SU1627324A1 - Method of preparing ferrite articles - Google Patents

Abstract

This invention relates to the production of ferrite products for the electronic and radio industries. The aim of the invention is to improve the electromagnetic parameters of ferrite products. The method includes the synthesis of ferrites, preparation of press powder, molding blanks, their sintering by heating with an electron beam. To improve the electromagnetic parameters, a low-melting additive is introduced into the ferrite powder, and during the heating process the extract is held for 10-20 minutes at the melting point of the additive. The obtained lithium ferrite products with the addition of 0.22 wt.% B (20 with the following characteristics: W 1840-1860 G; Bg 1690-1720 G and He 0.95-1.1 e, as well as products of manganese ferrite with the addition of 0.4 wt. .% CdO with parameters: W 1130-1160 Gs, Br 980-990 Gs, He 2.4-2.6 E. Table 1 g

Description

The invention relates to powder metallurgy and can be used in the electronic and radio industries in the manufacture of ferrite materials and products.

The purpose of the invention is to improve the electromagnetic parameters of ferrite products.

According to the proposed method, isothermal exposure is carried out in the process of radiation heating of ferrite blanks with an electron beam. The temperature range of isothermal exposure corresponds to the melting range of the low-melting additive: from a temperature of 5 ° C below the melting point of the low-melting additive to a temperature higher than the melting point of the low-melting additive by 30 ° C. It was established experimentally that carrying out such an exposure promotes a uniform distribution of the liquid phase throughout the volume of the press blanks, prevents the rapid evaporation of low-melting additives, and increases the reaction time of the liquid and solid phases. As a result, the porosity of products decreases, the compactness of the material increases, the degree of granularity decreases, excessive grain growth is prevented, and the degree of mutual solubility of the solid phases increases. As a result, an improvement in the electromagnetic parameters of the sintered products is observed.

When the parameters of isothermal exposure (temperature range and duration) deviate from the specified values,

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The invention is exemplified by the examples given in the table.

The examples were carried out for two types of ferrites: lithium and manganese.

From pre-synthesized ferrites, powders of two compositions were prepared.

Composition 1, wt.%: HCO3 10.71; TI02 13; MpSOz 2.66; ZnO 3.H; the rest of Fe203 with the addition of a low-melting additive B1203 (mp. 820 ° C) in an amount of 0.22 wt.%.

Composition 2, wt.%: MD 22.9: Mn 3.3; TiO2 9.2; the rest of Re203 with the addition of 0.4 wt.% CsU (mp. 900 ° C).

A 10% aqueous solution of polyvinyl alcohol was added to the powders in the amount of 12% by weight of the powder and was first wiped through a 0.9 sieve. and then through 0.45.

The resulting press powder was placed in a mold and the press blanks were pressed in the form of rings with a thickness of 2 mm. inner diameter 16 mm, outer diameter 23 mm. The density of the press blanks 3.0 g.

After this, the press blanks were sintered by the proposed and known (2) method. For this, pressed rings were placed on a chamotte brick stand. The rings were parallel to the output foil of the electron accelerator and were located at a distance of 30 cm from it. A pulsed electron accelerator was switched on. The beam parameters: the electron energy in the beam is 2 meV, the current density per pulse is 800 mA, the duration of one irradiation pulse is 600 µs, the pulse frequency is (5-20) Hz. Irradiation was performed at normal atmospheric pressure. The temperature of the rings was controlled with a Pt – PtRh thermocouple and a PP-63 potentiometer. The heating rate (950 ° C for 1 min) and the sintering temperature (1100 ° C for the first composition and 1300 ° C for the second) were controlled by changing the pulse frequency of the radiation from the panel operator accelerator. When the sintering temperature is reached, its value is stabilized by adjusting the frequency of the pulse irradiation and

withstand ring irradiation and a given temperature. Aging time for lithium ferrite is 60 min, for manganese 120 min.

After that, the accelerator was turned off, the rings were cooled spontaneously to room temperature, after which their magnetic parameters were determined at a ferrometer F5063. The frequency of the magnetizing floor is 50 Hz. size a floor 5 E.

During sintering of ferrite products by the proposed method, in the process of heating, isothermal aging was performed at the temperatures indicated in the table. The isothermal exposure time is also listed in the table. After holding the ring was heated to sintering temperature at the same rate (950 deg / min).

Electromagnetic parameters of ferrites (saturation induction W, residual induction Br. Coercive force He) are given in the table.

As follows from the table, the proposed method allows to increase the characteristics for lithium ferrites (examples 2-6) as compared to the known method (example 1) in watts from 1670 Gs to 1840-1860 Gs. on Вг from 1550 Gs to 1690-1720 Gs. the value of the coercive force does not decrease from 1.5 Oe to 0.95-1.1 E. For the manganese ferrite, respectively, the value of W increases from 980 Gs for the known method (example 1) to 1130-1160 Gs (examples 7-11), Vg accordingly from 860 Gs to 980-990 Gs. the value of the coercive force does not decrease from 3.1 Oe to 2.4-2.63.

Claims (1)

Invention Formula A method for producing ferrite products, which includes the synthesis of ferrite material, the preparation of press powder containing a low-melting additive, forming blanks, heating them to the sintering temperature by irradiation with a penetrating electron beam, and holding-v at a sintering temperature under irradiated, characterized in that it is uchaschen. Electromagnetic parameters of ferrite products, in the process of heating, isothermal discharge of v R is carried out for 10-20 minutes at temperatures of the low-melting additive.