JPS6221242B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a voltage nonlinear resistor made of an oxide semiconductor. One of the circuit elements using semiconductors is a voltage nonlinear resistor, and a typical example is a varistor using a sintered body of ZnO with various oxides added. This type of varistor has non-linear voltage-current characteristics, and as the voltage increases, the resistance rapidly decreases and the current increases significantly, so it is useful for absorbing abnormal voltages and stabilizing voltage. It has been put into practical use. By the way, the characteristics of a voltage nonlinear resistor are generally evaluated using the voltage-current characteristics expressed by the following approximate equation. = (V/C) (However, the current flowing through the varistor, V is the applied voltage, C is a constant, and α is a nonlinear coefficient.) Therefore, the general characteristics of a varistor can be expressed using two constants, C and α. It is usually expressed as a voltage V ₁ at 1 mA instead of C, and emphasis is placed on a large α value, which is an index indicating voltage nonlinear characteristics. While the above ZnO varistors (voltage nonlinear resistors) have many features such as being able to arbitrarily adjust the voltage-current characteristics, when using these ZnO varistors as power lightning arresters, they have the following drawbacks: It was hot. That is, in the conventional ZnO-based voltage nonlinear resistor, the characteristic change in the small current region when constantly energized is large, and the rate of change when an impact current is applied is large. Another disadvantage is that the nonlinear characteristics in the large current region are not sufficient. In addition, in order to eliminate the drawbacks of conventional ZnO-based nonlinear resistors, it is common to add several oxides or various glass components to the basic composition of ZnO and various oxides. A method is being taken. However, when the characteristics are improved by adding oxides, even if the nonlinear characteristics in the large current region are improved, the characteristics in the small current region due to constant charging or impact current change greatly.
Lacking reliability. In addition, when the characteristics are improved by using various glass components, the change in characteristics in the small current range due to constant energization is small, but there is no effect on the shock current characteristics and nonlinearity in the large current area, and it is not suitable for use as a power surge arrester. It wasn't enough to use. The present invention improves these drawbacks, has high reliability,
The object of the present invention is to provide an oxide voltage nonlinear resistor that is suitable for lightning arresters with excellent nonlinearity in a large current range. The present invention uses ZnO as the main component and as a subcomponent.
Bi, Co, Sb, Mn, Cr, Si respectively Bi ₂ O ₃ ,
Co ₂ O ₃ , Sb ₂ O ₃ , MnO, Cr ₂ O ₃ , 0.05 to 2 mol %, 0.05 to 2 mol %, 0.1 to 0.1 mol %, respectively, in terms of SiO ₂
3 mol%, 0.05 to 2 mol%, 0.05 to 2 mol%,
0.05 to 5 mol%, at least one of Ni and Al
Sn is added to the raw materials containing 0.05 to 2 mol% and 0.001 to 1 mol% in terms of NiO and Al ₂ O ₃ , respectively.
An oxide voltage nonlinear resistor comprising a sintered body containing at least one of Ti and 0.05 to 5 mol % and 0.05 to 5 mol %, respectively, in terms of SnO ₂ and TiO ₂ . It is something. The present invention will be explained below with reference to Example 1.
1.0 mol% each of Bi ₂ O ₃ and Sb ₂ O ₃ in ZnO,
_0.5 each of _Co2O3 , NiO, _SiO2 , MnO _{, Cr2O3}
The basic composition is 0.01 mol% of Al ₂ O ₃ , and 0.05 to 0.05 mol% of at least one of SnO ₂ and TiO ₂ .
Add and blend at a ratio of 5 mol % and thoroughly mix in a ball mill to obtain a prepared powder. The prepared powder thus obtained was blended with polyvinyl alcohol as a binder, molded into a disk shape with a diameter of 55 mm at a pressure of 1 ton/cm ² , and these molded bodies were sintered by firing at 1200°C in an air atmosphere. A body was obtained, both sides were polished parallel to each other to a thickness of 20 mm, and then Al was sprayed onto the polished surfaces and electrodes were attached to obtain a voltage nonlinear resistor. The nonlinearity of this voltage nonlinear resistor in the large current range is determined by the ratio of the voltage when a current of 10KA is passed through the resistor element (V _10KA ) and the voltage when a current of 1mA is passed through the element (V _1nA ). It is expressed as (V _10KA /V _1nA ), and the relationship between the amounts of SnO ₂ and TiO ₂ added to the basic composition is shown in FIG. Curve a is when SnO ₂ is added to the basic composition, curve b is when TiO ₂ is added, and curve C is when SnO ₂ is added to the basic composition.
and TiO ₂ are added in a molar ratio of 1:1. As is clear from Figure 1, for the basic composition
It can be seen that when at least one of SnO ₂ and TiO ₂ is added, the nonlinearity in the large current range is significantly improved. Figure 2 shows the change in characteristics in the small current range due to impact current. The rate of voltage change was expressed as the rate of change before and after the application of an impulse current of voltage V ₁₀ 〓 _A when a current of 10 μA was passed through the element. The impact current is 8×20μ
S10KA was applied 10 times at 30 second intervals. As is clear from FIG. 2, it can be seen that the stability of the characteristics in the small current region due to the application of an impact current is significantly improved. FIG. 3 shows the rate of change during constant power application, and it can be seen that the stability of the characteristics in the small current range is also significantly improved in the present invention. The above-mentioned significant improvement effects in nonlinearity, shock current characteristics, and constant charging characteristics in the large current range are essential when applying nonlinear resistors to lightning arresters, etc., and the voltage nonlinear resistor of this example has these effects. This fully satisfies the requirements. Next, if we explain Example 2, ZnO
Bi ₂ O ₃ , Co ₂ O ₃ , MnO, Cr ₂ O ₃ each from 0.05 to 2
Mol%, Sb ₂ O ₃ 0.1-3 mol%, SiO ₂ 0.05-5
0.5 mol each of at least one of SnO ₂ and TiO ₂ for a basic composition system containing 0.05 to 2 mol % and 0.001 to 1 mol % of at least one of NiO and Al ₂ O ₃ , respectively. % was added and blended, and experiments were conducted under the same conditions as in Example 1, including the conventional example, to obtain characteristic data of voltage nonlinear resistors as shown in the table. As is clear from this table, in Example 2 as well, the nonlinearity in the large current range and the characteristics in the small current range during application of an impact current and during constant voltage application are as shown in FIGS. It can be seen that the same effect as the result of Example 1 shown in FIG. 3 is exhibited. According to the present invention, the basic composition is ZnO as the main component.
Bi ₂ O ₃ , Co ₂ O ₃ , MnO, Cr ₂ O ₃ each from 0.05 to 2
Mol%, Sb ₂ O ₃ 0.1-3 mol%, SiO ₂ 0.05-5
Even if the mol% and at least one of NiO and Al ₂ O ₃ are changed from 0.05 to 2 mol% and 0.001 to 1 mol%, respectively, the present invention can be achieved by adding and blending at least one of SnO ₂ and TiO ₂ . The results are always promising. As explained above, the present invention provides an oxide nonlinear resistor that is suitable for lightning arresters and the like and has excellent nonlinearity in a large current range, and also has excellent reliability when applying an impact current and when being constantly charged. be. 【table】

[Brief explanation of the drawing]

Figure 1 is a curve diagram showing the added amounts of SnO ₂ and TiO ₂ of the present invention and non-linearity in the large current range, Figure 2 is a curve diagram showing the same added amount and the rate of change in impulse current characteristics, and Figure 3 The figure is also a curve diagram showing the rate of change in the constant energization characteristics.

Claims (1)

[Claims] 1 ZnO is the main component, and Bi, Co, and
Sb, Mn, Cr, and Si are respectively Bi ₂ O ₃ , Co ₂ O ₃ ,
Respectively in terms of Sb ₂ O ₃ , MnO, Cr ₂ O ₃ , and SiO ₂
0.05-2 mol%, 0.05-2 mol%, 0.1-3 mol%, 0.05-2 mol%, 0.05-2 mol%, 0.05-5
mol%, at least one of Ni and Al is 0.05 to 2 mol% each in terms of NiO and Al ₂ O ₃ ,
Sn and
An oxide voltage nonlinear resistor comprising a sintered body containing at least one type of Ti in an amount of 0.05 to 5 mol % and 0.05 to 5 mol % in terms of SnO ₂ and TiO ₂ , respectively.