JPH07130504A - Thermister for high temperature and its manufacture - Google Patents

Abstract

PURPOSE:To obtain a resistance value changing zone over a wide temperature range by using NiO and SiO2 as composition materials for thermister element assembly and by setting each composition material within a specific range. CONSTITUTION:A element assembly of thermister is made of an NiO-SiO2 composite oxide consisting of NiO (80 to 99.99mol%) and SiO2 (0.01 to 20mol%) or an NiO-MgO-SiO2 composite oxide consisting of NiO (40 to 99.99mol%), MgO (0.01 to 60mol%) and SiO2 (0.01 to 20mol%), or an NiO-MgO composite oxide consisting NiO (40 to 99.99mol%) and MgO (0.01 to 60mol%), and each thermister element assembly of these is connected to lead terminals made of Pd, Pt or Pd-Pt. In this way, a resistance value changing zone over a wide temperature range can be obtained and the resistance value and B-constant can be changed over wide ranges, thereby obtaining a high temperature thermister having good thermal cycle characteristics from normal temperature to high temperature and also a production method for said thermister.

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 which can be used at a high temperature of 300.degree.

[0002]

BACKGROUND ART composite oxide of the conventional Mn-Co-Ni-based oxide as a body of high-temperature thermistor and Al ₂ O ₃ oxide, ZrO ₂ based oxide, Cr ₂ O ₃ -Al ₂ O _3- MnO
Various oxides such as oxides and spinel oxides are known.

[0003]

[SUMMARY OF THE INVENTION However, body of high-temperature thermistor Mn-Co-Ni-based oxide and Al ₂
Complex oxide with O ₃ oxide, ZrO ₂ type oxide, Cr ₂ O ₃
-Al ₂ O ₃ -MnO-based oxide, or those of spinel oxide has a drawback that the change in resistance in the heat cycle test from room temperature to elevated temperature is large.

Further, the thermistor is required to have various resistance values and B constants depending on the purpose of use and the intended use. Therefore, in manufacturing a thermistor, it is important to be able to arbitrarily change the resistance value and the B constant at the operating temperature simply by changing the component ratio using the same component material. In recent years, 300
There is a strong demand for a thermistor that can withstand use at high temperatures above ℃ and can withstand frequent thermal cycles from room temperature to high temperature. Such requirements include, for example, temperature control (900 ° C.) of a catalytic muffler for completely burning exhaust gas of an automobile.

Therefore, the present invention has been made in view of the above circumstances, a resistance value changing region can be obtained over a wide temperature range, and the resistance value and the B constant can be freely changed in a wide range, and An object of the present invention is to provide a high temperature thermistor having good thermal cycle characteristics from normal temperature to high temperature and a method for manufacturing the thermistor.

[0006]

In order to achieve the above object, the high temperature thermistor according to claim 1 has a thermistor body of 80 to 99.99 mol% NiO and 0.01.
To 20 mol% SiO ₂ and NiO-SiO ₂
It is characterized by being a complex oxide.

Further, in the thermistor for high temperature according to claim 2, the thermistor body is 40 to 99.99 mol% NiO and 0.01 to 60 mol% MgO and 0.01.
To 20 mol% of SiO ₂ and NiO-MgO
It is characterized by being a —SiO ₂ composite oxide.

Further, the high temperature thermistor according to claim 3 is provided with a pair of lead terminals.

Further, the high temperature thermistor according to claim 4 uses Pd, Pt or Pd-Pt as a lead terminal.

In the high temperature thermistor according to claim 5, the thermistor body is a NiO-MgO composite oxide composed of 40 to 99.99 mol% NiO and 0.01 to 60 mol% MgO. Pd, Pt or P
It is characterized by using d-Pt as a lead terminal.

The high temperature thermistor according to claim 6 uses a metal having a linear thermal expansion coefficient in the range of 8 to 12 × 10 ^-6 / K as a lead terminal.

The method for manufacturing a high temperature thermistor according to the seventh aspect of the present invention is the NiO-containing 40 to 99.99 mol% NiO and 0.01 to 60 mol% MgO.
MgO composite oxide or 80 to 99.99 mol%
NiO-SiO ₂ composite oxide consisting of NiO and 0.01 to 20 mol% SiO ₂ or 40 to 9
9.99 mol% NiO and 0.01 to 60 mol%
Of the thermistor body and an NiO-MgO-SiO ₂ composite oxide of 0.01 to 20 mol% of SiO ₂ Metropolitan MgO, a method for producing a high-temperature thermistor comprising a pair of lead terminals, after forming Alternatively, it is characterized in that a hole is formed in the thermistor element body after provisional sintering, the lead terminal is inserted into the hole, and then the thermistor element body is fired to fix the lead terminal.

[0013]

According to the high temperature thermistor of claim 1,
By setting the composition materials of the thermistor element body to NiO and SiO ₂ and setting the composition materials to fall within the above ranges, the resistance value changing region can be obtained over a wide temperature range.

According to the high temperature thermistor of claim 2, the composition materials of the thermistor body are NiO and Mg.
By setting O and SiO ₂ and the respective composition materials within the above range, a resistance value change region can be obtained over a wide temperature range, and the resistance value and the B constant can be freely changed in a wide range.

Further, according to the high temperature thermistor of the third aspect, since the thermistor is provided with the lead terminals, it becomes suitable for high temperature.

Further, according to the high temperature thermistor of the fourth aspect, the lead terminals are Pd, Pt or Pd-P.
By using t, the linear thermal expansion coefficients of the element body and the lead terminal can be matched, and the temperature cycle from room temperature to high temperature becomes excellent. According to the thermistor for high temperature of claim 5, the composition material of the thermistor body is Ni.
When O and MgO are used and each composition material is within the above range, a resistance value change region can be obtained over a wide temperature range,
The resistance value and B constant can be freely changed over a wide range, and Pd, Pt or Pd-P can be used as a lead terminal.
By using t, the coefficient of thermal expansion of the element body and the lead terminal can be matched, and the thermal cycle from normal temperature to high temperature becomes excellent.

Further, according to the high temperature thermistor of the sixth aspect, by using a metal having a coefficient of thermal expansion of 8 to 12 × 10 ⁻⁶ / K as the lead terminal, the heat of the element body and the lead terminal is reduced. The expansion coefficients can be matched and the thermal cycle from room temperature to high temperature becomes excellent.

According to the method for manufacturing a high temperature thermistor described in claim 7, the same effect as that of the high temperature thermistor described in claim 1, 2 or 6 can be obtained, and the thermistor element body is fired. Since the hole contracts to fix the lead terminal, the work of connecting the lead terminal can be omitted, the manufacturing becomes easy, and the reliability at high temperature becomes excellent.

[0019]

EXAMPLES Examples of the present invention will be described in detail below.

FIG. 1 is a sectional view showing a first embodiment of a high temperature thermistor of the present invention.

The thermistor of the first embodiment shown in FIG.
70-99.99 mol% NiO and 0.01-3
It has a columnar thermistor body 1 which is a NiO—SiO ₂ composite oxide consisting of 0 mol% SiO _2, and has holes 1a formed in each terminal portion of the thermistor body 1, and Pd and Pd are formed in the holes 1a. -Pt or a lead terminal 2 made of Pt is inserted and fixed.

Next, an example of the manufacturing method of the first embodiment will be described.

First, commercially available powders of NiO and SiO ₂ were blended in a predetermined amount in the above-mentioned proportions and mixed using a ceramic means,
After calcination, pulverization and drying, for example, polyvinyl alcohol is added to granulate.

Then, these granulated powders are put into a mold,
Molding is performed by applying a pressure of about 500 to 1000 kg / cm ² . In this embodiment, the compact 1 has a diameter of 2
mm and length 5 mm. In addition, preliminary sintering may be performed here.

Next, a diameter of 0.3 mm is applied to both ends of the molded body 1.
The round hole 1a having a depth of 1.5 mm is digged with the above drill. This hole 1
The lead terminal 2 made of Pd, Pd-Pt or Pt having a diameter of 0.3 mm is inserted into a. Then, when the molded body sample is fired at 1400 ° C. for 1 hour, the molded body 1 contracts and the hole 1a also contracts, so that the lead terminal 2 is fixed and the high temperature thermistor of the first embodiment is obtained.

Next, a second embodiment of the high temperature thermistor of the present invention will be shown.

The thermistor of the second embodiment is shown in a sectional view in FIG. 1 similarly to the first embodiment.

The thermistor of the second embodiment shown in FIG.
29.70 to 99.98 mol% NiO and 0.01
To 69.30 mol% MgO and 0.01 to 30 m
It has a columnar thermistor element body 1 which is a NiO-MgO-SiO ₂ composite oxide consisting of ol% SiO ₂ and has holes 1 a formed in each terminal portion of the thermistor element body 1.
Lead terminal 2 made of Pd, Pd-Pt or Pt for a
Inserted and fixed.

Next, an example of the manufacturing method of the second embodiment will be described.

First, commercially available powders of NiO, MgO, and SiO ₂ were mixed in a predetermined amount in the above-mentioned proportions, mixed by using industrial means, calcined, pulverized and dried, and then, for example, polyvinyl alcohol was added to produce them. Grain.

Then, these granulated powders are put in a mold,
Molding is performed by applying a pressure of about 500 to 1000 kg / cm ² . In this embodiment, the compact 1 has a diameter of 2
mm and length 5 mm. In addition, preliminary sintering may be performed here.

Next, a diameter of 0.3 mm is applied to both ends of the molded body 1.
The round hole 1a having a depth of 1.5 mm is digged with the above drill. This hole 1
The lead terminal 2 made of Pd, Pd-Pt or Pt having a diameter of 0.3 mm is inserted into a. Then, when the molded body sample is fired at 1400 ° C. for 1 hour, the molded body 1 contracts and the hole 1a also contracts, so that the lead terminal 2 is fixed and the high temperature thermistor of the first embodiment is obtained.

Next, a third embodiment of the high temperature thermistor of the present invention will be shown.

The thermistor of the third embodiment is shown in a sectional view in FIG. 1 as in the first embodiment.

The thermistor of the third embodiment shown in FIG.
0-99.99 mol% NiO and 0.01-70
It has a columnar thermistor body 1 which is a NiO-MgO composite oxide composed of mol% MgO, and has holes 1a formed in each terminal portion of the thermistor body 1, and P is formed in the hole 1a.
A lead terminal 2 made of d, Pd-Pt or Pt is inserted and fixed.

Next, an example of the manufacturing method of the third embodiment will be described.

First, commercially available powders of NiO and MgO are blended in a predetermined amount in the above-mentioned proportions, mixed by using industrial means, calcined, pulverized and dried, and then, for example, polyvinyl alcohol is added for granulation.

Then, these granulated powders are put into a mold,
Molding is performed by applying a pressure of about 500 to 1000 kg / cm ² . In this embodiment, the compact 1 has a diameter of 2
mm and length 5 mm. In addition, preliminary sintering may be performed here.

Next, a diameter of 0.3 mm is applied to both ends of the molded body 1.
The round hole 1a having a depth of 1.5 mm is digged with the above drill. This hole 1
The lead terminal 2 made of Pd, Pd-Pt or Pt having a diameter of 0.3 mm is inserted into a. Then, when the molded body sample is fired at 1400 ° C. for 1 hour, the molded body 1 contracts and the hole 1a also contracts, so that the lead terminal 2 is fixed and the high temperature thermistor of the first embodiment is obtained.

Next, the first and second obtained in this way
The effect of the high temperature thermistor of the third embodiment will be described with reference to Table 1.

Table 1 shows samples based on the first, second and third embodiments in which the ratio of the composition powder of the thermistor body was changed by the above-mentioned method.
The resistance value at each temperature of ° C and 900 ° C, the B constant, and the resistance change rate after the heat cycle test were obtained.

[0042]

[Table 1]

As the sample, the high temperature thermistor produced as described above was used. The composition powders of Sample Nos. 1 to 9 were 30 to 99.99 mol% in powder NiO and 0.01 to 0.9 in powder MgO. It was changed by 70 mol%. In addition, the linear thermal expansion coefficient of the lead terminal is 11.8 × 10 ^-6 / K
The Pd line of was used.

The proportions of the composition powders of Sample Nos. 10 to 15 were changed from 70 to 99.99 mol% for powder NiO and 0.01 to 30 mol% for powder SiO ₂ . In addition, the linear thermal expansion coefficient of the lead terminal is 11.8 × 10 ^-6 / K
The Pd line of was used.

The proportion of the composition powders of sample Nos. 16 to 29 is 29.70 to 99.98 mol of powder NiO.
%, Powder MgO was changed from 0.01 to 69.30 mol%, and powder SiO ₂ was changed from 1 to 30 mol%. In addition, the lead terminal has a Pd with a linear thermal expansion coefficient of 11.8 × 10 ⁻⁶ / K.
A line was used.

The ratio of the composition powder of sample No. 30 is
The powder NiO was 90.00 mol% and the powder MgO was 10.
00 mol%, the lead terminal has a linear thermal expansion coefficient of 8.9 × 1
A Pt wire of 0 ^-6 / K was used.

The ratio of the composition powder of sample No. 31 is
The powder NiO is 99.00 mol% and the powder SiO2 is 1.
00 mol%, the lead terminal has a linear thermal expansion coefficient of 8.9 × 1
A Pt wire of 0 ^-6 / K was used.

The ratio of the composition powder of sample No. 32 is
The powder NiO is 89.10 mol% and the powder MgO is 9.9.
0 mol%, powder SiO ₂ was 1.00 mol%, and the lead terminal was a Pt wire having a linear thermal expansion coefficient of 8.9 × 10 ⁻⁶ / K.

The ratio of the composition powder of sample No. 33 is
The powder NiO was 90.00 mol% and the powder MgO was 10.
00 mol%, the linear thermal expansion coefficient of the lead terminal is 10.5 ×
A 10 ⁻⁶ / K Pd—Pt wire was used.

The ratio of the composition powder of sample No. 34 is
The powder NiO was 99.00 mol%, and the powder SiO ₂ was 1.
00 mol%, the linear thermal expansion coefficient of the lead terminal is 10.5 ×
A 10 ⁻⁶ / K Pd—Pt wire was used.

The ratio of the composition powder of sample No. 35 is
The powder NiO is 89.10 mol% and the powder MgO is 9.9.
0 mol%, powder SiO ₂ is 1.00 mol%, and the lead terminal has a linear thermal expansion coefficient of 10.5 × 10 ⁻⁶ / K Pd-P.
The t-line was used.

The B constant of the thermistor is obtained from the following equation.

B = ln (R ₁ / R ₀ ) / (1 / T ₁ −1 / T ₀ ) (where R ₁ and R ₀ are resistance values, T ₁ and T ₀ are absolute temperatures, and B is a B constant ) Also, the thermal cycle test for each sample is 9
The temperature inside the furnace held at 00 ° C and the room temperature are moved respectively, and after reaching the temperature of each atmosphere, the temperature is held for 5 minutes to reach the room temperature and 900
The resistance was measured at 900 ° C. after 1000 cycles, with one cycle of one reciprocation with respect to ° C. Based on the measurement results, the resistance change rate ΔR after 1000 cycles was determined, and the results are shown in Table 1. Further, the resistance change rate ΔR was calculated by the following equation.

ΔR = {(R _t −R ₀ ) / R ₀ } × 100% (where R _t is the resistance value after 1000 cycles and R ₀ is the resistance value at the time of departure) As is apparent from Table 1, According to the first embodiment, the composition ratio of SiO ₂ is 0.01 to 20 mol.
It was found that the resistance change rate after the heat cycle test was kept to 30% or less by changing the value to%. Further, as is clear from Table 1, the resistance value and the B constant could be arbitrarily changed by the composite material with SiO ₂ .

As is clear from Table 1, according to the second embodiment, the composition ratio of SiO ₂ is 0.01 to 20.
The composition ratio of MgO up to mol% is 0.01 to 60mo
It was found that the resistance change rate after the heat cycle test was kept within 30% by changing to 1%.

Further, the resistance value and the B constant could be arbitrarily changed by the composite material of SiO ₂ and MgO.

Further, as is clear from Table 1, according to the third embodiment, the composition ratio of MgO is 0.01 to 60 m.
It was found that the resistance change rate after the heat cycle test was kept within 30% by changing to ol%.

Further, as is clear from Table 1, by using a Pd wire, a Pt wire or a Pd-Pt wire having a linear thermal expansion coefficient of 8 to 12 × 10 ⁻⁶ / K for the lead terminal, It was found that the rate of resistance change after the heat cycle test can be suppressed to a low level.

The present invention is not limited to the above embodiment,
Various modifications can be made without changing the gist of the invention.
For example, in the first, second or third embodiment, the pair of lead terminals 2 and 2 may be led out in the same direction as shown in FIG.

[0060]

According to the invention described in claim 1 which has been described in detail above, the resistance value changing region can be obtained over a wide temperature range and the resistance value and the B constant can be obtained by using the thermistor element body having the above structure. It is possible to provide a high temperature thermistor which can be changed arbitrarily.

Similarly, according to the second aspect of the present invention, by forming the thermistor element body as described above, a resistance value change region can be obtained over a wide temperature range, and the resistance value and B constant can be arbitrarily changed. A high temperature thermistor that can be obtained can be provided.

According to the third aspect of the invention, since the lead terminal is provided, it is suitable for high temperatures.

According to the fourth aspect of the present invention, it is possible to provide a high temperature thermistor having good thermal cycle characteristics from normal temperature to high temperature by using Pd, Pt or Pd-Pt for the lead terminal.

According to the fifth aspect of the present invention, the thermistor element is constructed as described above, and the lead terminals are Pd and Pt.
Alternatively, by using Pd-Pt, a resistance value change region can be obtained over a wide temperature range, the resistance value and the B constant can be arbitrarily changed, and good thermal cycle characteristics from normal temperature to high temperature can be obtained. A thermistor for high temperature can be provided.

According to the sixth aspect of the invention, the lead terminal is made of a metal having a linear thermal expansion coefficient of 8 to 12 × 10 ⁻⁶ / K. A thermistor can be provided.

According to the invention described in claim 7, since the hole is contracted and the lead terminal is fixed by firing the thermistor element body, the work of connecting the lead terminal can be omitted, the manufacturing becomes easy, and the reliability at high temperature is improved. It has excellent properties.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing first, second and third embodiments of a high temperature thermistor of the present invention.

FIG. 2 is a sectional view showing another example of the first, second and third embodiments.

[Explanation of symbols]

 1, thermistor body 1a, hole 2, lead terminal

Claims (7)

[Claims] 1. The thermistor body is 80 to 99.99 mo.
A high temperature thermistor, which is a NiO-SiO ₂ composite oxide composed of 1% NiO and 0.01 to 20 mol% SiO ₂ . 2. The thermistor body is 40 to 99.98 mo.
NiO composed of 1% NiO, 0.01 to 60 mol% MgO, and 0.01 to 20 mol% SiO _2.
A high temperature thermistor which is a —MgO—SiO ₂ composite oxide. 3. The high temperature thermistor according to claim 1, further comprising a pair of lead terminals. 4. A high temperature thermistor comprising the thermistor body according to claim 1 or 2 and Pd, Pt or Pd-Pt as a lead terminal. 5. The thermistor body is 40 to 99.99 mo.
A high temperature thermistor, which is a NiO-MgO composite oxide composed of 1% NiO and 0.01 to 60 mol% MgO, and uses Pd, Pt or Pd-Pt as a lead terminal. 6. A high temperature thermistor having a lead terminal made of the thermistor element according to claim 1, 2 or 5 and a metal having a coefficient of linear thermal expansion of 8 to 12 × 10 ⁻⁶ / K. 7. A method of manufacturing a high temperature thermistor comprising the thermistor element body according to claim 1, 2 or 5 and a pair of lead terminals according to claim 4 or 6, which is after molding or after calcination. 1. A method for manufacturing a high temperature thermistor, characterized in that a hole is formed in the thermistor body, the lead terminal is inserted into the hole, and then the lead terminal is fixed by simultaneous firing with the thermistor body.