JPS58225602A - Method of producing nonlinear resistor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for manufacturing a nonlinear resistor containing zinc oxide as a main component of gold.

[Technical background of the invention and its problems]

Generally, in an electrical system V, an overvoltage protection device such as a surge absorber or lightning arrester is used to remove an overvoltage superimposed on a normal voltage in order to protect the electrical system and electrical equipment.

This overvoltage protection device uses a nonlinear resistor that exhibits almost insulating properties at a normal voltage and has a relatively low resistance value when an overvoltage is applied.

Non-linear resistors are manufactured by pressing a mixture of silicon carbide (8i0) or zinc oxide (ZnO) powder with a metal oxide into a molded body, and firing the molded body.

ZnO-based non-linear resistors have steep non-linear characteristics in the hand-stretched region and have a sharp profile even in the large current region, so we used an Sm0-based non-linear resistor. An excellent overvoltage protection device can also be made.

However, in the conventional ZnO-based nonlinear resistor, the leakage magnetic current increases sharply with respect to the constantly applied screw pressure, and the voltage drop due to the impulse #1 current is large. Therefore, it is an unsuitable anchor for an overvoltage protection device that is subjected to overvoltage pulses or voltage surge pulses over a long period of time, and there has been a demand for a nonlinear resistor that has stable electrical characteristics over a long period of time.

[Purpose of the invention]

The present invention was made in view of the above requests, and provides a method for manufacturing a ZnO-based nonlinear resistor used in overvoltage protection devices that require high performance and high reliability, such as gapless lightning arresters. .

[Summary of the invention]

ZnO-based non-linear resistors are made by mixing and molding zinc oxide with at least one substance such as bismuth oxide, copal oxide), anti-7 oxide, trit manganese, chromium oxide, nickel oxide, and silicon dioxide. After that, 10o.

It is a sintered body obtained by firing at a temperature below 0°. In the mixing step, an organic binder is added.

The inside of this sintered body contains crystal grains whose main component is zinc oxide.
It consists of a grain boundary layer containing other additive components and a spinel layer containing various components. The electrical properties of this non-linear resistor are mainly based on the electrical properties at the interface between the 1c ZnO crystal grains and the grain boundary layer. By forming such a non-linear resistor, a non-linear resistor with a small leakage current increase rate and good shock current withstand characteristics can be obtained.

As a result of research conducted by Hashira, the present inventor found that a molded rope body formed by adding and mixing an organic binder to a mixture component showed that the organic binder 'k100'0/H and Q also caused the molded body to sinter at a slower rate. By raising the temperature to a predetermined temperature below the bonding start temperature and removing this bond in advance by heating, the ZnO-based nonlinear material has a small leakage DC increase rate with respect to the constant am voltage and has excellent shock current withstand characteristics. It was discovered that a resistor could be obtained.

[Embodiments of the invention]

Hereinafter, the present invention will be explained based on examples.

Bismuth oxide (BizOa), antimony oxide (SbzOs), etc. are added to the main component, lead oxide (ZnO) powder.
Chromium chloride (Or20g), cobalt oxide (O
Powders such as OO) and manganese oxide (MnO) are added in the range of 0.01 to 6.0 mol each, and an organic binder PVA (polyvinyl alcohol) is added in an amount of 0.5 wt in total. % and mix thoroughly. This mixture is pressed, e.g.
yx, and mold into a disk shape with a thickness of 30 cm. Thereafter, this molded element is heated to 500°C for 10 hours, for example, and then held at 500°C for 2 hours, for example,
Allow time to cool.

Through this temperature raising and cooling process, the molded element becomes j5PVAff.
i remove. After that, it is fired at 1000-1400℃,
After polishing the entire surface of the obtained sintered body, an aluminum ram electrode was sprayed to form a non-direct a! Form mother antibodies.

In conventional processes for removing organic binders, emphasis has been placed only on the removal temperature of the organic binder, and there has been a tendency to neglect the removal rate.

The electrical characteristics of the nonlinear resistor obtained according to the present invention are shown in FIGS. 1 and 2.

Figure 1 shows the change in leakage current when a voltage of 85 mA (terminal voltage when 1 mA is applied to the non-linear resistor) is applied to the non-linear resistor in a constant temperature bath at 90°C.

Fig. 2 of the fc edition shows the rate of change in the value of VlmA (ΔV/V, mA) when a current of 10 KA was applied up to 100 times.

In each figure, solid line A indicates that the conventional organic binder removal rate is 2.
The chain line B shows the characteristics of a non-linear resistor having an organic binder removal rate of 50'O/H according to the present invention.

As is clear from FIG. 1, the non-linear resistor according to the present invention has a higher charge i than the conventional non-linear resistor. Changes in leakage direct current with respect to rolling rolling are significantly improved, in other words, life characteristics are improved. Furthermore, as is clear from FIG. 2, the non-linear resistor according to the present invention has an impact of 1! compared to the conventional non-linear resistor. The flow resistance characteristics are also significantly improved.

The reason why such a ZnO-based nonlinear resistor can obtain the excellent characteristics shown in Figures 1 and 2 is because no organic binder remains inside the nonlinear resistor, and ZnO particles and grain boundary layers This is because the spinel layer is uniformly dispersed and the grain boundary layer is stable.

If a molded element containing an organic binder is heated rapidly and the temperature is raised as in the conventional method, the organic binder will suddenly burn and its gas will spread into the atmosphere around the molded element. A disadvantage arises that the organic binder in the nonlinear resistor cannot be completely removed.

However, when the temperature of the molded rope is gradually increased as in the present invention, the combustion gas of the organic binder does not spread into the atmosphere around the molded element, and the organic binder does not remain. Similarly, the J: limit of the heating temperature is, for example, 700°0. (This is because the element body will sinter beyond this point.) In the same example, bismuth oxide (
Bi20g) + cobalt oxide (00203), e
Manganese oxide (MnO), antimony oxide (Sb20g
), (ljI chromium oxide (Or20g) was used, but additional additives such as lead oxide (PbO), barium oxide (Bad), nickel oxide (Nip), tin oxide (SnO), and silicon dioxide (StO2) were used. ,
Titanium oxide (T 102), ayaminium oxide (A4)
0g), IR silver oxide (AgzO) l Decayed boron (B
* os) All types of borosilicate glass frits, borosilicate lead glass frits, etc. that change the semiconductivity of zinc oxide particles, and those that change the properties of the part that constitutes the grain boundary layer surrounding zinc oxide particles. In this case, the effectiveness of the present invention is not impaired in any way.

Furthermore, it goes without saying that the conditions of the manufacturing process are not limited to those in Example L.

[Other embodiments of the invention]

1-A), instead of PVA, HPO (hydroxypropylcellulose), MO (methylcellulose) and PVA
Similar results were obtained with a mixture of two or more of , HPO, and MO.

In addition, in this example, the molded element was heated at a rate of 50 υ/H, but it has been confirmed that similar results can be obtained at a rate slower than 100° (]/H. Details are shown in Table 1. This is a guide to show.

Table 1 vlrIL is the voltage when an AC resistance of 1771A is applied. Vtoxmu/V1mi, V1mh/Vo
, tmh, Vo, u+u/■, and 01 mA are the ratios of the voltages when the respective currents are passed, and the smaller the value, the better the nonlinearity is.

In addition, the Mineden life test was performed at an ambient temperature of 90'O1! l! 'it
It shows the rate of change in the AC resistance current I when a rate of 85% is applied for 1000 hours, and the smaller the rate of change, the better the performance.

〔Effect of the invention〕

As explained above, according to the present invention, by improving the conditions for removing the organic binder from the molded element body, a nonlinear resistor with good life characteristics and excellent impact current resistance characteristics is provided. can.

[Brief explanation of the drawing]

Fig. m1 is a characteristic diagram showing the degree of change in leakage current vs. time of energization of the nonlinear resistor O according to an embodiment of the present invention, and Fig. 2 is a characteristic diagram of the impact current withstand capacity. (7317) Representative Patent Attorney Nori Yu Kinkayana (and 1 other person) Figure 1 Figure 2 Inuraian/(Luz Uo 0 times - f (around)

Claims (1)

[Claims] 1. At least one metal oxide and an organic binder are added to and mixed with zinc oxide as the main component, and then molded, and the molded element is heated to 100°O/I-x. After removing the organic binder by slowly increasing the temperature to a predetermined temperature below the sintering start temperature of the molded element, the molded element is further sintered to produce a non-linear resistor. Production method. 2. The method for manufacturing a nonlinear resistor according to claim 1, wherein the sintering temperature of the molded element is 1000 to 1500°0.