JP2000232003A - Material for bead-type thermistor element, bead-type thermistor element, and method of manufacturing the same - Google Patents

Abstract

[PROBLEMS] To provide a bead-type thermistor element material in which a resistance value R and a thermistor constant B have a small change with time during heating and a small residual strain when a glass-sealed bead-type thermistor element is formed. A composite oxide containing manganese, nickel, zirconium and chromium as metal components, wherein the relative amounts of these metal components are 0.01 to 0.3 mol of nickel and 0.01 to 0.3 mol of zirconium per 1 mol of manganese. 0.2
A material for a bead-type thermistor element having a mole content of 0.01 to 0.2 moles of chromium, a bead-type thermistor element made of the material, and a method of manufacturing the bead-type thermistor element.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bead type thermistor element material, a bead type thermistor element, and a method of manufacturing the same. The present invention relates to a bead-type thermistor element material having small residual distortion when used as a thermistor element, a bead-type thermistor element, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Thermistors are classified into an ordinary thermistor (NTC) having a negative temperature coefficient, a positive temperature coefficient thermistor (PTC) having a positive temperature coefficient, and a sudden change thermistor (CTR) whose resistance decreases rapidly in a narrow temperature range. Divided. Ordinary thermistor having a negative temperature coefficient is generally the formula _{R = R 0 exp [B (} 1 / T-1 / T 0)] ( wherein, R is the resistance value at temperature T, R ₀ is the temperature Is the resistance value at T ₀ , B is the thermistor constant, T is the absolute temperature, and T ₀ is any reference absolute temperature near room temperature. There is a correlation between the thermistor constant B and the resistance value R. As the resistance value R increases, the thermistor constant B increases accordingly.

[0003] As a general-purpose thermistor material,
Composite oxides containing metal components such as manganese, nickel, chromium, and iron are known. Further, as a thermistor material comprising a composite oxide obtained by adding zirconium oxide to manganese or a manganese-cobalt-based oxide, Japanese Unexamined Patent Publication No.
There is one described in Japanese Patent No. 31614, in which the resistance R can be changed without changing the thermistor constant B by adding zirconium oxide. It is also known that the thermistor constant B and the resistance value R can be adjusted by adding nickel oxide.

[0004]

By forming a composite oxide in which a zirconium oxide and a nickel oxide are added to a manganese-based oxide, the resistance value R and the thermistor constant B of the thermistor meet the required characteristics. Can be done. However, the resistance value R and the thermistor constant B of such a thermistor are not always satisfactory in terms of thermal stability (temperature-dependent changes in the resistance value R and the thermistor constant B).

A manganese-based oxide usually has a spinel-type crystal structure, and zirconium oxide hardly forms a solid solution in the spinel structure. When an attempt is made to prepare a composite oxide by adding a zirconium oxide, the zirconium oxide in an amount exceeding the specified amount forms an independent oxide crystal phase at the spinel crystal grain boundary. When a bead-type thermistor element is formed by sealing a thermistor material such as described above with glass at 800 to 1100 ° C., distortion remains in the glass, and particularly when significant distortion occurs, the sealing glass is destroyed. Become.

Accordingly, an object of the present invention is to provide a bead-type thermistor element material in which the resistance value R and the thermistor constant B have a small change with time during heating and have a small residual strain when formed into a glass-sealed bead-type thermistor element. And Another object of the present invention is to provide a bead-type thermistor element in which the resistance R and the thermistor constant B have a small change with time during heating and have a small residual strain when formed into a glass-sealed bead-type thermistor element. Still another object of the present invention is to provide a method of manufacturing a bead-type thermistor element in which the resistance R and the thermistor constant B have a small change with time during heating and a small residual strain when the glass-sealed bead-type thermistor element is used. I have.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above-mentioned object, and as a result, in the manganese-nickel-zirconium-based composite oxide, the addition amount of the nickel oxide component was limited to a specific range. In addition, by adding a chromium oxide component and using a specific amount of a zirconium oxide component and a specific amount of a chromium oxide component together, it is possible to keep the change of the resistance value R and the thermistor constant B of the thermistor with time during hot operation small. Further, it has been found that by setting the added amount of the zirconium oxide component to a specific amount or less, it is possible to maintain a small residual strain in a glass-sealed bead-type thermistor element, and have reached the present invention.

That is, the material for a bead-type thermistor element of the present invention is a composite oxide containing manganese, nickel, zirconium and chromium as metal components. 0
It is characterized by being 1 to 0.3 mol, 0.01 to 0.2 mol of zirconium and 0.01 to 0.2 mol of chromium. Further, a bead type thermistor element of the present invention is characterized by comprising the above-mentioned material for a bead type thermistor element.

The method for producing a bead-type thermistor element of the present invention is characterized in that a homogeneous mixture containing oxides of manganese, nickel, zirconium and chromium or precursors which can be converted into complex oxides by firing is prepared in the atmosphere at 1400 to 1550.
C., and the relative amounts of the metal components are 0.01 to 0.3 mol of nickel and 0.1 mol of zirconium per mol of manganese.
It is characterized by forming a composite oxide having 1 to 0.2 mol and chromium of 0.01 to 0.2 mol. Further, a method of manufacturing a bead-type thermistor element according to the present invention is characterized in that glass sealing of the bead-type thermistor element is performed at 800 to 1100 ° C.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, first,
It is necessary to prepare a composite oxide in which the relative amounts of the manganese oxide component, the nickel oxide component and the zirconium oxide component are adjusted, and to adjust the thermistor resistance R and the thermistor constant B.

At this time, in order to achieve the effect of adding the nickel oxide component, it is desirable that the relative amount of the metal component be 0.01 mol or more of nickel per mol of manganese. However, even if the added amount of the nickel oxide component exceeds 0.3 mol of nickel per mol of manganese as a relative amount of the metal component, the resistance value R is saturated and no further effect is obtained, .3
Conversely, if it exceeds mol, the change of the resistance value R with time tends to increase. Therefore, in the present invention, the added amount of the nickel oxide component is manganese 1 as the relative amount of the metal component.
0.01 to 0.3 mol of nickel per mol.

In order to achieve the effect of adding the zirconium oxide component, it is desirable that the relative amount of the metal component be 0.01 mol or more of zirconium per mol of manganese. However, if the added amount of the zirconium oxide component exceeds 0.2 mol per 1 mol of manganese as a relative amount of the metal component, the residual strain in a glass-sealed bead-type thermistor element tends to increase, which is not preferable. . That is, unlike the prior art in which a relatively large amount of zirconium oxide is added,
By setting the addition amount of the zirconium oxide component to 0.2 mol or less per 1 mol of manganese as a relative amount of the metal component, it becomes possible to keep the residual strain in the glass-sealed bead-type thermistor element small. . Therefore, in the present invention, the added amount of the zirconium oxide component is 0.01 to 0.2 mol of zirconium per 1 mol of manganese as a relative amount of the metal component.

The resistance value R and the thermistor constant B of the thermistor made of the manganese-nickel-zirconium-based composite oxide as described above are not necessarily required in terms of thermal stability (changes in the resistance value R and the thermistor constant B with time during hot). Not satisfactory. However, a thermistor composed of a composite oxide obtained by further adding a chromium oxide component to the manganese-nickel-zirconium-based composite oxide as described above has a small change in the resistance value R and the thermistor constant B with time, and has a long time. The thermal stability of the resistance value R and the thermistor constant B can be maintained over the period.

In order to achieve the effect of adding the chromium oxide component as described above, it is desirable that the relative amount of the metal component be 0.01 mol or more of chromium per 1 mol of manganese. However, when the added amount of the chromium oxide component exceeds 0.2 mol per 1 mol of manganese as a relative amount of the metal component, the sinterability deteriorates, the chromium evaporates remarkably, and a good sintered body cannot be produced. And a good thermistor material cannot be obtained. Therefore, in the present invention, the added amount of the chromium oxide component is 0.01 to 0.2 chromium per mole of manganese as a relative amount of the metal component.
Mole.

In the production method of the present invention, manganese,
A homogeneous mixture obtained by uniformly mixing oxides of nickel, zirconium, and chromium or precursors that can be converted to a composite oxide by firing is used. Precursors that can be used in the present invention include manganese, nickel, zirconium and chromium carbonates and hydroxides. Regarding the compounding ratio of each oxide or precursor of manganese, nickel, zirconium, and chromium, the relative amount of the metal component after firing was such that nickel was added in an amount of 0.1 mol / mol of manganese.
The compounding ratio is such that a complex oxide of 01 to 0.3 mol, 0.01 to 0.2 mol of zirconium and 0.01 to 0.2 mol of chromium can be formed. In addition, a necessary amount of carbitol, polyacrylic acid, polyvinyl butyral, or the like is mixed as an organic binder. Such a homogeneous mixture is fired at 1400 to 1550 ° C in the atmosphere. When the firing temperature is lower than 1400 ° C., the firing is insufficient, and it is difficult to obtain a stable quality thermistor element.
On the other hand, when the firing temperature exceeds 1550 ° C., chromium oxide evaporates remarkably, and it is difficult to obtain a thermistor element having good characteristics. Therefore, in the production method of the present invention, the above-mentioned homogeneous mixture is subjected to 1400
Bake at ~ 1550 ° C.

The present invention also includes sealing the bead type thermistor element with glass. The temperature condition at the time of glass sealing of the bead type thermistor element varies depending on the type of glass used, but is preferably inexpensive and 500 to 8 times.
Sealing is generally performed at 800 to 1100 ° C. in the air using glass having good glass productivity and having a glass softening point around 00 ° C.

Hereinafter, the present invention will be specifically described based on Examples and Comparative Examples. Examples 1 to 4 and Comparative Examples 1 to 5 Predetermined amounts of manganese carbonate, nickel oxide, zirconium oxide and chromium oxide so that the relative amounts of the metal components of the composite oxide obtained by calcination are the values shown in Table 1. Mix,
These compounding raw materials were wet-mixed by a ball mill for 24 hours. After dehydrating and drying the mixture, carbitol was mixed as an organic binder, and water was added to form a slurry. These slurries are applied in a granular form on two platinum wires (diameter 70 μm) stretched at a line interval of 300 μm,
Dry in an oven at 100 ° C. These in air
It was fired at 500 ° C. for 2 hours to obtain a bead type thermistor element of the present invention.

After each of the above bead type thermistor elements was spot-welded to a dumet wire, glass sealing was performed at 900 ° C. using a PbO.SiO ₂ -based glass to obtain a glass-sealed bead type thermistor element. For each of the thus obtained glass-sealed bead-type thermistor elements, the resistance R (kΩ) at 200 ° C. was 1 at 350 ° C.
Resistance change rate ΔR (%) after holding for 000 hours, and 1
The thermistor constant B at 00 to 200 ° C. was determined. 1
The resistance R at 00 ° C. and 100 ° C. was measured using a four-terminal digital resistance meter, and the thermistor constant B was calculated from the resistance between the measured temperatures. The values were as shown in Table 1.

Next, the strain distribution of the glass-sealed bead-type thermistor element was examined. The glass-sealed bead-type thermistor element was immersed in benzyl alcohol, and then observed with a deflection microscope, and the strain distribution was identified by a change in color. The relative magnitude of the strain was as shown in Table 1. FIG. 1 is a conceptual diagram showing the strain distribution of the glass-sealed bead-type thermistor element of Example 3.
FIG. 2 shows a conceptual diagram of the strain distribution of the glass-sealed bead-type thermistor element of Comparative Example 2. 1 and 2, reference numeral 1 denotes a sealing glass, 2 denotes a bead-type thermistor element, 3 denotes a platinum wire, and 4 denotes a discolored portion due to strain caused by tensile stress.

[0020]

[Table 1]

As is clear from the comparison between FIG. 1 and FIG.
The glass-sealed bead-type thermistor element of the present invention has a smaller strain due to tensile stress than the glass-sealed bead-type thermistor element of the comparative example, and, as is clear from the data in Table 1, the glass-sealed bead-type thermistor element of the present invention The glass-sealed bead-type thermistor element has a significantly smaller resistance change rate ΔR than the glass-sealed bead-type thermistor element of the comparative example.

[0022]

As described above, the bead-type thermistor element of the present invention is a glass-sealed bead-type thermistor element in which the resistance value R and the thermistor constant B have small changes with time during hot working. The residual strain at the time is small.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a strain distribution of a glass-sealed bead-type thermistor element of Example 3.

FIG. 2 is a conceptual diagram of a strain distribution of a glass-sealed bead-type thermistor element of Comparative Example 2.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sealing glass 2 Bead type thermistor element 3 Platinum wire 4 Discoloration part due to strain due to tensile stress

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazutomo Hoshino 1333-2 Hara-shi, Ageo-shi, Saitama Mitsui Mining & Smelting Co., Ltd. (72) Inventor Ken Sakata 1-17-17 Numakage, Urawa-shi, Saitama F term in the thermistor division of Mining Co., Ltd. (reference) 4G030 AA17 AA22 AA25 AA29 BA06 CA07 GA27 5E034 BA10 BB01 BC03 DA06 DA10 DB04 DE01 DE08

Claims (4)

[Claims] 1. A composite oxide containing manganese, nickel, zirconium and chromium as metal components, wherein the relative amounts of these metal components are 0.01 to 0.3 mol of nickel and 0.01 mol of zirconium per mol of manganese. ~ 0.2
A material for a bead-type thermistor element, characterized in that the amount of chromium is 0.01 to 0.2 mol. 2. A bead-type thermistor element comprising the material for a bead-type thermistor element according to claim 1. 3. A homogeneous mixture containing each oxide of manganese, nickel, zirconium and chromium or a precursor which can be converted to a complex oxide by calcination is obtained in the atmosphere at 1400-1 -1.
A composite oxide fired at 550 ° C., wherein the relative amounts of the metal components are 0.01 to 0.3 mol of nickel, 0.01 to 0.2 mol of zirconium and 0.01 to 0.2 mol of chromium per mol of manganese. A method for manufacturing a bead type thermistor element, comprising forming an object. 4. A method for manufacturing a bead-type thermistor element according to claim 2, wherein glass sealing of the bead-type thermistor element is performed at 800 to 1100 ° C.