in the sign of the slope of the transverse voltage waveform. The change in the sign of the slope indicates magnetic saturation. The voltage detection circuit is configured to detect an occurrence of an extremum in the transverse voltage waveform. The extremum indicates the change in the sign of the slope.

The invention discloses a defect detection system based on a bias alternating current magnetization modulation TMR sensor, and the system is characterized in that through the cooperation of an alternating current and direct current magnetization module, a TMR sensor and a defect prediction module, the alternating current and direct current magnetization module is used for simulating an alternating current and direct current superimposed magnetic field test environment, and a reverse alternating current and direct current magnetic saturation magnetic field is formed; the TMR sensor obtains defect signal characteristics of a to-be-detected workpiece and sends the obtained defect signal characteristics of the to-be-detected workpiece to the defect prediction module, and the defect prediction module achieves full-scale detection of defects from 20 micrometers to millimeter by analyzing peak values (micron-scale narrow defects) and waveform widths (millimeter-scale defects) of alternating-current waveforms. The balance of high sensitivity and wide range of the same sensor is realized, and meanwhile, the dual requirements on precision and efficiency in actual detection are met. Meanwhile, through alternating current and direct current magnetic field cooperative modulation, the measuring range TMR sensor is expanded to 300 Gs, and the full range from weak magnetic leakage to strong magnetic leakage is covered.

The invention belongs to the field of hard alloy materials, and provides a modified high-performance non-magnetic hard alloy and a preparation process thereof. The surface of a WC particle is chemically plated with a Ni-P-B-Cr-Cu amorphous shell layer, and a binding phase is converted into Ni3P and Ni3B nanophase through two-stage sintering. The WC alloy comprises the following components in parts by weight: 85-95 parts of WC, 12-25 parts of a binding phase and 0.5-1.4 parts of a grain growth inhibitor, the nanophase accounts for 35-50% of the volume of the binding phase and 35-50% of the total volume of the binding phase, and the grain size is 80-125 nm; the average grain size of WC is 0.6-1.0 [mu] m; and the thickness of an interface P enrichment layer is 8-15 nm (the coverage rate is 85-95%). Through interface engineering and controlled crystallization from amorphous to nanocrystalline, the relative magnetic conductivity is 1.001-1.015, the hardness HRA is 90.5-93.0, the strength TRS is 2.2-3.0 GPa, the toughness KWP is 300-450 N / mm, and the magnetic saturation strength is 0.02-0.15 T. The problem of decoupling of the magnetic property and the mechanical property of a traditional non-magnetic hard alloy is solved, and the non-magnetic hard alloy is suitable for magnetic sensitive environments such as semiconductor equipment, precise measurement, MRI tools and oil service logging.

The invention discloses a method for preparing (SmxY1-x) Co5 rare earth magnetic particles with high magnetic properties by a chemical method, and belongs to the field of rare earth magnetic materials. The invention particularly relates to a novel technology for preparing (SmxY1-x) Co5 ternary alloy magnetic powder with high magnetic properties by combining chemical liquid phase synthesis with calcium reduction reaction. A Sm (OH) 3 / Y (OH) 3 / Co (OH) 2 (at) Ca (OH) 2 crystalline state mixed precursor prepared by chemical coprecipitation and a hydrothermal reaction is uniformly subjected to a complete calcium reduction reaction with a certain amount of metal calcium particles, KCl and CaCl2 diffusion media in an argon atmosphere, and the magnetic powder is prepared. The saturation magnetization intensity and the residual magnetization intensity of the magnetic powder are improved by doping the yttrium element, but the coercive force of the magnetic powder is slightly reduced, and the method provides a new thought for preparing high-performance rare earth magnetic particles.

The invention provides NiCuZn ferrite with high magnetic conductivity and a preparation method thereof. The preparation method comprises the following steps: (1) carrying out primary ball milling on raw materials of the NiCuZn ferrite, and pre-sintering to obtain a pre-sintered material; and (2) the pre-sintered material and a doping agent are subjected to secondary ball milling, and after granulation, molding and sintering, the NiCuZn ferrite is obtained, and the doping agent comprises WO3 and TiO2. Through combined doping of WO3 and TiO2, the sample density can be improved, the magnetic conductivity, the Curie temperature and the saturation flux density can be improved, meanwhile, the magnetic loss is reduced, and the final ferrite can be suitable for electronic elements with high requirements for the magnetic conductivity.

The invention belongs to the technical field of low-voltage power distribution, and particularly relates to a control method and system for low inductive reactance and low transient impulse voltage, the magnetic flux density and the change rate of a magnetic core are collected in real time through a sensor, a dynamic threshold value is calculated based on the magnetic flux density, and the critical point of the magnetic core entering a nonlinear magnetization area is accurately identified. And comparing the magnetic flux density monitored in real time with a dynamic threshold value, generating a deviation signal and judging the state of the magnetic core. Once it is confirmed that the magnetic core is in a non-linear magnetization state, an adjustment mechanism is triggered immediately, winding current distribution is adjusted to change the magnetic flux path length of the magnetic core, and periodic pulse signals are applied to prevent depth saturation of the magnetic core. In addition, by monitoring the adjusted magnetic core magnetic flux density recovery rate, demagnetization processing parameters and pulse signal strategies are optimized, and continuous and efficient operation of the system is ensured. According to the method, the transient voltage suppression capability and stability of the system are remarkably improved, and the overall performance and reliability are enhanced.

The present invention discloses a nanocrystalline current transformer with DC component resistance and a method for using the same, comprising: a current transformer having a magnetic core hole extending from front to back in the middle of the front side of the current transformer. The device is provided with a secondary-side disconnection detection and protection mechanism, which effectively prevents the internal magnetic field imbalance of the transformer caused by the disconnection of the secondary circuit, avoids the core magnetic flux saturation and the generation of potential high electromotive force, thereby protecting the transformer itself and peripheral equipment, and reducing the risk of power system failures such as fire or short circuit. At the same time, a live conductor centering fixing mechanism is provided to ensure the stable centering position of the conductor in the transformer core hole, optimize the magnetic field distribution, reduce magnetic leakage, significantly improve the accuracy and stability of current measurement, and reduce measurement fluctuations introduced by conductor shaking, providing more accurate data support for harmonic analysis, fault detection, and power quality monitoring of the power system.

The application relates to a method for one-step synthesis of strong magnetic hydrophobic Fe3O4 nanoparticles at low temperature and the Fe3O4 nanoparticles and application, and belongs to the technical field of nano material preparation. The method comprises the following steps: adding a ferrous sulfate solution into a mixed solution of sodium hydroxide and sodium nitrate, heating and stirring to react, adding oleic acid in the reaction process, and obtaining black Fe3O4 crystals after the reaction is completed. The saturation magnetization of the obtained strong magnetic hydrophobic Fe3O4 nanoparticles can reach 85.69 emu / g at most, and the water contact angle can reach 148.95 DEG. The one-step synthesis reaction only needs to use oleic acid as a regulator, avoids an extreme high-temperature and high-pressure environment, does not need to use a toxic chemical solvent, the condition is mild, the process is simple, the operation condition is easy to control, and the method has a wide application prospect.

The invention discloses a ferromagnetic material internal defect leakage magnetic field increasing method based on alternating current and direct current composite magnetization, which comprises the following steps of: fixing a workpiece at the center of a composite exciting coil, and synchronously applying direct current and high-frequency alternating current; after pure direct current magnetization is saturated, current is locked, and a basic leakage magnetic field is established; the surface magnetic conductivity is dynamically reduced by overlapping alternating current, and the magnetic shielding effect is weakened; a leakage magnetic field signal is scanned and collected through a differential Hall sensor array, and background magnetic field deduction, peak value comparison and adaptive filtering processing are carried out; and determining an optimal magnetization parameter combination by adopting a gradient descent method and Bayesian optimization. The system is integrated with a composite excitation coil and a signal conditioning unit, so that synchronous excitation, signal acquisition and real-time analysis are realized. The leakage magnetic field signal at the deep defect is enhanced through alternating-current and direct-current composite magnetization, the problem of signal weakening caused by traditional direct-current saturation is solved, the defect detection sensitivity and efficiency are improved, and the method is suitable for non-destructive detection scenes of ferromagnetic materials.

The invention discloses an ocean deepwater weakly cemented sandstone saturated water nuclear magnetic T2 spectrum correction method, which comprises the following steps: 1, making a standard rock sample, and drying the rock sample until the quality is kept stable; 2, saturating the dried rock sample to a completely saturated state by using a turbid liquid, and carrying out nuclear magnetic T2 spectrum measurement to obtain a nuclear magnetic T2 spectrum of the weakly cemented rock sample under the condition that pores contain tiny solid impurities; 3, after displacing and drying the rock sample in the previous step, carrying out saturated water treatment by utilizing pure water, and then carrying out nuclear magnetic T2 spectrum measurement to obtain a nuclear magnetic T2 spectrum of the rock sample in a state that the pores contain the pure water; 4, constructing the nuclear magnetic T2 spectrums in the two states into a data set, and inputting the data set into a deep neural network model for training; and 5, correcting the nuclear magnetic T2 spectrum under the condition that the pores contain the tiny solid impurities by using the trained deep neural network model. According to the method, the nuclear magnetic T2 spectrum is corrected by using the deep neural network model, and the problem of signal attenuation distortion caused by impurity interference is effectively solved.

The present invention comprises a method for jointly processing data from the nuclear magnetic resonant (NMR) response of oil and rock samples in in natura condition, and its main product is the delimitation of the oil saturation (So) present in the rock samples, i.e., the determination of the range of admissible values of the volumetric fraction of the porous volume of the rock occupied by such fluid. The method requires a small volume of oil, originating from or of a composition similar to the oil present in the rock being tested, since it is based on both the measurement of the NMR response of the rock sample and the response of the fluid sample. These two sets of data feed a statistical inference scheme that (1) determines a range of admissible values for the So of the sample, delimited by the minimum and maximum oil saturation values compatible with the two sets of data presented; (2) produces, for each of these extreme values of admissible So, a decomposition of the rock relaxation time spectrum into two complementary spectra, the first highlighting the signatures relating to oil and the second comprising the distribution of the rock relaxometric signatures that cannot correspond to such fluid under the prescribed saturation condition.

The invention discloses a plastic package magnetic material for a chip inductor, a preparation method of the plastic package magnetic material and the inductor. The plastic package magnetic material comprises 96wt%-99wt% of alloy powder, 1wt%-4wt% of a resin layer and at least two atomic layer deposition layers, the two adjacent layers in the at least two atomic layer deposition layers are made of different materials; the at least two atomic layer deposition layers are coated on the outer surface of the alloy powder, and the resin layer is coated on the outer surfaces of the at least two atomic layer deposition layers. The plastic package magnetic material provided by the invention has relatively high magnetic conductivity, high saturation and low loss in a low-frequency band while having good fluidity, insulation and voltage resistance, so that miniaturization, lightness, thinness and high performance of an inductor are realized.

The invention discloses saturation magnetic induction prediction and component design of an iron-based amorphous alloy and an ultrahigh saturation magnetic induction iron-based amorphous / nanocrystalline alloy. The core effects of ferromagnetic element content, alloy mixing enthalpy and poor electronegativity are disclosed by combining a machine learning model XGBoost with SHAP analysis, the amorphous forming ability is not deteriorated while the high ferromagnetic element content is kept, extremely low coercive force can be obtained after annealing, and collaborative optimization of high saturation magnetic induction, the amorphous forming ability and the coercive force is realized. Parameters used by the component design criterion provided by the invention do not need experimental data, and can be directly calculated from alloy components. High-performance components are rapidly screened in combination with a machine learning model, the research and development period and cost of a traditional trial and error method are remarkably reduced, systematic theoretical guidance is provided for development of high-performance soft magnetic materials, and industrial feasibility is improved.

The invention provides a composite groove type stator punching sheet and a motor formed thereof.The stator punching sheet comprises M composite grooves distributed in the circumferential direction of the stator punching sheet, each composite groove comprises a first winding groove and a second winding groove which are distributed along the two sides of the center line of the groove, and the first winding grooves and the second winding grooves are different in structure; the inner side wall of the first winding groove comprises at least one section of arc, and the inner side wall of the second winding groove does not comprise an arc and is only enclosed by straight lines; m is an integer greater than or equal to 3. The first winding slots effectively modulate an air-gap magnetic field by utilizing smooth arc-shaped contours of the first winding slots, so that cogging torque and torque pulsation caused by magnetic conductance change are greatly reduced; the second winding groove is used for enhancing the magnetic circuit capacity and ensuring that the main magnetic flux can pass through efficiently without saturation, so that the harmonic content and the stator iron loss are greatly reduced; the first winding groove and the second winding groove complement each other in the aspects of electromagnetic performance and process advantages and are synergistically enhanced, so that a high-performance and low-cost synergistic effect is realized.

The invention discloses a high-power inverter and a control method thereof, and belongs to the technical field of power electronics, the high-power inverter comprises a sensing enhanced magnetic assembly, the sensing enhanced magnetic assembly comprises a high-thermal-conductivity metal shell, a magnetic core arranged in the high-thermal-conductivity metal shell, a main power coil, a high-precision sensing coil and an integrated thermal probe; wherein the high-precision sensing coil is wound by clinging to a central column of the magnetic core, the main power coil is coaxially wound on the outer side of the high-precision sensing coil, and the magnetic core, the main power coil and the high-precision sensing coil jointly form an inductor core body. According to the invention, the controller can monitor the working point of the magnetic core on the magnetization curve in real time, so that the margin of the magnetic core away from the magnetic saturation state is directly judged.

The invention discloses a transmission tower body angle steel corrosion defect detection method, which comprises the following steps: designing an excitation device, and carrying out saturation magnetization on transmission tower body angle steel; arranging a Hall sensor, and collecting a magnetic flux leakage signal; carrying out filtering processing and feature extraction on the magnetic flux leakage signal acquired by the Hall sensor; establishing a fitting relationship between the defect parameters and the magnetic flux leakage characteristic quantity; and quantitatively detecting the size of the angle steel corrosion defect of the to-be-detected transmission tower body. Whether the transmission tower has a defect or not is judged and the size of the defect is quantitatively judged by detecting the magnetic flux leakage signal on the surface of the transmission tower angle steel, so that the corrosion defect size of the transmission tower body angle steel is accurately and quickly diagnosed, the reliability is good, the detection efficiency is high, the operation is simple and convenient, and the magnetic flux leakage detection device is simple and portable in structure, low in cost and easy to popularize. A theoretical basis is provided for avoiding electric power accidents caused by tower corrosion defects, and the method has important engineering significance.

The invention discloses a transformer direct current magnetic bias temperature rise calculation method, system, medium and equipment, and the method comprises the steps: carrying out the classification estimation of the non-linear magnetic resistance value of each part of an iron core structure based on the magnetization characteristic of an iron core material, and obtaining the magnetic resistance estimation value of each part; building a transformer iron core magnetic circuit simulation model according to the magnetic resistance estimated value of each part to obtain a saturation magnetization characteristic phi-i curve of the transformer; a transformer circuit-magnetic circuit model is built, and winding current and iron core magnetic flux are obtained through circuit and magnetic circuit coupling calculation; establishing a transformer thermal circuit lumped parameter model under the direct current magnetic bias condition based on a thermoelectric analogy method, and fitting thermal capacity and thermal resistance parameters in the transformer thermal circuit lumped parameter model according to data of a transformer temperature rise experiment; in combination with short-circuit test data of the transformer, calculating winding loss of the transformer under direct-current magnetic bias; based on the BP loss characteristic of the iron core material, calculating the iron core loss of the transformer under the direct current magnetic bias; and temperature rise is calculated based on the transformer thermal circuit lumped parameter model.

The invention discloses a port area flexible load millisecond-level cooperative suppression method based on magnetic flux jump prediction, and the method comprises the steps: obtaining the external vibration and electrical data of a transformer, combining the Bayesian inversion of physical constraint, and reconstructing an internal three-dimensional magnetic flux field; based on time sequence evolution of the magnetic flux field, a dual-mode self-adaptive prediction algorithm is adopted, and a magnetic flux jump early warning vector containing jump time, amplitude and position is generated; and according to the early warning vector, through a multi-layer cooperative control strategy of time sequence decoupling, a control instruction for the flexible load of the harbor district is generated and executed. Advanced early warning and millisecond-level active suppression of the potential magnetic saturation risk are realized, and the operation reliability and equipment safety of a harbor district power distribution system are improved.

The invention relates to the technical field of flywheel energy storage electromagnetic suppression, in particular to an electromagnetic radiation suppression method for a data center flywheel energy storage system, which comprises the following steps: acquiring grounding potential data to generate a response node set, comparing a rotating speed with a power event to construct a synchronous topology, identifying a coupling path to generate a path map, and adjusting a magnetic shielding assembly. And monitoring magnetic flux change to generate an electromagnetic compatibility state report. According to the method, the sudden change potential and the recovery rate of a grounding node are analyzed, response nodes with disturbance characteristics are screened, rotating speed and load power events are fused, multi-source data response mapping in a time domain is constructed, a coupling path is recognized based on a node physical connection relation, and the magnetic saturation trend is recognized by collecting magnetic flux density and hysteresis characteristics. The excitation phase is matched to implement dynamic adjustment, the response adaptability of the shielding assembly is improved, the stability is judged according to the magnetic flux density change rate trend, the reset operation of the shielding structure is controlled, the shielding effectiveness retention is enhanced, and electromagnetic suppression in a dynamic interference scene is achieved.

The invention relates to the technical field of motors, in particular to a magnetic conductance motor adopting a magnetic conductance reinforcing material, which comprises a stator assembly and a rotor assembly which are concentrically arranged, and the rotor assembly is arranged in the stator assembly. The stator assembly is formed by radially positioning and splicing 12-24 silicon steel sheet inserts through a dovetail joint structure, traditional lamination gap loss is eliminated, T-shaped teeth (iron-nickel-based magnetically soft alloy 1J34 / 1J36) which are deeply embedded (1 / 3-1 / 2 of the tooth height) are combined, the magnetic circuit conduction efficiency is remarkably optimized through the high magnetic conductivity (larger than or equal to 60,000 H / m) and the saturation flux density (larger than or equal to 1.5 T), and the magnetic saturation risk is avoided; a non-magnetic stainless steel base body (304 / 316) is adopted on the rotor side to block a stray magnetic circuit, and a low-loss magnetic field closed loop is formed by matching the magnetism gathering design of a V-shaped neodymium iron boron insert (Br is larger than or equal to 1.2 T, Hc is larger than or equal to 900 kA / m, and the included angle is 60-90 degrees) and directional magnetism conduction of a 20-30-degree fan-shaped angle magnetic barrier insert, so that the purposes of high efficiency, low consumption, high reliability and low cost are achieved.

The invention discloses a transformer magnetic powder core, a transformer and a preparation method of the transformer magnetic powder core, the transformer magnetic powder core comprises a main body formed by a coarse powder layer, a fine powder layer is formed on at least one matching surface, used for being in contact with another magnetic powder core of the transformer, of the main body, and the powder granularity of the coarse powder layer and the fine powder layer forms gradient distribution. A fine powder layer structure with the particle size smaller than that of a magnetic powder core body is arranged on the matching face of the magnetic powder core of the transformer, and the performance bottleneck caused by low saturation flux density, weak large-current direct-current bias capacity and size limitation of a traditional ferrite core is effectively solved through the coarse / fine powder layer particle size gradient distribution design. According to the design, by optimizing filling of the interface fine powder layer, the risk that powder falls off to form an air gap in the grinding and polishing machining process is remarkably reduced, the flatness of the matching face and the continuity of a magnetic circuit are improved, and therefore the inductance value is increased and the power loss is reduced on the basis that the comprehensive performance is guaranteed.

The invention relates to the technical field of microwave ferrite devices, and discloses a miniaturized broadband microstrip circulator based on a double-ferrite nested structure, comprising a substrate, the upper surface of which is provided with a magnetic conductive sheet; a high dielectric ceramic is arranged on the magnetic conductive sheet, and a low magnetic saturation ferrite and a high magnetic saturation ferrite are sequentially nested in an inner cavity of the high dielectric ceramic; a circuit is arranged on the upper surface of the high-dielectric ceramic, and a ceramic piece and a permanent magnet are sequentially installed above the circuit. According to the circulator, a magnetic conductive sheet is additionally arranged, a structure with high dielectric ceramics as a core is constructed, the characteristic difference of two ferrite gyromagnetic materials with different magnetic saturation intensities is utilized, and the frequency resonance characteristic of a center junction is adjusted through nested arrangement, so that gyromagnetic effects under different frequencies are complementary to expand the working frequency band. Meanwhile, the high-dielectric ceramic optimizes port impedance matching and reduces electromagnetic wave reflection by virtue of a high dielectric constant, and cooperates with an internal ferrite nested structure, so that the frequency bandwidth is widened through a composite material mode, and miniaturization and broadband effects are achieved.

The invention relates to the technical field of shale exploitation, and discloses a shale reservoir wettability dynamic determination method, which comprises: S1, selecting a shale plunger core, carrying out supercritical CO2 cleaning and vacuum drying, and carrying out high pressure saturation by using simulated crude oil to obtain an initial oil saturation; and S2, the saturated rock core is loaded into a high-temperature and high-pressure rock core holder, and under the simulated formation temperature and pressure condition, simulated formation water containing the paramagnetic contrast agent is injected at the constant flow speed for displacement till the water content of the outlet end reaches 98%. According to the invention, dynamic and three-dimensional space representation of wettability is realized: three modal data of nuclear magnetic resonance, resistivity and sound wave are synchronously acquired in the displacement process, so that the limitation of a traditional static method is overcome, and the dynamic process of the wettability changing along with the fluid saturation state can be captured in real time; and finally, a high-resolution three-dimensional wettability distribution map is generated, and non-uniform distribution of wettability in the core is visually revealed.

The invention belongs to the technical field of magnetic shielding materials, and particularly relates to a nanocrystalline slotting and soft magnetic alloy powder filling composite magnetic sheet and a preparation method thereof. The composite magnetic sheet comprises a magnetic material layer formed by alternately compounding a nanocrystalline material layer and a double-faced adhesive tape, the magnetic material layer is provided with regularly distributed slotting structures, and the slotting structures are filled with soft magnetic alloy powder. The preparation method comprises the following steps: alternately compounding a nanocrystalline material layer and a double-faced adhesive tape to form a magnetic material layer, and performing die cutting to form a regularly distributed slotting structure; or the nanocrystalline material composite layer is subjected to die cutting to form a regularly-distributed through slotting structure, and then the structure is compounded with the composite layer which is not slotted to obtain the magnetic material layer; and then filling and fixing the slotting structure by adopting soft magnetic alloy powder to obtain the composite magnetic sheet. According to the invention, the defect of easy magnetic saturation due to local lack of magnetic materials after slotting can be avoided, and the obtained composite magnetic sheet has low loss and high saturation current at the same time.