RU2139898C1 - Composition for manufacturing anisotropic magnets and method of preparing thereof - Google Patents

Abstract

FIELD: electrotechnical industry. SUBSTANCE: described is composition comprising magnetic powder, calcium or zinc stearate, castor oil and polyamine, dioctyl phthalate, chromate, laminated alumosilicate and pyrite cinder and anisotropic powder of magnetically rigid rare-earth alloy with specific surface of 870-950 sq.cm/g with average particle size of 25 mcm, and magnetic strontium ferrite powder, ratios of components being as follows: strontium ferrite, 58-72; calcium or zinc stearate, 0.2-0.5; castor oil, 0.2-0.5; dioctyl phthalate, 0.15-0.3; chromate, 0.2-1.5; laminated alumosilicate, 0.2-1.0; pyrite cinder, 0.1-1.0; anisotropic powder of magnetically rigid, rare-earth alloy with specific surface of 870-950 sq.cm/g, 16-30.0; polyamide, the balance. Also described is method of preparing anisotropic magnets. EFFECT: same level of magnetic properties of the resulting anisotropic magnets and lower power consumption for manufacture thereof, molding of small magnets of thickness and complicated configuration for products for electrotechnical purposes. 3 cl, 2 tbl

Description

 The invention relates to the industry for the production of magnets, namely to polyamide composite materials and can be used for forming magnets of small thickness and complex configuration for products for electrical purposes.

 A known composition for the manufacture of magnets, including magnetic ferrite powder, an organic polymer, aluminum and an acidic salt of chromium (see published application of Japan N 1268001, CL H 01 F 1/11; G 01 G 49/00, publ. 25.10.89 g .).

 A known composition for the manufacture of permanent magnets from a magnetoplastic with a synthetic binder (compound of a polyamide, polyolefin groups, etc.) by adding a plasticizer to it - normal benzenesulfonamide or a similar compound (see published application of Japan N 60-136207, class H 01 F 1 / 113, C 08 K 3/22, publ. 07/19/85).

The closest in technical essence and the achieved effect is a magnetic polyamide composition, including, wt.%:
Magnetic powder - 80 - 95
Polydimethylsiloxane - 0.5 - 2.0
Castor oil - 0.5 - 2.0
Calcium or Zinc Stearate - 0.5 - 2.0
Polyamide - Else
(see A.S. USSR N 1804466, class C 08 L 77/60, C 08 K 13/22, 1991).

 A disadvantage of the known mixtures are not high enough magnetic properties of the obtained anisotropic magnets and high energy consumption.

 A known method of producing permanent magnets by pressing and injection molding of hard magnetic powders with a binder of polyamide, moreover, in the manufacture of products by casting, the volume fraction of the binder is 10 wt.% (See journal "Elektrotechnik" (Schweiz), 1988, 9 N 11, s .61 - 64).

A known method of producing anisotropic magnets by mixing for 10 to 15 minutes in a dry mixer mixing the components, followed by mixing and granulating the mixture in an extruder at a temperature of 270 ± 10 ^o C and casting products at a temperature of 270 ± 10 ^o C in a magnetic field of 10,000 Oe (see A.S. USSR N 1804466, class C 08 L 77/60, C 08 K 13/22, 1991).

 A disadvantage of the known methods are the high energy consumption in the manufacture of magnets.

 The purpose of the invention is the preservation of the magnetic properties of the obtained anisotropic magnets while reducing energy costs for their manufacture.

This goal is achieved in that the composition for the manufacture of anisotropic magnets, including magnetic powder, calcium or zinc stearate, polyamide, castor oil, additionally contains dioctyl phthalate, an acid chromium salt, layered aluminosilicate, a pyrite cinder and an anisotropic powder of a rare-earth magnetically hard alloy with a specific surface area of 870 - 950 cm ² / g with an average particle size of 25 μm, and strontium ferrite as a magnetic powder, with the following ratio of components, wt.%:
Ferrite Strontium - 58 - 72
Calcium or Zinc Stearate - 0.2 - 0.5
Castor oil - 0.2 - 0.5
Dioctyl phthalate - 0.15 - 0.3
Acid chromium salt - 0.2 - 1.5
Laminated Aluminosilicate - 0.2 - 1.0
Pyrite cinder - 0.1 - 1.0
Anisotropic powder of rare-earth hard magnetic alloy with a specific surface area of 870 - 950 cm ² / g - 16 - 30
Polyamide - Else
This goal is also achieved by the fact that in the method of producing anisotropic magnets, including the preparation of a mixture of the starting components, its melting and molding of the magnets of the casting methods in a magnetic field with a voltage of 10,000 - 12,000 Oe, the above composition is used as a mixture of the starting components, and when preparing the mixture, first anisotropic magnetically hard rare earth powder on the right is mixed with 50 wt.% castor oil of its total content in the composition, then the resulting mixture is introduced into a preliminary prepared dry mixture of strontium ferrite, an acidic salt of chromium, a finely ground layered aluminosilicate, calcium or zinc stearate, pyrite cinder and polyamide and melt, and then the remaining 50 wt.% castor oil and dioctyl phthalate are introduced into the melt, and the magnets are formed at a temperature of 240 - 250 ^o C.

 The set of the above features is significant, because allows you to save the magnetic properties of anisotropic magnets while reducing energy costs for their manufacture.

 The claimed group of inventions meets the requirement of the unity of inventions, since the group of diverse inventions forms a single inventive concept, moreover, one of the claimed objects of the group, namely, "a composition for the manufacture of anisotropic magnets", is intended to implement another claimed object of the group - the "method for their preparation", when this both objects of the group of the invention are aimed at solving the same problem with obtaining a single technical result.

 The analysis of the prior art and the identification of analogues of the claimed group of inventions for both the “composition” and the “production method” allowed us to establish that no analogues have been found that are characterized by characteristics identical to all the essential features of the claimed group of inventions, and the prototypes make it possible to identify a set of essential distinguishing features in relation to the technical result for the "composition" and for the "method. Therefore, each object from the group of inventions meets the condition of" novelty ".

To prepare the proposed composition using:
- as an acidic salt of chromium - strontium or barium chromate;
- as an anisotropic powder of rare-earth hard magnetic alloy - powder of rare-earth alloy "neodymium-iron-boron";
- polyamide grade PA-6.

 Examples of compositions of the claimed composition and prototype for the manufacture of anisotropic magnets are given in table. 1 (see the end of the description).

The proposed composition is prepared as follows: the magnetic powder of strontium ferrite is mixed with an acidic salt of chromium, a finely ground layered aluminosilicate, calcium or zinc stearate, pyrite cinder and polyamide. Then the anisotropic powder of the neodymium-iron-boron rare-earth alloy is mixed with 50 wt.% Castor oil of its total content in the composition and introduced into the previously obtained mixture by mixing, the composition is heated and the remaining 50 wt. % of castor oil and dioctyl phthalate are introduced into the melt, and molding of the magnets by casting is carried out at a temperature of 240 - 250 ^o C in a magnetic field with a strength of 10000 - 12000 E.

 In the table. 2 shows the properties of the obtained compositions (see the end of the description).

Energy consumption in the preparation of anisotropic magnets is reduced due to the fact that the proposed composition and the method of its preparation provide fluidity of the mixture at a relatively low processing temperature (240 - 250 ^o C) and allow to obtain a wetting angle of magnetically solid ferrite powder with a thermoplastic melt from 43 to 75 conventional units

Claims (1)

1. A composition for the manufacture of anisotropic magnets, including magnetic powder, calcium or zinc stearate, castor oil and polyamide, characterized in that it further comprises dioctyl phthalate, an acidic chromium salt, layered aluminosilicate, a pyrite cinder and anisotropic powder of a rare-earth hard magnetic alloy with a specific surface area of 870 - 950 cm ² / g with an average particle size of 25 μm, and strontium ferrite as a magnetic powder in the following ratio of components, wt.%:
Ferrite Strontium - 58 - 72
Calcium or Zinc Stearate - 0.2 - 0.5
Castor oil - 0.2 - 0.5
Dioctyl phthalate - 0.15 - 0.3
Acid chromium salt - 0.2 - 1.5
Laminated Aluminosilicate - 0.2 - 1.0
Pyrite cinder - 0.1 - 1.0
Anisotropic powder of rare-earth hard magnetic alloy with a specific surface area of 870 - 950 cm ² / g - 16 - 30
Polyamide - Else
2. A method of producing anisotropic magnets, including the preparation of a mixture of the starting components, its melting and molding of the magnets by casting in a magnetic field with a voltage of 10,000 - 12,000 Oe, characterized in that the composition according to claim 1 is used as a mixture of the starting components, in which the mixture is first mixed anisotropic powder of hard magnetic rare-earth alloy with 50 wt.% castor oil of its total content in the composition, then the resulting mixture is introduced into a previously prepared dry mixture of strontium ferrite , Acid salts of chromium, from fine layered aluminosilicate, calcium or zinc stearate, pyrite cinder and polyamide and subjected to melt, then the melt is introduced the remaining 50% by weight castor oil and dioctyl phthalate, and the magnet molding is carried out at a temperature of 240 -. 250 ^o C.

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