14 results about "Crystal anisotropy" patented technology

The invention discloses a method and system for detecting the magnetization direction of an unmagnetized magnet, and belongs to the technical field of magnetic material detection. The method comprises the following steps: applying an external guide magnetic field to a to-be-detected non-magnetized magnet; detecting a signal related to the physical state of the non-magnetized magnet under the action of the guide magnetic field as a response signal; and judging the magnetization direction of the non-magnetized magnet based on the corresponding relation between the response signal and the preset magnetization direction. The corresponding system comprises a guide magnetic field generation unit, a detection unit and a discrimination unit. The modulation effect of magnetocrystalline anisotropy of a non-magnetized magnet on an external magnetic field is utilized, invisible magnetic domain orientation information is converted into externally observable physical field difference, efficient, visual and lossless recognition of the preset magnetization direction is achieved, and the method is suitable for production quality control of magnetic assemblies such as a Halbach magnetic circuit and the like.

Broadband high T c High-conductivity manganese-zinc ferrite and preparation method, belong to ferrite material preparation technical field. High specific surface area raw material is adopted, contact area of powder in ball milling process is increased, reaction activity is improved, and sintering temperature is reduced; MnZn ferrite main formula adopts iron-rich zinc-deficient system, superexchange interaction is enhanced, and material Curie temperature is realized; secondary ball milling introduces combined additives, sintering process grain growth mechanism is regulated by means of fluxing and crystal resistance dual effects, Co2O3 is used to compensate MnZn ferrite magnetic crystal anisotropy constant, and initial magnetic permeability is improved; CaSiO3 is introduced, and is enriched in grain boundary in the sintering process, grain boundary resistivity is improved, and magnetic permeability frequency characteristic is improved; in the sintering process, oxygen partial pressure is accurately controlled in the holding and cooling stages, Fe 2+ Ion generation amount is influenced, sample resistivity is improved, and suitable sintering temperature and holding time are beneficial to grain growth and material densification.

The laser chip and its fabrication method disclosed herein include a first reflective layer, an active region, an oxide layer, and a second reflective layer sequentially disposed on a substrate. The laser chip has a first trench and a second trench for oxidizing and etching the oxide layer. A first connecting portion connects one end of the first trench to one end of the second trench, and a second connecting portion connects the other end of the first trench to the other end of the second trench. Due to the influence of crystal anisotropy on the oxidation rate, and the mutual coordination of the first and second connecting portions on the oxidation rate, the oxide aperture includes a first oxide arc, a second oxide arc, a third oxide arc, and a fourth oxide arc. The first and second oxide arcs are arranged opposite each other, as are the third and fourth oxide arcs. The third and fourth oxide arcs have different radii of curvature, forming a specific irregular morphology. The oxide aperture based on the irregular morphology can effectively suppress transverse multimode lasing of the optical signal and reduce mode degeneracy.

The invention discloses a method for preparing a high-performance cerium neodymium iron boron magnet based on a powder modification process, and belongs to the technical field of rare earth permanent magnet materials. The component-process collaborative optimization strategy is characterized in that a proper low-melting-point rare earth alloy diffusion source is selected and a magnetic powder rotating coating process is combined according to the change characteristics of magnetocrystalline anisotropy fields HA in main phase grain cores with different Ce substitution amounts based on magnet component design; and a high-HA magnetic hardening shell layer is constructed on the surface layer of the main phase crystal grains in situ. Therefore, by regulating and controlling the components of the shell layer, the HA in the core and the HA in the shell layer reach a dynamic synergistically enhanced balance state, and the synchronous reversal of the core-shell structure in the demagnetization process is ensured, so that the demagnetization process is inhibited to the greatest extent, and the coercive force of the magnet is improved.

The application belongs to the technical field of electronic information materials, and specifically provides a method for preparing M-type barium ferrite monocrystal thin film under low temperature conditions; the method is characterized by innovative design of liquid phase raw materials and strict design of liquid phase epitaxy process parameters, and can grow the M-type barium ferrite monocrystal thin film with excellent performance on SGGG (111) substrate by liquid phase epitaxy method under low temperature conditions of 830-850 DEG C, which is not only simple in process and low in cost, but also has high crystallization quality, no impurities and defects. The M-type barium ferrite monocrystal thin film prepared by the method is a single crystal material, the film thickness is up to 150 mu m, the saturation magnetization is about 4500 Oe, the remanence is about 1000 Oe, the easy magnetization axis (c axis) is perpendicular to the film surface, has high uniaxial magnetic crystal anisotropy field, and is very beneficial to realize self-bias design of the device.

The application discloses a cold-rolled steel low-residual-magnetic annealing process, which comprises the following steps: placing steel into an annealing furnace and heating to 670-700 DEG C, keeping for 55-70 min to eliminate deformation strengthening and residual stress; then reducing the temperature of the steel to 480-520 DEG C at an average cooling speed less than 1.5 DEG C / min; then heating the steel to 780-810 DEG C, keeping for 170-190 min to increase the grain size and eliminate the residual magnetic field in the material through the movement of the thermal activated magnetic domain wall; injecting a protective atmosphere, reducing the temperature of the steel to 640-670 DEG C at an average cooling speed less than 1 DEG C / min, and performing magnetic gas annealing to reduce the oxides and impurities in the steel, improve the magnetic crystal anisotropy of the magnetic material, improve the magnetic permeability and the magnetic saturation induction intensity of the magnetic material, and finally make the steel reach an extremely low residual magnetism with a magnetic field intensity less than 1 a / cm and good magnetic properties.

According to the low-cost high-magnetic-conductivity high-magnetic-shielding magnetically soft alloy and the preparation method thereof, Fe-Si-Al is adopted as a basic system, microalloying elements such as B and Nb are creatively introduced, specific critical cold rolling and magnetic field heat treatment processes are adopted, and the obtained magnetically soft alloy has high magnetic conductivity and high magnetic shielding effectiveness. Wherein the resistivity of the alloy is effectively improved and the magnetocrystalline anisotropy is optimized through the synergistic effect of Si and Al; the grain boundary segregation effect of the B element purifies the grain boundary, and the moving resistance of the magnetic domain wall is remarkably reduced; and the dispersed precipitated phase formed by the Nb element effectively refines the initial crystal grains and lays a foundation for subsequent formation of uniform and thick recrystallized crystal grains. Particularly, a strong Gaussian texture is induced through accurately controlled critical cold rolling deformation, and magnetic domains are directionally arranged in an easy magnetization direction in combination with magnetic field heat treatment applied near a Curie point, so that the coercive force is fundamentally reduced, and the initial magnetic conductivity is improved.

The invention discloses a barium-strontium permanent magnetic ferrite material with a high torque-to-magnetic ratio and a preparation method thereof, relates to the technical field of electronic information materials, and discloses the barium-strontium permanent magnetic ferrite material with the high torque-to-magnetic ratio and the preparation method thereof. The barium-strontium permanent magnetic ferrite material with the high torque magnetic ratio is based on barium-strontium ferrite of a magnetoplumbite structure, the chemical formula is expressed as Ba < 0.5-x > Pr < x > Sr < 0.5-y > HoyFe < 12-x-y > Co < x + y > O < 19 >, x is equal to 0.05-0.15, y is equal to 0.05-0.15, x and y are molar stoichiometric ratios, and the barium-strontium permanent magnetic ferrite material with the high torque magnetic ratio has the advantages that rare earth Pr < 3 + > ions and Ho < 3 + > ions capable of improving magnetocrystalline anisotropy are added to replace Ba < 3 + > ions and Sr < 3 + > ions on the basis of a ferrite material of Ba < 0.5 > Sr < 0.5 > Fe < 12 > O < 19 >, so that the magnetic anisotropy of meanwhile, Fe < 3 + > ions are replaced by Co < 2 + > ions, so that the Curie temperature and the equilibrium valence of the material are improved; and secondly, a constant-pressure cold sintering process is adopted in the process, and magnetic field orientation is added, so that a microstructure with a high orientation degree is obtained, the torque-to-magnetic ratio performance of the material is improved, and the barium-strontium permanent magnetic ferrite material with a high torque-to-magnetic ratio is obtained.

The application discloses a horizontal steering wheel strip-shaped automatic magnetic free-stretching data line, a preparation method and application. The data line comprises a flexible coating on the core, a flexible permanent magnetic coating layer in the middle and a flexible outer coating layer from inside to outside, and the preparation method comprises the following steps: step A, extrusion molding; step B, first north-south direction 180° constant magnetic field orientation magnetization, horizontal steering wheel strip-shaped shaping and preliminary forming; and then magnetization, horizontal reverse steering wheel strip-shaped automatic magnetic free-stretching data line. The application aims to solve the phenomenon that the existing technology data line automatic curling magnetic attraction is not completed, and the samarium iron nitrogen magnetic performance of the magnetic crystal anisotropy field which is much higher than other permanent magnetic materials can be better played through the improvement of the magnetization mode, so that the data line has the advantages of temperature resistance, corrosion resistance and demagnetization resistance, and the magnetic layer thickness is not required to be increased to meet the data line attraction requirement.

The application relates to the technical field of magnetic functional materials, in particular to a light rare earth Pr-based ultrahigh magnetostrictive material and a preparation method thereof. The material is prepared from the following raw materials in parts by weight: 20-35 parts of praseodymium-neodymium mixed rare earth metal, 60-75 parts of pure iron, 3-8 parts of metal cobalt, 0.5-2 parts of metal niobium, 0.1-0.5 parts of additive A and 0.5-2 parts of additive B. The additive A is enriched at the grain boundaries, hinders the coarsening of the grains in the processing process, thereby obtaining fine grain structures, and provides an optimized microstructure basis for the magnetostrictive performance. Meanwhile, the additive B is used to improve the bonding state between the rare earth phase and the ferromagnetic matrix, and promotes the directional rotation process of the magnetic domains under the external magnetic field. The effects are combined with the inherent strong magnetic crystal anisotropy of the Pr element and the specific hydrogen crushing and magnetic field orientation hot-pressing process, and the magnetostrictive strain and driving capacity of the material are synergistically enhanced.

The application discloses a data line with a vertical steering wheel strip-shaped automatic magnetic free stretching data line and a preparation method and application, the data line comprises a flexible coating on a core, a flexible permanent magnetic coating layer in the middle and a flexible outer coating layer from inside to outside in sequence, and the preparation method comprises the following steps: step A, extrusion molding; step B, first, pre-magnetization is performed to form a vertical steering wheel strip-shaped shape, then, a 180-degree constant magnetic field in the north-south direction is used for orientation, and finally, magnetization is performed. The application aims to solve the phenomenon that the automatic winding and magnetic attraction of the prior art data line are not completed, so that the magnetic crystal anisotropy field of samarium iron nitrogen which is much higher than other permanent magnetic materials can be better used, the data line has better advantages such as temperature resistance, corrosion resistance and demagnetization resistance, and the requirement of the data line attraction force can be met by thickening the magnetic layer.

The invention discloses a preparation method of flower-like nano-silver particles, which comprises the following steps: preparing a mixed aqueous solution of ascorbic acid and a surfactant, heating and stirring; preparing a silver nitrate aqueous solution, heating and stirring; and dropwise adding the silver nitrate aqueous solution into the mixed aqueous solution at the rate of 10-35 mL / min, and continuously reacting for 5-10 minutes after dropwise adding is finished, so as to obtain the flower-shaped nano-silver particles. The method is simple in process operation, the reaction is carried out in a water phase at normal pressure and medium temperature, ascorbic acid is used as a reducing agent, toxic solvents are avoided, complicated equipment (such as vacuum and laser) is not needed, the method is green and environment-friendly, and controllable growth of flower-like morphology is finally formed by controlling anisotropic growth of silver crystals; and flower-like nano-silver particles with uniform morphology and high purity are prepared under mild conditions by a one-step method.

The application provides a ceramic injection molding 3D winding surface type Ni-Zn ferrite material and a preparation method thereof. The material is composed of Fe2O3 45wt%-49wt%, NiO 18wt%-33wt%, ZnO 22wt%-33wt%, CuO 5wt%-7wt%, SnO2 0.2wt%-1.0wt%, Co3O4 0.3wt%-0.7wt% and modified multi-walled carbon nanotubes 1.2wt%-1.5wt% by weight. The modified multi-walled carbon nanotubes are multi-walled carbon nanotubes loaded with Fe2O3 / Fe3O4 on the surface. The material is suitable for ceramic injection molding, can accurately form the required curved surface, thin wall and fine groove of the 3D winding surface type, can improve the sintering density by adding SnO2, can optimize the powder dispersibility by adding the modified multi-walled carbon nanotubes, can greatly improve the material fluidity and forming stability, can avoid the problem of low magnetic core precision, can adjust the magnetic crystal anisotropy by adding Co3O4, can reduce the permeability fluctuation rate at low temperature, can improve the mechanical strength after debinding and sintering, and can reduce damage in use. The material has the advantages of long service life, reasonable component design, simple implementation, and easy popularization and implementation.

The invention discloses a method and a device for predicting the high-temperature creep fatigue life of a nickel-based single crystal. The method comprises the following steps: obtaining a stress-strain hysteretic loop of a material in a stable cycle or a half-life cycle through experimental testing or combination of a material constitutive model and finite element simulation; extracting slitting shear stress, slitting shear strain, slitting positive stress and slitting positive strain on octahedral and hexahedral slip systems according to the stress-strain hysteretic loop and the orientation of the test sample; fatigue damage is calculated according to the stress-strain amplitude on the slip system, creep damage is calculated according to the stress-strain hysteresis loop, and creep-fatigue coupling damage is calculated according to the creep damage and the fatigue damage; and judging whether the creep damage is tensile creep or compression creep so as to calculate total damage, and obtaining the creep fatigue life according to the total damage. According to the method, the crystal anisotropy characteristics of the nickel-based single-crystal high-temperature alloy can be considered in a unified manner, and creep fatigue life prediction based on a physical mechanism is realized.