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

The invention discloses high-frequency low-loss manganese zinc ferrite and a manufacture method thereof; the manufacture method comprises: weighing the main materials at a molar ratio, mixing in a ball mill, sintering in a sintering furnace at 850-980 DEG C, and holding the temperature for 1-3 hours to obtain pre-sintered material; ball-milling for the second time, adding auxiliaries into the pre-sintered material, and ball-milling to form powder; adding first and second additives, and granulating with a machine; press-forming powder with the granulated material by using a press, and sintering for the second time, the formed blanks in an atmospheric sintering furnace to obtain the high-frequency low-loss manganese zinc ferrite. By adjusting the component ratio of the main materials, auxiliaries and additives and using microwave sintering technique, manganese zinc ferrite capable of high-power transmission under high frequency is acquired; the manganese zinc ferrite has small and uniform crystal grain structure, has few pores, and high crystal boundary resistivity, and accordingly has greatly reduced high-frequency loss, with high-temperature stability of a transformer greatly improved.

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 method for producing a soft magnetic core of load palladium oxide. The method comprises the following steps of: pre-burning mixtures, wherein the components of the mixture A comprise Fe3O4, manganese oxide, palladium oxide, molybdenum powder, ferrosilicon, nanoscale titanium dioxide, carbonyl iron powder and chromium powder; and the components of the mixture B comprise Nb2O5, Bi2O3, tungsten trioxide, Pd, V, manganese sulfide, molybdenum disulfide powder, and graphite powder according to the ratio equivalent to the total weight of the mixture A; then grinding, mixed pulping, spray drying of powder, pressing and sintering green bodies orderly, so as to obtain the soft magnetic core. The initial magnetic conductivity of the produced product is 13300 by optimizing the formula design and sintering technology; cracks of the sintered product are reduced; the qualified rate can be up to over 9.05%; the produced product has the characteristics of high grain boundary resistivity, low porosity, large and even grain size, excellent impedance characteristic in a high-frequency range, and stable electromagnetic property; a magnetic core product is suitable for each electronic field.

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 a nickel-oxide-based ferrite core material used for a transformer. The nickel-oxide-based ferrite core material comprises main materials and additives. The main materials comprise, by molar ratio, 60.2 mol to 66 mol of Fe2O3, 13.0 mol to 18 mol of manganese oxide, 11.3 mol to 16 mol of zinc oxide, 3 mol to 4 mol of magnesium oxide, 0.1 mol to 0.2 mol of sodium metasilicate, 0.6 mol to 1 mol of cobaltosic 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, 70 ppm to 100 ppm of lithium nitride and 60 ppm to 80 ppm of ferrous sulfate. The rare-earth composite magnetic powder added into the nickel-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 lanthanum base ferrite magnetic core material for a transformer. The lanthanum base ferrite magnetic core material comprises a main material and additives, wherein the main material comprises the following ingredients according to the mol ratio: 60.2 to 66mol of Fe2O3, 13.4 to 17mol of manganese oxide, 9.1 to 11mol of zinc oxide, 1 to 2.7mol of graphite, 0.5 to 0.8mol of tin oxide, 0.1 to 0.2mol of barium sulfate and 0.01 to 0.02mol of rare earth composite magnetism conduction powder bodies, and the additives comprise the following materials through being metered by the weight ratio of the materials to the ferrite magnetic core material: 70 to 100ppm of potassium permanganate and 60 to 70ppm of cobalt oxide. The lanthanum base ferrite magnetic core material has the advantages that the magnetic energy product of the rare earth composite magnetism conduction powder bodies added into the ferrite magnetic core material is high, the magnetism is stable, a preparing method is simple, and a finished product has the characteristics of high crystal boundary resistivity, low porosity and large and uniform crystal particles.

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 rear-earth ferrite magnetic core material used for a transformer. The rear-earth ferrite magnetic core material comprises main ingredients and additives, wherein the main ingredients comprise the following components in molar ratio: 61.4-70 mol of Fe2O3, 16.7-20 mol of manganese oxide, 10-14.2 mol of zinc oxide, 1-2 mol of copper oxide, 0.4-0.6 mol of calcium sulfate and 0.01-0.02 mol of rear-earth composite magnetic powder; the additives comprise the following components in proportion by weight (based on the ferrite magnetic core material): 40-50 ppm of chromic oxide and 800-1000 ppm of zinc borate. The rear-earth composite magnetic powder added in the ferrite magnetic core material disclosed by the invention is high in magnetic energy product, stable in magnetism and simple in preparation method; a finished product has characteristics of high crystal boundary resistivity, low porosity, great and uniform 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 relates to the technical field of ferrite materials, and discloses a preparation method of a high-temperature high-frequency low-loss ferrite material, which comprises the following steps: 1) mixing and grinding 52-58 mol% of ferric oxide, 9-13 mol% of zinc oxide, 0.5-5 mol% of nickel oxide and 31-38 mol% of manganese carbonate to form ground powder; 2) presintering the ground powderat the temperature of 950-1050 DEG C to form fired powder; 3) adding stannic oxide, titanium dioxide and vanadium pentoxide into the fired powder according to a mass ratio, and grinding the primary powder of which the particle size reaches a sub-micron level again; 4) adding an organic adhesive into the primary powder, and forming into granular blanks; and 5) placing the granular blank in a sintering furnace for high-temperature sintering for several hours to form a high-temperature high-frequency low-loss ferrite material; so that the purpose of reducing power loss under high-temperature andhigh-frequency conditions is achieved.

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 niobium-based ferrite core material used for a transformer. The niobium-based ferrite core material comprises main materials and additives. The main materials comprise, by molar ratio, 62 mol to 72.3 mol of Fe2O3, 20.1 mol to 25 mol of manganese oxide, 10 mol to 13.5 mol of zinc oxide, 0.6 mol to 0.8 mol of titanium dioxide, 0.1 mol to 0.3 mol of barium 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 sodium silicate, 20 ppm to 60 ppm of cobaltosic oxide and 70 ppm to 100 ppm of magnesium oxide. The rare-earth composite magnetic powder added into the niobium-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 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 (Ba1-xCax)z(Ti1-yZry)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 present invention discloses a maifanite base ferrite magnetic core material for transformers. The maifanite base ferrite magnetic core material comprises main materials and additives, wherein the main materials comprise, by molar, 59-66.2 mol of Fe2O3, 15.7-21 mol of manganese oxide, 10.2-15 mol of zinc oxide, 1.3-2 mol of ferrocene, 1-1.2 mol of boron oxide, 0.1-0.2 mol of cobalt powder, and 0.01-0.02 mol of a rare earth composite magnetic conduction powder body, and the additives comprise, by weight (calculated as the weight of the ferrite magnetic core material), 70-100 ppm of beryllium oxide, 70-100 ppm of aluminum oxide, and 60-100 ppm of nickel. According to the ferrite magnetic core material of the present invention, the added rare earth magnetic conduction powder body has the high magnetic energy product, the magnetism is stable, the preparation method is simple, and the finished product has characteristics of high grain boundary resistivity, low porosity, and large and uniform grain.

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 tantalum-based ferrite magnetic core material used for transformer, which comprises a main material and an additive, the main material comprises the following components according to mol ratio: 57.1-64mol of Fe2O3, 16.2-20mol of manganese oxide, 10.1-15mol of zinc oxide, 4-5.2mol of copper oxide, 0.2-1 mol of zinc borate, 1-1.3mol of barium oxide and 0.01-0.02mol of rare earth composite magnetic conductive powder; and the additive comprises the following components according to weight ratio of the additive in the ferrite magnetic core material: 30-50ppm of aluminium triphosphate, 10-20ppm of titanium tetrachloride and 40-50ppm of silicon powder. The magnetic energy product of the rare earth composite magnetic conductive powder in the ferrite magnetic core material is high, and magnetic performance is stable, preparation method is simple, and the finished product has the characteristics of high crystal boundary resistivity, low porosity and large crystal grain.

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 preparation method of a MnZn (Manganese-Zinc) soft magnetic ferrite material containing modified tree ash. The preparation method comprises the following steps of: preparing main materials, preparing auxiliary materials, pre-burning, mixing and secondarily ball-milling the main materials and the auxiliary materials, shaping and sintering to obtain a MnZn soft magnetic ferrite magnetic core of modified tree ash. Through the addition of the modified tree ash, the MnZn soft magnetic ferrite material can play a bridge combination role among different raw materials; the used raw materials have the advantages of better distribution, high density, high grain boundary resistivity, low porosity and great and even grains; the prescription of the raw materials is reasonably improved, so that the magnetic core has higher magnetic conductivity after firing; and the indexes such as power loss, frequency feature, curie temperature, saturation flux density and the like are greatly improved.

The invention discloses a method for manufacturing a ferromagnetic core loaded with boric oxide. The method includes steps of performing pre-sintering on a mixture A comprising Fe<3>O<4>, manganese oxide, the boric oxide, zirconium fluoride, nickel oxide, borax, ferric oxide powder and aluminum powder and a mixture B comprising tantalum, titanium, tungsten, MoO<3>, Nb<2>O<5>, magnesium carbonate, lanthanum oxide and barium carbonate; 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 12500, cracking of the sintered product is little, the qualified rate of the product reaches 93.0% 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 carbon-based ferrite magnetic core material for a transformer. The material comprises major ingredients and additives, wherein the major ingredients comprise 58 to 65.4 moles of Fe2O3, 16.3 to 21 moles of manganese oxide, 9.4 to 13 moles of zinc oxide, 1.2 to 2 moles of chromium oxide, 0.1 to 0.2 mole of ferrous disulfide, 0.6 to 1 mole of calcium oxide and 0.01 to 0.02 mole of rare earth composite magnetic-conducting powder according to a molar ratio; the additives comprise 100 to 200 parts per million of aluminum oxide, 60 to 100 parts per million of tin oxide and 50 to 70 parts per million of aluminum silicate based on the weight of the ferrite magnetic core material. The rare earth composite magnetic-conducting powder added to the ferrite magnetic core material has a magnetic energy product and stable magnetism, a preparation method is simple, and a finished product has the characteristics of high grain boundary resistivity, low porosity and large and uniform crystal grain sizes.

The invention discloses a HfO2-containing ferromagnetic core manufacturing method, which comprises the following steps of: proportioning 68-75 parts of reduced iron powder by weight, 15-17 parts of oxidized iron powder by weight, 4.2-4.5 parts of MnO by weight, 3.6-4.2 parts of ZnO by weight, 1.7-2.3 parts of modified tree ash by weight, 0.5-0.7 part of nano carbon by weight, 1-3 parts of HfO2 by weight, 2.5-2.7 parts of SiO2 by weight, 3.4-3.8 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 HfO2-containing ferromagnetic core. The HfO2-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 tree ash and the nano carbon 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 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.