75results about How to "High grain boundary resistivity" patented technology

The invention discloses a preparation method for a high-frequency high-temperature low-loss MnNiZn ferrite material, which relates to the material technology, in particular to a preparation method for a ferrite material. The invention employs the following technique: 1. ball-grinding and uniformly mixing 52 to 58mol percent of Fe2O3, 3 to 9mol percent of ZnO, 0.5 to 5mol percent of NiO, as well as 35 to 45mol percent of MnCO3; 2. preburning the powder obtained in step 1 at certain temperature; 3. adding additive into the powder obtained in step 2 according to a weight percentage and then ball-grinding secondarily to lead the grain diameter of the powder to achieve submicron; 4. shaping; and 5. sintering. The invention employs a proper compounding formula, enlarges the mixed amount of the additive, and employs the characteristic of sintering under an oxidizing atmosphere condition to enlarge the grain boundary resistance rate of the materials, and reduce the vortex loss under high frequency, thereby achieving the goal of reducing the loss under the conditions of high frequency and high temperature.

The invention discloses a boron-oxide-based ferrite core material used for a transformer. The boron-oxide-based ferrite core material comprises main materials and additives. The main materials comprise, by molar ratio, 58.3 mol to 65 mol of Fe2O3, 16.3 mol to 20 mol of manganese oxide, 11.4 mol to 15 mol of zinc oxide, 0.1 mol to 0.2 mol of tungsten trioxide, 0.2 mol to 0.3 mol of aluminum oxide and 0.01 mol to 0.02 mol of rare-earth composite magnetic powder. The additives comprise, by weight ratio of components to the ferrite core material, 50 ppm to 60 ppm of molybdenum trioxide, 30 ppm to 40 ppm of aluminum silicate and 60 ppm to 70 ppm of zirconium dioxide. The rare-earth composite magnetic powder added into the boron-oxide-based ferrite core material is high in magnetic energy product, stable in magnetism and simple in preparing method, and the finished product has the advantages of being high in crystal boundary resistivity, low in gas hole ratio and large and even in crystal particle.

The invention discloses a cerium-based ferrite core material for a transformer. The core material comprises main materials and additives, wherein the main materials comprise the following components according to molar ratios: 61-66.6 mol of Fe2O3 (ferric oxide), 14.3-27 mol of manganese oxide, 11.4-14 mol of zinc oxide, 0.1-0.2 mol of cobalt, 0.1-0.2 mol of hafnium oxide, 0.01-0.02 mol sodium molybdate, and 0.01-0.02 mol of rare earth composite magnetic conducting power bodies; the additives comprise the following components according to the weight ratios of the components accounting for the ferrite core material: 70-100 ppm of copper powder, and 50-80 ppm of neodymia. The rare earth composite magnetic conducting powder bodies are added to the ferrite core material disclosed by the invention, so that the magnetic energy product is high, the magnetic property is stable, a preparation method is simple, and finished products have the characteristics of high grain boundary resistivity, low porosity and large and uniform crystal grains.

A ferrite material with high magnetic permeance is disclosed. Raw materials of the ferrite material comprise Fe2O3, MnO, ZnO, sodium dodecylbenzenesulfonate, CaO, SiO2, V2O5, MoO3, Bi2O3 and P2O5, wherein the molar ratio of the Fe2O3, the MnO and the ZnO is (50-55):(20-27):(20-28), and based on the weight sum of the Fe2O3, the MnO and the ZnO, the weight percentages of the sodium dodecylbenzenesulfonate, the CaO, the SiO2, the V2O5, the MoO3, the Bi2O3 and the P2O5 are respectively 0.9-1.5%, 0.025-0.035%, 0.002-0.013%, 0.018-0.022%, 0.01-0.02%, 0.02-0.03% and 0.02-0.03%. The ferrite material is prepared by steps of weighing each of the raw materials, granulating, performing dry pressing and moulding, sintering and cooling.

The invention discloses a molybdenum-based ferrite core material used for a transformer. The molybdenum-based ferrite core material comprises main materials and additives. The main materials comprise, by molar ratio, 57.2 mol to 66 mol of Fe2O3, 17 mol to 24.6 mol of manganese oxide, 12.5 mol to 17.6 mol of zinc oxide, 2 mol to 2.6 mol of silicon oxide, 0.04 mol to 0.1 mol of aluminum dihydrogen phosphate, 0.02 mol to 0.04 mol of yttrium oxide and 0.01 mol to 0.02 mol of rare-earth composite magnetic powder. The additives comprise, by weight ratio of components to the ferrite core material, 50 ppm to 100 ppm of nano carbon, 40 ppm to 70 ppm of nickel oxide and 20 ppm to 30 ppm of aluminum silicate. The rare-earth composite magnetic powder added into the molybdenum-based ferrite core material is high in magnetic energy product, stable in magnetism and simple in preparing method, and the finished product has the advantages of being high in crystal boundary resistivity, low in gas hole ratio and large and even in crystal particle.

The invention discloses cobalt-based ferrite core materials which comprise main materials and annexing agents. The main materials comprise, by molar ratio, 62.1-68 mol of Fe2O3, 14.7-18 mol of manganese oxide, 11.2-16 mol of zinc oxide, 0.1-0.2 mol of silicon carbide, 0.1-0.3 mol of lithium carbonate and 0.01-0.02 mol of rare earth composite magnetic permeable powder; the annexing agents comprise, by weight ratio of components to the ferrite core materials, 10-20 ppm of iron sulfide and 20-30 ppm of silver nitrate. The rare earth composite magnetic permeable powder added into the ferrite core materials is high in magnetic energy product, the magnetism is stable, the preparation method is simple, and the finished product has the advantages of being high in crystal boundary electrical resistivity, low in air hole rate and large and even in crystalline grain.

The invention discloses a zirconium-based ferrite core material used for a transformer. The zirconium-based ferrite core material comprises main materials and additives. The main materials comprise, by molar ratio, 60 mol to 67.3 mol of Fe2O3, 15 mol to 24.7 mol of manganese oxide, 10.2 mol to 13 mol of zinc oxide, 0.6 mol to 1 mol of titanium dioxide, 0.1 mol to 0.2 mol of ferrous sulfate, 0.01 mol to 0.02 mol of nickel oxide and 0.01 mol to 0.02 mol of rare-earth composite magnetic powder. The additives comprise, by weight ratio of components to the ferrite core material, 60 ppm to 100 ppm of lithium nitride and 40 ppm to 60 ppm of aluminum silicate. The rare-earth composite magnetic powder added into the zirconium-based ferrite core material is high in magnetic energy product, stable in magnetism and simple in preparing method, and the finished product has the advantages of being high in crystal boundary resistivity, low in gas hole ratio and large and even in crystal particle.

The invention discloses a low-loss ferrite material. The low-loss ferrite material is prepared from the following raw materials: Fe2O3, MnO, ZnO, sodium pyrophosphate, CaO, SiO2, V2O5, MoO3, Bi2O3 and P2O5, wherein the molar ratio of Fe2O3 to MnO to ZnO is (50-55) to (33-35) to (9-12); by using the sum of the mass of Fe2O3, MnO and ZnO as a standard, the low-loss ferrite material is prepared from the following raw materials in percentage by weight: 0.9-1.5% of sodium pyrophosphate, 0.025-0.035% of CaO, 0.004-0.012% of SiO2, 0.018-0.032% of V2O5, 0.01-0.02% of MoO3, 0.01-0.03% of Bi2O3 and 0.01-0.03% of P2O5. The low-loss ferrite material is prepared by virtue of the following steps: primary ball-milling, pre-sintering, secondary ball-milling, granulating, dry-press molding and sintering.

The invention discloses a TiO2-containing ferromagnetic core manufacturing method, which comprises the following steps of: proportioning 74-78 parts of reduced iron powder by weight, 8.5-12 parts of oxidized iron powder by weight, 2.6-3 parts of MnO by weight, 3.5-5 parts of ZnO by weight, 6-7 parts of modified Fe3O4 by weight, 3.5-4.5 parts of TiO2, 1-2 parts of SnO2 by weight, 2-3.5 parts of V2O5 by weight and 2-3 parts of CuO by weight, and then sequentially conducting pre-sintering, primary ball milling, secondary ball milling, molding and sintering to obtain a TiO2-containing ferromagnetic core. The TiO2-containing ferromagnetic core manufacturing method has the advantages that the magnetic core formula is reasonable, the preparation method is simple, the saturation induction density of the manufactured magnetic core is higher, the loss is lower, the temperature resistance is higher, the added modified Fe3O4 can take a bridge bonding effect among different raw materials, the distribution of the used raw materials is better, the density is high, the crystal boundary resistivity is high, the porosity is low, the grains are large and uniform, the cracks are prevented from occurring during sintering, the texture is compact, the deformation is small, the raw material formula is reasonably improved, the deformation degree is small during sintering, and the magnetic core can be wire-cut, cut, ground and the like.

The invention discloses a preparation method of ultra-fine grain high-temperature-resistant high-frequency manganese zinc ferrite, which mainly comprises the following steps: taking Fe2O3, MnO2 and ZnO as main raw materials, taking SnO2 as an auxiliary raw material, proportioning, carrying out primary ball milling, pre-sintering, doping CaCO3, V2O5, TiO2 and Co2O3, carrying out secondary ball milling, adding PVA, granulating, pre-pressurizing and forming at room temperature, deforming at high temperature, pressurizing and forming at high temperature, sintering, and quenching and cooling to obtain the manganese zinc ferrite. According to the invention, SnO2 is used as an auxiliary raw material, and Sn can enter the crystal lattice of the manganese zinc ferrite, so that transition of electrons at high temperature and high frequency is hindered, and loss is reduced; CaCO3, V2O5, TiO2 and Co2O3 are adopted for doping, impurity elements are enriched in a grain boundary, the grain boundary resistivity is increased, and loss is reduced; high-temperature compression deformation is adopted, deformation storage energy is provided, crystal grain forming positions are increased, then crystal grains are refined, and loss is reduced; and by adopting quenching cooling, element diffusion in the cooling process is reduced, and the high-temperature characteristic of the ferrite is enhanced. The obtained manganese zinc ferrite has the advantages of ultra-fine grains, high saturation flux density, high temperature resistance and low high-frequency loss.

The present invention relates to a dielectric element such as a thin-film capacitor including a dielectric film. The dielectric film contains a main component represented by the general formula (Ba_1-xCa_x)_z(Ti_1-yZr_y)O₃ wherein 0<x≦0.500, 0<y≦0.350, and 0.900≦z≦0.995. The dielectric film includes a layer containing columnar crystal grains and a layer containing spherical crystal grains, and contains as a sub-component at least one of divalent metal elements and trivalent metal elements.

The invention discloses a titanium-based ferrite core material used for a transformer. The titanium-based ferrite core material comprises main materials and additives. The main materials comprise, by molar ratio, 57.3 mol to 65 mol of Fe2O3, 18.5 mol to 24 mol of manganese oxide, 12.3 mol to 15 mol of zinc oxide, 0.2 mol to 0.3 mol of lithium nitride, 0.3 mol to 0.5 mol of molybdenum trioxide and 0.01 mol to 0.02 mol of rare-earth composite magnetic powder. The additives comprise, by weight ratio of components to the ferrite core material, 60 ppm to 70 ppm of chromic oxide and 50 ppm to 60 ppm of nano carbon. The rare-earth composite magnetic powder added into the titanium-based ferrite core material is high in magnetic energy product, stable in magnetism and simple in preparing method, and the finished product has the advantages of being high in crystal boundary resistivity, low in gas hole ratio and large and even in crystal particle.

The invention discloses a method for manufacturing a ferromagnetic core containing silicon dioxide. The method include steps of performing pre-sintering on a mixture A comprising Fe<2>O<3>, MoO, ZnO, aluminum nitride, copper, boron, aluminum, the silicon dioxide, titanium dioxide and tin and a mixture B comprising MoO<3>, V<2>O<5>, Bi<2>O<3>, boron dioxide, zirconium dioxide, barium dioxide, Ti and Ni; then sequentially performing grinding, mixing and pulping, powder spray-drying, green body pressing and sintering processes on the mixture A and the mixture B to obtain the ferromagnetic core. The method has the advantages that owing to an optimized formulation design and the sintering process, the initial permeability of a product manufactured by the method is 15000, cracking of the sintered product is little, the qualified rate of the product reaches 95% at least, the product is high in grain boundary resistivity and low in porosity, crystal grains of the product are large and uniform, the impendence characteristic of the product in a high-frequency range is excellent, various electromagnetic properties of the product are stable, and the ferromagnetic core product is applicable to various electronic fields.

The invention discloses a ferrite material with high magnetic strength. The ferrite material comprises the following raw materials: Fe2O3, MnO, ZnO, sodium hexametaphosphate, CaO, SiO2, V2O5, MoO3, Bi2O3 and P2O5, wherein the molar ratio of Fe2O3 to MnO to ZnO is (50-55) to (20-27) to (20-28); based on the mass sum of Fe2O3, MnO and ZnO, the mass fractions of sodium hexametaphosphate, CaO, SiO2, V2O5, MoO3, Bi2O3 and P2O5 are respectively 0.9-1.5%, 0.025-0.035%, 0.005-0.015%, 0.018-0.042%, 0.01-0.02%, 0.02-0.04% and 0.02-0.03%. The ferrite material with high magnetic strength is prepared by the following steps: weighing the raw materials; primarily ball-milling; pre-sintering; secondarily ball-milling; pelleting; dry pressing; and sintering.

The invention discloses a nickel-based ferrite core material used for a transformer. The nickel-based ferrite core material comprises main materials and additives. The main materials comprise, by molar ratio, 57 mol to 63.6 mol of Fe2O3, 17.0 mol to 22 mol of manganese oxide, 10.2 mol to 16 mol of zinc oxide, 0.01 mol to 0.03 mol of stainless steel powder, 0.2 mol to 0.3 mol of barium sulfate and 0.01 mol to 0.02 mol of rare-earth composite magnetic powder. The additives comprise, by weight ratio of components to the ferrite core material, 80 ppm to 90 ppm of molybdenum powder, 40 ppm to 60 ppm of lithium nitride and 70 ppm to 90 ppm of magnesium hydrate. The rare-earth composite magnetic powder added into the nickel-based ferrite core material is high in magnetic energy product, stable in magnetism and simple in preparing method, and the finished product has the advantages of being high in crystal boundary resistivity, low in gas hole ratio and large and even in crystal particle.

The invention discloses a method for manufacturing a ferromagnetic core containing modified aluminum nitride. The method includes steps of performing pre-sintering on a mixture A comprising Fe<2>O<3>, MoO, ceramic powder, boron, titanium, aluminum hydroxide, the modified aluminum nitride and bentonite and a mixture B comprising SiO<2>, Nb<2>O<5>, yttrium oxide, tantalum oxide, Al, tin, vanadium and rubidium; sequentially performing grinding, mixing and pulping, powder spray-drying, green body pressing and sintering processes on the mixture A and the mixture B to obtain the ferromagnetic core. The total weight of the mixture B is equivalent to that of the mixture A. The method has the advantages that owing to an optimized formulation design and the sintering process, the initial permeability of a product manufactured by the method is 20000, cracking of the sintered product is little, the qualified rate of the product reaches 94.5% at least, the product is high in grain boundary resistivity and low in porosity, crystal grains of the product are large and uniform, the impendence characteristic of the product in a high-frequency range is excellent, various electromagnetic properties of the product are stable, and the ferromagnetic core product is applicable to various electronic fields.