JPS5854482B2 - Manufacturing method of temperature-sensitive resistor ceramic element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a temperature-sensitive resistor ceramic element.

Conventionally known Co-Mn-Ni oxide thermistor materials are used at temperatures below 300°C, and zrO2- is a temperature-sensitive resistor material that can be used at high temperatures.
Y2O2 series Review of Scientific Instruments 40 [4] 544-549 (1969) is known.

However, even with this temperature-sensitive material, there are still problems to be solved regarding the stability of life characteristics.

The reason for this is that at high temperatures, the temperature-sensitive resistor ceramic element
This means that it can be reduced or oxidized, and can be affected by other gases.

Therefore, an object of the present invention is to provide a method for manufacturing a temperature-sensitive resistor ceramic element that can be used at high temperatures of 300° C. or higher and has stable life characteristics. be.

The method for manufacturing a temperature-sensitive resistor ceramic element of the present invention includes MgCr2O4 having a spinel structure and TiO2 having a rutile structure.
14 while pressurizing a molded body whose main component is a mixed composition of
Since the temperature sensitive resistor ceramic element is produced by sintering at a temperature of 908C to 1000C, the obtained temperature sensitive resistor ceramic element can be used at high temperatures of 300C or higher, and the temperature sensitive resistor ceramic element can be used at high temperatures of 300C or higher. becomes denser, improving mechanical strength and thermal responsiveness, resulting in gas resistance, stable life characteristics under various atmospheres, and easier processing into thinner layers. There is.

Such a temperature-sensitive resistive ceramic element is used to control the temperature of a medium muffler (approximately 800 m
℃), etc.

Examples will be described below.

MgO with a purity of 99.99% or more as a starting material.

Cr2O3 and TiO2 were blended in a predetermined composition and wet mixed, then dried and press-molded (750 kg/=).

This molded product was fired at a temperature of 1350° C. for 2 hours while applying a pressure of 300 kg/i to obtain a temperature-sensitive resistor ceramic element body 1 as shown in FIG.

The dimensions of this temperature-sensitive resistor ceramic element body 1 are 6 mrrt in diameter.
, thickness was 0.5 gm.

Electrodes 2 are formed by baking Ru02 paste at 1000°C on the upper and lower surfaces of the temperature-sensitive resistor ceramic element body 1 obtained in this way, and platinum wires 3 with a thickness of Q and 151 m are attached to the R
A temperature-sensitive resistor ceramic element was manufactured by attaching it to the electrode 2 at 1000° C. using nOz-based paste.

Note that in this case, no special manufacturing technology was required.

In this temperature-sensitive resistor ceramic element, as shown in the following table,
Samples 1 to 10 were prepared with sequentially different composition ratios of MgCr204 and TiO2.

For these samples 1 to 10, temperature changes in resistance were measured from room temperature to 100° C. using a resistance meter.

The results are shown in the table below.

The table shows the resistance values at 400° C. and SOO° C. and the B constant between those temperatures.

However, the B constant is defined by R=R□exp(B/T), where R is the resistance value at temperature T, T is the absolute temperature, and Ro is a constant.

In addition, the load life characteristics of Samples 1 to 10 were similarly measured.

This measurement is performed by keeping the sample at 800°C and applying a DC voltage of I
Apply V, 3V, and 6V and measure the change in resistance value over time.
The rate of change in resistance after 1000 hours is calculated, and the values are shown in the table.

However, Rt is the resistance value after 1000 hours, and R8 is the initial resistance value.

As can be seen from this table, depending on the mixing ratio of MgCr204 and TiO2, the resistance value will be 101. It changes from Q order to 103 g order, and the B constant changes significantly from 5000 to 9000.

FIG. 2 shows the characteristics of composition ratio and resistance value at room temperature.

According to FIG. 2, it can be seen that the resistance value can be freely changed depending on the composition ratio.

On the other hand, as a high temperature temperature sensitive resistor ceramic element commonly used at SOO°C, it is desirable that the resistance change rate be 10% or less.

For example, in the table, the B constant is 9272° and the resistance at 800°C is 4.
The resistance value at 800°C of the temperature sensitive resistor ceramic element having the composition of sample 5 with 0x102ρ is 5 after 1000 hours.
% rise, the actual temperature is approximately 10℃ higher than the measured temperature.
This change after 1000 hours does not pose any practical problem.

As can be seen from the DC load life characteristics in the table, all compositions satisfy the above conditions at DC voltages of 6V or less, and all of these mixture systems can be used in low to high temperature ranges. Met.

Since the firing was carried out under pressure, a very dense element was obtained.

As a result, the mechanical strength was improved and the thermal response to bending became very good.

Also, because it is dense, it is resistant to gases (oxidation, reduction, and sulfidation gases).
It had sex.

Moreover, it has become easy to process it into a very thin layer.

And (1-x)MgCr2O4XTlO2(x=0
．． This effect was found over the entire composition range (000.1 to 0.99).

In addition, when the firing temperature was too high, the grain growth of the crystals was large and the mechanical strength was poor.

On the other hand, if the firing temperature is too low, the sinterability will be poor.
Furthermore, the temperature-sensitive resistance characteristics and mechanical strength were also low.

For the above-mentioned reasons, it is preferable to perform pressure firing at a temperature of 14900C to 100C.

Note that the temperature-sensitive resistor ceramic element body 1 is made of MgO.

Al2O3p 5n02p Cr2O3t Fe2O
3s Ni0tSi02t Ba1t Zn0t Z
rO2t HfO2, MnO2.

By adding other metal oxides such as C1te, Coo, In2O3s TiO2, etc., the B constant, element resistance value, etc. could be controlled, and the characteristics as a temperature-sensitive resistor could be improved.

Furthermore, the dimensions, shapes, etc. of the embodiments are not limited to those described above.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of an embodiment of the present invention, and Fig. 2 is a perspective view of an embodiment of the present invention.
2 is a characteristic diagram of the composition ratio of TiO2 and the resistance value. 1... Temperature-sensitive resistor ceramic element body.

Claims (1)

[Claims] 1 (1-x) MgCr2O4+ xT i02
1. A method for producing a temperature-sensitive resistor ceramic element, comprising sintering a molded body mainly having a composition of (xo, oooi to 0.99) at a temperature of 1490° C. to 100° C. while pressurizing.