421 results about "High saturation magnetization" patented technology

A magnetic recording medium includes a substrate, an underlayer, a lower magnetic layer formed on the underlayer, an intermediate layer, and an upper magnetic layer formed on the intermediate layer. The intermediate layer is typically Ru, and promotes antiferromagnetic coupling between the upper and lower magnetic layers. The upper and lower magnetic layers are typically Co alloys. The lower magnetic layer has a high saturation magnetization Ms to promote high exchange coupling between the upper and lower magnetic layers. The dynamic coercivity of the lower magnetic layer is lower than the exchange field to ensure rapid switching of the lower magnetic layer.

A thermal spring magnetic medium is provided having first and second stacks providing two exchange coupled ferromagnetic layers having different Curie temperatures. The first stack has a high magneto-crystalline anisotropy, a relatively low saturation magnetization and a low Curie temperature. The second stack has a relatively low magneto-crystalline anisotropy, a high saturation magnetization and a high Curie temperature. Preferably the first stack includes an alloy of Fe—Pt or Co—Pt, and the second stack includes an allow of Co—Pt or Co—Pd. A disk drive system having the novel medium is also provided.

A family of iron-based, phosphor-containing bulk metallic glasses having excellent processability and toughness, methods for forming such alloys, and processes for manufacturing articles therefrom are provided. The inventive iron-based alloy is based on the observation that by very tightly controlling the composition of the metalloid moiety of the Fe-based, P-containing bulk metallic glass alloys it is possible to obtain highly processable alloys with surprisingly low shear modulus and high toughness. Further, by incorporating small fractions of silicon (Si) and cobalt (Co) into the Fe—Ni—Mo—P—C—B system, alloys of 3 and 4 mm have been synthesized with high saturation magnetization and low switching losses.

The invention relates to a high saturation magnetization intensity Fe-based nanocrystalline magnetically soft alloy material and a preparation method thereof. The high saturation magnetization intensity Fe-based nanocrystalline magnetically soft alloy material is a FexSiyBzPaCub alloy comprising ferrum, silicon, boron, phosphorus and copper, wherein x, y, z, a and b in the formula respectively represent atom percentage content of each corresponding component, x=70-90%, y=1-15%, z=1-20 %, a=1-20% and b=0.1-1%, and x+y+z+a+b=100%; the microstructure of the Fe-based nanocrystalline magnetically soft alloy is as follows: a body-centered cubic Alpha-Fe(Si) nanocrystalline phase with the size of 1-35nm and an amorphous phase rich in phosphorus and boron coexist, and the amorphous phase is the basic phase. The preparation method comprises steps of: preparing proportioned raw materials into an alloy ingot, preparing into amorphous alloy and carrying out other procedures to obtain the high saturation magnetization intensity Fe-based nanocrystalline magnetically soft alloy. The invention can greatly enhance the saturation magnetization intensity of the nanocrystalline magnetically soft alloy, maintain lower coercivity and effectively reduce cost of raw materials simultaneously.

The invention discloses a high-saturated magnetization intensity Fe-based amorphous nanocrystalline soft magnetic alloy and its preparation method. The alloy is prepared from the following components, by mole, 68-90% of Fe, 0-6% of X, 0-2% of Cu, 3-20% of Si, 4-20% of B and 0-10% of P, wherein the X comprises one or more of Al, Cr, Mn and Ti. The preparation method of the alloy comprises the technological steps of component designing and burdening, mother alloy melting, mother alloy fragmentation, band preparation through single-roller quenching, and band nanocrystallization processing. The preparation method of the invention can solve a problem of low saturated magnetic induction intensity of present Fe-based amorphous nanocrystalline soft magnetic alloys.

A magnetic recording system is provided having a write head employing a combination of magnetic write field gradient and thermal gradient to write data on a ‘thermal spring’ magnetic recording media. The write head comprises a magnetic element using a write current to induce a magnetic write field at the magnetic media and a thermal element using a very small aperture laser to heat a portion of the media. The thermal spring magnetic media comprises [comprises] first and second stacks providing two exchange coupled ferromagnetic layers having different Curie temperatures [The first stack has a high magneto-crystalline anisotropy, a relatively low saturation magnetization and a low Curie temperature.] [The second stack has a relatively low magneto-crystalline anisotropy, a high saturation magnetization and a high Curie temperature.] The magnetic field gradient and the thermal gradient are arranged to substantially overlap at the trailing edge of the heated portion of the magnetic media allowing data at high density with high thermal stability to be recorded on the rapidly cooling thermal spring magnetic recording media.

Provided is amorphous soft magnetic alloy powder which has high saturation magnetization and low core loss and which is almost spherical and manufactured by water atomization method, and to provide a green compact core and radio wave absorber using the same. This amorphous soft magnetic alloy powder is formed substantially spherical by the water atomization method. The powder mainly consists of Fe and contains at least P, C and B, and is formed of amorphous soft magnetic alloy powder consisting of an amorphous phase with a temperature interval DeltaTx of the supercooled liquid of >= 20K. A green compact core is formed by solidifying the granulated mixture of this amorphous soft magnetic alloy powder, insulator and lubricant. The radio wave absorber is formed by mixing the amorphous soft magnetic alloy powder the particles of which is flattened and insulator.

The invention discloses a method for preparing magnetic mesoporous carbon nanometer microspheres with high adsorption property, relates to a method for preparing carbon nanometer microspheres, and aims to solve the problems of complex operation and high time and energy consumption in the process of preparing magnetic mesoporous carbon by the conventional method. Fe3O4 nanometer microspheres are introduced into mesoporous carbon by a solvothermal method, and mesoporous carbon microspheres with high saturation magnetization degree are prepared and used for removing pollutants such as dyes during water treatment. The magnetic mesoporous carbon nanometer microspheres have the large pore diameter of 4.3nm, the high specific surface area of 741.8m<2>/g, the large pore volume of 1.20cm<3>/g and the high magnetic saturation degree of 7.15emu/g, and can be applied to the fields of water treatment, catalyst carriers, biomedicine and the like.

The invention relates to nano-crystalline Fe3O4 particles with high absorption capacity and a preparation method thereof which belong to the field of material science. The microstructure of the particles comprises equiaxed nano-grains, and the particle size of the nano-grains is 5-100nm; the average particle size is 8-25nm, and the saturated magnetization MS is 6.7-7.2 multiplied by 10<minus 3>A/m. The preparation method is as follows: solution containing ferric ions and ferrous ions is prepared, ammonia solution is added under nitrogen atmosphere, ultrasonic waves are transmitted to carry out the ultrasonic dispersion, and heating, stirring and reaction are carried out; solids are washed till neutral by water under the condition of a magnetic field; water is removed by drying after the centrifugal separation. The invention utilizes the simple chemical reaction co-precipitation technology and combines the ultrasonic stirring, the centrifugal separation, the vacuum drying and other technologies to obtain the Fe3O4 powder materials with the average particle size of 8-25nm and the higher saturated magnetization.

The high stability and high magnetism quenched R-Fe-B base permanent magnetic alloy powder has the basic expression of RxFe100-x-y-z-vMzCovBy, where R is light RE element(s) Nd, Pr and La, and M is element(s) of Nb, Zr, Ti, etc; and consists of main R2Fe14B phase and small amount of superfine auxiliary Fe-alpha-M-beta phase. Adding Nb and other transition elements to form small amount of superfine auxiliary Fe-alpha-M-beta phase during fast solidification can inhibit over nucleation and growth of Nd2Fe14B crystal grain, improve the performance of the quenched material, fine the Nd2Fe14B crystal grain and raise the temperature stability and antioxidant process of the material. In addition, the permanent magnetic alloy powder has obviously raised intrinsic coercive force, high saturated magnetization, high residual magnetism and other advantages.

The invention discloses a high-thermal-stability insulated coating treatment method of a metal soft magnetic composite material. The method comprises the following steps: (1) sieving metal magnetic powder, and performing particle size distribution; (2) performing insulated coating on the distributed metal magnetic powder by using a sol-gel method, and then drying the metal magnetic powder; (3) uniformly mixing the dried magnetic powder and an adhesive, adding a release agent, and performing dry pressing to obtain a magnetic ring; (4) performing heat preservation on the magnetic ring in protective atmosphere for 0.5-2 h, and then performing air cooling and spraying to obtain a target product. Composite powder prepared by using the sol-gel method is coated uniformly and densely, and a coating layer is controllable in thickness, and high thermal stability, high resistivity, high saturation magnetization intensity, an excellent magnetic property and an excellent mechanical property are achieved; the surface of the metal magnetic powder is uniformly coated with an Al2O3 insulated layer by using the sol-gel method, so that the coating effect is superior to that of an existing method; the method is high in operability and facilitates batch production; the magnetic core loss of the soft magnetic composite material is greatly reduced.

The embodiment of the invention provides soft magnetic alloy powder. The components of the soft magnetic alloy powder meet the following formula in mass percentage: Fe100- x-y-zSixCyMz, wherein x is more than 2 and less than 8, y is more than 0.5 and less than 3, z is more than 1 and less than 5, and M is at least one of Cr, V, Al and Mn. The embodiment of the invention also provides a magnetic powder core which is prepared from the soft magnetic alloy powder. The soft magnetic alloy powder contains a great amount of Fe, so that saturation magnetic induction strength is higher; the powder contains an adequate amount of Si and C, so that the powder has high soft magnetic property; and the powder contains M (M is at least one of Cr, V, Al and Mn), so that the powder has good process characteristics. The soft magnetic alloy powder and the magnetic powder core having high saturation magnetic induction strength and low loss are obtained so as to obviously improve the characteristics of the DC superposition characteristic of the magnetic core and solve the problem of magnetic core heating.

The invention provides an iron base non-crystalline material and a preparation method thereof. The iron base non-crystalline material has components of Fe100-a-b-cMcBbAa, wherein M is any one or more of Si, Zr, Nb, Cr, P, Al, Co, Ni and Ti, A is N and/or C, a is not less than 0.5 and not more than 2 at%, b is not less than 9 and not more than 14 at%, and c is not less than 0 and not more than 10 at%; the non-crystalline material comprises a non-crystalline basal body layer and a surface layer positioned on the non-crystalline basal body layer; and the surface layer is a FeA enriched layer. The non-crystalline basal body layer in the iron base non-crystalline material is used for providing basic performances of the iron base non-crystalline material; and through auxiliary cooperation of the performances of the surface layer, the performances of the iron base non-crystalline material can be enhanced, the saturation magnetization is improved, the coercive force is reduced, and the overall performances of the iron base non-crystalline material are improved.

The invention relates to a preparation method for a superparamagnetism ferroferric oxide sub-micron hollow microsphere. The preparation method comprises the following steps: 1) taking a reducing agent, an iron source and an alkali source, and dissolving into distilled water; 2) dissolving a surfactant into a solution obtained from step 1); 3) introducing a solution obtained from step 2) into a reaction kettle, reacting in a drying oven, performing natural cooling to room temperature for seasoning, water washing, alcohol washing, and drying in a vacuum drying box, so that the superparamagnetism ferroferric oxide sub-micron hollow microsphere is obtained. The preparation method has the following good effects: 1) according to the invention, the ferroferric oxide sub-micron hollow microsphere is compounded, and has superparamagnetism, high saturation magnetization and excellent oxidation resistance; 2) dispersing agents such as PEG (polyethylene glycol) and PVP (polyvinylpyrrolidone) are adopted to solve the problem of magnetic microsphere agglomeration, so that the ferroferric oxide sub-micron hollow microsphere with uniform particle size is obtained; 3) according to the invention, adopted raw materials is cheap, so that cost is minimized.

The invention discloses a composite permagnetferrite with functions of two-phase exchange coupling and keeping high coercive force and belongs to the technical field of preparation of magnetic ferrites. The composite ferrite is prepared by pressing SrFe12O19 ferrite nano-powder and CoFe2O4 ferrite nano-powder which are prepared by adopting a hydrothermal method alone and subjected to acid washing according to a certain mass ratio to form circular sheets, and finally calcining at the temperature of 700-900 DEG C for 2h respectively. The ferrite containing two phases displays single-phase magnetic behavior to the outside, namely the exchange coupling effect exists. As the composite ferrite adopts a CoFe2O4 ferrite with high saturation magnetization and coercive force as a 'soft magnetic phase', the composite ferrite is conductive to improving the saturation magnetization and can ensure that the composite ferrite can still keep the high coercive force which is 152.5kA/m (about 1915Oe) at least after be calcined.

The invention discloses a method for preparing iron-coated graphene. The improved Hummer method is used to prepare graphene, and then graphene, reducing agent, iron salt, stabilizer, complexing agent, surface treatment agent and pH regulator are used as raw materials, and the The iron/graphene composite material is prepared by in-situ reduction method; the iron-coated graphene provided by the invention has high electromagnetic wave absorption effect, and is an iron/graphene composite material with stable performance, and is applied to a new type of intelligent anti-interference electric meter box; the iron /Graphene composites can combine the high Snooker frequency, high saturation magnetization of iron particles and the better impedance matching of graphene, electric dipole polarization relaxation, etc., which can bring a wider absorption frequency band and Stronger absorption strength, better absorption and shielding effects can be obtained according to the frequency band and strength information of the jammer.

A low-loss LiZn ferrite material for a phase shifter relates to the technical field of preparation of ferrite materials. The low-loss LiZn ferrite material consists of main materials, additives and binding agents, calculated by Fe2O3, ZnO, Mn3O4 and Li2CO3, the main materials comprise 64-71 mol percent of Fe2O3, 15-22 mol percent of ZnO, 0.8-1.5 mol percent of Mn3O4 and 9.9-12 mol percent of Li2CO3; relative to the main materials, the additives are calculated by Bi2O3, BST and Nb2O5, and the proportion is 0.5-3.0 wt percent of Bi2O3, 0.1-0.5 wt percent of BST and 0.05-0.4 wt percent of Nb2O5. The invention reduces the coercivity and the dielectric loss, and improves the saturation magnetization, thus realizing the low temperature preparation of the LiZn ferrite material with low coercivity, low dielectric loss and high saturation magnetization.

The invention relates to a high-saturation-magnetization iron-base amorphous nanocrystal soft magnetic alloy and a preparation method thereof. The alloy is expressed as FeaMbCucSixByPz, wherein M is one or more of Al, Cr, Mn, Ti and V; and 68<=a<=90, 0<=b<=6, 0<=c<=2, 3<=x<=20, 4<=y<=20, 0<=z<=10, and a+b+c+x+y+z=100. Compared with the prior art, the product has the advantages of high saturation magnetization and the like.

The invention discloses a nano Fe3O4/graphene composite material with high saturation magnetization and an electromagnetic shielding function as well as a preparation method of the composite material. According to the method, Fe3<+> and Fe2<+> salts are used as iron sources, in combination with urea, reduced graphene oxide and water, the composite material is prepared with a hydrothermal method. The prepared nano Fe3O4/graphene composite material is evenly distributed nanoparticles of 40-50 nm, the crystal form is complete, the specific saturation magnetization is 75 emu/g or above, and the electromagnetic shielding effectiveness of the composite material can reach 26 dB or above within 2-18 GHz when the filling amount is 50%. The preparation technology is simple, raw materials are wide in source, water is taken as a medium, and the production requirement of green chemistry is met. The composite material is a multifunctional nanomaterial and has broad application prospect in fields of biomedical materials, electromagnetic shielding materials, electrode materials, catalytic materials, sewage treatment and the like.

A magnetic layer that may serve as a top pole layer and bottom pole layer in a magnetic write head is disclosed. The magnetic layer has a composition represented by Fe_wCo_xNi_yV_z in which w, x, y, and z are the atomic % of Fe, Co, Ni, and V, respectively, and where w is between about 60 and 85, x is between about 10 and 30, y is between 0 and about 20, z is between about 0.1 and 3, and wherein w+x+y+z=100. An electroplating process having a plating current density of 3 to 30 mA/cm² is used to deposit the magnetic layer and involves an electrolyte solution with a small amount of VOSO₄ which is the V source. The resulting magnetic layer has a magnetic saturation flux density B_s greater than 1.9 Telsa and a resistivity ρ higher than 70 μohms-cm.

The invention discloses an inhomogeneous nucleation insulation coating processing method of a metal soft magnetic composite material. The method includes the following steps that (1) particle size distribution is conducted on metal magnetic powder after sieving is conducted; (2) insulation coating is conducted on the distributed metal powder through an inhomogeneous nucleation method, and then the metal powder is dried; (3) the dried magnetic powder and a binding agent are evenly fixed, a release agent is added to conduct dry pressing and forming, and the mixture is pressed to form blank samples; (4) heat preservation is conducted on the blank samples for half an hour to two hours in a protective atmosphere, and air cooling and spray coating are conducted to obtain the target product. The composite powder prepared through the inhomogeneous nucleation method is even and compact in coating and controllable in coating layer thickness, and has high oxidation resistance, high resistivity, high saturation magnetization intensity, the good magnetic property and the good mechanical property; the surface of the metal magnetic powder is evenly coated with an A12O3 insulation layer through the inhomogeneous nucleation method, so that the coating effect is superior to that of an existing method, the operability is high and volume production is facilitated.

The invention provides a method for preparing monodisperse Fe3O4 magnetic nanoparticles. Precursor is Fe2O3 or iron oxide yellow which has the chemical formula of Fe2O3.H2O; stabilizing agent is oleic acid; high temperature organic solvent is 1-octadecylene (b. p. 318DEG C); precipitating agent is prepared by mixing any two of toluene, dimethyl benzene, ethanol, isopropanol and acetone according to the volume ratio of 1:4-2:3; the mol ratio between the precursor and the stabilizing agent is 1:4-1:9; the mol ratio between the precursor and the high temperature organic solvent is 1:10; inert gas protection is not needed, and the Fe3O4 magnetic nanoparticles which have small sizes, monodisperse, narrow distribution, high saturation magnetization intensity and superparamagnetism. The method can be widely applied to biomedicine fields such as magnetic resonance imaging, biological magnetic separation, magnetic target drug carrier, biological magnetic marker and the like, and the high technical fields such as magnetic sealing, aerospace lubrication, magnetic anti-counterfeiting ink material, etc.

The invention relates to a preparation method of superparamagnetic cyclodextrin composite particles. The preparation method comprises the following steps: firstly preparing a magnetic nanometer particle mixed system, and then, adding cyclodextrin powder; adding the cyclodextrin powder to the obtained magnetic nanometer particle mixed system containing a small amount of water and adjusting the pH value of the magnetic nanometer particle mixed system to be larger than 10 by an aqueous alkali; dispersing the cyclodextrin powder under ultrasound for 5-30 minutes so as to dissolve cyclodextrin; and obtaining the superparamagnetic cyclodextrin composite particles by compounding, increasing the temperature of the reaction system to 40-80 DEG C, fully stirring the reaction system and reacting for 3-20 hours before ending, and magnetically separating and centrifugating or dialyzing the system to be neutral so as to obtain the magnetic cyclodextrin composite particles. The invention aims to utilize active groups of the cyclodextrin and the magnetic nanometer particles and does not need adding a coupling reagent so as to be directly compounded into the magnetic composite particles which have high biological compatibility and saturation magnetization intensity and can slowly release a plurality of medicaments.

The invention discloses Mn element and Zn element-doped super-paramagnetic ferrite nanoparticles and a preparation method thereof. Manganese element is added or manganese element and zinc element are simultaneously added into a face-centered cubic crystal structure of ferriferrous oxide nanoparticles by using a method of decomposing metal precursor compound at a high temperature; the magnetic performance of the prepared super-paramagnetic nanoparticles is improved by changing the doping amount and the distribution of the metal element; and primarily, the saturation magnetization is improved. The preparation method specifically comprises the following steps of: mixing acetylacetones of Fe and Mn as well as Zn with 1,2-hexadecanol; performing high-temperature decomposition in high-boiling-point solvent by taking oleic acid and oleylamine as surfactants; or performing high-temperature decomposition on composite oleate of Fe, Mn and Zn by taking the oleic acid as the surfactant; heating and preserving heat in stages in argon or nitrogen protective atmosphere to guarantee growth of nanoparticle nuclear; and cooling to room temperature after reaction is finished and settling and centrifuging to finally obtain the super-paramagnetic ferrite nanoparticles which are uniformly dispersed in normal hexane solution.

The invention provides a microwave composite material which is compounded from nano magnets made of ferromagnetic materials and organic materials, wherein the nano magnets are distributed in the organic materials, the size of the nano magnets made of the ferromagnetic materials is greater than the room-temperature superparamagnetic critical dimension of the ferromagnetic materials, and the resistivity of the organic material is greater than 1 ohm. cm. The invention also correspondingly provides multiple methods for preparing the microwave composite material. The microwave composite material has the characteristics of high resistivity and high saturated magnetic intensity, has good flexibility and certain elasticity, and is beneficial to the miniaturization and portability of devices. Besides, the preparation process of the microwave composite material can be compatible with the conventional semiconductor process, and realizes the integral monolithic integrated circuit.