Method of producing barium hexaferrite

FIELD: chemistry.

SUBSTANCE: invention can be used in producing magnetic powders, permanent magnets, resin-bonded magnets, magnetic liquids and high-density magnetic recording devices. The method of producing barium hexaferrite includes preparing a barium hexaferrite suspension, depositing said suspension in a neutral or weakly alkaline medium and drying. The barium hexaferrite suspension is obtained using an electrochemical method by dissolving electrodes made of steel St3, the distance between which is 5-15 mm, in an electroconductive solution of barium hydroxide and sodium chloride. The process is carried out with concentration of Ba(OH)2 7-10 mg/dm3, NaCl 3-5 mg/dm3, voltage 8-10 V, temperature 85-90°C, current density 0.11 A/cm2.

EFFECT: invention simplifies production of fine barium hexaferrite powder.

1 tbl, 1 ex

 

The invention relates to the technology of magnetic materials that can be used for the production of magnetic powders, permanent magnets, magnetoplasma, magnetic fluids for various purposes, as well as devices magnetic recording of high density.

A method of producing fine powder hexaferrite by the General formula M(MeTi)xFe12-2xO19where M is Ba or Sr, Me-Zn, Ni and / or Co, x=0-2,0. The method consists in that the metal salt included in the composition of the ferrite, in the form of chlorides or carbonates are milled in a ball mill, mixed with carbonate of sodium or potassium, and the resulting mixture was subjected to heat treatment at 700-1100°C. After cooling, the mixture consisting of ferrite and alkali metal chloride, washed from the last water. The method does not ensure the reproducibility of ferrite powders because of the lack of homogeneity of mixtures of substances after mechanical operations of grinding and mixing [EP 0072437 (B1) 1987-01-07].

The closest in technical essence to the claimed method is a method of obtaining powder of barium hexaferrite [RF Patent 2026159, B22F 9/22, H01F 1/11, date of the publication. 09.01.1995 G.], the essence of which is that from solutions of chlorides territooriumil elements contained in amounts corresponding to the stoichiometric aspect]�to elements in the formula of the ferrite solution of Na 2CO3that precipitate the hydroxides and carbonates. Complete precipitation of the components is possible only at pH 7,0-7,8. The barium is precipitated in the form of BaCO3at pH 7.

The disadvantage of all these methods is the high complexity of the technology, the complexity and duration of the processes.

The object of the present invention is to simplify the production method of barium hexaferrite.

The problem is solved as follows. A method of producing barium hexaferrite includes a step for suspension of hexaferrite, which is performed by an electrochemical method by dissolving the electrodes of steel St3, the distance between which is 5-15 mm, conductive barium hydroxide solution at a concentration of Ba(OH)2- 7-10 mg/DM3and sodium chloride with the concentration of NaCl is 3-5 mg/DM3at a voltage of 8-10 V, a temperature of 85-90°C and a current density of 0.11 A/cm2the sedimentation of the obtained suspension in a neutral or slightly alkaline environment, drying.

The electrochemical method is simple, low cost hardware design and the ability to control the intensity of the process of formation of fine ferrite powder by changing the parameters of electrolysis (temperature, concentration of NaCl, Ba(OH)2, voltage).

A method of producing barium hexaferrite is illustrated by the following example.

In EMK�St', containing barium hydroxide solution (concentration of Ba(OH)2- 7-10 mg/DM3) and sodium chloride (NaCl concentration of 3-5 mg/DM3), immersed electrodes from St3, the distance between which is 5-15 mm, the solution temperature 85-90°C, was energised 8-10 In providing a current density of 0.11 A/cm2. As a result of electrolysis in a neutral or slightly alkaline medium, a precipitate of barium hexaferrite, which was identified by x-ray diffraction analysis and Mössbauer spectroscopy. Received hexaferrite barium has a dispersion that is easily stabilized and dispersed. Properties of the obtained powder (GBF 1) are shown in table 1. For comparison, the table shows properties of barium hexaferrite obtained by a chemical method [K. V. Chernyakov, etc. Structure and magnetic properties of hexagonal barium ferrite. / Vestnik BGU, ser. 2, 2008, no. 1, Pp. 9-13]. - GBF 2.

Thus, the objective of the proposed method is solved.

The main simplification of the technology of the claimed method of producing barium hexaferrite is that hexaferrite barium is obtained one-step at a temperature of 85-90°C, while during the chemical deposition process of thermal treatment of the deposited barium hexaferrite at a temperature of 1200°C is a separate operation and requires heat-resistant equipment.

In the proposed method �oblucenie and changing the distance between the electrodes, adjustment of voltage, temperature, current density is not technical complexity.

A method of producing barium hexaferrite, which includes the deposition of a suspension of barium hexaferrite in a neutral or slightly alkaline environment, drying the formed slurry, characterized in that the process of obtaining a suspension of barium hexaferrite performed by an electrochemical method by dissolving the electrodes of steel St3, the distance between which is 5-15 mm, conductive barium hydroxide solution (concentration of Ba(OH)2- 7-10 mg/DM3) and sodium chloride (NaCl concentration of 3-5 mg/DM3) at a voltage of 8-10 V, a temperature of 85-90°C and a current density of 0.11 A/cm2.



 

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