JP2000233971A - Highly heat resistant composite material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a highly heat resistant composite material containing a small amount of electrically conductive particles in a matrix material and having little temperature dependency, a low cost but excellent mechanical characteristics. SOLUTION: The composite material consists of a 1st phase comprising insulating 1st particles and a 2nd phase forming an electrically conductive path in the 1st phase. The 2nd phase is obtained by discontinuously dispersing 2nd electrically conductive particles and 3rd electrically conductive particles having a sign of temperature resistance variation reverse to that of the 2nd electrically conductive particles in the 1st phase. The electrically conductive path formed by the 2nd phase are as small as the particle diameter order of the 2nd and 3rd electrically conductive particles.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a high heat resistant composite material comprising a base material and conductive paths.

[0002]

2. Description of the Related Art Materials having a temperature resistance change rate of 0 or close to 0 do not require temperature compensation for the resistance value. Therefore, low-cost high-temperature mechanical quantity sensor materials, gas sensors, electrode materials with heat generation, varistors, capacitors, It can be applied as a position sensor, a high heat-resistant electrode, and a heating element for a high-temperature heater.

[0003] In other words, in the case of an ordinary material in which the resistance value is substantially constant when the temperature is within a specific range, but the resistance value changes when the temperature is out of the range, it is difficult to provide the material for the above-mentioned applications. , The usable temperature range is naturally determined. Further, when the electrical characteristics of a material have temperature dependence, it is necessary to perform temperature compensation by an electric circuit or the like in order to eliminate the influence of temperature, which increases the cost.

Therefore, as a material having a temperature resistance change rate of 0 or close to 0, a material as disclosed in Japanese Patent Publication No. 4-61832 has been conventionally proposed. In this method, an N-type conductor SiC powder and a P-type conductor MoSi ₂ powder are mixed with an insulating nitride powder such as Si ₃ N ₄ and sintered. This is a material produced by

[0005] Since the change in the resistance value with respect to temperature is opposite between the P-type conductor and the N-type conductor (the resistance increases as the temperature rises in the P-type conductor, and the opposite in the N-type conductor). If it is added in an appropriate amount, the rate of change in temperature resistance can be made close to zero. Further, the temperature resistance characteristics can be arbitrarily varied by adjusting the amounts of the two.

[0006]

However, in conventional materials, it is necessary to add a large amount of N-type conductors or P-type conductors to insulating materials such as Si ₃ N ₄ , SiO ₂ , Al ₂ O ₃ , and ZnO. In addition, since the N-type conductor and / or the P-type conductor are continuously dispersed or mixed in the insulating material, both have to be mixed in equal or close amounts, resulting in high cost and burning. There have been problems such as deterioration of bonding properties, non-uniform mixing and deterioration of mechanical properties.

[0007] In addition, a large amount of conductor must be added in order to exhibit conductivity, and the sinterability is reduced and the cost is increased. There was a fear. Due to such a problem that the coexisting characteristics are adversely affected, it is difficult to actually use the material according to the prior art, in which the rate of change in temperature resistance is almost zero.

The present invention has been made in view of the above-mentioned conventional problems, and has a small amount of conductive particles with respect to a base material, has almost no temperature dependency, is low in cost, and has high mechanical properties with high mechanical properties. It is intended to provide materials.

[0009]

According to a first aspect of the present invention, there is provided a first phase comprising an insulating first particle, and a second phase forming a conductive path in the first phase. The two phases are
The second conductive particles discontinuously dispersed in the first phase and the second conductive particles;
The conductive particles are formed by discontinuous dispersion of conductive particles and third conductive particles having the opposite sign of the temperature resistance change rate, and the conductive path formed by the second phase has a particle diameter of the second and third conductive particles. A highly heat-resistant composite material characterized by being on the order of fineness.

The operation of the present invention will be described. In the high heat resistant composite material according to the present invention, the second conductive particles and the third conductive particles that are discontinuously dispersed in the first phase serving as the base material form a second phase, which functions as a conductive path. The second phase also has a structure in which the second conductive particles and the third conductive particles are discontinuously dispersed. That is, in the second phase, the third conductive particles are irregularly dispersed between the second conductive particles. Further, as described later, the third conductive particles have a temperature resistance change rate of a sign opposite to that of the second conductive particles.

In the high heat-resistant composite material according to the present invention, the fineness of the conductive path formed of the second phase, that is, the width of the conductive path is on the order of the particle diameter of the second and third conductive particles.
In other words, at most a few second and third conductive particles are arranged in the width direction of the second phase, and most of the second phase is formed by arranging the second and third conductive particles in series. It is configured.

Since the high heat-resistant composite material according to the present invention has the above-described structure, when electricity is supplied to the composite material, electrons cannot move through the insulating first phase.
That is, the second and third conductive particles in the second phase move.
In the high heat resistant composite material according to the present invention, two types of conductive particles having different temperature characteristics are dispersed in the above-described state, and the conductive particles in which the second conductive particles and the third conductive particles are arranged substantially in series. Passes are formed in the first phase. Therefore, the change in electric resistance with respect to the temperature at the time of energization is controlled by the second conductive particles and the third conductive particles, and the electric resistance hardly changes due to the temperature rise (see FIG. 1 described later), or the required resistance value is reduced. A highly heat-resistant composite material that can be easily adjusted can be obtained.

The highly heat-resistant composite material according to the present invention is produced by adding a small amount of the second and third conductive particles to the first phase so as to form the fine conductive paths as described above. Can be. Therefore, the problem of high cost is unlikely to occur when manufacturing this material. In addition, since the amount of the third and third conductive particles is small and discontinuous dispersion, problems such as deterioration of sinterability, non-uniform mixing, and deterioration of mechanical characteristics hardly occur.

As described above, according to the present invention, it is possible to provide a high heat resistant composite material having a small amount of conductive particles with respect to a base material, having little temperature dependency, and having low cost and high mechanical properties.

In the high heat-resistant composite material according to the present invention, the ratio of the number of conductive particles can be controlled by changing the particle size of the second conductive particles and the third conductive particles. This makes it possible to adjust the mobility of electrons in the discontinuous portion where the second conductive particles and the third conductive particles are in contact with each other in the second phase. Thereby, the amounts of the second conductive particles and the third conductive particles with respect to the first phase can be adjusted.

Further, by applying the high heat resistant composite material according to the present invention to a mechanical quantity sensor material or the like disclosed in JP-A-8-205320, it is possible to obtain an electric resistance change only with respect to pressure, stress and force. That is, a characteristic that an electric resistance can be obtained only for a force, that is, a mechanical quantity (mechanical quantity) sensor having no temperature dependency can be obtained.

Further, by adjusting the particle size ratio between the second conductive particles and the third conductive particles, the distance between the two particles in the second phase, and the interposition of an insulator between the two particles, high heat resistance can be obtained. The electrical resistance value and the temperature resistance change rate of the conductive composite material can be set to arbitrary values.

Next, the material that becomes the first particles constituting the first phase will be described. As this material, metal oxides such as insulating ceramics, metal nitrides, or composite compounds thereof can be used.

For example, aluminum, silicon, magnesium, calcium, chromium, zirconium, yttrium, ytterbium, lanthanum, vanadium, barium, strontium, scandium, boron, hafnium, bismuth, titanium, iron, zinc, nickel, manganese, lanthanum, molybdenum , Beryllium, indium,
Oxides, nitrides, or composite oxides or composites of at least one element selected from tin, strontium, vanadium, cobalt, iron, niobium, tungsten, cerium, dysprosium, rhenium, lithium, samarium, tantalum, etc. Compounds, solid solutions and the like can be mentioned. Further, various ceramic materials such as sialon, cordierite, mullite, zircon, forsterite, ferrite, spinel, αSiC and the like can also be mentioned.

Further, as the second conductive particles and the third conductive particles, those having a positive and negative rate of change in temperature resistance can be selected. If the second conductive particles are positive, negative third conductive particles are used. The reverse is also possible.

Substances having a positive rate of change in temperature resistance include:
VO ₂ , Cr ₂ O ₃ , MgCr ₂ O ₄ , FeCrO ₄ , CoC
rO ₄ , ZnCr ₂ O ₄ , WO ₂ , MnO, Cu ₂ O, Mo
O ₂ , Mn ₃ O ₄ , Mn ₂ O ₃ , FeO, NiO, CoO,
Co ₃ O ₄ , PdO, Cu ₂ O, Al ₂ O ₃ , CoAl
₂ O ₄ , α-Bi ₂ O ₃ , LaMnO ₃ , NiAl ₂ O ₄ , T
Examples include i ₂ O ₃ , PbO, and borides, carbides, silicides, nitrides, sulfides, fluorides, and composite compounds thereof of Groups II to IV.

The negative ones are BeO, Mg
O, CaO, SrO, BaO, CeO _Two, ThO_Two, VO
_Three, V_ThreeO_Five, TiO_Two, ZrO_Two, V_TwoO_Three, SnO_Two, Mo
O_Three, WO_Three, MnO_Two, Fe_TwoO_Three, MgFe_TwoO_Four, Ni
Fe_TwoO_Four, ZnFe_TwoO_Four, ZnCo_TwoO_Four, ZnO, Cd
O, Al_TwoO_Three, MgAl_TwoO_Four, Tl_TwoO_Three, In_TwoO_Three, S
iO_Two, PbO_Two, ReO_Two, SiC, VO_Two, Ta_TwoO_Fiveetc
Is mentioned. In the present invention, the second conductive particles and the third conductive particles
The above-mentioned substances as appropriate for the particles or other conductive particles
They can be used in combination.

When the first phase is made of a nitride-based insulating material such as silicon, aluminum or boron,
Particles consisting of one or more of carbides, nitrides, silicides, or borides of elements selected from the group IB, VIII and IIIA to IV may be used as the second conductive particles and the third conductive particles. it can.

When the first phase is made of AlN,
Particles of one or more selected from borides, silicides, and nitrides of groups II to IV can be used as the second conductive particles and the third conductive particles.

Further, the amount of the second conductive particles with respect to the first phase is preferably 3 to 60 wt%. As a result, the second conductive particles can form a conductive path in a mesh shape or the like without deteriorating the mechanical properties of the first phase serving as a base material, thereby providing a high heat resistant composite material with a predetermined shape. Can be developed. When the amount of the second conductive particles is less than 3 wt%, a conductive path is hardly formed in the first phase, and there is a possibility that conductivity is hardly developed. On the other hand, when the content is more than 60 wt%, it becomes difficult to discontinuously disperse the second conductive particles in the first phase, and there is a possibility that sinterability is reduced and mechanical properties are reduced.
In addition, a large amount of third conductive particles may be required for adjusting the resistance value.

In the high heat resistant composite material according to the present invention, the second conductive particles are two-dimensionally or three-dimensionally dispersed in a network so as to surround the plurality of crystal grains constituting the first phase. Preferably, the second phase is configured so that a conductive path can be formed. In this case, it is preferable that the conductive paths dispersed in a two-dimensional or three-dimensional network are in a dispersed state in which the conductive paths are partially or partially replaced by third conductive particles. Thereby, the second conductive particles and the third conductive particles
Even if the amount of the conductive particles is small, a conductive path in which these particles are arranged substantially in series in the first phase can be formed in a mesh shape.

The highly heat-resistant composite material according to the present invention can be used as a physical quantity sensor material, an electrode material, a heater material, a chemical sensor such as a gas sensor, a hygrometer, a momentum sensor material, and the like. In particular, when used as a physical quantity sensor material, the distance between the second conductive particles and the third conductive particles is preferably 0.1 nm to 1 μm.

When the distance between the particles is smaller than 0.1 nm, the second conductive particles and the third conductive particles are in a state where they are continuously dispersed in the first phase. There is a possibility that it cannot be obtained. On the other hand, when it is larger than 1 μm, the resistance value of the high heat resistant composite material increases,
There is a possibility that the function as the physical quantity sensor cannot be obtained.

Next, as in the second aspect of the present invention, the first
It is preferable that the particle diameter of the second and third particles is smaller than the particle diameter of the particles. As a result, the conductive path can be easily formed with a smaller amount of addition, the above-mentioned electrical characteristics can be easily exhibited, high mechanical characteristics can be obtained, and the electric resistance value of the material can be easily adjusted. Can be obtained.

Next, it is preferable that the first, second, and third particles have different coefficients of thermal expansion. Thereby, it is possible to obtain an effect that the electric resistance value of the whole material can be adjusted by adjusting the interval between the second conductive particles and the third conductive particles dispersed discontinuously and changing the electric resistance between the particles. .

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment A high heat resistant composite material according to an embodiment of the present invention will be described. The high heat resistant composite material according to the present example includes a first phase composed of insulating first particles and a second phase forming a conductive path in the first phase.
The second conductive particles discontinuously dispersed in the first phase and the second conductive particles;
The conductive particles and the third conductive particles having the opposite signs of the rate of change in temperature resistance are discontinuously dispersed. The conductive path formed by the second phase is as thin as the particle diameter of the second and third conductive particles.

Hereinafter, Samples 1 to 5, which are high heat-resistant composite materials according to the present example, will be described together with a manufacturing method. In addition, comparative samples C1 to C3 will be described together with the manufacturing method, and the performance of both will be compared.

<Sample 1> Average particle size for second conductive particles:
0.1 μm βSiC raw material powder (resistivity: 0.01Ω ·
cm) and the average particle size for the third conductive particles: Zr of 0.4 μm
B ₂ raw material powder and a 6: 1 were mixed at a volume ratio, 100 hours in a wet ball mill, and mixed and pulverized to obtain a slurry.
35% by volume of the solid content of the slurry was mixed with Si ₃ for the first phase having a particle size ratio of about 2.5 to 8 times that of the raw material powder.
N ₄ (average particle diameter: 0.8 μm) 59 vol% of raw material powder
(Volume with respect to the whole, hereinafter the same.), 6 vol% of Y ₂ O ₃ raw material powder functioning as a sintering aid for the first phase was added, further ball-milled in ethanol, and dried to obtain a composite powder. .

After subjecting the above composite powder to uniaxial molding under a pressing pressure of 20 MPa, the temperature was 1850 ° C. × 20 MPa ×
Hot pressing was performed for one hour. From the obtained hot pressed body, a 4 × 4 × 20 mm prismatic test piece was cut out to obtain a composite material according to Sample 1.

A cross section of the obtained sample 1 was subjected to ECR (Energy D
Ispersive X-ray Spectroscape) plasma etching was performed, and the etched surface was observed by SEM. Furthermore, ED
Elemental analysis was performed using X (Electron Cyclotron Resonance). As a result, it was found that Sample 1 has a conductive path having a network structure formed by surrounding a plurality of Si ₃ N ₄ crystal grains with SiC particles at regular intervals.
Then, it was found that ZrB ₂ particles were mixed in place of the SiC particles in some places of this conductive path.

<Sample 2> Average particle size for second conductive particles:
0.1 μm βSiC raw material powder (resistivity: 0.01Ω ·
cm) and average particle size for third conductive particles: 0.2 μm Ti
B ₂ raw material powder and a 3: 1 ratio, 100 hours in a wet ball mill, and mixed and pulverized to obtain a slurry. The first phase of Si ₃ N having a particle size ratio of about 4 to 8 times the raw material powder with respect to a solid content of 35% by volume of this slurry.
₄ (Average particle size: 0.8 μm)
Y ₂ O ₃ raw material powder was added 6Vo1%, after further mixing ball mill in ethanol, to obtain a composite powder and dried.

After the composite powder was subjected to uniaxial molding under a press pressure of 20 MPa, the temperature was 1850 ° C. × 20 MPa.
Hot pressing was performed under the condition of × 1 hour. From the obtained hot pressed body, a 4 × 4 × 20 mm prismatic test piece was cut out to obtain a composite material for Sample 2.

The cross section of the obtained sample 2 was subjected to ECR plasma etching, and the etched surface was observed by SEM. Further, elemental analysis was performed using EDX. As a result, similarly to Sample 1, it was found that Sample 2 had a conductive path having a network structure formed by surrounding a plurality of Si ₃ N ₄ crystal grains with SiC particles at regular intervals. Then, it was found that TiB ₂ particles were mixed in place of the SiC particles in some places of this conductive path.

<Sample 3> Average particle size for second conductive particles:
0.1 μm βSiC raw material powder (resistivity: 0.01Ω ·
cm) and average particle diameter for the third conductive particles: 0.4 μm Ti
N raw material powder was mixed at a ratio of 3: 1 and mixed and pulverized for 100 hours by a wet ball mill to obtain a slurry. The first phase Si ₃ N ₄ having a particle size ratio of about 2.5 to 8 times the raw material powder with respect to a solid content of 35% by volume of this slurry.
(Average particle diameter: 0.8 μm) 59 vol 1% of raw material powder, Y
₆ vol 1% of ₂ O ₃ raw material powder was added, and the mixture was further ball-milled in ethanol, and then dried to obtain a composite powder.

The composite powder was subjected to uniaxial molding under a pressure of 20 MPa, and then subjected to a temperature of 1850 ° C. × 20 MPa.
Hot pressing was performed under the condition of × 1 hour. From the obtained hot pressed body, a 4 × 4 × 20 mm prismatic test piece was cut out to obtain a composite material according to Sample 3.

The cross section of the obtained sample 3 was subjected to ECR plasma etching, and the etched surface was observed by SEM. Further, elemental analysis was performed using EDX. As a result, similarly to Sample 1, it was found that Sample 3 has a conductive path having a network structure in which SiC particles surround a plurality of Si ₃ N ₄ crystal grains at regular intervals. Then, it was found that TiN particles were mixed in place of the SiC particles in some places of this conductive path.

<Sample 4> Average particle size for second conductive particles:
0.1 μm βSiC raw material powder (resistivity: 0.01Ω ·
cm) and a W material powder having an average particle size of 0.4 μm for the third conductive particles were mixed at a ratio of 3: 1 and mixed with a wet ball mill to form a mixture.
The mixture was mixed and pulverized for 00 hours to obtain a slurry. 59 vol% of the first phase Si ₃ N ₄ (average particle size: 0.8 μm) raw powder having a particle size ratio of about 2.5 to 8 times the solid content of the slurry of 35 vol% , Y ₂ O ₃
6 vol 1% of the raw material powder was added, and the mixture was further ball-milled in ethanol, and then dried to obtain a composite powder.

The composite powder was subjected to uniaxial molding at a press pressure of 20 MPa, and then subjected to a temperature of 1850 ° C. × 20 MPa.
Hot pressing was performed under the condition of × 1 hour. From the obtained hot-pressed body, a 4 × 4 × 20 mm prismatic test piece was cut out to obtain a composite material according to Sample 4.

The cross section of the obtained sample 4 was subjected to ECR plasma etching, and the etched surface was observed by SEM. Further, elemental analysis was performed using EDX. As a result, similar to Sample 1, it was found that Sample 4 has a conductive path having a network structure in which SiC particles surround a plurality of Si ₃ N ₄ crystal grains at regular intervals. Then, it was found that W particles were mixed in place of the SiC particles in some places of this conductive path.

<Sample 5> Average particle size for second conductive particles:
0.1 μm βSiC raw material powder (resistivity: 0.01Ω ·
cm) and average particle size for the third conductive particles: Cr of 0.4 μm
B ₂ raw material powder and a 3: 1 ratio, 100 hours in a wet ball mill, and mixed and pulverized to obtain a slurry. The first phase Si ₃ having a particle size ratio of about 2.5 to 8 times the solid content of the slurry with respect to a solid content of 35 vol% of the slurry.
N ₄ (average particle size: 0.8 μm) raw material powder 59 vol%
And 6% by volume of Y ₂ O ₃ raw material powder were added, and the mixture was further mixed with a ball mill and dried to obtain a composite powder.

The composite powder was subjected to uniaxial molding under a press pressure of 20 MPa, and then subjected to a temperature of 1850 ° C. × 20 MPa.
Hot pressing was performed under the condition of × 1 hour. From the obtained hot pressed body, a 4 × 4 × 20 mm prismatic test piece was cut out to obtain a composite material according to Sample 5.

The cross section of the obtained sample 5 was subjected to ECR plasma etching, and the etched surface was observed by SEM. Further, elemental analysis was performed using EDX. As a result, similar to Sample 1, it was found that Sample 5 has a conductive path having a network structure in which SiC particles surround a plurality of Si ₃ N ₄ crystal grains at regular intervals. Then, it was found that CrB ₂ particles were mixed in place of the SiC particles in some places of this conductive path.

<Sample 6> Average particle size for second conductive particles:
0.1 μm βSiC raw material powder (resistivity: 0.01Ω ·
cm) and the average particle size for the third conductive particles: Zr of 0.4 μm
B ₂ raw material powder and a 3: 1 ratio, to obtain a slurry with 100 hours mixed and pulverized in a wet ball mill. The obtained slurry has a particle size ratio of about 4
AlN for the first phase that is ８8 times (average particle size: 0.8 μm)
m) 59 vol 1% of raw material powder and 6 vol 1 of Y ₂ O ₃ raw material powder
% And further mixed with a ball mill, followed by drying to obtain a composite powder.

The composite powder was subjected to uniaxial molding at a press pressure of 20 MPa, and then subjected to a temperature of 1850 ° C. × 20 MPa.
Hot pressing was performed under the condition of × 1 hour. From the obtained hot pressed body, a 4 × 4 × 20 mm prismatic test piece was cut out to obtain a sample 6.

The cross section of the obtained sample 6 was subjected to ECR plasma etching, and the etched surface was observed by SEM. As a result, similar to Sample 1, it was found that Sample 6 has a conductive path having a network structure in which SiC particles surround a plurality of AlN crystal grains at regular intervals. And
In some places of this conductive path, Zr is used instead of SiC particles.
It was found that B ₂ particles were mixed.

<Comparative Sample C1> 64 wt% of Si ₃ N ₄ raw material powder having an average particle diameter of 0.2 μm and 6 wt% of Y ₂ O ₃ raw material powder
%, An average particle diameter of 0.03 μm and 30 wt% of SiC raw material powder (resistivity: 0.03 kΩ · cm) were mixed by a wet ball mill, and then dried and molded. The obtained compact was hot-pressed at a temperature of 1850 ° C. and a press pressure of 20 MPa for 1 hour. From this hot pressed body, a test piece was cut out to obtain a comparative sample C1.

The cross section of this comparative sample C1 was subjected to ECR plasma etching, and the etched surface was observed by SEM.
As a result, it was found that the comparative sample C1 had a conductive path having a network structure in which a plurality of Si ₃ N ₄ crystal grains were surrounded by SiC particles.

<Comparative Sample C2> Si having an average particle diameter of 2 μm
₃ N ₄ and the raw material powder 44wt%, Y ₂ O ₃ raw material powder 6 wt%
And 30 wt% of βSiC raw material powder having an average particle size of 2 μm
And 20 wt% of MoSi ₂ raw material powder having an average particle diameter of 1 μm
Were mixed with a wet ball mill, dried and molded. This compact was hot-pressed at a temperature of 1850 ° C. and a press pressure of 20 MPa for 1 hour. Then, a test piece was cut out from the obtained hot pressed body to obtain a comparative sample C2.

The cross section of the obtained comparative sample C2 was subjected to ECR plasma etching, and the etched surface was observed by SEM. As a result, the comparative sample C2 has a conductive path in which MoSi2 particles are continuously dispersed around the Si ₃ N ₄ crystal grains.
It was confirmed that a structure in which SiC particles were mixed was formed inside the conductive path phase.

<Comparative Sample C3> 64 wt% of Si ₃ N ₄ raw material powder having an average particle diameter of 0.9 μm and 6 wt% of Y ₂ O ₃ raw material powder
% And 30 wt% of αSiC raw material powder having an average particle diameter of 0.4 μm (resistivity: 220 kΩ · cm) were mixed by a wet ball mill, and then dried and molded. The obtained molded body was hot-pressed at a temperature of 1850 ° C. and a press pressure of 20 MPa for 1 hour. From this hot pressed body, a test piece was cut out to obtain a comparative sample C3.

The cross section of the comparative sample C3 was subjected to ECR plasma etching, and the etched surface was observed by SEM. As a result, the comparative sample C3 has the SiC around the Si ₃ N ₄ crystal grains.
It was confirmed that the conductive paths of the particles were formed.

<Performance Evaluation Test> As described above, for the samples 1 to 6 and the comparative samples C1 to C3, the resistivity at room temperature and the temperature 105
The resistivity at 0 ° C. was measured, and the ratio between the two was determined.

According to the table, the resistance ratio of samples 1 to 6 is about 1.
Degree, and the resistivity is too low even at room temperature or at 1050 ° C.
It turned out to be the same. On the other hand, the comparative sample C1
-C3 is the resistance ratio greater than 1 (C1, C3), 1
Smaller (C2). In other words, the resistivity depends on the temperature.
Was found to be a substance that greatly changed. Also, the ratio
Comparative sample C2 was compared to the amount of the third conductive particles added to samples 1 to 6.
All MoSi _TwoBut the resistance ratio is more than 1.
Very small, densification is hindered and mechanical and functional properties
Lowering the resistance, making it difficult to adjust the resistance, and
It turned out to be high.

[0059]

[Table 1]

For sample 1, room temperature to 1050 ° C.
Was measured by the four-terminal method. The results are shown in FIG. As is clear from the figure, it was found that the electrical resistance of Sample 1 was almost constant from room temperature to 1050 ° C., and the strain-electric resistance characteristic with small temperature dependence could be exhibited. FIG. 1 also shows the relationship between stress and electric resistance at each temperature. It was found that the temperature-resistance characteristics of Sample 1 exhibited almost the same change rate and linearity regardless of the temperature. The same was found for samples 2 to 6.

The operation and effect of this embodiment will be described. In the highly heat-resistant composite material according to the present example, two kinds of second conductive particles and third conductive particles having different temperature characteristics are in the dispersion form as described above, and the conductive path in which both are arranged substantially in series is the first phase. It is in a state formed inside. For this reason, the third conductive particles can cancel the change in the electric resistance of the second conductive particles with respect to the temperature, and a material whose electric resistance hardly changes due to the temperature rise can be obtained as a whole (see FIG. 1).

In the high heat-resistant composite material according to the present example, since the amount of the second and third conductive particles with respect to the first phase is small, the production cost is high and the sinterability is deteriorated. In addition, problems such as non-uniform mixing and deterioration of mechanical properties are unlikely to occur.

As described above, according to the present embodiment, it is possible to provide a highly heat-resistant composite material having a small amount of conductive particles with respect to the base material, having little temperature dependency, and having low cost and high mechanical properties.

Since the high heat-resistant composite material according to the present embodiment has the above-mentioned excellent characteristics, it has a small temperature coefficient, a physical quantity sensor material, a low-temperature to high-temperature electrode material, a gas sensor,
It can be used as electrode materials with heat generation such as temperature sensors, position sensors, knock sensors, combustion pressure sensors, acceleration sensors, torque sensors, varistors, electrode materials for capacitors, heater materials, load cells, and liquid volume systems.

[0065]

As described above, according to the present invention, the amount of conductive particles relative to the base material is small, there is almost no temperature dependency,
A highly heat-resistant composite material having high mechanical properties at low cost can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing a relationship between a temperature, a resistance value, and a stress in a sample 1 in a first embodiment.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Mitsuru Asai 41-1, Oku-cho, Yokomichi, Nagakute-cho, Aichi-gun, Aichi F-term in Toyota Central R & D Laboratories Co., Ltd. 4G001 BA09 BA22 BA32 BA44 BA45 BB09 BB22 BB32 BB44 BB45 BC42 BC73 BD22 BE11 BE26 4G030 AA12 AA47 AA52 AA54 BA02 GA04 GA11 GA29

Claims (3)

[Claims] 1. A first phase comprising an insulating first particle and a second phase forming a conductive path in the first phase, wherein the second phase is included in the first phase. The second conductive particles are formed by the discontinuous dispersion of the second conductive particles and the third conductive particles having the opposite sign of the temperature resistance change rate from the second conductive particles, and the conductive particles formed by the second phase. A high heat-resistant composite material, wherein the path is as thin as the particle size of the second and third conductive particles. 2. The high heat resistant composite material according to claim 1, wherein the particle diameter of the second and third particles is smaller than the particle diameter of the first particle. 3. The high heat resistant composite material according to claim 2, wherein the first, second and third particles have different coefficients of thermal expansion.