JPS59220902A - Temperature sensitive resistance element - 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 The present invention provides barium titanate (B aTi Us ) k
This is related to the temperature-sensitive resistance element which is the main component.

Barium titanate H1l [One cucumber in the temperature range of 1-120℃? It is a ceramic semiconductor material with

This substance generally has a specific resistance of 10' to 10' at room temperature.
It is used as the main component of temperature-sensitive resistance elements because it has the property of rapidly increasing due to the phase transition of barium titanate in a temperature range exceeding one point of curie. This type of temperature-sensitive resistance element is installed, for example, in the protection equipment of electric appliances, and when a large l'lI current flows t'l due to a short circuit accident, the specific resistance increases due to the temperature rise due to the Joule heat. And the current in the circuit? It will play the full role of limiting.

However, when the temperature-sensitive resistance element of type C is used by being incorporated into the protection equipment of high-power equipment, the following problems occur because the rated voltage and rated current of the equipment are large. In other words, if the specific resistance of the pressure-sensitive resistance element at room temperature is not so small that it can be ignored with respect to the entire circuit, the constant power consumption will increase, and as the power consumption increases, the specific resistance of the element will increase due to Joule heat VC. Therefore, there is a risk that a current-limiting effect may occur even when not in use. Furthermore, since the element is made of ceramic, if the temperature of the element suddenly rises due to a large current flowing immediately after a short circuit accident, there is a risk that the element will be destroyed due to distortion caused by the temperature difference.

The present invention has been made based on these circumstances, and provides a temperature-sensitive resistance element that has a low resistivity at room temperature and a high mechanical strength, and can be suitably used as a current-limiting element for high power, for example. ? The purpose is to provide

The present invention will be explained in detail below.

The temperature-sensitive resistance element according to the present invention is a metal powder having a particle size of 53 μm or less. This metal powder is obtained by completely oxidizing a sintered body of barium titanate containing 2i to 30% by weight of the metal powder. Here, the metal powder is copper powder,
Silver powder, cobalt powder, etc. can be used.

The temperature-sensitive resistance element according to the T/c of the present invention can be manufactured as follows. In other words, metal powder with a particle size of J3μ or less?
For example, alcohol? Using the V-shaped rotary mixer used, the mixed powder is uniformly mixed with barium titanate powder, and the mixed powder is sufficiently dried to form a molded body. A di-sintered body is obtained by firing for 1 to 6 hours. Further, this sintered body is subjected to an oxidation treatment in a fully oxidizing atmosphere for, for example, 1 to 6 hours, thereby obtaining a temperature-sensitive resistance element. Here, it is important that the sintering temperature Q is in a temperature range that is higher than the melting point of the mixed metal powder, and the sintering is performed in a state where the metal powder interposed in the barium titanate powder is molten. By sintering? At the same time, it is possible to increase the bonding strength between barium titanate powders after sintering, that is, the mechanical strength of the element.
It is preferable to carry out the sintering at a temperature of 1400°C to 1400°C. In addition, if the oxidation treatment temperature is too high, the oxidation of the metal powder will be promoted and the specific resistance of the element at room temperature will become too large.
For example, when copper powder is used as the metal powder, it is 900 to 13.
Preferably, the temperature is 00°C. The atmosphere of the selective oxidation treatment is
It is not limited to nitrogen, but may be in oxygen-rich air or in an oxidizing atmosphere such as oxygen. The reason why the sintered body is subjected to the oxidation treatment is to increase the ratio of the resistivity at high temperature to the resistivity at room temperature of the element.

The pressure-sensitive resistance element according to the present invention is a metal powder having a particle size of 53 μm or less. 11" containing 1 to 30% by weight, has a low specific resistance at room temperature, as is clear from the experimental examples described later. The reason for this is that the resistance of the grain boundaries between the metal powder and the barium titanate powder is This is thought to be because the resistance is smaller than the grain boundary resistance between barium oxide powders, and the particle size of the metal powder is 5.
This is thought to be due to the fact that the oxide film on the surface of the metal powder does not become very thick since it is 3 μm or less. Here, if the metal powder content is lower than 1% by weight, the resistivity of the element at room temperature becomes large, while if the content is as high as 30I, sintering becomes difficult. In addition, the particle size of the metal powder is 53μ
If it is larger than m, the oxide film on the surface of the metal powder becomes too thick, and the resistivity of the element at room temperature increases, and the ratio of the resistivity at high temperature to the resistivity at room temperature becomes large.

Next, an experimental example will be explained.

Example First, titanium 7 having a particle size J μm or less of 50 to 100%
flll High II +7mm powder and pure water? In addition, this nt-
Place the ball in a plastic round ball (Teflon coated), use an 8-12ψ agate spherical cobblestone, run the ball at 75-85 revolutions per minute for a total of 6-30 hours, and then crush it. Dry in air at 20°C for more than 2 days and nights and pass through a 3° mesh sieve to obtain -3° mesh barium titanate powder.

In addition, 500 mesh units of copper powder with a purity of 99.9 cm was added.
Sea bream powder with a diameter of 25 μm or less when passed through 11i'? obtain. Next, 5% by weight of the above copper powder was added to -30 mesh barium titanate powder and mixed uniformly using an Ai glass mold rotary mixer Equa-Cole (reagent special grade ethanol). The mixture is mixed for 30 to 60 minutes, and then removed by scattering with an alcohol needle and evaporated to form a dry mixed powder. The above-mentioned mixed powder is placed in a mold and pressurized at a pressure of 250 kg/cr/l, causing shrinkage due to sintering. Taking into consideration, a disc-shaped molded body having the diameter and thickness of XCPar was made, and this molded body was placed in a porcelain (Albasu) sheath and heated to a temperature of 130071 in an inert atmosphere (Abongas). Sinter for 1 hour. Finally, the above-mentioned sintered body was oxidized in nitrogen atmosphere at a temperature of 1100° C. for 1 hour, thereby forming a temperature-sensitive resistance element. citr temperature sensitive resistance element/and f7S,.

Example 99.9% purity steel powder? 1J (l) of 350 mesh
50 (1 mesh sieve to remove particles with a particle size of 25 μm or less (r), which means particles with a particle size of 25 μm
Copper powder with a diameter larger than 36 μm can be obtained. Particle size 25
Instead of copper powder of less than μm, this copper powder' has 5 layers and 1 ton.
A temperature-sensitive resistance element was prepared in the same manner as in Experiment fil 1, except that the powder was mixed with the powder of aluminum titanate at a ratio of 1.5%. Kowa? Temperature sensitive μ (assumed to be anti-element).

Example 11. Copper powder with a purity of 99.9% was passed through a 250 mesh sieve. (Put through a 50-mesh sieve to obtain particles with a particle size of 36 μm.
Something less than m? Thus, all steel powder having a particle size of 53 μm or less, which is larger than 36 μtn↓, is obtained. In addition to mixing copper powder with a particle size of 25 μm or less with barium titanate powder at a ratio of 5% by weight, one temperature-sensitive resistor was obtained in the same manner as in Experimental Example 1. Ta. This element is referred to as a temperature-sensitive resistance element 3.

Example: 99.9% purity copper powder passed through a T150 mesh sieve and passed through a 250 mesh sieve to remove particles with a particle size of 53 μm or less, so that the particle size was 11 larger than the normal 5:3 μm and 105 μm or less. Get the copper powder. A temperature-sensitive resistance element was obtained in the same manner as in Experimental Example 1, except that instead of the copper powder having a particle size of 25 μm or less, this copper powder was mixed with barium titanate powder at a ratio of 5% by weight. This element is referred to as a temperature-sensitive resistance element l.

Example He 99.9% Copper powder* What was left over after passing through a 150-meter sieve? and 9, the particle size is 1 (15μ) from K.
Copper powder over m? obtain. This copper powder instead of copper powder with a particle size of 25 μm or less? A temperature-sensitive resistance element was obtained in the same manner as in Experimental Example 1 except that it was mixed with barium titanate powder at a proportion of 55% by weight. Let this n be a temperature-sensitive resistance element j.

The table below shows the grain size of the copper powder and the steel powder contained in the above-mentioned resistor and resistor.

After thoroughly polishing and cleaning both sides of the temperature-sensitive resistance elements/~j obtained by straining as described above,
, made the following sub-legs.

Temperature sensitive resistance element/2. Regarding η, the relationship between the temperature of each element and the specific resistance is plotted. The results are as shown in Section 1III. The solid lines, dotted lines, and dashed-dotted lines in the figure correspond to the temperature-sensitive resistance elements /, J, and i4, respectively.

Furthermore, the temperature-sensitive resistance element/~JVc each has a specific resistance value that is low at room temperature. In addition to measuring FE, we also measured Ro
The ratio of specific resistance ('/'o)k at 0°C was determined.The results are as shown in Figure 2, and the graph in this figure shows the dependence of Ro and )(,/R, on particle size of copper powder) It is a value representing the total effect.R/+, +.P'I'C is a value representing the effect.

Also, what is the thickness of the oxide film on the surface of each copper powder for the temperature-sensitive resistance element/~jVc? Examined. The result P: is as shown in FIG. d on the vertical axis of the figure is the oxidation 1jQ thickness.

Considering the above results, Figure 2 shows that the larger the particle size of copper iodine powder, the higher the specific resistance at room temperature. becomes larger,
And Lu/Lu. You can see that it is getting smaller. And those with particle size up to C have small R8 and
It. The particle size is large enough to meet the practical characteristics, and the temperature characteristics of resistivity are also suitable as shown in Figure 1, but the particle size exceeds C (1 dl), and the As shown in Figure 1, the resistivity does not increase that much even at high temperatures, making it unusable for practical use.
It can be assumed that the cause is that as the particle size increases, the oxide film on the surface of the copper powder becomes thicker and the amount of oxidized copper increases. It is feared that the oxide film will thicken rapidly, which will deteriorate the characteristics of the device.

Here, the same results as in the case of copper powder were obtained for temperature-sensitive resistance elements manufactured in the same manner by mixing silver powder or cobalt powder with barium titanate powder instead of copper powder. .

As described above, according to the present invention, the temperature-sensitive resistance element has a small specific resistance at the temperature of the temperature and has a large mechanical strength, so that the temperature-sensitive resistance element can be used as a current-limiting element for high power, for example.
(%) can be used appropriately.

[Brief explanation of drawings]

If! Figure 1 is a graph showing the relationship between the specific resistance of a temperature-sensitive resistance element and temperature, and Figure 2 is a graph showing the particle size of copper powder, the specific resistance of the temperature-sensitive resistance element at room temperature, and the specific resistance at 200°C with respect to the specific resistance at room temperature. The relationship between the percentage and the amount of money shown is 7
, Figure 3 shows the relationship between the grain size of the copper powder and the thickness of the oxide film on the surface of the copper powder. This is a graph showing. Figure 1 Figure 2 BCDE Translocation BCDE ;t degrees

Claims (1)

[Claims] 1. A temperature-sensitive resistance element characterized in that a sintered body of barium titanate containing 1 to 30% by weight of metal powder having a particle size of 53 μm or less is subjected to a total oxidation treatment.