JPH03280501A - Non-linearly voltage dependent resistor - Google Patents

Abstract

PURPOSE:To enhance the non-linearity, impulse current characteristic and the charge life characteristics in a large current region by a method wherein specific amount of Mo compound in the form of MoO2 is contained in a composition mainly composed of zinc oxide. CONSTITUTION:In order to manufacture the title non-linear voltage resistor, a composition containing the components as follows is sintered i.e., zinc oxide as the main component as well as bismuth, antimony, cobalt, manganese, chrome, nickel, silicon and aluminum compound as the sub-components respectively in the forms of Bi2O3, Sb2O3, CoO, MnO, Cr2O3, NiO, SiO2 and Al2O3 at the ratios of 0.05-2.0mol%, 0.05-3mol%, 0.1-2.0mol%, 1-3.0mol%, 0.05-2.0mol%, 0.05-2.0mol%, 0.05-3.0mol% and 0.001-0.5mol% furthermore, molybdenum compound in the form of MoO2 and in the ratio of 0.02-3.0mol%.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a ZnO-based voltage nonlinear resistor containing zinc oxide (ZnO) as a main component.

[Prior art] Voltage non-linear resistors (varistors) have non-linear voltage-current characteristics, and as the voltage increases, the electrical resistance rapidly decreases and the current increases significantly, causing abnormalities. Widely used for absorbing overvoltage and stabilizing voltage.

The characteristics of this voltage nonlinear resistor are generally evaluated using the voltage-current characteristics expressed by the following approximate expression.

I = (V/C) Here, ■ is the current flowing through the voltage nonlinear resistor, ■ is the applied voltage, C is a constant, and a is the nonlinear coefficient.

Usually, the characteristics of a voltage nonlinear resistor are expressed by a voltage at a certain current (varistor voltage) and a nonlinear coefficient a.

For convenience, the varistor voltage is often expressed as the terminal voltage (V, . . . ) when 1 mA of 1aδ flows.

Further, the nonlinear coefficient a is usually determined from the voltage-current characteristics at 0.1 mA to 1 mA. As a voltage nonlinear resistor, it is preferable that the value of the nonlinear coefficient α is large.

Incidentally, there has recently been a remarkable effort in the development of non-linear resistors for each phase voltage for the purpose of circuit protection.

In particular, a ZnO-based voltage nonlinear resistor consisting of a sintered body containing zinc oxide as the main component and various oxides added thereto has an α
It has an extremely large value of 40 to 100, has excellent nonlinearity, and has high stability in terms of shock current absorption and constant voltage properties, and is widely used as a protective varistor against lightning surges and abnormal voltages.

[Problems to be Solved by the Invention] However, conventional ZnO-based voltage nonlinear resistors have poor nonlinearity in the large current region, large characteristic changes in the small current region during constant energization, and It had the disadvantage of a large voltage drop.

The present invention provides a voltage nonlinear resistor that has excellent nonlinearity in the large current region, a small voltage change rate in the small current region a before and after the application of an impact current, and a small voltage change rate in the small current region before and after constant voltage application. The purpose is to obtain a body.

[Means for Solving the Problems] The voltage nonlinear resistor of the present invention contains zinc oxide as a main component,
Compounds of bismuth, antimony, cobalt, manganese, chromium, nickel, silicon, and aluminum are used as subcomponents, respectively: Bit On, Sb*Ox, Co
o, MnO.

Crz Os, N i O, S i Ox and A
In the form of 1 z 03, 0.05-2.0wo1%,
0.05-3.0 mol%, 0. 1-2. 0m
ol%, 0.1-3.0 mol%, 0.05-2.0p
a1%, 0.05-2.0IIo1%, 0. 05
~3. It is made by sintering a composition containing 0 mol% and 0.001 to 0.5 SO1%, and further containing a molybdenum compound in the form of Moo at a rate of 0.02 to 3.0 mol%. .

Here, bismuth and antimony are added as secondary ingredients.

Compounds of cobalt, manganese, chromium, nickel, silicon and aluminum, B 1 Os and S
b*Os,COO+MnO+CrxO
s, N i O, S i Ox and A1.0°, 0.05 to 2.0 mol%, 0.05 to 3.0
moH, 0.1-2. Os+oB, 0.1~3.0so
1%, 0.05-2.0mol%, 0.05-2.0m
ol%, 0, 05-3, 0mol% and 0
．． 001 to 0.5 mol%, and further contains a molybdenum compound in the form of MoO□ in an amount of 0.02 to 3.0 mol%.
The reason why these subcomponents are included at a ratio of 1% is that if these subcomponents deviate from their respective ranges, the characteristics of the varistor (limiting voltage ratio,
This is because the surge current characteristics, t#P life characteristics, and non-linear coefficients deteriorate.

Moreover, as the above-mentioned compound, not only oxides but also chlorides, carbonates, and other compounds can be used. Further, sintering is preferably performed in an oxidizing atmosphere.

[Example] Examples of the present invention will be described in detail below.

First, zinc oxide fZnol, bismuth oxide (Bx20
i).

Antimony oxide fsb20. ), III:] (Coal manganese oxide fMnOl ra l Niam fcr2 al nickel oxide (Nip),
Silicon oxide (SiO,l, aluminum oxide fAl2O
3) and molybdenum oxide iMoLl were weighed in the proportions shown in Table 1 (-01%j), these compounds were placed in a ball mill, and mixed with stirring for 20 hours to obtain a raw material powder.

Next, this raw material powder was dried and then calcined at 700 to 950°C for 1 to 4 hours to obtain a calcined product.

Next, a binder (PVA: 5% water soluble't) was added to this calcined product.
1) and granulate it, mold it with a molding machine to a diameter of 1
A 0.8 mm disc-shaped molded product was obtained.

Next, this molded product was placed in the air at a temperature of 1100 to 1300
A sintered body was obtained by firing at ℃ for 2 hours.

Next, aluminum was sprayed on both sides of this sintered body to obtain a voltage nonlinear resistor equipped with an aluminum sprayed electrode having a diameter of 7.6 mm.

Next, regarding this voltage nonlinear resistor, we will discuss the nonlinearity in the large current region, the rate of voltage change in the small current region (impact current characteristics) before and after applying an impact current, and the voltage change in the small current region before and after constant voltage application. When the ratio (electrification life characteristic) and nonlinear coefficient a were investigated, they were as shown in Table 1.

Here, the amount of bismuth compound was changed in samples Nos. 1 to 5, the amount of antimony compound was changed in samples Nos. 16 to 9, and the amount of cobalt compound was changed in samples Nos. 10 to 14. In samples Nos. 15 to 19, the amount of nickel compounds was changed, in samples Nos. 20 to 24, the amount of chromium compounds was changed, and in samples Nos. 25 to 24, the amount of chromium compounds was changed.
In 29, the amount of manganese compound was changed, and sample No.
In samples No. 30 to 35, the amount of silicon was changed, and sample No.
In Nos. 36 to 41, the amount of aluminum compound was changed,
In samples Nos. 42 to 47, the amount of molybdenum compound was varied.

In addition, nonlinearity in the large current region is determined by the terminal voltage V 1 mm when a current of 1 mm is passed through the element, and the
It was determined as a ratio (V l-A/V +-: referred to as limit voltage ratio) with the inter-terminal voltage V lkA when a current of kA was passed.

In addition, the impact current characteristics are as follows:
The voltage between the terminals when a current of 10 uA is applied before and after applying a shock current of 00 OA in the same direction twice (
It is expressed by the rate of change (ΔV/V, ., sa) of V+o, -^).

In addition, the energized life characteristic is 0.85X for the element at 85℃.
The voltage between the terminals (V, r
A) rate of change (ΔV/V, expressed in β pieces).

In addition, the nonlinear coefficient α is the terminal voltage V1. & and V. , &.

※ ※ ※ × × ※ ※ X ※ ※ ※ ※ ※ ※ ※ ※ ※ ※ As is clear from Table 1, No.
, 2-4.7.8. 11-13. 16-18.2
The characteristics of the samples No. 1-23.26-28.31-34°37-40 are comparative examples No. 1.5, 6, 9, 10.
．． 14,15゜19.20,24,25.29,30,
It can be seen that this is significantly improved compared to the samples of 35°36.41 to 47.

[Effects of the Invention] According to the present invention, Mo
0.02-3.0w in the form of M o Ox
Since +O1% is contained, it is possible to obtain a highly reliable voltage nonlinear resistor that has excellent nonlinearity in a large current region, excellent impact current characteristics and energized life characteristics.

Claims (1)

[Claims] Bi_2O_ contains zinc oxide as the main component and compounds of bismuth, antimony, cobalt, manganese, chromium, nickel, silicon, and aluminum as subcomponents, respectively.
3, Sb_2O_3, CoO, MnO, Cr_2O_3
, in the form of NiO, SiO_2 and Al_2O_3,
0.05-2.0 mol% 0.05-3.0 mol%,
0.1-2.0 mol%, 0.1-3.0 mol%, 0
．． 05-2.0 mol%, 0.05-2.0 mol%,
0.05-3.0 mol%, and 0.001-0.5 m
ol% and further contains molybdenum compound MoO
A voltage nonlinear resistor obtained by sintering a composition containing 0.02 to 3.0 mol% in the form of _2.