SU1650356A1 - Method of manufacturing manganese-ferrite products with rectangular hysteresis loop - Google Patents

Abstract

The invention relates to methods for producing articles from manganese-containing ferrites with a rectangular hysteresis loop used in random access memory devices. The aim of the invention is to improve the quality of products by increasing the temperature stability of the electromagnetic parameters of manganese-containing ferrites. The proposed method, after quenching ferrite products from an air sintering temperature, conducts additional annealing at 350-450 ° C for 1-10 hours. Products from manganese-containing ferrites with a pulse square hysteresis loop (uVi / dVz) equal to 7 are obtained 0-7.8, and a change in readout current (MF), no more than 25 mA in the temperature range from -60 ° C and no more than -32 mA in the temperature range 25-70 ° C. 1 tab. yo

Description

The invention relates to the field of magnetic materials, in particular to the manufacture of ferrite products with a rectangular hysteresis loop (BCP) used in random access memory devices.

The aim of the invention is to improve the quality of products by increasing the temperature stability of the electromagnetic parameters.

This goal is achieved by the fact that hardened products from ferrites of BCPs are subjected to additional annealing in air at 350–450 ° C for 1–10 h.

Upon annealing under these conditions, manganese is not oxidized in ferrite, and consequently, the electromagnetic parameters do not deteriorate. This is due to the fact that at 350–450 ° C, the thermal oscillation of the ions is still not sufficient to allow penetration into the crystalline

lattice from the air oxygen ions, which are relatively large in size. The remaining lattice ions (Fe3, Mn2 +, Li, Co24) have significantly smaller ion radii and at 350-450 ° C the methods are redistributed between the octahedral and tetrahedral lattice sites, thereby transitioning from the high-temperature, distribution of cations fixed by quenching to equilibrium at 350-450 ° C. Such a redistribution of cations and causes an increase in the stability of electromagnetic parameters. At the same time, the parameters of ferrite products do not deteriorate.

The invention is illustrated by the examples in the table.

The method is carried out as follows.

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Powders of iron (HI), zinc, cobalt (II), lithium and manganese (II), bismuth oxides were taken to obtain ferrites in the following ratio, wt%: MpO 7.21; ZIO 2.92; B (2Oz 2.91; CoO 0.18; ZnO 0.93; ReaOz 85.85.

Then the powders of oxides of iron, zinc, cobalt, lithium and manganese were mixed and crushed in a vibrating mill filled with distilled water for 1 h. After grinding, the mixture was dried, briquetted and burned in air at 800 ° С for 3 h.

After firing, the briquettes were crushed, bismuth (III) oxide was added to the powders and refined for 1.5 hours. Next, npecc poroimsy was prepared, toroidal samples of the product with dimensions 0.60x0.40x0.13 mm were pressed and sintering was performed in air at 1050 ° C for 0.5 h, and then quenched by discharging from the furnace into the air at 1050 ° C. After that, the hardened samples were annealed according to the modes presented in the table. The same table shows the electromagnetic parameters of the samples. For comparison, the characteristics of products from ferrite without annealing (a known method) are given.

As follows from the table, additional annealing of the ferrite product after quenching from sintering temperature at temperatures

350-450 ° C for 1-10 hours allows to improve the quality of ferrite cores (products) by reducing the change in readout current 0Ch) from (+38) mA to (+ 22N + 25) mA

in the temperature range (+ 25M-60) ° C and from (-37) mA to (-25N-32) mA in the temperature range 25-70 ° C (examples 2-4). When going beyond the scope of the invention (examples 5-8) or the temperature stability deteriorates

products made from ferrites (examples 5–8), or the pulse squareness of the hysteresis loop decreases sharply (examples 6–7).

The use of the proposed invention will improve the quality of ferrite elements, and, consequently, of random access memory by increasing the temperature stability of the electromagnetic parameters.

Formula of invention

The method of obtaining products from margarite-containing ferrites with a rectangular hysteresis loop, including pressing, sintering in air and quenching, is about the fact that, in order to improve the quality of products by increasing the temperature stability of electromagnetic parameters, after quenching the wire t additional annealing at 350-450 ° C for 1-10 hours

Table continuation

Claims (1)

A method of obtaining products from manganese-containing ferrites with a rectangular hysteresis loop, including pressing, sintering in air and hardening, characterized in that, in order to improve the quality of the products by increasing the temperature stability of electromagnetic parameters, after quenching, additional annealing is carried out at 350-450 ° C for 1-10 hours Example The method of obtaining products from ferrite Parameters of additional annealing of ferrite products The electromagnetic parameters of a ferrite product Temperature ° C Duration h Reading current 1sch. mA Amplitude of the signal of an undestroyed unit uVi, mV one 2 3 four 5 6 one Famous - - 617 34 2 Proposed 450 one 623 35 3 Also 350 10 623 35 four Proposed 400 5 612 35 5 When going beyond the scope of the invention 400 0.5 717 34 6 Also 400 12 637 31 7 . .н__ 480 1.5 617 29th 8 300 10 659 33