RU2454296C2 - Charge for producing magnetostrictive ferrites with high constants of magnetostriction - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to powder metallurgy, particularly, to materials intended for production of magnetostrictive ferrites. Ferrites may be used in high-power ultrasound cleaning and machining systems, polymer welding machines, servicing equipment of hydraulic and thermal power stations, etc. Proposed charge comprises, in wt %: gallium oxide - up to 52.39, iron oxide - 44.63-96.39, at least, one of lithium oxide - up to 3,61; magnesium oxide - up to 20.15; cobalt oxide - up to 25.44; copper oxide - up to 33.25; nickel oxide - up to 31.87; zinc oxide - up to 8.89; aluminium oxide - up to 9.25; titanium dioxide - up to 4.86 and manganese oxide - up to 38.01. Ferrite is produced from said charge on cooling in magnetic field from synthesis temperature down to 100°C.

EFFECT: magnetostriction over 26×10^-6, operating temperatures of - 70 to 600°C.

3 cl, 1 tbl, 1 ex

Description

The invention relates to a technology for creating and processing composite and ceramic materials, in particular to powder metallurgy processes, and in particular to the creation of magnetostrictive ferrite ceramic materials.

Known mixture (USSR author's certificate N 25847) used for the manufacture of ferrite cores, which has the following composition, wt.%: Nickel oxide - 25.0-35.0; cobalt oxide - 0.1-10.0; copper oxide - 0.1-10.0; lead oxide - 0.5-3.0; silicon dioxide - 0.2-1.0; boric anhydrite - 0.1-0.5; iron oxide - the rest. The disadvantage of products based on it is the insufficient magnitude of the magnetostriction constant, limiting the scope of their application.

Also known is the ferrite material of the lithium-titanium system Li _1.2 Fe _0.4 Ti _1.4 O ₄ , containing, wt.%: Lithium carbonate - 33.53; iron oxide -24.16; titanium dioxide - 42.31. The temperature of the Curie point of this material is -148 ° C (125 K), which allows it to be used only in a small range of operating temperatures, because at higher temperatures it is paramagnetic.

Closest to the proposed technical essence and the achieved effect is a magnetostrictive ferrite material having the following composition, wt.%: Nickel oxide - 30.89; zinc oxide - 0.35; iron oxide - 68.76. The magnetostriction constant of ferrite cores based on this material is 25 × 10 ^-6 , the operating temperature range is from 0 to 500 ° C. The disadvantage of the prototype is the impossibility of its use in low-intensity magnetic fields (up to 1000 Oe) (JP 55-009431 A, IPC H01F 1/34, 01/23/1980, abstract).

The aim of the invention is to obtain magnetostrictive ferrites with high values of the magnetostriction constant used in low-intensity magnetic fields in wide temperature ranges.

The technical result is achieved by using a mixture having the composition Li _a Mg _b Co _c Cu _d Ni _e Zn _f Ga _g Al _h Ti _x Mn _y Fe _z O ₄ , and a can take values from 0 to 0.56, b can take values from 0 to 1, c can take values from 0 to 0.8, d can take values from 0 to 1, e can take values from 0 to 1, f can take values from 0 to 0.22, g can take values from 0 to 1, h can take values from 0 to 0.35, x can take values from 0 to 0.56, y can take values from 0 to 1.11, z can take values from 1.1 to 3.

The mixture for producing magnetostrictive ferrites with high values of the magnetostriction constant may contain, wt.%:

Lithium oxide 0-3.61 Magnesium oxide 0-20.15 Cobalt oxide 0-25.44 Copper oxide 0-33.25 Nickel oxide 0-31.87 Zinc oxide 0-8.89 Gallium oxide 0-52.39 Alumina 0-9.25 Titanium dioxide 0-4.86 Manganese Oxide 0-3 8.01 Iron oxide 44.63-96.39.

The mixture for producing magnetostrictive ferrites with high values of the magnetostriction constant is made by conventional oxide technology by mixing oxides in the ratio of wt.% According to table 1. The mixture of oxides and the first grinding are carried out in a ball mill for four hours. The ferritization step is carried out at a temperature of 1000 ° C. for 4 hours. The second grinding is carried out in a ball mill for 10 hours. As a binder, a solution of polyvinyl alcohol is used, which is introduced in an amount of 3%.

Additional introduction of ammonium sulfate in an amount of 5% by weight of the powder allows you to create a mixture with a disordered crystal lattice, which leads to surface activation (Levin B.E., Tretyakov Yu.D., Letiuk L.F. Physicochemical principles of preparation, properties and the use of ferrites. - 1979, - 471 pp.), and therefore, sinterability, which, in turn, ensures the improvement of all technological properties of finished products and a decrease in the number of defective products.

Products made from a mixture to obtain magnetostrictive ferrites with high values of the magnetostriction constant can be cooled from the synthesis temperature to 100 ° C in a constant magnetic field. Based on the fact that in polycrystalline ferrites there are directions of difficult and easy magnetization, the magnetostriction in different directions of magnetization has different signs (Smith J., Wayne X. Ferrites. - 1962, - 223 s.), Cooling the product in a magnetic field, and thereby forming the magnetic texture of the sample, it is possible to increase the magnetostriction constant for the region of strong magnetic fields. In addition, the interaction of an external magnetic field with the magnetic field of a magnetized sample can lead to complex mechanical deformations. For example, when a longitudinally magnetized sample interacts with a perpendicular field of a magnet, torsion deformation occurs.

Example

The mixture for producing magnetostrictive ferrites with high values of the magnetostriction constant, containing, wt.%: NiO - 30.74; ZnO - 0.49; Fe ₂ O ₃ - 69.04. A product based on this charge is characterized by a magnetostriction constant of 28.5 × 10 ^-6 and a range of operating temperatures from 0 to 570 ° C.

Products obtained on the basis of the charge under consideration differ in magnetostriction value in excess of 26 × 10 ^-6 , operating temperatures from -70 to 600 ° C, and are also characterized by a higher load capacity.

Charge-based products for producing magnetostrictive ferrites with high values of the magnetostriction constant can be used in powerful ultrasonic cleaning and metalworking systems, apparatus for welding polymers, maintenance devices for hydroelectric power stations and thermal power plants, as well as in ultra-sensitive sound receivers, micro- and nanoscale mechanisms for high-tech, scientific and medical equipment, pressure devices, valves, flow meters, delay lines for sound and electrical signals, Comp act level sensors, mechanical modulation systems, laser technology, optics inspection.

Claims (3)

1. The mixture for producing magnetostrictive ferrites with high values of the magnetostriction constant, containing iron oxide, characterized in that it further comprises gallium oxide and at least one of lithium oxide, magnesium oxide, cobalt oxide, copper oxide, nickel oxide, zinc oxide, alumina, titanium dioxide, manganese oxide in the following ratio of components, wt.%:
lithium oxide up to 3.61 magnesium oxide up to 20.15 cobalt oxide up to 25.44 copper oxide up to 33.25 nickel oxide up to 31.87 zinc oxide up to 8.89 gallium oxide up to 52.39 alumina up to 9.25 titanium dioxide up to 4.86 manganese oxide up to 38.01 iron oxide 44.63-96.39 2. The mixture to obtain magnetostrictive ferrites with high values of the magnetostriction constant according to claim 1, characterized in that an additional 5 wt.% Of ammonium sulfate powder is added to the mixture. 3. Magnetostrictive ferrite obtained from the mixture according to claim 1 or 2 by cooling in a constant magnetic field from the synthesis temperature to 100 ° C.