46results about How to "Good coercivity" patented technology

Provided is a magnetic recording medium including: a non-magnetic support; and a magnetic layer including particles of at least one kind of epsilon type iron oxide-based compound selected from the group consisting of ε-Fe₂O₃ and a compound represented by Formula (1), an abrasive, and a binding agent, at least on one surface of the non-magnetic support, in which an average equivalent circle diameter of the particles of the epsilon type iron oxide-based compound is 7 nm to 18 nm, an average equivalent circle diameter of the abrasive in a plan view of the magnetic layer is 20 nm to 1,000 nm, and a coefficient of variation of the equivalent circle diameter of the abrasive is 30% to 60%. In Formula (1), A represents at least one kind of metal element other than Fe and a satisfies a relationship of 0<a<2.

ε-A_aFe_2-aO₃  (1)

The invention discloses a method of improving the coercivity of sintering Nd-Fe-B magnetic materials. The method includes the following steps of using hydrogen to crush Nd-Fe-B alloy, powder processing, compression moulding, sintering and tempering under the protection of vacuum or protective gases. The sintering condition consists of heating to 300 to 600 DEG C, keeping the temperature for 5 to 6 hours to dehydrogenize, heating once again to 1060 to 1120 DEG C, sintering for 1 to 60 minutes under high temperature, finally decreasing the temperature to 1000 to 1050 DEG C, keeping sintering for 1 to 4 hours under the temperature and cooling. The method adopts the steps of sintering for a short period under high temperature to precipitate the liquid phase and then sintering under lower temperature. The liquid phase is rapidly precipitated under high temperature, thereby improving the sintering process of the magnetic materials, promoting the performance of sintering process, controlling the grain size through sintering under lower temperature, inhabiting grain growth and benefiting obtaining an excellent coercivity of magnetic materials.

The invention relates to a treating agent and an electro-deposition method for forming a rare earth hydride particle coating, and belongs to the technical field of magnetic materials. Rare earth hydride particles are dispersed in a dispersing agent, wherein n-hexane or n-heptane is taken as the dispersing agent; the rare earth is at least one element of Pr, Nd, Tb, Dy and Ho. The hydride particles are deposited on the surface of a sintered NdFeB rare earth magnet by using the electro-deposition method so as to form the uniform and dense coating with controllable thickness. The rare earth hydride particle coating can be used for obviously improving the magnetic property of the sintered NdFeB rare earth magnet and especially the coercivity of the magnet. As the method is adopted, the usage amounts of heavy rare earths in the sintered NdFeB rare earth is decreased on the premise of guaranteeing good magnetic property of the magnet, so that the manufacturing cost of the magnet with high coercivity is reduced.

A hard bias (HB) structure for longitudinally biasing a free layer in a MR sensor is disclosed that includes a mildly etched seed layer and a hard bias (HB) layer on the etched seed layer. The HB layer may contain one or more HB sub-layers stacked on a lower sub-layer which contacts the etched seed layer. Each HB sub-layer is mildly etched before depositing another HB sub-layer thereon. The etch may be performed in an IBD chamber and creates a higher concentration of nucleation sites on the etched surface thereby promoting a smaller HB average grain size than would be realized with no etch treatments. A smaller HB average grain size is responsible for increasing Hcr in a CoPt HB layer to as high as 2500 to 3000 Oe. Higher Hcr is achieved without changing the seed layer or HB material and without changing the thickness of the aforementioned layers.

A preparation method of a high-performance sintered neodymium-iron-boron magnet belongs to the technical field of rare earth permanent magnet materials and comprises the following steps: preparing single alloy or main alloy and auxiliary alloy micro powder by adopting vacuum rapid hardening melt-spinning and hydrogen decrepitation processes; adding a lubricating agent, an antioxidant and a dispersing agent, and mixing; grinding powder by airflow, adding a lubricant into magnetic powder, mixing, orienting the magnetic powder in a magnetic field, pressing and molding, and carrying out isostaticcool pressing treatment; carrying out heat preservation and deflation treatment in three temperature sections; cooling to 300-500 DEG C, introducing high-purity argon with the pressure intensity of 2-10 MPa, and carrying out hot pressing treatment; sintering at high temperature, naturally cooling to 800-900 DEG C, introducing room-temperature argon or liquid argon, and performing rapid cooling; and then carrying out two-stage heat treatment and argon rapid cooling respectively. According to the invention, the density of the final magnet is improved by improving the density before high-temperature sintering, so that the residual magnetism and the maximum magnetic energy product are enhanced. By reducing the sintering temperature, the coercive force can be obviously improved under the conditions of high residual magnetism and high magnetic energy product. The method has good economic benefits and is suitable for industrial production.

A method of manufacturing an R-T-B rare earth sintered magnet includes a process of disposing and sintering a compact of a first alloy powder and an alloy material of a second alloy in a chamber of a sintering furnace. The first alloy consists of R which represents a rare earth element, T which represents a transition metal essentially containing Fe, a metal element M which represents Al and/or Ga, B, Cu, and inevitable impurities. The first alloy contains 11 at % to 17 at % of R, 4.5 at % to 6 at % of B, 0 at % to 1.6 at % of M, and T as the balance, and Dy content in all of the rare earth elements is 0 at % to 29 at %. The second alloy consists of R which represents a rare earth element, T which represents a transition metal essentially containing Fe, a metal element M which represents Al and/or Ga, B, Cu, and inevitable impurities. The second alloy contains 11 at % to 20 at % of R, 4.5 at % to 6 at % of B, and 0 at % to 1.6 at % of M, and T as the balance, and Dy content in all of the rare earth elements is 0 at % to 29 at %.

An epitaxial growth method of a yttrium iron garnet film comprises the following steps: vacuumizing a vacuum cavity with a treated yttrium iron garnet substrate to be 8.6+/-1*10-6 Pa, and heating the yttrium iron garnet substrate to the constant temperature which is 736 DEG C; in a heating process, feeding ozone when heating to the temperature of 250 DEG C; after heating to the temperature of 736 DEG C, maintaining air pressure of the vacuum cavity, adjusting the mass fraction of the ozone to be 40%, meanwhile insulating for half a hour, and starting a reflective high-energy electron diffraction instrument (RHEED) to adjust so as to obtain diffraction spots of a substrate; maintaining real-time and in-situ monitoring of the RHEED in the whole process, and focusing laser onto a YIG target through a lens by using a KrF excimer laser of which the wavelength is 248 nm; after growth of the film is finished, maintaining the temperature of the substrate unchanged, annealing in situ for 15 minutes, then naturally cooling the film to the temperature about 250 DEG C, stopping protective gas and cooling to the room temperature. The obtained YIG film has uniform components, is controllable in thickness and good in process repeatability, and has high preparation efficiency.

The invention relates to an Fe-based bulk permanent magnet alloy with excellent coercive force and a preparation method thereof. The composition (atomic percentage) of the Fe-based bulk permanent magnet alloy of the present invention is: Fe55-75%, Nd5-15%, Nb1-7%, B18-30%. The preparation process is as follows: (1) The industrial pure metal raw materials Fe, Nd, Nb and FeB alloy are mixed according to the above formula, and then smelted in a vacuum non-consumable electric arc furnace under the protection of argon, and the alloy is smelted repeatedly for 3~ 5 times, the master alloy was obtained; (2) after remelting the master alloy, it was poured by copper mold negative pressure suction casting method, and the Fe-based bulk amorphous alloy was obtained. (3) Vacuum annealing the above bulk amorphous alloy at 580-850°C and a vacuum degree of 3-5×10-3Pa for 10-35 minutes to obtain Fe with excellent coercive force Base bulk permanent magnet alloy. The Fe-based alloy of the present invention has soft magnetic properties in the as-cast state. After vacuum annealing, the alloy changes from soft magnetic to hard magnetic, with saturation magnetization Ms=61Am2/kg and coercive force jHc=819kA/m.

The invention discloses an R-T-B series magnetic material and a preparation method thereof. The R-T-B series magnetic material provided by the invention comprises the following components (1) to (6) in percentage by weight: (1) 29.50wt.% to 33.00wt.% of R, wherein R is a rare earth element and comprises Pr and RH, Pr is greater than or equal to 15.00wt.%, and RH comprises Tb and/or Dy; (2) 0.24wt.% to 0.80wt.% of Cu; (3) 0.05wt.% to 0.50wt.% of Ti, and/or 0.10wt.% to 1.20wt.% of Nb; (4) 0wt.% to 1.52wt.% of Al; (5) 0.90wt.% to 1.03wt.% of B; and (6) 0.05wt.% to 1.50wt.% of Ga. The material hasgood residual magnetism, coercive force and the like.

The invention discloses a rare earth permanent magnet material and a preparation method and application thereof. The raw material composition of the rare earth permanent magnet material comprises thefollowing components in percentage by mass: 28.5-33.0% of R, 0.5%-1.8% of Ga, but not 0.5 wt% of Ga, 0.84%-0.94% of B, 0.05 to 0.07% of Al, and <=2.5% but not 0 of Co, 62-69% of Fe; N is one or moreof 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%; and the percentage is the mass percentage of each component in the total mass of the raw material composition. The rare earth permanent magnet material has better magnetic properties (residual magnetism, coercive force, squareness and temperature stability), and the magnetic properties of the same batch of products are uniform.

An R-T-B based permanent magnet includes R-T-B based compounds as main-phase crystal grains. R is a rare earth element. T is iron group element(s) essentially including Fe or Fe and Co. B is boron. A two-grain boundary is contained between the two adjacent main-phase crystal grains. An average grain size of the main-phase crystal grains is 0.9 μm or more and 2.8 μm or less. A thickness of the two-grain boundary is 5 nm or more and 200 nm or less.

The invention discloses a neodymium iron boron material and a preparation method and application thereof. The raw material composition of the neodymium iron boron material comprises the following components by mass: 28.5-34% of R; R is a rare earth element and comprises Nd; 0.84%-0.94% of B; Cu: 0.45 < Cu < = 2%; Co: < = 2.5%, but not 0; Fe: 61 to 69 %; N, containing 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, 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. According to the neodymium iron boron material, on the premise of not adding heavy rare earth elements, the neodymium iron boron material which is good in magnetic performance and uniform in magnetic performance in the same batch can still be prepared by adopting a low-boron aluminum-free system.

The invention discloses a neodymium iron boron material and a preparation method and application thereof. The raw material composition of the neodymium-iron-boron material comprises the following components in percentage by mass: 28.5-33.0% of R and the balance of Fe and inevitable impurities, r is a rare earth element at least containing Nd; 0.45%-2% of Cu, but not 0.45% of Cu; b: 0.84%-0.94% ofthe total weight of the raw materials; 0.05 to 0.07% of Al; co: < = 2.5% but not 0; 62 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 neodymium iron boron material is good in magnetic performance, and the magnetic performance of products of the same batch is uniform.

The invention discloses a wireless charging magnetic sheet screening method which comprises the following steps: selecting and stirring ferrite powder with uniform granularity and high activity, adding TbFx and copper-tin alloy powder into a stirrer step by step for stirring, then introducing an ingredient additive, performing doping treatment and pre-sintering treatment, pressing the mixture intoa strip-type green body, and cleaning, drying, cutting and grinding the green body in sequence to obtain a magnetic core. The method is environmentally friendly and low in energy consumption; a magnetic core product is high in performance and high in reliability.