JPH06163207A - High temperature thermistor element - Google Patents

Abstract

(57) [Summary] [Purpose] An object of the present invention is to provide a high temperature thermistor element which can be fired at a low temperature and has stable high temperature load test characteristics. [Structure] In order to achieve this purpose, 3Y ₂ O ₃ · (5
_{-X-y) Fe 2 O 3} · xAl 2 O 3 · yCr 2 O 3 (0 ≦ x
The main component is an yttrium-iron garnet structure oxide having a composition formula of <1, 0 ≦ y <1), and the main component 10
A mixture of ZrO ₂ and CaCO is added within a range where the total amount of the subcomponents added is within 1.0 part by weight with respect to 0 part by weight.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high temperature thermistor element used for an automobile sensor, for example.

[0002]

2. Description of the Related Art As a constituent material of a conventional high temperature thermistor element used at around 1000 ° C., Zr--Y type, Mg
The -Al-Cr-Fe type | system | group and the Co-Al-Cr type | system | group oxide were used.

[0003]

With the above conventional materials,
In order to construct a high temperature thermistor element, the firing temperature is set to 1
If the temperature is not higher than 600 ° C, the resistance value will change greatly in the high temperature load test after firing, and the stability will be poor. It was

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide a high temperature thermistor element which can be fired at a low temperature and has stable high temperature load test characteristics.

[0005]

In order to achieve this object, the high temperature thermistor element of the present invention contains an oxide of the yttrium-iron garnet structure represented by the formula (1) as a main component. In addition, ZrO ₂ , Ca is added as an accessory component.
CO ₃ is added in an amount of 0.01 to 100 parts by weight for each main component.
1.00, 0.10 to 1.00 parts by weight Added in the form of composite. The amount of the subcomponent added was 1.00 parts by weight or less based on 100 parts by weight of the main component.

[0006]

Since the garnet type ferrite material is used according to the above construction, it can be fired at a relatively low temperature.
Further, by adding the mixture of the sub-components ZrO ₂ and CaCO ₃ , the sintered compact becomes dense and the high temperature load test characteristics become stable.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. Resistance - 3Y the main component of the composition formula in consideration of the temperature characteristic _{2 O 3 · 4Fe 2 O 3} · 0.8Al 2 O 3 · 0.2
It was Cr ₂ O ₃ .

In addition, ZrO ₂ and CaCO ₃ as subcomponents (Table 1)
Samples 1 to 8 were prepared by adding them at the ratio shown in. The raw materials are commercially available Y ₂ O ₃ , Fe ₂ O ₃ , Al ₂ O ₃ , Cr ₂ O ₃ and Zr.
O ₂ was used.

[0009]

[Table 1]

First, sample 1 was wet-mixed with a ball mill, and the resulting slurry was dried, then roughly crushed and calcined at 1000 ° C. Then, wet pulverization was performed again, the obtained slurry was dried, and polyvinyl alcohol was added as a binder to form a molded body 12 having two through holes 11 as shown in FIG. Next, as shown in FIG. 3, the Pt electrode 1 is formed in the through hole 11.
3 and insert it in the air at 1400 to 1450 degrees. The same operation was performed on Samples 2 to 8.

The high temperature thermistor element 14 thus obtained was subjected to a high temperature load test at 1000 ° C. and DC2V. The result is shown in FIG. As shown in FIG. 1, the ones to which the sub-components ZrO ₂ and CaCO ₃ were added (Samples 2 to 8) have small resistance value change rates and are stable in the high temperature load test.

If the amount of the subcomponent added exceeds 1.00 parts by weight, cracks will occur during sintering. Zr to be added
The amounts of O ₂ and CaCO ₃ were determined from the stability in the high temperature load test when added individually.

[0013]

As described above, the high temperature thermistor element of the present invention has the following composition with respect to the main component composed of the yttrium-iron garnet structure oxide represented by the compositional formula (Formula 1).
By adding a small amount of ZrO ₂ and CaCO ₃ as an accessory component, it becomes possible to carry out low temperature firing and to obtain a stable one having a small resistance value change rate in a high temperature load test.

[Brief description of drawings]

FIG. 1 is a graph showing the resistance change rate of a high temperature thermistor of the present invention after a high temperature load test.

FIG. 2 is a cross-sectional view showing a molded body of a high temperature thermistor element in one embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a sintered body of a high temperature thermistor element in one embodiment of the present invention.

[Explanation of symbols]

 1 sample 1 2 sample 2 3 sample 3 4 sample 4 5 sample 5 6 sample 6 7 sample 7 11 through hole 12 molded body 13 Pt electrode 14 sintered body

Claims (1)

[Claims] Claims: 0.01 to 1.00 parts by weight of ZrO ₂ as a subcomponent, and Ca to 100 parts by weight of the main component composed of the yttrium-iron garnet structure oxide represented by the composition formula
CO ₃ is added in the form of 0.10 to 1.00 parts by weight,
A high temperature thermistor element in which the total amount of subcomponents is 1.00 parts by weight or less based on 100 parts by weight of the main component.