WO2019003984A1

WO2019003984A1 - Electrical resistor, honeycomb structure and electrically heated catalyst device

Info

Publication number: WO2019003984A1
Application number: PCT/JP2018/023137
Authority: WO
Inventors: 剛大徳野; 淳一成瀬; 平田　和希; 美香川北; 泰史 ▲高▼山
Original assignee: 株式会社デンソー
Priority date: 2017-06-30
Filing date: 2018-06-18
Publication date: 2019-01-03

Abstract

An electrical resistor (1) comprises a matrix (10) which is configured of a borosilicate containing at least one alkali atom selected from the group consisting of Na, Mg, K, Ca, Li, Be, Rb, Sr, Cs, Ba, Fr and Ra. Preferably, the electrical resistor (1) comprises an electrically conductive filler (11). A honeycomb structure (2) is configured including the electrical resistor (1). An electrically heated catalyst device (3) comprises the honeycomb structure (2). Preferably, the electrical resistor (1) has an electrical resistivity of 0.0001-1 Ω∙m and an electrical resistivity rise rate of 0.01×10-6 to5.0×10-4/K in a temperature range of 25-500°C.

Description

Electric resistor, honeycomb structure, and electrically heated catalyst device

Cross-reference to related applications

This application is based on Japanese Patent Application No. 2017-129229 filed on June 30, 2017, and Japanese Patent Application No. 2017-243080 filed on December 19, 2017, as described herein. The contents are incorporated.

The present disclosure relates to an electric resistor, a honeycomb structure, and an electrically heated catalyst device.

Conventionally, in various fields, electric resistors are used for electric heating. For example, in the field of vehicles, there is known an electrically heated catalyst device in which a honeycomb structure supporting a catalyst is formed of an electric resistor such as SiC and the honeycomb structure is heated by electric heating.

Incidentally, in the prior patent document 1, water is added to a mixed powder consisting of 20 to 35 wt% of metal Si powder, 5 to 15 wt% of quartz powder, 20 to 30 wt% of borosilicate glass, and 30 to 40 wt% of clay powder and kneaded. A conductive ceramic is described which is formed and heat treated at a temperature of 1200 to 1300 ° C. in the atmosphere.

JP 2004-131302 A

In order to cause the electric resistor to generate heat efficiently by current heating, there is an optimum value of the current voltage with respect to the electric resistivity of the electric resistor. However, as represented by SiC, in many electric resistors, the temperature dependency of electric resistivity is large, and the optimum value of the current voltage changes with the temperature of the electric resistor. Therefore, an electrical resistor having a small temperature dependency of electrical resistivity is required.

If the electrical resistivity of the electrical resistor changes significantly with temperature, for example, in a constant voltage control electrical circuit, the fluctuation range of the current flowing through the electrical resistor becomes large. Therefore, the electric circuit becomes complicated to avoid this, and the cost of the electric circuit increases. In the case of an electrical resistor that exhibits NTC characteristics, such as SiC, in which the temperature change of the electrical resistivity is large and the electrical resistivity decreases as the temperature rises, the current is concentrated in a short distance between electrodes during current heating. Flow locally and generate heat locally. Therefore, an electrical resistor exhibiting NTC characteristics is likely to cause temperature distribution. When temperature distribution occurs in the electric resistor, a thermal expansion difference is generated inside the electric resistor, and the electric resistor is easily broken. The characteristic that the electrical resistivity increases as the temperature rises is called a PTC characteristic.

The present disclosure is an electric resistor having a small temperature dependence of the electric resistivity and exhibiting an PTC characteristic of the electric resistivity, or having little temperature dependence of the electric resistivity, and a honeycomb structure using the electric resistor. An object of the present invention is to provide an electrically heated catalyst device using a body and the honeycomb structure.

One aspect of the present disclosure is a borosilicate including at least one alkali-based atom selected from the group consisting of Na, Mg, K, Ca, Li, Be, Rb, Sr, Cs, Ba, Fr, and Ra. The electric resistor has a matrix composed of:

Another aspect of the present disclosure is a honeycomb structure configured to include the electric resistor.

Yet another aspect of the present disclosure is an electrically heated catalyst device having the above honeycomb structure.

The electric resistor is made of borosilicate containing at least one alkali-based atom selected from the group consisting of Na, Mg, K, Ca, Li, Be, Rb, Sr, Cs, Ba, Fr, and Ra. It has a matrix that is configured.

According to the electrical resistor, the region that governs the electrical resistance at the time of electric current heating is the matrix that is the base material. The matrix has a smaller temperature dependency of the electrical resistivity than SiC, and the electrical resistivity exhibits a PTC characteristic. Therefore, when the electrical resistivity of another substance different from the matrix that can be included in the electrical resistor exhibits PTC characteristics, the electrical resistivity of the electrical resistor has a small temperature dependency, and the PTC is It can show the characteristics. On the other hand, when the electric resistivity of the other substance shows NTC characteristics, the electric resistance of the matrix showing the PTC characteristic and the electric resistivity of the other substance showing the NTC characteristic gives the electric resistance. The electrical resistivity of the body can be designed to have low temperature dependence and to exhibit PTC properties or to have little temperature dependence.

Therefore, according to the electric resistor, by adopting the matrix, the temperature dependency of the electric resistivity is small, and the electric resistivity exhibits the PTC characteristic, or the temperature dependency of the electric resistivity is almost the same. No electrical resistor is obtained.

Further, as described above, since the electric resistor can be configured such that the electric resistivity does not have the NTC characteristic, it becomes possible to avoid current concentration at the time of current heating. Therefore, in the electric resistor, temperature distribution is hard to occur inside, and cracking due to the thermal expansion difference is hard to occur. In addition, although it is possible to prevent generation of a crack due to a thermal expansion coefficient difference by electrically heating SiC with a small current, it takes time to sufficiently heat it.

Furthermore, the said electrical resistor can achieve the low electrical resistance of a matrix by employ | adopting the said matrix. Therefore, when the above-mentioned electric resistor is made to contain the above-mentioned other substance, for example, the thing with low electric resistivity as the above-mentioned other substance is selected, and the above-mentioned electric resistor is made by increasing the content. It is easy to lower the electrical resistivity of Therefore, the electric resistor has an advantage that the temperature dependency of the electric resistivity can be reduced, as compared with a resistor or SiC or the like in which the whole bulk is made of the matrix.

The honeycomb structure includes the electric resistor. Therefore, in the above-mentioned honeycomb structure, temperature distribution does not easily occur inside the structure at the time of electric current heating, and cracking due to the difference in thermal expansion hardly occurs. In addition, since the above-mentioned electric resistor is used in the above-mentioned honeycomb structure, heat can be generated earlier at a lower temperature at the time of electric heating.

The electrically heated catalyst device has the honeycomb structure. Therefore, in the electrically heated catalyst device, the honeycomb structure is less likely to be broken during electric heating, and the reliability can be improved. Further, since the electrically heated catalyst device uses the honeycomb structure, the honeycomb structure can generate heat earlier at a lower temperature during electric heating, which is advantageous for early activation of the catalyst.

In addition, the code in the parentheses described in the claims indicates the correspondence with the specific means described in the embodiments to be described later, and does not limit the technical scope of the present disclosure.

The above object and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description with reference to the attached drawings. The drawing is
FIG. 1 is an explanatory view schematically showing a fine structure of the electric resistor according to the first embodiment, FIG. 2 is an explanatory view schematically showing a fine structure of the electric resistor according to the second embodiment, FIG. 3 is an explanatory view schematically showing a honeycomb structure of Embodiment 3. FIG. 4 is an explanatory view schematically showing an electrically heated catalyst device of Embodiment 4. FIG. 5 is a graph showing the relationship between the temperature and the electrical resistivity of Sample 1 and Sample 2 in Experimental Example 1, FIG. 6 is a graph showing the relationship between the temperature and the electrical resistivity of Sample 2 and Sample 1C in Experimental Example 1, FIG. 7 is a graph showing the relationship between the addition ratio of sodium carbonate and the electrical resistivity of the sample in Experimental Example 2, FIG. 8 shows (a) an atomic mapping image of aluminum of sample 2 and (b) an optical microscope image of the periphery of the emission portion in Experimental Example 3, FIG. 9 is an atomic mapping image of aluminum in the vicinity of the emission part of Sample 2 in Experimental Example 4; FIG. 10 shows the result of analysis of the composition of Sample 2 by SEM-EDX in Experimental Example 5, 11 is a graph showing the relationship between the temperature and the electrical resistivity of Sample 6 and Sample 7 in Experimental Example 6, FIG. 12 is an atomic mapping image of a cross section of a material of Sample 6 in Experimental Example 6, FIG. 13 is an atomic mapping image of a cross section of a material of sample 7 in Experimental Example 6, FIG. 14 is a line profile of Ca in the depth direction from the material surface of sample 6 in Experimental Example 6, FIG. 15 is a line profile of Ca in the depth direction from the material surface of sample 7 in Experimental Example 6, FIG. 16 is a graph showing the relationship between the temperature and the electrical resistivity of Samples 8 and 9 (baked product at 1250 ° C.) in Experimental Example 7; FIG. 17 is a graph showing the relationship between the temperature and the electrical resistivity of Samples 10 to 12 (baked article at 1300 ° C.) in Experimental Example 7.

(Embodiment 1)
The electrical resistor according to the first embodiment will be described with reference to FIG. As illustrated in FIG. 1, the electric resistor 1 of the present embodiment has a matrix 10. The matrix 10 is a portion to be a base material of the electric resistor 1. The matrix 10 may be amorphous or crystalline.

The matrix 10 is made of Na (sodium), Mg (magnesium), K (potassium), Ca (calcium), Li (lithium), Be (beryllium), Rb (rubidium), Sr (strontium), Cs (cesium), Ba. It is comprised from the borosilicate containing at least 1 sort (s) of alkali-type atom selected from the group which consists of (barium), Fr (francium), and Ra (radium). Each alkali-based atom may be contained in the borosilicate singly or in any combination. That is, the borosilicate may contain one or more alkali metal atoms, one or more alkaline earth metal atoms, or a combination of these. It is also good. The borosilicate preferably contains at least one selected from the group consisting of Na, Mg, K, and Ca as an alkali atom, from the viewpoint of facilitating reduction of the electrical resistance of the matrix 10 and the like. Can. More preferably, the borosilicate can include at least Na, K, or both Na and K.

In the borosilicate, the total content of alkali-based atoms can be 10% by mass or less. According to this configuration, the reduction of the electrical resistance of the matrix 10 can be facilitated. Moreover, according to this configuration, the temperature dependence of the electrical resistivity is smaller than that of SiC, and the matrix 10 in which the electrical resistivity exhibits the PTC characteristic can be made reliable. In addition, "total content of an alkali type atom" means the mass% of one type of alkali type atom, when borosilicate contains 1 type of alkali type atoms. Moreover, when borosilicate contains multiple types of alkali-type atoms, the total content (mass%) which added each content (mass%) of each of these several alkali-type atoms is meant.

The total content of alkali-based atoms is preferably 8% by mass or less, more preferably 5% by mass or less, still more preferably 3% by mass or less, from the viewpoint of suppression of shape change due to softening point reduction of matrix 10 It can be done. In addition, the total content of alkali atoms is more preferably 2 in view of suppression of formation of insulating glass film by segregation of alkali atoms to the surface side of electric resistor 1 at the time of firing in an oxidizing atmosphere. The content may be less than or equal to mass%, more preferably less than or equal to 1.5 mass%, still more preferably less than or equal to 1.2 mass%, and most preferably less than or equal to 1 mass%.

The borosilicate specifically includes at least one selected from the group consisting of Na, Mg, K, and Ca as alkali atoms, and the total content of the alkali atoms is 2 It can be set as the mass% or less. According to this configuration, even if the gas barrier film for blocking the oxygen gas is not formed at the time of firing in the atmosphere containing the oxygen gas, the oxygen in the atmosphere is an alkali-based atom eluted and segregated to the surface side of the electric resistor 1 It is easy to suppress the formation of an insulating glass film by reacting with In addition, when using the electric resistor 1 as a material of the conductive honeycomb structure, it is not necessary to remove the insulating glass film in advance when forming the electrode on the surface of the honeycomb structure, and the productivity of the honeycomb structure There is also an advantage that The total content of alkali atoms in this case is preferably 1.5% by mass or less, more preferably 1.2% by mass or less, from the viewpoint of suppression of formation of insulating glass film, etc. May be 1% by mass or less.

However, in order to suppress oxidation of the conductive filler 11 due to the phenomenon of forming a film on the surface of the material when alkali atoms are present, or the phenomenon that alkali atoms surround the periphery of the conductive filler 11 such as Si particles described later. When oxidation of the conductive filler 11 such as Si particles is a problem, alkali atoms may be intentionally added. Therefore, it is important to appropriately select the total content of the alkali-based atoms described above depending on the manufacturing conditions, the method of use, and the like. However, an alkali-based atom is an element which is relatively easy to be mixed from the raw material of the electric resistor 1. Therefore, it takes cost and time to completely remove alkali atoms from the raw material so that the borosilicate does not contain alkali atoms. Therefore, the total content of alkali-based atoms is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, still more preferably 0.1% by mass or more, still more preferably 0. It can be 2% by mass or more. In addition, in the electric resistance body 1, it becomes possible to aim at reduction of an alkali type atom by using a boric acid as a raw material, without using the borosilicate glass containing an alkali type atom. The details will be described later in experimental examples.

The borosilicate can contain B (boron) atoms of 0.1% by mass or more and 5% by mass or less. According to this configuration, there is an advantage that the PTC characteristics can be easily expressed.

The content of B atoms is preferably 0.2% by mass or more, more preferably 0.5% by mass or more, and further preferably 1% by mass from the viewpoint of facilitating reduction of the electrical resistance of the matrix 10 and the like. % Or more, still more preferably 1.2% by mass or more, still more preferably 1.5% by mass or more, still more preferably the temperature dependence of the electrical resistivity is small, and the electrical resistivity is PTC From the viewpoint of easily showing characteristics, etc., it can be more than 2% by mass. In addition, the content of B atoms is limited in the amount of doping to the silicate, and when not doped, it is unevenly distributed in the material as B ₂ O ₃ which is an insulator, which causes a decrease in conductivity, etc. From this, preferably, it can be 4% by mass or less, more preferably, 3.5% by mass or less, and still more preferably, 3% by mass or less.

The borosilicate can contain 5 mass% or more and 40 mass% or less of Si (silicon) atoms. According to this configuration, the electrical resistivity of the borosilicate tends to exhibit PTC characteristics.

The content of the Si atom is preferably 7% by mass or more, more preferably 10% by mass or more, and still more preferably 15 from the viewpoint of ensuring the above effects and raising the softening point of the matrix. It can be made to be% by mass or more. In addition, the content of Si atoms is preferably 30% by mass or less, more preferably 26% by mass or less, and still more preferably 24% by mass or less from the viewpoint of ensuring the above effects and the like. Can.

The borosilicate can contain 40% by mass or more and 85% by mass or less of O (oxygen) atoms. According to this configuration, there is an advantage that the PTC characteristics can be easily expressed.

The content of O atom is preferably 45% by mass or more, more preferably 50% by mass or more, still more preferably 55% by mass or more, and still more preferably, from the viewpoint of ensuring the above effects and the like. , 60 mass% or more. In addition, the content of O atom is preferably 82% by mass or less, more preferably 80% by mass or less, and still more preferably 78% by mass or less from the viewpoint of ensuring the above effects and the like. Can.

The borosilicate can be specifically an aluminoborosilicate or the like. According to this configuration, the temperature dependency of the electrical resistivity is small, and the electrical resistivity exhibits PTC characteristics, or the temperature resistance of the electrical resistivity has almost no temperature dependency. Can.

When the borosilicate is an aluminoborosilicate, the aluminoborosilicate can contain an Al atom content of 0.5% by mass or more and 10% by mass or less. The content of Al (aluminum) atom is preferably 1% by mass or more, more preferably 2% by mass or more, and still more preferably 3% by mass or more from the viewpoint of ensuring the above effects and the like. be able to. In addition, the content of Al atoms is preferably 8% by mass or less, more preferably 6% by mass or less, and still more preferably 5% by mass or less from the viewpoint of ensuring the above effects and the like. Can.

In addition, content of each atom in the borosilicate mentioned above can be selected from the range mentioned above so that it may be 100 mass% in total. In addition, when the total content of the alkali-based atoms, the content of the B atoms, the content of the Si atoms, the content of the O atoms, and the content of the Al atoms described above in the borosilicate are all simultaneously satisfied. Thus, the electric resistor 1 can be made sure that the temperature dependence of the electric resistivity is small and the electric resistivity exhibits a PTC characteristic or the temperature dependence of the electric resistivity is hardly present. Moreover, as an atom which may be contained in the borosilicate which comprises the matrix 10, Fe, C, etc. can be illustrated in addition to the above. In addition, about each content of an alkali type atom, Si, O, and Al among each atom mentioned above, it measures using an electron beam micro analyzer (EPMA) analyzer. Among the atoms described above, the content of B is measured using an inductively coupled plasma (ICP) analyzer. However, according to ICP analysis, since the B content in the entire electric resistor 1 is measured, the obtained measurement result is converted to the B content in the borosilicate.

The electric resistor 1 may have only the matrix 10 or may have one or more other substances besides the matrix 10. Examples of other substances include fillers, materials that lower the coefficient of thermal expansion, materials that increase the thermal conductivity, and materials that improve the strength.

In the present embodiment, the electric resistor 1 further includes a conductive filler 11 as illustrated in FIG. 1. According to this configuration, by combining the matrix 10 and the conductive filler 11, the electric resistivity of the entire electric resistor 1 is determined by the addition of the electric resistivity of the matrix 10 and the electric resistivity of the conductive filler 11. Be done. Therefore, according to this configuration, by adjusting the conductivity of the conductive filler 11 and the content of the conductive filler 11, control of the electric resistivity of the electric resistor 1 becomes possible. In addition, the electrical resistivity of the conductive filler 11 may show any of a PTC characteristic and an NTC characteristic, and there may be no temperature dependency of the electrical resistivity. Moreover, the electric resistor 1 can have the microstructure of the sea-island structure which makes the matrix 10 the sea-like part, and makes the conductive filler 11 an island-like part, as illustrated in FIG.

Specifically, the conductive filler 11 preferably contains Si atoms. According to this configuration, when manufacturing the electric resistor 1 by sintering the raw material containing the borosilicate and the conductive filler 11, the Si atoms of the conductive filler 11 diffuse into the borosilicate, and the borosilicate The silicon enrichment of the salt is promoted, and the softening point of the matrix 10 can be improved. Therefore, according to this configuration, it is possible to improve the shape retentivity of the electric resistor 1, and the electric resistor 1 useful as a material of the structure can be obtained. In particular, the honeycomb structure is a structure having thin cell walls. Therefore, the electric resistor 1 according to the above configuration is useful as a material of a conductive honeycomb structure having high structural reliability.

As the conductive filler 11 containing Si atoms, those which can easily diffuse Si atoms into borosilicate are preferable. For example, Si particles, Fe-Si based particles, Si-W based particles, Si-C based particles, Si- Examples include Mo-based particles and Si-Ti-based particles. These can be used alone or in combination of two or more.

When the electric resistor 1 has the matrix 10 and the conductive filler 11, specifically, the electric resistor 1 can be configured to contain the matrix 10 and the conductive filler 11 in a total of 50 vol% or more. . In the electric resistor 1, since the matrix 10 composed of the borosilicate described above is adopted, the electric resistance of the matrix 10 can be reduced, and the matrix 10 can also transmit electrons. According to the above configuration, although it depends on the shape of the electric resistor 1, the conductivity of the electric resistor 1 can be reliably ensured by the known percolation theory. The total content of the matrix 10 and the conductive filler 11 is preferably 52 vol% or more, more preferably 55 vol% or more, still more preferably 57 vol% or more, further preferably from the viewpoint of conductivity by formation of percolation, etc. Preferably, it can be 60 vol% or more. When the electric resistor 1 has the matrix 10 and the conductive filler 11, electrons flow while traveling through the conductive filler 11 and the matrix 10. The reason why the electric resistor 1 exhibits the PTC characteristic is presumed to be that the electrons moving in the electric resistor 1 are affected by lattice vibration. Specifically, it is presumed that the large polaron reported for Na _x WO ₃ substances and the like is also generated in the electric resistor 1. By replacing the position of the tetravalent silicon atom with trivalent boron, the skeleton of the atom is negatively charged, and it is presumed that electrons of the alkali-based atom receive a confinement effect to generate a large polaron.

The electric resistor 1 can be configured such that a glass film containing an alkali-based atom is not substantially formed on the surface. According to this configuration, when the electric resistor 1 is used as a material of the conductive honeycomb structure, it is not necessary to remove the insulating glass film in advance when forming the electrode on the surface of the honeycomb structure, and the honeycomb structure The improvement of the manufacturability of the body can be ensured. In addition, "the glass film containing an alkali type atom is not substantially formed on the surface" has the following meaning. Even if the glass coating is slightly formed on the surface of the electric resistor 1, the electric heating generates heat in the electric resistor 1 even if the glass coating is not removed when forming the electrode on the surface of the electric resistor 1. In the case where there is no problem in causing the glass coating, it can be assumed that the glass coating is not substantially formed on the surface.

In the temperature range from 25 ° C. to 500 ° C., the electric resistor 1 has an electrical resistivity of 0.0001 Ω · m or more and 1 Ω · m or less, and an electric resistance increase rate of 0.01 × 10 ⁻⁶ / K or more 5 The configuration can be in the range of not more than 0 × 10 ⁻⁴ / K. In the temperature range of 25 ° C. to 500 ° C., the electric resistor 1 has an electric resistivity of 0.0001 Ω · m or more and 1 Ω · m or less, and an electric resistance increase rate of 0 or more and 0.01 × 10 ^−6. It can be configured to be in the range of less than / K. According to these configurations, it is possible to reliably make the electric resistor 1 in which the temperature distribution is not easily generated at the time of electric current heating and the crack due to the thermal expansion difference is not easily generated. Moreover, according to the above configuration, since the electric resistor 1 can generate heat earlier at a lower temperature during electric heating, the material of the honeycomb structure is required to be heated early for early activation of the catalyst. Useful as. When the rate of increase in electrical resistance is in the range of 0 or more and less than 0.01 × 10 ⁻⁶ / K, it can be considered that the temperature dependence of the electrical resistivity is almost nonexistent.

The electrical resistivity of the electrical resistor 1 varies depending on the required specification of the system using the electrical resistor 1 and the like, but from the viewpoint of reducing the electrical resistance of the electrical resistor 1, for example, preferably 0.5 Ω · m or less , More preferably 0.3 Ω · m or less, still more preferably 0.1 Ω · m or less, still more preferably 0.05 Ω · m or less, still more preferably 0.01 Ω · m or less, still more still Preferably, it may be less than 0.01 Ω · m, most preferably 0.005 Ω · m or less. The electrical resistivity of the electrical resistor 1 is preferably 0.0002 Ω · m or more, more preferably 0.0005 Ω · m or more, still more preferably 0.001 Ω, from the viewpoint of increase in calorific value at the time of electric current heating. It can be m or more. According to this configuration, the electric resistor 1 suitable for the material of the honeycomb structure used for the electrically heated catalyst device can be obtained.

The electrical resistance increase rate of the electric resistor 1 is preferably 0.001 × 10 ⁻⁶ / K or more, more preferably 0.01 × 10 ⁶ from the viewpoint of facilitating suppression of the temperature distribution by electric heating. ^{It can be made −6} / K or more, more preferably 0.1 × 10 ⁻⁶ / K or more. It is ideal that the rate of increase in electrical resistance of the electrical resistor 1 does not change from the viewpoint of the presence of an electrical resistance value that is optimal for current heating in an electrical circuit. From this point of view, the rate of increase in electrical resistance of the electrical resistor 1 is preferably 100 × 10 ⁻⁶ / K or less, more preferably 10 × 10 ⁻⁶ / K or less, still more preferably 1 × 10 ⁻⁶ / K. It can be less than or equal to K.

The electrical resistivity of the electrical resistor 1 is the average value of the measured values (n = 3) measured by the four probe method. Further, the rate of increase in electrical resistance of the electrical resistor 1 can be calculated by the following calculation method after measuring the electrical resistivity of the electrical resistor 1 by the above method. First, the electrical resistivity is measured at three points of 50 ° C., 200 ° C., and 400 ° C. The value derived by subtracting the electrical resistivity at 50 ° C. from the electrical resistivity at 400 ° C. is divided by the temperature difference between 400 ° C. and 50 ° C. at 350 ° C. to calculate the rate of increase in electrical resistance.

The electrical resistor 1 can be manufactured, for example, as follows, but is not limited thereto.

A boric acid, a Si atom containing substance, and kaolin are mixed. Or you may mix the borosilicate containing an alkali type atom, Si atom containing substance, and kaolin. The shape of the borosilicate may be fibrous, particulate or the like. The shape of the borosilicate is preferably fibrous from the viewpoint of improving the extrudability of the mixture and the like. Moreover, as a Si atom containing substance, the electroconductive filler etc. which contain the Si atom mentioned above can be illustrated. In the above, when using boric acid, the mass ratio of boric acid can be, for example, 4 or more and 8 or less. If the mass ratio of boric acid is within the above range, it becomes easy to obtain the electric resistor 1 having a small temperature dependency of the electric resistivity. In addition, content of the boron contained in borosilicate becomes easy to raise by raising the calcination temperature mentioned later. In addition, as the amount of boron doped in the silicate increases, it is advantageous for reducing the electrical resistance of the electrical resistor 1.

The binder, water, is then added to the mixture. As a binder, organic binders, such as a methyl cellulose, can be used, for example. Moreover, content of a binder can be about 2 mass%, for example.

The resulting mixture is then shaped into a predetermined shape.

Then, the obtained molded body is fired. Specifically, the firing conditions can be, for example, under an inert gas atmosphere or in the air, under atmospheric pressure, a firing temperature of 1150 ° C. to 1350 ° C., and a firing time of 0.1 to 50 hours. The firing atmosphere may be, for example, an inert gas atmosphere, and the pressure during firing may be normal pressure or the like. In order to reduce the electrical resistance of the electrical resistor 1, it is preferable to reduce the residual oxygen from the viewpoint of preventing oxidation, and the atmosphere at the time of firing is set to a high vacuum of 1.0 × 10 ⁻⁴ Pa or more. It is good to purge and bake an inert gas later. As the inert gas atmosphere, an N ₂ gas atmosphere, a helium gas atmosphere, an argon gas atmosphere, and the like can be exemplified. Moreover, before the said baking, the said molded object can also be calcined as needed. Specifically, the calcination conditions can be a calcination temperature of 500 ° C. to 700 ° C. and an calcination time of 1 to 50 hours in an air atmosphere or an inert gas atmosphere. Thus, the electric resistor 1 can be obtained.

According to the electric resistor 1 of the present embodiment, the temperature dependence of the electric resistivity is small, and the electric resistivity exhibits PTC characteristics, or the electric resistivity 1 has almost no temperature dependence of the electric resistivity. It can be realized. Moreover, since the electrical resistor 1 of the present embodiment can be configured such that the electrical resistivity does not have NTC characteristics, it becomes possible to avoid current concentration at the time of current heating. Therefore, in the electric resistor 1 of the present embodiment, temperature distribution is hard to occur inside, and cracking due to thermal expansion difference is hard to occur. Furthermore, the electrical resistor 1 of the present embodiment has an advantage that the temperature dependency of the electrical resistivity can be reduced with a lower electrical resistance than the resistor or SiC or the like in which the entire bulk is made of the matrix 10 described above. is there.

Second Embodiment
The electric resistor according to the second embodiment will be described with reference to FIG. In addition, the code | symbol same as the code | symbol used in already-appeared embodiment among the code | symbols used after Embodiment 2 represents the component similar to the thing in already-appeared embodiment etc., unless shown otherwise.

As exemplified in FIG. 2, the electrical resistor 1 of the present embodiment contains another substance in addition to the matrix 10, and the other substance is the nonconductive filler 12 in that the embodiment is implemented. It is different from Form 1. According to this configuration, by combining the matrix 10 and the nonconductive filler 12, the electric resistivity of the entire electric resistor 1 is obtained by the addition of the electric resistivity of the matrix 10 and the electric resistivity of the nonconductive filler 12. Is determined. Therefore, according to this configuration, it is possible to control the electrical resistivity of the electrical resistor 1 by adjusting the content of the nonconductive filler 12 or the like.

Specifically, the nonconductive filler 12 preferably contains Si atoms. According to this configuration, when manufacturing the electric resistor 1 by sintering the raw material containing the borosilicate and the nonconductive filler 12, Si atoms of the nonconductive filler 12 diffuse into the borosilicate, The silicon enrichment of the borosilicate is promoted and the softening point of the matrix 10 can be improved. Therefore, according to this configuration, it is possible to improve the shape retentivity of the electric resistor 1, and the electric resistor 1 useful as a material of the structure can be obtained.

The nonconductive filler 12 containing Si atoms is not particularly limited as long as Si atoms can be diffused into the borosilicate, and for example, SiO ₂ particles, Si ₃ N ₄ particles, etc. may be exemplified. it can. These can be used alone or in combination of two or more. Moreover, specifically, the electric resistor 1 can be configured to contain 50 vol% or more of the matrix 10 and the nonconductive filler 12 in total.

The other configurations and effects are basically the same as in the first embodiment.

(Embodiment 3)
The honeycomb structure of the third embodiment will be described with reference to FIG. As illustrated in FIG. 3, the honeycomb structure 2 of the present embodiment is configured to include the electric resistor 1 of the first embodiment. Specifically, in the present embodiment, the honeycomb structure 2 is configured of the electric resistor 1 of the first embodiment. In FIG. 3, specifically, the plurality of cells 20 adjacent to each other, the cell wall 21 forming the cells 20, and the outer peripheral portion of the cell wall 21 in a honeycomb cross-sectional view perpendicular to the central axis of the honeycomb structure 2 And a peripheral wall 22 provided to hold the cell wall 21 integrally. In addition, a well-known structure can be applied to the honeycomb structure 1, and it is not limited to the structure of FIG. Although FIG. 3 shows an example in which the cell 20 has a rectangular shape in cross section, the cell 20 may also have a hexagonal shape in cross section.

The honeycomb structure 2 of the present embodiment is configured to include the electric resistor 1 of the present embodiment. Therefore, in the honeycomb structure 2 of the present embodiment, temperature distribution is less likely to occur inside the structure at the time of electric heating, and cracking due to the thermal expansion difference is less likely to occur. In addition, since the honeycomb structure 2 of the present embodiment uses the electric resistor 1 of the present embodiment, it can generate heat earlier at a lower temperature at the time of electric heating.

(Embodiment 4)
The electrically heated catalyst device of Embodiment 4 will be described with reference to FIG. As illustrated in FIG. 4, the electrically heated catalyst device 3 of the present embodiment includes the honeycomb structure 2 of the third embodiment. Specifically, in the present embodiment, the electrically heated catalyst device 3 includes the honeycomb structure 2, a three-way catalyst (not shown) supported on the cell walls 21 of the honeycomb structure 2, and the honeycomb structure 2. A pair of

electrodes

31 and 32 disposed opposite to the outer peripheral wall 22 and a voltage application unit 33 for applying a voltage to the

electrodes

31 and 32 are provided. In addition, a well-known structure can be applied to the electrically heated catalyst device 3, and it is not limited to the structure of FIG.

The electrically heated catalyst device 3 of the present embodiment has the honeycomb structure 2 of the present embodiment. Therefore, in the electrically heated catalyst device 3 of the present embodiment, the honeycomb structure 2 is not easily broken at the time of electric current heating, and the reliability can be improved. Further, since the electrically heated catalyst device 3 of the present embodiment uses the honeycomb structure 2 of the present embodiment, the honeycomb structure 2 can generate heat earlier at a lower temperature during electric heating, which is a catalyst It is advantageous for the early activation of

(Experimental example)
Experimental Example 1
-Sample 1-
Borosilicate glass particles containing Na, Mg, K, Ca and Si particles were mixed at a mass ratio of 48:52. Subsequently, 2 mass% of methylcellulose was added to this mixture as a binder, water was added, and it knead | mixed. Next, the obtained mixture was formed into pellets by an extruder and subjected to primary firing. The conditions for the primary firing were a firing temperature of 700 ° C., a temperature raising time of 100 ° C./hour, a holding time of 1 hour, and an atmospheric pressure / atmospheric pressure. Next, the primarily fired fired body was secondarily fired. Conditions of the secondary firing, _{N 2} gas atmosphere and pressure, the firing temperature 1300 ° C., firing time 30 min, and the heating rate 200 ° C. / hour. Thus, a sample 1 having a shape of 5 mm × 5 mm × 18 mm was obtained. According to EPMA measurement, the matrix in sample 1 is 2.9 mass% in total of alkali type atoms (Na, Mg, K and Ca), Si: 24.7 mass%, O: 69.5 mass% , Al: contained 1.1% by mass. Further, according to ICP measurement, the matrix in Sample 1 contained B: 0.8% by mass. As the EPMA analyzer, "JXA-8500F" manufactured by Nippon Denshi Co., Ltd. was used. As an ICP analyzer, "SPS-3520 UV" manufactured by Hitachi High-Tech Science Co., Ltd. was used. The same applies below.

-Sample 2-
Sample 2 was obtained in the same manner as in sample 1 except that borosilicate glass particles, Si particles and kaolin were mixed at a mass ratio of 29:31:40. Note that according to EPMA measurement, the matrix in sample 2 has a total of 2.4 mass% of alkali type atoms (Na, Mg, K and Ca), Si: 22.7 mass%, O: 68.1 % By mass and Al: 5.4% by mass. Further, according to ICP measurement, the matrix in Sample 2 contained B: 0.6% by mass.

-Sample 1C-
SiC was used as sample 1C.

The electrical resistivity was measured for each of the obtained samples. The electrical resistivity was measured by a four-terminal method using a thermoelectric characteristic evaluation apparatus (“ZEM-2” manufactured by ULVAC-RIKO, Inc.) on a 5 mm × 5 mm × 18 mm prism sample. As shown in FIGS. 5 and 6, both sample 1 and sample 2 have significantly smaller temperature dependence of electrical resistivity than SiC of sample 1C, and the electrical resistivity exhibits PTC characteristics. Recognize. Further, it can also be seen that the sample 1 and the sample 2 have smaller electric resistivity in the measurement temperature range as compared to the SiC of the sample 1C. Moreover, according to sample 1, it is also understood that the electrical resistivity exhibits PTC characteristics without using kaolin.

Samples

1 and 2 have an electrical resistivity of 0.0001 Ω · m or more and 1 Ω · m or less and an electric resistance increase rate of 0.01 × 10 ⁻⁶ / K or more in a temperature range of 25 ° C. to 500 ° C. It turns out that it exists in the range below 5.0 * 10 < ^-4 > / K.

<Experimental Example 2>
-Sample 3-
Borosilicate glass particles containing Na, Mg, K, Ca, Si particles and kaolin were mixed in a mass ratio of 29:31:40. Next, 0.4 mass% of sodium carbonate (Na ₂ CO ₃ ) and 2 mass% of methyl cellulose as a binder were added to this mixture, water was added, and the mixture was kneaded. Next, the obtained mixture was formed into pellets by an extruder and fired. The firing conditions were as follows: atmosphere pressure: atmospheric pressure, firing temperature 1300 ° C., firing time 30 minutes, heating rate 200 ° C./hour under argon gas atmosphere. This obtained sample 3 which has a shape of 5 mm x 5 mm x 18 mm. According to the EPMA measurement, the matrix in the sample 3 is 3.1 mass% in total of alkali-based atoms (Na, Mg, K and Ca), Si: 22.3 mass%, O: 67.7 % By mass, and Al: 5.3% by mass. Further, according to ICP measurement, the matrix in Sample 3 contained B: 0.6% by mass.

-Sample 4-
A sample 4 was obtained in the same manner as in the preparation of the sample 3, except that the addition amount of sodium carbonate was 0.8 mass%. According to the EPMA measurement, the matrix in the sample 4 contains 3.5 mass% in total of alkali atoms (Na, Mg, K and Ca), Si: 22.4 mass%, O: 66.7 % By mass, and Al: 5.5% by mass. Further, according to ICP measurement, the matrix in sample 4 contained B: 0.6% by mass.

-Sample 5-
A sample 5 was obtained in the same manner as in the preparation of the sample 3, except that sodium carbonate was not added. Incidentally, according to EPMA measurement, the matrix in the sample 5 has a total of 2.4 mass% of alkali type atoms (Na, Mg, K and Ca), Si: 22.7 mass%, O: 68.1 % By mass, and Al: 5.7% by mass. Further, according to ICP measurement, the matrix in Sample 5 contained B: 0.6% by mass.

The electrical resistivity at room temperature was measured for each of the obtained samples. As shown in FIG. 7, the electrical resistivity of the sample decreased by adding an alkali-based atom-containing compound such as sodium carbonate. It is considered that the electrical resistivity of the sample is lowered by the addition of the alkali-based atom-containing compound because the oxidation of the Si particles is suppressed. In addition, it was confirmed that the total content of alkali-based atoms is increased in the samples 3 and 4 to which sodium carbonate is added as compared with the sample 5 to which sodium carbonate is not added. This is because the borosilicate glass used as the raw material is doped with Na by the addition of sodium carbonate, and the total content of alkali atoms is increased.

<Experimental Example 3>
Using the sample 2 described above, an experiment for identifying a conductive portion in the sample 2 was performed. Specifically, a pair of Au electrode pads 9 are attached to the surface of the sample 2 and electrically heated, and an atomic mapping image of aluminum around the Au electrode pads 9 with an emission microscope ("PHEMOS-1000" manufactured by Hamamatsu Photonics Co., Ltd.) (FIG. 8 (a)) was obtained. In the above atomic mapping image, the color of the area (emission part E) heated by electric heating is changed and shown. Further, FIG. 8 (b) shows an optical microscope image of the periphery of the emission part E in the sample 2. In FIG. 8, reference numeral 101 denotes a matrix, and reference numeral 111 denotes Si particles. Also, the arrow Y indicates the estimated conductive path.

According to FIG. 8, it can be seen that electrons flow while traveling through Si and the matrix. Further, it can be seen that the Si site does not generate heat, but generates heat in the portion of the matrix made of borosilicate glass. From this result, it was confirmed that the region that governs the electric resistance at the time of electric current heating is a matrix which is a base material.

<Experimental Example 4>
In order to investigate in detail the composition of the emission part in the sample 2 of the above <Experimental Example 3>, an atomic mapping image around the emission part was acquired by EPMA measurement. FIG. 9 shows an atomic mapping image of aluminum in the vicinity of the emission part of sample 2. As shown in FIG. In FIG. 9, the circled part is an emission part. Further, the chemical composition at each site of the symbols a to l in FIG. 9 was measured. The results are shown in Table 1. In addition, the part of the code | symbol a is an electrode.

As shown in Table 1, according to this experiment, the part i and the part j corresponding to the emission part were aluminosilicates. The site b, the site e, the site f, the site k, and the site 1 were also aluminosilicates. The part c and the part d were borosilicate glass. The site g and the site h were silicon. However, according to another experimental example 5, it is clear that B is contained in the part i and the part j corresponding to the emission part. Therefore, the part i and the part j corresponding to the emission part are presumed to be aluminoborosilicate. However, in EPMA, boron may not be detected due to low detection sensitivity. Moreover, it is speculated that the reason why a large amount of Fe was detected at the part a was because the point at which Fe was segregated was measured.

Experimental Example 5
The composition analysis by SEM-EDX was performed on the sample 2 of the above <Experimental Example 3>. The results are shown in FIG. FIG. 10 (a) shows a base site to be subjected to composition analysis. FIG. 10 (b) shows the composition ratio of Phase 1 shown in Table 2 or a region having the composition ratio. FIG. 10C shows a composition ratio of Phase 2 shown in Table 2 or a region having the composition ratio. FIG. 10D shows the composition ratio of Phase 5 shown in Table 2 or a region having the composition ratio. FIG. 10E shows a composition ratio of Phase 6 shown in Table 2 or a region having the composition ratio. It can be seen that Phase 2 is a Si portion, and Phases 1, 5 and 6 are matrix portions. From the results of this experiment, the matrix part is composed of an aluminoborosilicate containing at least one selected from the group consisting of Na, Mg, K, and Ca, and this aluminoborosilicate is alkaline-based. Total 0.01 to 10 mass% of atoms, 0.1 to 5 mass% of B atoms, 5 to 40 mass% of Si atoms, 40 to 85 mass of O atoms It can be seen that the Al atom is contained in an amount of 0.5% by mass or more and 10% by mass or less. In addition, it is because kaolin was used for the raw material that the matrix part became an alumino borosilicate containing an alkali-type atom. Therefore, when kaolin is not used as the raw material, it can be said that the matrix part is a borosilicate containing an alkali atom.

Experimental Example 6
-Sample 6-
Borosilicate glass fibers containing Na, Mg, K, Ca, Si particles, and kaolin were mixed at a mass ratio of 29:31:40. The borosilicate glass fiber (average diameter 10 μm, average length 25 μm) used in this experimental example contains more Ca than the borosilicate glass particles used in each of the above-described experimental examples. Subsequently, 2 mass% of methylcellulose was added to this mixture as a binder, water was added, and it knead | mixed. Next, the obtained mixture was formed into pellets by an extruder and subjected to primary firing. The conditions for the primary firing were a firing temperature of 700 ° C., a temperature raising time of 100 ° C./hour, a holding time of 1 hour, and an atmospheric pressure / atmospheric pressure. Next, the primarily fired fired body was secondarily fired. Conditions of the secondary firing, _{N 2} gas atmosphere and pressure, the firing temperature 1300 ° C., firing time 30 min, and the heating rate 200 ° C. / hour. This obtained sample 6 which has a shape of 5 mm x 5 mm x 18 mm. According to EPMA measurement, the matrix in the sample 6 has a total of 6.4 mass% of alkali atoms (Na, Mg, K and Ca), Si: 21.4 mass%, O: 65.4 mass% , Al: contained 5.1% by mass. Further, according to ICP measurement, the matrix in Sample 6 contained B: 0.8 mass%.

-Sample 7-
The boric acid, the Si particles and the kaolin were mixed in a mass ratio of 4:42:54. Subsequently, 2 mass% of methylcellulose was added to this mixture as a binder, water was added, and it knead | mixed. Next, the obtained mixture was formed into pellets by an extruder and subjected to primary firing. The conditions for the primary firing were a firing temperature of 700 ° C., a temperature raising time of 100 ° C./hour, a holding time of 1 hour, and an atmospheric pressure / atmospheric pressure. Next, the primarily fired fired body was secondarily fired. Conditions of the secondary firing, _{N 2} gas atmosphere and pressure, the firing temperature 1250 ° C., firing time 30 min, and the heating rate 200 ° C. / hour. Thereby, the sample 7 which has a shape of 5 mm x 5 mm x 18 mm was obtained. According to EPMA measurement, the matrix in sample 7 is 0.5 mass% in total of alkali type atoms (Na, Mg, K and Ca), Si: 22.7 mass%, O: 68.1 mass% , Al: contained 5.7% by mass. Further, according to ICP measurement, the matrix in Sample 7 contained B: 0.9% by mass.

The electrical resistivity of each of the obtained samples was measured in the same manner as in Experimental Example 1. As shown in FIG. 11, the temperature dependence of the electrical resistivity of each of the samples 6 and 7 is significantly smaller than that of the SiC of the sample 1C described in the experimental example 1, and the electrical resistivity has PTC characteristics. It can be seen that Samples 6 and 7 have an electrical resistivity of 0.0001 Ω · m or more and 1 Ω · m or less and an electric resistance increase rate of 0.01 × 10 ⁻⁶ / K or more in a temperature range of 25 ° C. to 500 ° C. It turns out that it exists in the range below 5.0 * 10 < ^-4 > / K. Although the sample 7 is fired at a lower temperature than the sample 6, predetermined characteristics are obtained. When the firing temperature of the sample 7 is made the same as the firing temperature of the sample 6, the doping of boron (B) to the aluminoborosilicate which is the matrix in the sample 7 is promoted to further reduce the electrical resistivity. It is guessed that it can be done. This point will be described later in Experimental Example 7.

Next, EPMA measurement was performed on the material cross section of each sample. The results are shown in FIG. 12 and FIG. As shown in FIG. 12, it can be seen that, in the sample 6 using borosilicate glass as a raw material, many alkali-based atoms such as Na, Mg, K, Ca, etc. and O atoms exist on the surface of the material. In other words, Sample 6 uses borosilicate glass containing a large amount of alkali atoms as a raw material, so it can be seen that alkali atoms eluted on the surface of the material react with oxygen to form an insulating glass film on the surface of the material .

On the other hand, as shown in FIG. 13, in the sample 7 in which the content of alkaline atoms contained in the raw material was actively reduced using boric acid as the raw material, Na, Mg, K, Ca on the material surface were used. It can be seen that the alkali atoms and O atoms such as are significantly reduced as compared with the sample 6. That is, it is understood that Sample 7 uses boric acid containing no alkali atom as a raw material, so that the phenomenon that an insulating glass film is formed on the surface of the material can be suppressed. Although a slight amount of K was observed on the surface of the material of sample 7, no insulating glass film was formed.

Next, the line profile of Ca in the depth direction from the material surface of each sample was measured. The results are shown in FIG. 14 and FIG. As shown in FIG. 14, it can be seen that the sample 6 has a high Ca concentration on the material surface due to Ca eluted and segregated to the material surface side. On the other hand, in the sample 7, almost no change was observed in the Ca concentration on the material surface and in the material inside. From this result, in the borosilicate containing at least one alkali atom selected from the group consisting of Na, Mg, K, and Ca, the total content of the alkali atoms is regulated to 2% by mass or less. Thus, it was confirmed that an electric resistor having almost no insulating glass film on the surface can be obtained without forming a gas barrier film for blocking oxygen gas at the time of firing in an atmosphere containing oxygen gas. In the present experimental example, the sample 6 and the sample 7 had a large difference in the concentration of Ca due to the difference in the boron source, so in FIG. 14 and FIG. Although Ca was selected, it is easily inferred from the above results that the same tendency as above is shown for other alkali atoms.

Experimental Example 7
-Sample 8-
A sample 8 was obtained in the same manner as the sample 7 of Experimental Example 6 except that the boric acid, the Si particles, and the kaolin were mixed at a mass ratio of 6:41:53, and the firing temperature was 1250 ° C. According to the EPMA measurement, the matrix in sample 8 contains 0.5 mass% of alkali-based atoms in total, 23.6 mass% of Si, 66.8 mass% of O, and 5.8 mass% of Al. It was. Further, according to ICP measurement, the matrix in Sample 8 contained B: 1.3% by mass.
-Sample 9-
A sample 9 was obtained in the same manner as the sample 7 of Experimental Example 6 except that the boric acid, the Si particles, and the kaolin were mixed at a mass ratio of 8:40:52, and the baking temperature was 1250 ° C. According to the EPMA measurement, the matrix in sample 9 contains 0.4 mass% of alkali-based atoms in total, 23.9 mass% of Si, 66.1 mass% of O, and 5.6 mass% of Al. It was. Further, according to ICP measurement, the matrix in Sample 9 contained B: 2.1% by mass.
-Sample 10-
A sample 10 was obtained in the same manner as the sample 7 of Experimental Example 6 except that the boric acid, the Si particles, and the kaolin were mixed at a mass ratio of 4:42:54, and the firing temperature was 1300.degree. According to EPMA measurement, the matrix in the sample 10 contains 0.4 mass% of alkali-based atoms in total, 24.1 mass% of Si, 65.9 mass% of O, and 5.9 mass% of Al. It was. Further, according to ICP measurement, the matrix in sample 10 contained B: 0.9% by mass.
-Sample 11-
A sample 11 was obtained in the same manner as the sample 7 of the experimental example 6, except that the boric acid, the Si particles, and the kaolin were mixed at a mass ratio of 6:41:53, and the firing temperature was 1300.degree. According to the EPMA measurement, the matrix in the sample 11 contains 0.4 mass% in total of alkali-based atoms, 23.0 mass% of Si, 67.1 mass% of O, and 5.5 mass% of Al. It was. Further, according to ICP measurement, the matrix in the sample 11 contained B: 1.4% by mass.
-Sample 12-
A sample 12 was obtained in the same manner as the sample 7 of Experimental Example 6 except that the boric acid, the Si particles, and the kaolin were mixed at a mass ratio of 8:40:52, and the baking temperature was 1300 ° C. According to EPMA measurement, the matrix in the sample 12 contains 0.4 mass% of alkali-based atoms in total, 22.8 mass% of Si, 68.2 mass% of O, and 5.4 mass% of Al. It was. Further, according to ICP measurement, the matrix in the sample 12 contained B: 2.0% by mass.

The electrical resistivity of each of the obtained samples was measured in the same manner as in Experimental Example 1. The results are shown in FIG. 16 and FIG. As shown in FIG. 16 and FIG. 17, it was confirmed that, as the baking temperature is higher and the preparation amount of boric acid is larger, boron doping to the aluminosilicate is promoted and the electrical resistivity is lowered.

According to the above experimental results, the following can be said by using a borosilicate containing at least one or more alkali atoms such as Na, Mg, K and Ca as a matrix of the electric resistor. According to the electrical resistor, the region that governs the electrical resistance at the time of electric current heating is the matrix that is the base material. The matrix has a smaller temperature dependency of the electrical resistivity than SiC, and the electrical resistivity exhibits a PTC characteristic. Therefore, when the electrical resistivity of another substance different from the matrix that can be included in the electrical resistor shows PTC characteristics, the temperature dependence of the electrical resistivity of the electrical resistor is small, and the PTC characteristics are It can be configured as shown. On the other hand, when the electrical resistivity of the other substance exhibits NTC characteristics, the electrical resistivity of the matrix exhibiting the PTC characteristic and the electrical resistivity of the other substance exhibiting the NTC characteristic add up to the electrical resistance of the electrical resistor. The resistivity can be designed to have a small temperature dependence and to exhibit PTC characteristics or to have little temperature dependence. Therefore, by employing the above matrix, it is possible to obtain an electric resistor having a small temperature dependency of the electrical resistivity and exhibiting a PTC characteristic of the electrical resistivity or having little temperature dependency of the electrical resistivity. It will be possible. In addition, since the electric resistor can be configured such that the electric resistivity does not have the NTC characteristic, it becomes possible to avoid current concentration at the time of current heating. Therefore, it becomes possible to obtain an electric resistor in which a temperature distribution does not easily occur inside and a crack due to a thermal expansion difference is not easily produced. Furthermore, by adopting the matrix, the electric resistor can achieve low electric resistance of the matrix, and obtains an electric resistor with low electric resistance and small temperature dependency of electric resistivity. It becomes possible.

The present disclosure is not limited to the above embodiments and experimental examples, and various modifications can be made without departing from the scope of the invention. Moreover, each structure shown by each embodiment and each experiment example can each be combined arbitrarily. That is, although the present disclosure has been described based on the embodiments, it is understood that the present disclosure is not limited to the embodiments, structures, and the like. The present disclosure includes various modifications and variations within the equivalent range. In addition, various combinations and forms, and further, other combinations and forms including only one element, or more or less than these elements are also within the scope and the scope of the present disclosure. For example, in the third embodiment, an example in which the honeycomb structure is formed of the electrical resistor of the first embodiment is described. However, the honeycomb structure may be formed of the electrical resistor of the second embodiment. In the fourth embodiment, although the example of applying the honeycomb structure of the third embodiment has been described, the electrically heated catalyst device can also apply the honeycomb structure configured of the electric resistor of the second embodiment. It is.

Claims

A matrix composed of a borosilicate containing at least one alkali-based atom selected from the group consisting of Na, Mg, K, Ca, Li, Be, Rb, Sr, Cs, Ba, Fr and Ra 10) An electrical resistor (1).
In the temperature range of 25 ° C. to 500 ° C., the electrical resistivity is 0.0001 Ω · m or more and 1 Ω · m or less, and the electric resistance increase rate is 0.01 × 10 −6 / K or more 5.0 × 10 −4 The electric resistivity is in the range of 0.0001 Ω · m to 1 Ω · m, and the electric resistance increase rate is in the range of 0 to 0.01 × 10 −6 / K. The electrical resistor according to Item 1.
The electrical resistor according to claim 1, wherein in the borosilicate, the content of B atoms is 0.1% by mass or more and 5% by mass or less.
The electric resistor according to any one of claims 1 to 3, wherein the total content of the alkali-based atoms in the borosilicate is 10% by mass or less.
The borosilicate contains at least one selected from the group consisting of Na, Mg, K, and Ca as the alkali atom, and the total content of the alkali atom is 2% by mass or less. The electric resistor according to any one of claims 1 to 4, which is
The electric resistor according to any one of claims 1 to 5, wherein in the borosilicate, the total content of the alkali-based atoms is 0.01 mass% or more.
The electric resistor according to any one of claims 1 to 6, wherein the content of the Si atom in the borosilicate is 5% by mass or more and 40% by mass or less.
The electric resistor according to any one of claims 1 to 7, wherein in the borosilicate, the content of O atoms is 40% by mass or more and 85% by mass or less.
The electric resistor according to any one of claims 1 to 8, wherein the borosilicate is an aluminoborosilicate.
The electrical resistor according to claim 9, wherein in the aluminoborosilicate, the content of Al atoms is 0.5% by mass or more and 10% by mass or less.
The electric resistor according to any one of claims 1 to 10, further comprising a conductive filler (11).
The electric resistor according to claim 11, wherein the conductive filler contains a Si atom.
The electric resistor according to claim 11, wherein the matrix and the conductive filler are contained in a total amount of 50 vol% or more.
The electric resistor according to any one of claims 1 to 13, which is configured to be used for a honeycomb structure in an electrically heated catalyst device.
A honeycomb structure (2) comprising the electric resistor according to any one of claims 1 to 13.
An electrically heated catalyst device (3) comprising the honeycomb structure according to claim 15.