99results about How to "Improve squareness" patented technology

The present invention provides a permanent magnet that a fluorine compound is formed on the surfaces of Fe-based magnetic particles, and a recoil permeability is determined in a range of 1.05 to 1.30 by controlling an iron concentration in the fluorine compound to a range of 1 to 50% to reduce a loss due to magnetization rotation, thereby remedying reduction of a residual magnetic flux density and degradation of steady-state characteristics.

The invention provides a high-temperature high-coercivity samarium-cobalt permanent magnet material and a preparation method thereof. The permanent magnet material is Sm(Co1-u-v-wFeuCuvZrw)z, whereinu ranges from 0.09-0.18, v ranges from 0.05-0.10, w ranges from 0.02-0.04 and z ranges from 6.9-7.8. The preparation method includes the steps that the rare earth element Sm with the purity of 99.95%,Co with the purity of 99.98%, Cu with the purity of 99.99%, Fe with the purity of 99.9% and Zr with the purity of 99.9% are evenly mixed and smelted into an alloy ingot, and the ingot is subjected tostructure optimization treatment; micron-sized alloy powder is prepared by using the powder metallurgy technology, then orientation forming, high-temperature sintering, solid solution and aging treatment are conducted, and the samarium-cobalt permanent magnetic alloy is prepared. According to the method, the proportion of a TbCu7 structure is effectively improved, and a samarium-cobalt permanentmagnet free of a Zr6(FeCo)23 phase and uniform in structure is prepared, has high coercivity, high magnetic energy and other excellent properties at ultra-high temperature and can be suitable for ultra-high-temperature environments with the temperature of 550 DEG C or above.

A fabrication method of a magnetic tunnel junction includes the steps of: forming a magnetic tunnel junction constructed having a first magnetic layer, a tunnel barrier formed at an upper surface of the first magnetic layer and a second magnetic layer formed at an upper surface of the tunnel barrier; and thermally treating the junction rapidly for 5 seconds˜10 minutes at a temperature of 200˜600° C. to re-distribute oxygens in the tunnel barrier and make the interface between the tunnel barrier and the magnetic layer to be even. The tunneling magnetoresistance and thermal stability of the magnetic tunnel junction can be improved through the rapid thermal annealing.

The invention relates to a double-hard magnetic main phase mixed rare-earth permanent magnet and a preparation method thereof. The permanent magnet comprises double hard magnetic main phases and a rear-earth-rich phase, wherein the double hard magnetic main phases are MM<2>Fe<14>B and (PrNd)<2>Fe<14>B respectively; the permanent magnet is prepared from the following chemical component in percentage by mass: [MM<x1>(PrNd)<1-x1>]<x>Fe<100-x-y-z>B<y>TM<z>; x is smaller than or equal to 31 and greater than or equal to 27; x1 is smaller than or equal to 1 and greater than or equal to 0; y is smaller than or equal to 1 and greater than or equal to 0.9; z is smaller than or equal to 1.5 and greater than 0; TM is a composition of more of the elements Al, Cu, Co, Nb, Ga, Tb and Zr; and MM is a mixed rare-earth alloy which is directly separated from raw ore and contains La, Ce, Pr and Nd. The anisotropic sintered mixed rare-earth permanent magnet with high cost performance within a range of 10-48MGOe can be prepared by adjusting the content of PrNd. A basic rare-earth raw material used by the permanent magnet is cheap mixed rare earth, so that a separation and purification technology for the rare earth can be reduced, efficient utilization of lanthanum-cerium rare earth is achieved and the double-hard magnetic main phase mixed rare-earth permanent magnet meets the requirements of low carbon economy on green production technology innovation of a rare-earth permanent magnet product.

A nanogranular thin film consisting of nonmagnetic matrix and ferromagnetic fine particles in nano scale is improved to enhance the thermal stability and the S/N ratio. The ferromagnetic fine particles consist of (FeaCo1-a)1-xPtx, (0.3<=x<=0.7, 0.1<=x<=1), (FeaCo1-a)1-xPdx, (0.3<=x<=0.7, 0.1<=x<=1) or (FeaCo1-a)1-x(PtbPd1-b)x, (0.3<=x<=0.7, 0.1<=x<=1, and 0<b<1).

The invention provides an NdFeB magnet which comprises, by mass, 29% to 33% of Pr-Nd, 0.97% to 1.5% of B, 0.4% to 0.6% of Dy, 0.2% to 0.8% of Al, 0.6% to 0.8% of Co, 0.01% to 0.5% of Cu, 0.01% to 0.2% of Zr and the balance Fe. The invention further discloses a preparation method of the NdFeB magnet. The method includes the steps that firstly, Pr-Nd alloy, Zr-Fe alloy, B-Fe alloy, Dy-Fe alloy, aluminum, cobalt, copper and iron are molten to prepare an NdFeB cast ingot; secondly, the obtained NdFeB cast ingot is milled into NdFeB powder; finally, the NdFeB powder is sintered into the NdFeB magnet. The NdFeB magnet prepared through the method has a more refined magnet grain size and higher magnet stability.

The invention provides a novel material distribution device and a floor concrete casting construction method of the novel material distribution device, wherein the novel material distribution device mainly comprises a foundation section, a standard section, a material distribution rod, a pump pipe and a pump pipe loop, wherein the foundation section is fixed on the lower two layers of a construction layer; the standard section is fixed on the standard section; the standard section sequentially passes through holes reserved in the lower layer of the construction layer and the construction layer but is not in contact with the holes; the material distribution rod is fixed above the standard section; the pump pipe is connected with one end of the material distribution pipe arranged on the material distribution rod; the other end of the material distribution pipe is connected with a hose used for concrete casting; the pump pipe loop is specially used for cleaning a material distribution machine; and waste water can be directly conveyed into a collecting device arranged on the ground. The novel material distribution device and the floor concrete casting construction method of the concrete casting construction method can solve the following technical problems that the problem of damage of a conventional floor concrete cast pump pipe to floor steel bars is solved; the problem of influence of the vibration of the conventional floor concrete cast pump pipe on a formwork support frame system and a formwork system is solved; and the problems of pollution and cleaning complexity of the conventional floor concrete cast pump pipe are solved.

The invention discloses alloy powder for a rare-earth magnet, methods for manufacturing the alloy powder and the rare-earth magnet and a powder manufacturing device. The method for manufacturing the alloy powder includes acquiring all powder with the grain size smaller than 50 micrometers in working procedures for finely crushing at least one type of alloy for the rare-earth magnet and at least one type of alloy coarse powder for the rare-earth magnet by the aid of high-speed inert gas flow with the oxygen content lower than 1000ppm. By the aid of the alloy powder, the methods and the powder manufacturing device, ultrafine powder with the grain size smaller than 1 micrometer does not need to be separated from crushed powder which is transmitted from a crushing device and has a low oxygen content, the oxygen content of atmosphere of the crushing device is reduced and is lower than 1000ppm when the crushing device is used for crushing, and accordingly abnormal grain growth (AGG) can be prevented in a follow-up sintering procedure for acquiring a sintered magnet with a low oxygen content. The alloy powder, the methods and the powder manufacturing device have the advantages that working procedures can be simplified, and the manufacturing cost can be reduced.

The invention discloses a preparation method of a sintered neodymium iron boron magnet free of heavy rare earth. The preparation method comprises the following steps of (a), configuring neodymium ironboron alloy and preparing a quick hardening sheet; (b), performing hydrogen demolish treatment on the quick hardening sheet to obtain rough powder; (c), adding a reagent to the rough powder, next performing grinding until the average grain diameter SMD is equal to 3.0-4.0[mu]m; (d), adding a reagent to the grinded powder, and performing re-grinding until the SMD is equal to 1.5-2.0[mu]m; (e), performing pressing and shaping in a magnetic field orientation condition, wherein the orientation magnetic field is 2.0-3.0T, and then carrying out an isostatic pressing mode to further enable the magnet to be sense; and (f), performing sintering on the green body obtained after isostatic pressing in a vacuum sintering furnace, performing cooling, and then carrying out first-stage aging tempering treatment and second-stage aging tempering treatment. According to the preparation method disclosed in the invention, in the air flow milling process, an additive is added and secondary grinding is performed, so that rough particles are reduced, and the mixed reagent can fully coat fine powder, powder oxidization is prevented, powder fluidity is improved, corrosion is eliminated, and powder consistency is improved.

The invention discloses a sintered Nd-Fe-B magnet manufacturing method and device. The method comprises the following steps: in the manufacturing procedure of Nd-Fe-B system sintered magnet in which the oxygen content is below 2,500 ppm and in the crushing procedure under the condition that the oxygen content in inert gas is below 1,000 ppm, after the grading step, a mixing step is added to re-mix the originally separated ultrafine powder into finished crushed powder, and the originally separated ultrafine powder enters the follow-up processing procedure together with the finished crushed powder. By adopting the method, in the follow-up sintering procedure, AGG (Abnormal Grain Growth) can not be easily caused in the follow-up sintering procedure, besides, precious rare earth can be saved and extremely high pricing competitiveness is achieved through material conservation.

The invention discloses a neodymium-iron-boron permanent magnet material, and a raw material composition and a preparation method thereof. The raw material composition for preparing the neodymium ironboron permanent magnet material comprises the following components: 0.25-0.5 mass percent of Nb and 0.55-0.8 mass percent of Cu. The squareness of the neodymium-iron-boron permanent magnet material prepared from the raw material composition is 99% or above. The absolute values of the temperature coefficients of Hcj at the temperature of 20-150 DEG C are all 0.422% or below; the heat treatment temperature zone is 470-510 DEG C; Br is greater than or equal to 14kGs, and the coercive force is greater than or equal to 25kOe.

A magnetic tunneling junction structure for magnetic random access memory is disclosed. A composite structure includes at least a pinning layer, a barrier layer, a ferromagnetic layer and a free layer, and the material of the pinning layer and the free layer are perpendicularly anisotropic ferrimagnetic. As the structures include of several barrier layers, free layers and ferrimagnetic layers, that lower coercivity and high squareness for the hysteresis curves can be obtained, and reduction of the coercivity of the free layer can be achieved.

The invention provides a tempering technology for an NdFeB magnet. The tempering technology comprises steps as follows: firstly, under the condition of vacuum or protective gas, a sintered NdFeB magnet blank is subjected to primary heating and primary heat preservation, and a primary tempered intermediate is obtained after cooling; then, the primary tempered intermediate obtained in the step is tempered N times, and the NdFeB magnet is obtained; each tempering process is as follows: heating is performed firstly, cooling is performed, heat preservation is performed, and cooling is performed finally; the heat preservation temperature is T, and heat preservation temperatures of the tempering processes decrease sequentially; n is a natural number larger than or equal to 1. The technology starts from the tempering processes during preparation of the magnet, a technology of multistage tempering heat treatment is adopted, that is, a method adopting three-stage tempering after two-stage tempering is adopted, a multistage tempering method adopting four-stage tempering after two-stage tempering and three-stage tempering can be adopted, the coercivity can be effectively improved, and the density and square degree of the magnet can be improved.

The invention discloses an R-T-B series permanent magnet material, a raw material composition and a preparation method and application thereof. The raw material composition of the R-T-B series permanent magnet material comprises the following components in percentage by mass: 29.5-32% of R which is a rare earth element at least containing Nd, whereinthe content of Pr is 0-17%; 0.15-0.50% Zr; 0-0.08% of Cu, wherein Cu is not 0 or 0.08; 0-0.3% of M, wherein M is one or more of Al, Ga, Ti, Nb, Hf, Si, Sn, Ge, Ag, Au, Bi and Mn; 0.95-1.05% of B; and 64-70% of Fe, wherein the percentage is the masspercentage accounting for the total mass of the raw material composition of the R-T-B series permanent magnet material, and the sum of the contents of all the components is 100%. The R-T-B series permanent magnet material has the advantages of being good in squareness, good in high-temperature performance and excellent in mechanical performance.

The invention provides a sintering method for a neodymium-iron-boron magnet. The method comprises the following steps: firstly, carrying out continuous warming or stepped warming on a green neodymium-iron-boron magnet body to reach a sintering temperature under a vacuum or protective gas condition, and obtaining a neodymium-iron-boron magnet intermediate; and carrying out constant-temperature firing on the neodymium-iron-boron magnet intermediate obtained in the previous step under a hydrogen condition, and obtaining a neodymium-iron-boron magnet blank. In a plurality of steps for preparing the neodymium-iron-boron magnet, hydrogen is filled into a system at a specific high-temperature sintering stage in the sintering process from the sintering method, so that a neodymium-rich phase in the blank material is uniform in distribution; a rare-earth phase is prevented from being consumed; a rare-earth phase oxide is avoided; rare earth does not need to add when a formula is designed; the cost is saved; the coercivity of a product is also improved; and the sintering method has very important significance for development of a neodymium-iron-boron magnet product.

The invention discloses an R-T-B series permanent magnet material and a preparation method and application thereof. The raw material composition of the R-T-B series permanent magnet material is prepared from the following components in percentage by mass: 28.5 to 33.0 percent of R; ga:>0.5%; cu: > = 0.4%; b: 0.84%-0.94% of the total weight of the raw materials; 0.05 to 0.07% of Al; co: < = 2.5% but not 0; 60 to 70 percent of Fe; n is one or more of Ti, Zr and Nb; when N contains Ti, the content of Ti is 0.15%-0.25%; when N contains Zr, the content of Zr is 0.2%-0.35%; when N contains Nb, the content of Nb is 0.2%-0.5%; wherein the percentage is the mass percentage of each component in the total mass of the raw material composition. The R-T-B series permanent magnet material disclosed by the invention is relatively good in magnetic performance, and the magnetic performance of the same batch of products is uniform.

The invention provides a cerium-containing neodymium-iron-boron magnet and a heat treatment processs and application thereof. The cerium-containing neodymium-iron-boron magnet comprises that followingcomponent in parts by weight: 20-32 parts by weight of praseodymium-neodymium alloy (Pr-Nd), 3-11 parts by weight of cerium (Ce), 40.65 to 76.06 parts by weight of iron (Fe), wherein the percentage content of heavy rare earth elements in the cerium-containing neodymium-iron-boron magnet is low than 3 percent, and the cerium-containing neodymium-iron-boron magnet does not contain low melting pointrare earth liquid phase alloy. The heat treatment process comprises a three-stage tempering treatment. The cerium-containing neodymium-iron-boron magnet can be used for preparing motors, the cerium-containing NdFeB magnet has excellent performance.

The invention relates to high-performance permanent magnet ferrite with an extremely-low Hcj temperature coefficient. A main phase molecular formula is SrxAyB1-x-yFezCnOm, wherein A is one or more of elements Ca, Ba and Pb; B is one or more of elements La, Bi and Y; C is one or more of elements Co, Zn, Ni, Cd, Mn, Cu and Cr; x, y, z, n and m represent a molar ratio, and the value taking ranges are that x is more than or equal to 0.1 but less than or equal to 0.6, y is more than or equal to 0.05 but less than or equal to 0.5, n is more than or equal to 0 but less than or equal to 0.3, z is more than or equal to 9.0 but less than or equal to 12, and m is more than or equal to 0.15 but less than or equal to 19. The permanent magnet ferrite provided by the invention can achieve high performance and has low Hcj temperature coefficient. According to a preparation method of the high-performance permanent magnet ferrite with the extremely-low Hcj temperature coefficients, a primary additive contains boric acid and ammonium bicarbonate, can promote the full generation of an M phase of the permanent magnet ferrite and plays a great role in promoting the magnetic property and the stability of the low Hcj temperature coefficient.