UA124086U - MATERIAL FOR LOW VOLTAGE VARISTORS - Google Patents

Abstract

Material for low-voltage varistors based on transition metal oxide, including other metal oxides, and it contains, as the main component, tungsten oxide and, as additives, oxides of sodium and manganese, in the following ratio of components, mol. %: sodium oxide Na2O 0.3-2.0 manganese oxide MnO2 0.3-3.0 tungsten oxide WO3 the rest.

Description

A useful model belongs to electronic engineering and can be used in the production of low-voltage ceramic varistors, which are used to protect electrical circuits from overvoltage.

A known ceramic material based on zinc oxide |1| with non-linear electrical properties is widely used for the production of varistors. However, such material has a high classification voltage, which prevents its use in low-voltage devices.

To reduce the classification voltage, the distance between the electrodes of the varistor is reduced to 50 μm (2), or the size of the zinc oxide grain is increased to 200 μm by introducing seed grains |Z) into the charge. The disadvantage of such material is the complexity of its manufacture and insufficiently low classification voltage.

A well-known material for low-voltage varistors is based on tin oxide |4|, however, such materials have a low non-linearity coefficient of the current-current characteristic (VAH) and require a very high firing temperature (1600 "С).

The closest to a useful model is the material for low-voltage varistors based on titanium oxide |5| with additives of strontium and niobium oxides. This material provides a low-voltage range of classification voltage of 3-10 V/mm. The disadvantage of the known material is a small coefficient of nonlinearity of the I-V.

The task of a useful model is to increase the coefficient of nonlinearity of the I-V.

The problem is solved by the fact that in the material for low-voltage varistors based on transition metal oxide with additives of oxides of other metals, the new thing is that it contains tungsten oxide as the main component, and sodium and manganese oxides as additives, with the following ratio of components, mol. 9o: sodium oxide MagO 0.3-2.0 manganese oxide MpO»2 0.3-3.0 tungsten oxide UMOz the rest.

This composition provides an increase in the coefficient of nonlinearity of the I-V.

A comparative analysis with the closest analogue allows us to conclude that the material composition of a useful model for low-voltage varistors differs from the known one in that it contains tungsten oxide as the main component, and sodium and manganese oxides as additives.

The analysis of known material compositions for varistors showed that the additives used in the claimed utility model are known, however, their use in these materials in combination with other components does not provide the material with such properties as they manifest in the claimed

From a useful model, namely, a fairly high coefficient of nonlinearity of the I-V while maintaining a low classification voltage.

To evaluate the varistor properties of the material, material samples with different contents of tungsten, manganese and sodium oxides were prepared. Table 1 shows the values of the I-V characteristics of the proposed material. The IAC of the material samples was measured at direct current and is non-linear. The coefficient of nonlinearity of the I-V was determined by a known method in the range of currents of 1039-1072 A/cm, and the classification voltage at a current of 1 mA/cm-.

As can be seen from the table, the material samples have a higher coefficient of nonlinearity of the I-V, while maintaining a rather low classification voltage. The greatest positive effect is achieved with the content of manganese oxide in the range of 0.3-3.0 mol. 95, and sodium oxide in the range of 0.3-2.0 mol. 95. When choosing the composition of the material outside the specified limits, it does not have noticeable nonlinear properties.

The optimal composition necessary to achieve the task of a useful model should be considered a material based on tungsten oxide, which contains

Table

Electrical parameters of the material for low-voltage varistors mole moles 0 nelnnyut | WMO to accept it. rhymes

MOl. Uo | minor 95 | MOL. 905 nonlinearities V/mm 1-1 - 1-1 55 | 95 | Approx. analog 4 9890 | 05 | 05 | 502 | - 91 965 | 05 | 30 | Х38 2 ЮЩщщ | 97 | - 10 962 | 05 | 33 | 34 | --/950 юЦКМ | example 131 975 | 05 | 20 | (BO | .777777070789444477771111717111кс 151 | 920 | t5 | Z | 7777/0/768777111171717111sks 161,960 | 20 | 20 | 837 2 shЩ | 64 | -

For electrical measurements, copper electrodes were applied to the surface of the disks by the method of thermal spraying in a vacuum. The test results are presented in the table. As can be seen from the table, within the composition of the useful model, the obtained ceramic material has nonlinear electrical properties with a low classification voltage and a high coefficient of nonlinearity of the I-V.

The use of the declared useful model will allow to more effectively protect low-voltage electric circuits from overvoltages due to a higher coefficient of nonlinearity of the I-V and to reduce the energy consumption of the production process of low-voltage varistors due to a low firing temperature.

Sources of information: 1. Japan patent Mo 54-12994, Mayenpia! og pop Ippeag geviviog. NOTE 7/10, 1971. 2. Patent EPV Mo 0034511, Mop Ipeag segatis gezibiog pamipd a Iozh/ ipgezpoii mopKade. NOTS 7/L10, 1981. 3. US patent Mo 4169071, Monkade-derepaepi gezisog apa teinoa oi takKipd (Pe zate, NO1TV 1/08, 1980. 4. Japanese patent Mo 52-40760, Mopiipeag geziziog. NOTS 7/ 10, 1978. 5. USSR Academy of Sciences Mo 1468282, Material for low-voltage varistors. NO1TS 7/10, 1986

Claims (1)

USEFUL MODEL FORMULA Material for low-voltage varistors based on transition metal oxide, including oxides of other metals, which is characterized by the fact that it contains, as the main component, tungsten oxide and, as additives, sodium and manganese oxides, with the following ratio of components, mol. 9bo: sodium oxide Maho 0.3-2.0 manganese oxide MpO» 0.3-3.0 tungsten oxide U/Oz the rest.