Heater and heating member

Abstract

To provide a heater which has a long-term durability even under a severe environment.SOLUTION: A heater 100 includes: a first ceramic base material 10; a glass part 20 provided on the first ceramic base material 10; and an electric heating unit 30 buried in the glass part 20. The glass part 20 has a closing hole 21. The electric heating unit 30 is formed of metal in which the change rate of the mass at the temperature of 700°C to the mass at the temperature of 25°C under atmospheric atmospheres is 0.1% at a maximum.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a heater and a heating member.

Background Art

[0002] There is an increasing demand for reducing harmful components (HC, NOx, CO) in automobile exhaust gas. In particular, purification of NOx emitted from diesel engines is an important issue. As a measure for NOx purification, a technique called a urea SCR system is generally known. In the urea SCR system, NH 3 is generated by thermal decomposition and hydrolysis of urea. In order to efficiently promote the thermal decomposition and hydrolysis of urea, it is necessary to efficiently heat the urea. However, as the engine efficiency improves, the exhaust gas temperature becomes lower, and the exhaust gas temperature is also low immediately after the engine is started. When the exhaust gas temperature is low, even if urea is injected into the exhaust gas, the decomposition reaction hardly occurs, so that sufficient NH 3 is not generated. Further, when the injected urea collides with the inner wall surface of the exhaust pipe, if the temperature of the inner wall surface is low, the urea is not completely decomposed into NH 3 and deposits as a solid deposit of an intermediate product. As a result, it may become an obstacle to the flow of the exhaust gas, or the mixing of the generated NH 3 and the exhaust gas may be inhibited due to a change in the flow of the exhaust gas. Therefore, a heater that can efficiently heat the exhaust gas and keep the inner wall surface of the exhaust pipe at a high temperature has been developed.

[0003] In addition, in battery electric vehicles (BEV) and fuel cell vehicles (FCV) that do not have a heat source from an internal combustion engine, and plug-in hybrid vehicles (PHV, PHEV) that frequently stop the internal combustion engine, since the heating load affects the driving range, it is an important issue to improve the heating efficiency. Therefore, instead of heating the entire passenger compartment, development of heaters that efficiently warm only a specific space in a short time is underway.

[0004] Furthermore, in order to achieve carbon neutrality, development of synthetic fuels obtained by synthesizing hydrogen generated by electrolysis of water and CO 2 emitted from power plants, factories, etc. is underway, but heating is required in the manufacturing process of synthetic fuels. When this manufacturing process is carried out in a place where supply such as factory waste heat is available, a heat source can be easily secured. On the other hand, when it is carried out in a place without a heat source, heating must be done using electricity. The electricity is preferably produced from renewable energy that does not emit CO 2 during the manufacturing process, and improvement in heating efficiency is also required for heaters.

[0005] A heater in which a conductor is embedded in a base material with a small heat capacity or a conductor is arranged between the base materials is one of the powerful heating means in various applications as described above. For example, Patent Document 1 proposes a heater including a plate-shaped first heater substrate, heating wires arranged in a parallel circuit on the first surface of the first heater substrate, electrodes connected to the heating wires to energize the heating wires, and a plate-shaped cover substrate that covers the first surface, the heating wires, and the electrodes of the first heater substrate on the second surface side. In this heater, the first heater substrate and / or the cover substrate contains Si 3 N 4 or Al 2 O 3 and the heating wires are WC, TiN, TaC, ZrN, MoSi 2It contains at least one metal selected from the group consisting of Pt, Ru, and W.

[0006] Patent Document 2 proposes a heater including an insulating substrate composed of alumina ceramics, silicon nitride ceramics, etc., and a resistor embedded in the insulating substrate, where the resistor contains first conductor particles mainly composed of tungsten and second conductor particles mainly composed of molybdenum. Patent Document 3 proposes a mixer for an exhaust gas purification device including an outer cylinder made of insulating ceramics such as alumina, silicon nitride, and cordierite, fins made of insulating ceramics provided inside the outer cylinder, and a heating part embedded in at least a part of the outer cylinder and / or the fins.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0008] For heaters used in the above-mentioned applications, it is required to be able to heat quickly and efficiently, and to have long-term durability in harsh environments (specifically, environments where corrosion resistance, heat resistance, impact resistance, insulation, etc. are required). However, for the heaters described in the above prior art, depending on the type of base material and conductor, it is difficult to ensure long-term durability in a harsh environment. For example, since alumina base materials have a high coefficient of thermal expansion, in an environment with large temperature changes, the thermal stress becomes large and it is difficult to ensure long-term durability. Also, although cordierite base materials have a low coefficient of thermal expansion, when a conductor with a high coefficient of thermal expansion is embedded in the cordierite base material or a conductor is disposed between the cordierite base materials, cracks are likely to occur in the cordierite base material due to the difference in the coefficient of thermal expansion in an environment with large temperature changes, and it is difficult to ensure long-term durability. Furthermore, conductors such as molybdenum and tungsten are easily oxidized when exposed to high temperatures in the presence of a small amount of air, and there is a risk of final disconnection as oxidation progresses, so it is difficult to ensure long-term durability.

[0009] The present invention has been made to solve the above problems, and an object thereof is to provide a heater and a heating member having long-term durability even in a harsh environment.

Means for Solving the Problems

[0010] As a result of intensive research on the structure of the heater, the present inventors have found that the above problems can be solved by embedding a specific electrothermal part (conductor) in a glass part having closed pores and providing it on a ceramic base material, and have completed the present invention. That is, the present invention is exemplified as follows.

[0011] [1] A heater comprising a first ceramic base material, a glass part provided on the first ceramic base material, and an electrothermal part embedded in the glass part, wherein the glass part has closed pores, and the electrothermal part is composed of a metal having a mass change rate of 0.1% or less of the mass at 700°C with respect to the mass at 25°C in an air atmosphere.

[0012] [2] The heater according to [1], further comprising a second ceramic base material provided on the glass part.

[0013] [3] The heater according to [1] or [2], wherein the ceramic base material is a cordierite base material.

[0014] [4] The heater according to any one of [1] to [3], wherein the coefficient of thermal expansion of the glass part is less than 2.0×10 -6 ~6.0×10 -6 / K.

[0015] [5] The heater according to any one of [1] to [4], wherein the Young's modulus of the glass part is 5 to 50 GPa.

[0016] [6] The heater according to any one of [1] to [5], wherein the glass part contains boron and / or silicon and has a glass transition temperature of 600 to 1100 °C.

[0017] [7] The heater according to any one of [1] to [6], wherein the change rate of the volume resistivity at 300 °C with respect to the volume resistivity at 25 °C of the electrothermal part is 10% or less.

[0018] [8] The heater according to any one of [1] to [7], wherein the electrothermal part is composed of an alloy containing one or more selected from Ni, Fe, and Cr.

[0019] [9] The heater according to [8], wherein the alloy is a Ni-Cr alloy or an Fe-Cr alloy.

[0020]

[10] The heater according to any one of [1] to [9], further comprising a terminal connected to the electrothermal part.

[0021]

[11] The heater according to

[10] , wherein the terminal is connected to the electrothermal part by a brazing material.

[0022]

[12] The heater according to any one of [1] to

[11] , which is used for heating exhaust gas.

[0023]

[13] A cylindrical member, A plurality of heaters according to any one of [1] to

[12] , disposed along at least a part of the inner peripheral surface of the cylindrical member, An insulating material disposed between the cylindrical member and the heater, Comprising, A heating member in which the heating portions of the plurality of heaters can be electrically connected to a power source in series or in parallel.

[0024]

[14] The heating member according to

[13] , which is used to heat a reducing agent precursor to generate a reducing agent, Disposed on at least a part of the cylindrical member, and further comprising a nozzle capable of injecting the reducing agent precursor onto the inner peripheral surface of the cylindrical member, The heater is disposed on the inner peripheral surface of the cylindrical member where the reducing agent precursor is injected from the nozzle, A heating member in which the cylindrical member is an exhaust pipe of a diesel engine.

[0025]

[15] One end of the heating portion of the heater is electrically connected to the power source, and the other end is electrically connected to the cylindrical member, The heating member according to

[14] , wherein the applied voltage from the power source is 80 V or less.

Advantages of the Invention

[0026] According to the present invention, it is possible to provide a heater and a heating member having long-term durability even in a harsh environment.

Brief Description of the Drawings

[0027]

Figure 1A

Figure 1B

Figure 1C

Figure 2

Figure 3A

Figure 3B

Figure 3C

Figure 4

Figure 5A

Figure 5B

Figure 6

Figure 7

Figure 8

Figure 9

Mode for Carrying Out the Invention

[0028] The heater of the present invention includes a first ceramic substrate, a glass part provided on the first ceramic substrate, and a heating part embedded in the glass part. The glass part has closed pores, and the heating part is composed of a metal having a mass change rate of 700 °C with respect to the mass at 25 °C of 0.1% or less in an air atmosphere. In a heater having such a configuration, the glass part functions as an intermediate region for alleviating the difference in thermal expansion coefficient between the first ceramic substrate and the heating part. In addition, since the Young's modulus can be reduced by the closed pores of the glass part, the thermal stress in a harsh environment is reduced. Furthermore, by using a metal having a mass change rate of 700 °C with respect to the mass at 25 °C of 0.1 mass% or less, the metal is less likely to oxidize even at high temperatures. Therefore, this heater has long-term durability even in a harsh environment.

[0029] Further, the heating member of the present invention includes a cylindrical member, the plurality of heaters disposed along at least a part of the inner peripheral surface of the cylindrical member, and an insulating material disposed between the cylindrical member and the heaters. The electrothermal parts of the plurality of heaters can be electrically connected to a power source in series or in parallel. Since this heating member is provided with the heaters described above, it has long-term durability even in a harsh environment.

[0030] Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings. The present invention is not limited to the following embodiments, and it should be understood that modifications and improvements can be appropriately made to the following embodiments based on the ordinary knowledge of those skilled in the art without departing from the spirit of the present invention, and such modified and improved embodiments also fall within the scope of the present invention.

[0031] (1) Heater FIG. 1A is a top view of a heater according to an embodiment of the present invention, and FIG. 1B is a cross-sectional view of the heater taken along line a-a'. Further, FIG. 1C is an enlarged cross-sectional view of the R region in FIG. 1B. As shown in FIGS. 1A to 1C, the heater 100 includes a first ceramic base material 10, a glass part 20 provided on the first ceramic base material 10, and an electrothermal part 30 embedded in the glass part 20. In FIG. 1A, the dotted line represents the position of the electrothermal part 30 embedded in the glass part 20. Since the glass part 20 has a coefficient of thermal expansion between the first ceramic base material 10 and the electrothermal part 30, it can relieve the difference in coefficient of thermal expansion between the first ceramic base material 10 and the electrothermal part 30 and reduce the thermal stress in a harsh environment. Further, since the first ceramic base material 10 and the electrothermal part 30 do not come into direct contact, it is possible to suppress the occurrence of cracks in the first ceramic base material 10. Hereinafter, each component will be described.

[0032] <First ceramic base material 10> The first ceramic substrate 10 is not particularly limited, and a substrate mainly composed of an insulating ceramic such as alumina, silicon nitride, or cordierite can be used. Among these, from the viewpoint of stably ensuring long-term durability in a harsh environment, the first ceramic substrate 10 is preferably a cordierite substrate. Here, the cordierite substrate means a substrate mainly composed of cordierite (2MgO·2Al 2 O 3 ·5SiO 2 ). In this specification, the "main component" means a component whose proportion in all components exceeds 50% by mass, preferably 90% by mass or more.

[0033] The cordierite substrate is preferably composed of 90% by mass or more of a cordierite phase, 5% by mass or less of a crystal phase containing mullite and / or spinel, and the balance of a glass phase. With such a composition, properties such as the coefficient of thermal expansion and Young's modulus can be controlled within a desired range. Here, the mass% of each phase in the cordierite substrate is determined as follows. First, a plurality of samples are prepared by mixing with different mass ratios of cordierite, mullite, spinel, and glass, and a calibration curve of the peak values of X-ray diffraction is prepared in advance. Next, the peak values are obtained by X-ray diffraction of the cordierite substrate, and based on the calibration curve, the mass ratio (mass%) of each phase in the cordierite substrate is obtained.

[0034] The open porosity of the first ceramic substrate 10 is not particularly limited, but is preferably 10% or less, more preferably 5% or less. By controlling the open porosity within this range, when the heater 100 is used in an environment where a liquid such as a reducing agent precursor (for example, urea water) adheres, it is possible to make it difficult for the liquid to penetrate into the first ceramic substrate 10. Here, the open porosity of the first ceramic substrate 10 can be measured using an existing test method (Archimedes method, JIS R1634:1998). The open porosity of the first ceramic substrate 10 can be controlled by reducing the particle size of the raw material powder or adding a sintering aid or the like.

[0035] The coefficient of thermal expansion (thermal expansion rate) of the first ceramic substrate 10 is not particularly limited, but is preferably 1.5×10 -6 ~2.0×10 -6 / K. With a coefficient of thermal expansion within such a range, the thermal stress in a harsh environment with large thermal fluctuations can be stably reduced, thus improving the long-term durability of the heater 100. Here, the coefficient of thermal expansion of the first ceramic substrate 10 can be measured in accordance with JIS R1618:2002.

[0036] The Young's modulus of the first ceramic substrate 10 is not particularly limited, but is preferably 160 GPa or less. With a Young's modulus within such a range, the thermal stress in a harsh environment with large thermal fluctuations can be stably reduced, thus improving the long-term durability of the heater 100. Also, from the viewpoint of suppressing deformation and breakage of the heater 100 due to vibration, the Young's modulus of the first ceramic substrate 10 is preferably 100 GPa or more. Here, the Young's modulus of the first ceramic substrate 10 can be calculated as follows. For the first ceramic substrate 10, the flexural strength is measured in accordance with the four-point bending strength test method shown in JIS R1601:2008, and a "stress-strain curve" is created from this measurement result. The slope of the thus obtained "stress-strain curve" is calculated, and this slope of the "stress-strain curve" is taken as the Young's modulus.

[0037] <Glass part 20> The glass part 20 has closed pores 21. By having the closed pores 21 in the glass part 20, the Young's modulus of the glass part 20 is reduced, so that the thermal stress in a harsh environment with large thermal fluctuations can be reduced. Here, in this specification, the "closed pores 21" mean pores that exist isolated inside the glass part 20 and are not connected to the outside. The glass part 20 having closed pores 21 can be formed by a method known in the art (such as controlling components and manufacturing conditions). Also, the open pores on the surface of the glass part 20 having open pores may be filled with a repair material or the like to form closed pores. The repair material may be glass or other materials.

[0038] The coefficient of thermal expansion (thermal expansion rate) of the glass part 20 is not particularly limited, but preferably it is less than 2.0×10 -6 ~6.0×10 -6 / K, more preferably less than 2.0×10 -6 ~5.0×10 -6 / K, and even more preferably less than 2.0×10 -6 ~4.0×10 -6 / K. If the coefficient of thermal expansion is within such a range, the difference in the coefficient of thermal expansion between the glass part 20 and the first ceramic substrate 10 can be reduced. As a result, the thermal stress in a harsh environment with large thermal fluctuations can be reduced, so the long-term durability of the heater 100 is improved. Here, the coefficient of thermal expansion of the glass part 20 can be measured in the same manner as the coefficient of thermal expansion of the first ceramic substrate 10.

[0039] The Young's modulus of the glass part 20 is not particularly limited, but preferably it is 5~50 GPa, more preferably 5~40 GPa. If the Young's modulus is within such a range, the thermal stress in a harsh environment with large thermal fluctuations can be stably reduced, so the long-term durability of the heater 100 is improved. Here, the Young's modulus of the glass part 20 can be measured in the same manner as the Young's modulus of the first ceramic substrate 10.

[0040] The glass part 20 can be formed using various known glasses. The glass part 20 generally contains boron and / or silicon. Examples of the glass used for the glass part 20 include fused silica, borosilicate glass, soda-lime glass, aluminoborosilicate glass, aluminosilicate glass, and devitrified glass. Among these, borosilicate glass is preferred because of its high heat resistance and low coefficient of thermal expansion. Also, the glass part 20 preferably has a glass transition temperature (Tg) of 600 to 1100°C. If the glass transition temperature is within such a range, the heat resistance can be enhanced, and the long-term durability of the heater 100 is improved. Here, the glass transition temperature of the glass part 20 can be measured in accordance with JIS R3103-3:2001.

[0041] <The electrothermal part 30> The electrothermal part 30 is a conductor that generates heat when energized. The electrothermal part 30 is composed of a metal having a rate of change R1 of the mass at 700°C with respect to the mass at 25°C in an air atmosphere of 0.1% or less. By forming the electrothermal part 30 from such a metal, it becomes difficult to oxidize even under high-temperature conditions, and the long-term durability of the heater 100 is improved. Here, the rate of change R1 of the mass at 700°C with respect to the mass at 25°C of the metal can be measured by measuring the change in mass accompanying the temperature change of the metal using a thermogravimetric differential thermal analysis (TG-DTA) apparatus, and can be calculated from the measured masses of the metal at 25°C and 700°C by the following formula. Rate of change R1 = (Mass at 25°C - Mass at 700°C) / Mass at 25°C × 100

[0042] The metal having the above-described rate of change R1 of the mass is not particularly limited, but an alloy containing one or more selected from Ni, Fe, and Cr can be used. Examples of the alloy include Ni-Cr alloy and Fe-Cr alloy. These can be used alone or in combination. By using such an alloy, oxidation under high-temperature conditions can be stably suppressed.

[0043] Here, for reference, FIG. 2 shows a graph representing the relationship between the temperature of Mo (molybdenum), W (tungsten), Ni-Cr alloy, Fe-Cr alloy, and Fe-Ni alloy (invar), which were measured and calculated using a TG-DTA apparatus, and the mass change rate R1 of the mass at 700°C with respect to the mass at 25°C. As shown in FIG. 2, among the exemplified metals, only the Ni-Cr alloy and the Fe-Cr alloy have a mass change rate R1 of the mass at 700°C with respect to the mass at 25°C of 0.1% or less, indicating that they are difficult to oxidize even under high-temperature conditions.

[0044] Also, heaters 100 using Ni-Cr alloy, W, and Mo as the heating part 30 were actually manufactured, and the durability of the heaters 100 was evaluated. In this evaluation, a cordierite substrate was used as the first ceramic substrate 10, and borosilicate glass having closed pores 21 was used as the glass part 20. The durability evaluation was performed by applying a voltage to the heater 100 and measuring the temperature of the heater over time. The evaluation results of the durability of the heater 100 using Ni-Cr alloy as the heating part 30 are shown in FIG. 3A, the evaluation results of the durability of the heater 100 using W as the heating part 30 are shown in FIG. 3B, and the evaluation results of the durability of the heater 100 using Mo as the heating part 30 are shown in FIG. 3C. As shown in FIG. 3A, even when a voltage was applied to the heater 100 using Ni-Cr alloy as the heating part 30 for 55 hours, the temperature of the heater 100 hardly changed. In contrast, as shown in FIG. 3B, for the heater 100 using W as the heating part 30, the temperature of the heater 100 decreased when the time exceeded about 620 seconds. When investigating the cause, it was confirmed that the heating part 30 was disconnected. Also, as shown in FIG. 3C, for the heater 100 using Mo as the heating part 30, the temperature of the heater 100 decreased when the time exceeded about 14,500 seconds (about 4 hours). When investigating the cause, it was confirmed that the heating part 30 was disconnected.

[0045] The heating element 30 preferably has a change rate R2 of the volume resistivity at 300 °C with respect to the volume resistivity at 25 °C of 10% or less. With a change rate R2 of the volume resistivity within such a range, it can be said that the change in the volume resistivity is small even due to temperature changes, so that the heating performance can be stably maintained even under high-temperature conditions. Here, the volume resistivity at each temperature of the heating element 30 can be measured by the four-terminal method.

[0046] The coefficient of thermal expansion (thermal expansion coefficient) of the heating element 30 is not particularly limited, but is preferably 2.0×10 -6 ~15.0×10 -6 / K, more preferably 2.0×10 -6 ~14.0×10 -6 / K. Since the closed pores 21 of the glass part 20 can absorb the thermal expansion of the heating element 30, the coefficient of thermal expansion of the heating element 30 may be relatively large.

[0047] The shape of the heating element 30 is not particularly limited and can be various shapes such as linear, plate-like, and sheet-like. In FIGS. 1A to 1C, the case where a linear heating element 30 is formed is shown as an example.

[0048] When the heating element 30 is linear, its arrangement pattern is not particularly limited. For example, it can be an arrangement pattern as shown by the dotted line in FIG. 1A. Further, since the outer peripheral portion of the heater 100 is likely to cool, from the viewpoint of uniformly heating the heater 100, as shown in FIG. 4, it is preferable to increase the density of the linear heating element 30 in the outer peripheral portion of the heater 100 (that is, narrow the interval between the linear heating elements 30). Note that FIG. 4 is a schematic diagram (cross-sectional view of the heating element 30 parallel to the upper surface of the heater 100) for explaining the arrangement pattern of the linear heating element 30.

[0049] A second ceramic substrate can be further provided on the glass part 20 in which the heating element 30 is embedded. Here, FIG. 5A shows a top view of the heater further provided with the second ceramic substrate, and FIG. 5B shows a cross-sectional view of the heater taken along line b-b'. As shown in FIGS. 5A and 5B, the heater 200 includes a first ceramic substrate 10, a glass portion 20 provided on the first ceramic substrate 10, a heating portion 30 embedded in the glass portion 20, and a second ceramic substrate 40 provided on the glass portion 20. In FIG. 5A, the dotted line represents the position of the heating portion 30 embedded in the glass portion 20. In the heater 200 having such a structure, the glass portion 20 functions as an intermediate region that alleviates the difference in the coefficient of thermal expansion between the first ceramic substrate 10 and the second ceramic substrate 40 and the heating portion 30. Further, since the Young's modulus can be reduced by the closed pores 21 of the glass portion 20, the thermal stress in a harsh environment is reduced. Furthermore, since the first ceramic substrate 10 and the second ceramic substrate 40 do not come into direct contact with the heating portion 30, cracks in the first ceramic substrate 10 and the second ceramic substrate 40 can be suppressed. Therefore, the long-term durability of the heater 200 is improved.

[0050] Since the second ceramic substrate 40 can be the same as the first ceramic substrate 10, its details are omitted. The type of the second ceramic substrate 40 may be the same as or different from that of the first ceramic substrate 10, but it is preferably the same. By making the types of the first ceramic substrate 10 and the second ceramic substrate 40 the same, the thermal stress in a harsh environment with large thermal fluctuations can be stably reduced, so that the long-term durability of the heater 200 is improved.

[0051] As shown in FIGS. 1A to 1B and 5A to 5B, the heaters 100 and 200 can further include terminals 50 connected to the heating portion 30 by a brazing material 60. With such a configuration, it becomes easy to electrically connect the heating portion 30 to an external power source (not shown).

[0052] The terminal 50 is composed of an energizable conductor. The conductor used for the terminal 50 is not particularly limited, and a metal or alloy known in the art can be used. Among them, the conductor used for the terminal 50 preferably contains Fe, Ni, and Co. As such a material, for example, Kovar can be used. Note that the conductor used for the terminal 50 may be composed of the same conductor as the heating part 30, or may be composed of a conductor different from the heating part 30.

[0053] The coefficient of thermal expansion (thermal expansion coefficient) of the conductor constituting the terminal 50 is not particularly limited, but is preferably more than 1.6×10 -6 / K and less than 6.0×10 -6 / K, more preferably more than 3.0×10 -6 / K and less than 6.0×10 -6 / K. If the coefficient of thermal expansion of the conductor constituting the terminal 50 is within the above range, particularly in the heater 200 shown in FIGS. 5A and 5B, the difference in the coefficient of thermal expansion between the second ceramic substrate 40 and the conductor constituting the terminal 50 can be reduced. As a result, the thermal stress in an environment with large thermal fluctuations can be reduced, so the reliability of the heater 200 is improved. For example, Kovar has a coefficient of thermal expansion of about 5.0×10 -6 / K.

[0054] In the heater 200 shown in FIGS. 5A and 5B, the terminal 50 is preferably inserted and disposed in a through hole provided in the second ceramic substrate 40. With such a configuration, it becomes easy to electrically connect the heating part 30 to an external power source (not shown).

[0055] The brazing material 60 is a material for joining between the heating part 30 and the terminal 50. The brazing material 60 is not particularly limited, and an appropriate material may be selected according to the types of the heating part 30 and the terminal 50. For example, the brazing material 60 preferably contains Ag, Ti, and Cu. With the brazing material 60 containing such components, it can be appropriately joined without affecting the heating part 30 and the terminal 50.

[0056] As shown in FIGS. 1A-1B and 5A-5B, the heaters 100 and 200 may further include a seal portion 70 provided on the boundary surface between the terminal 50 and the glass portion 20 or the second ceramic substrate 40. Specifically, in the heater 100, the seal portion 70 may be provided on the boundary surface between the terminal 50 and the glass portion 20. Also, in the heater 200, the seal portion 70 may be provided on the boundary surface between the terminal 50 and the second ceramic substrate 40. By adopting such a configuration, it is possible to suppress the intrusion of liquid, air, etc. from the boundary, thereby improving the reliability of the heaters 100 and 200.

[0057] The material constituting the seal portion 70 is not particularly limited, and a sealing material known in the art can be used. Among them, the material constituting the seal portion 70 is preferably glass. Also, the seal portion 70 (glass) preferably contains SiO 2 and B 2 O 3 If the seal portion 70 contains such components, since the thermal expansion coefficient is low, cracks in the seal portion 70 and the surrounding members (glass portion 20 and second ceramic substrate 40) can be suppressed.

[0058] The thermal expansion coefficient (coefficient of thermal expansion) of the glass constituting the seal portion 70 is not particularly limited, but is preferably more than 1.6×10 -6 / K and less than 6.0×10 -6 / K, more preferably more than 2.0×10 -6 / K and less than 4.0×10 -6 / K. If the thermal expansion coefficient of the glass constituting the seal portion 70 is within the above range, in the heater 100, the difference in thermal expansion coefficient between the glass portion 20, the conductor constituting the terminal 50, and the glass constituting the seal portion 70 becomes small, and in the heater 200, the difference in thermal expansion coefficient between the second ceramic substrate 40, the conductor constituting the terminal 50, and the glass constituting the seal portion 70 becomes small. As a result, the thermal stress in a harsh environment with large thermal fluctuations can be reduced, thereby improving the reliability of the heaters 100 and 200.

[0059] By having the above-described configuration, the heaters 100 and 200 have long-term durability even in a harsh environment, and it is possible to suppress the occurrence of cracks in the ceramic base materials (the first ceramic base material 10 and the second ceramic base material 40), so they can be used in various applications. For example, the heaters 100 and 200 are useful for heating the exhaust gas in an exhaust gas mixer that mixes urea and exhaust gas in a urea SCR system of a diesel engine. Also, in this urea SCR system, it is useful for keeping the temperature of the inner wall surface of the cylindrical member (exhaust pipe) constituting the exhaust gas mixer high and suppressing the deposition of the intermediate solid deposit when urea collides with the inner wall surface. In the urea SCR system, by injecting urea water into the exhaust gas heated by the heaters 100 and 200, ammonia (NH 3 ) that becomes a NOx reducing agent can be generated. Also, the heaters 100 and 200 are useful for use as heating equipment in electric vehicles, fuel cell vehicles, and plug-in hybrid vehicles, and as heating means in a synthetic fuel manufacturing process.

[0060] The heaters 100 and 200 can be manufactured according to a method known in the art. For example, the heater 100 can be manufactured as follows. First, after molding a molding material containing ceramic raw material powder, the first ceramic base material 10 is produced by sintering. The molding method is not particularly limited, and extrusion molding, mold casting molding, etc. can be used. Also, the first ceramic base material 10 may be produced by machining a sintered body having a predetermined shape. Next, the electrothermal part 30 is sandwiched between two glass sheets that will become the glass part 20, and it is placed on the first ceramic base material 10 to form a laminated structure. At this time, an opening for connecting the electrothermal part 30 and the terminal 50 with a brazing material 60 is provided in the glass sheet on the surface side. Further, when a glass sheet having open pores is used as the glass sheet, a closed pore formation treatment for closing the open pores on the surface with a repair material such as glass is performed. If a glass sheet having closed pores is used, the closed pore formation treatment does not need to be performed. Next, the laminated structure is integrated by heat and pressure treatment. At this time, the glass sheets are integrated to become the glass part 20, and the electrothermal part 30 is embedded in the glass part 20. The conditions for heating and pressing may be appropriately set according to the type of glass sheet used and are not particularly limited. Next, the terminal 50 is disposed via the brazing material 60 on the electrothermal part 30 exposed in the opening of the glass sheet on the surface side, and heat treatment is performed for joining. The heating conditions may be appropriately set according to the type of brazing material 60 used and are not particularly limited. Finally, after applying a sealing material to the boundary between the terminal 50 and the glass part 20 on the surface of the glass part 20, heat treatment is performed to form the sealing part 70, and the heater 100 is completed. The heating conditions may be appropriately set according to the type of sealing material used and are not particularly limited.

[0061] Also, the heater 200 can be manufactured as follows. First, after molding a molding material containing cordierite raw material powder, the first ceramic base material 10 and the second ceramic base material 40 are produced by sintering. Next, the electrothermal part 30 is sandwiched between two glass sheets that will become the glass part 20, and this is disposed between the first ceramic base material 10 and the second ceramic base material 40 to form a laminated structure. At this time, openings for connecting the electrothermal part 30 and the terminal 50 with a brazing material 60 are provided in the second ceramic base material 40 and the glass sheet on the second ceramic base material 40 side. Further, when a glass sheet having open pores is used as the glass sheet, a closed pore formation process for closing the open pores on the surface with a repair material such as glass is performed. If a glass sheet having closed pores is used, the closed pore formation process need not be performed. Next, in order to improve the adhesion between the first ceramic base material 10, the second ceramic base material 40, and the glass sheet sandwiching the electrothermal part 30, the laminated structure is integrated by heat treatment while applying pressure. Next, the terminal 50 is disposed via the brazing material 60 on the electrothermal part 30 exposed in the openings of the second ceramic base material 40 and the glass sheet on the second ceramic base material 40 side, and heat treatment is performed for joining. Finally, after applying a sealing material to the boundary between the terminal 50 and the second ceramic base material 40 on the surface of the second ceramic base material 40, heat treatment is performed to form a sealing part 70, and the heater 200 is completed.

[0062] (2) Heating member FIG. 6 is a cross-sectional view of a heating member according to an embodiment of the present invention. Note that FIG. 6 is a cross-sectional view in a direction perpendicular to the axial direction of the cylindrical member 300 constituting the heating member 1000. As shown in FIG. 6, the heating member 1000 includes a cylindrical member 300, a plurality of heaters 100 and 200 disposed along at least a part of the inner peripheral surface of the cylindrical member 300, and an insulating material 400 disposed between the cylindrical member 300 and the heaters 100 and 200. By adopting such a structure, it becomes possible to heat the inside of the cylindrical member 300.

[0063] The cylindrical member 300 is not particularly limited, and may have a uniform diameter in the axial direction, or may have a reduced diameter and / or an enlarged diameter in the axial direction. The material of the cylindrical member 300 is not particularly limited, but from the viewpoint of manufacturability, it is preferably a metal. As the metal, for example, stainless steel, titanium alloy, copper alloy, aluminum alloy, brass, etc. can be used. Among these, stainless steel is preferable because of its high durability and reliability and low cost.

[0064] The thickness of the cylindrical member 300 is not particularly limited, but it is preferably 0.1 mm or more, more preferably 0.3 mm or more, and still more preferably 0.5 mm or more. By setting the thickness of the cylindrical member 300 to 0.1 mm or more, durability and reliability can be ensured. Also, the thickness of the cylindrical member 300 is preferably 10 mm or less, more preferably 5 mm or less, and still more preferably 3 mm or less. By setting the thickness of the cylindrical member 300 to 10 mm or less, weight reduction can be achieved.

[0065] The insulating material 400 is not particularly limited, and a fiber mat composed of silicon nitride, alumina, etc. can be used. The thickness of the insulating material 400 is not particularly limited as long as it can ensure insulation.

[0066] The plurality of heaters 100, 200 are arranged along at least a part of the inner peripheral surface of the cylindrical member 300. The fixing method of the heaters 100, 200 is not particularly limited, but for example, they may be fixed to the inner peripheral surface of the cylindrical member 300 using a fixing jig such as a bolt 500.

[0067] The plurality of heaters 100, 200 are configured such that the heating part 30 can be electrically connected to the power source in series or in parallel. By such a configuration, by applying a voltage from the power source, the plurality of heaters 100, 200 generate heat, and it becomes possible to heat the inside of the cylindrical member 300. Here, FIG. 7 shows a top view showing a state in which the heating units 30 of the plurality of heaters 100 and 200 are electrically connected in series to a power source. FIG. 8 shows a top view showing a state in which the heating units 30 of the plurality of heaters 100 and 200 are electrically connected in parallel to a power source. In FIGS. 7 and 8, for ease of understanding, three heaters 100 are represented planar. Also, the dotted line represents the position of the embedded heating unit 30.

[0068] In FIG. 7, the heating units 30 of the plurality of heaters 100 and 200 are electrically connected in series, one end of the serially connected heating units 30 is electrically connected to a power source, and the other end is electrically connected to ground (for example, the cylindrical member 300). In FIG. 8, the heating units 30 of the plurality of heaters 100 and 200 are electrically connected in parallel, one end of each heating unit 30 is electrically connected to a power source, and the other end is electrically connected to ground (for example, the cylindrical member 300).

[0069] The applied voltage from the power source is not particularly limited, but is preferably 80 V or less. With a voltage in this range, special insulation is not required. Also, considering the heating efficiency of the heaters 100 and 200, the applied voltage is preferably 12 V or more.

[0070] The heating member according to the embodiment of the present invention is suitable for use in a urea SCR system of a diesel engine. That is, the heating member according to the embodiment of the present invention keeps the temperature of the inner wall surface of the cylindrical member 300 that constitutes the exhaust gas mixer that mixes the reductant precursor (for example, aqueous urea) and the exhaust gas high, and when the reductant precursor collides with the inner wall surface, it can be used to heat the reductant precursor to generate a reductant (for example, ammonia) while suppressing the deposition as a solid deposit of the intermediate product.

[0071] Here, FIG. 9 shows a cross-sectional view of the heating member used to heat the reductant precursor to generate a reductant. Note that FIG. 9 is a cross-sectional view in a direction perpendicular to the axial direction of the cylindrical member 300 that constitutes the heating member 2000. As shown in Fig. 9, the heating member 2000 is disposed on at least a part of the cylindrical member 300, and further includes a nozzle 600 capable of injecting a reductant precursor onto the inner circumferential surface of the cylindrical member 300. A plurality of heaters 100 and 200 are disposed on the inner circumferential surface of the cylindrical member 300 where the reductant precursor is injected from the nozzle 600. Further, the cylindrical member 300 is an exhaust pipe of a diesel engine. With such a configuration, the exhaust gas flowing through the cylindrical member 300 (exhaust pipe) can be heated by the plurality of heaters 100 and 200, and a reductant can be generated by injecting the reductant precursor into the heated exhaust gas. Further, even if the reductant precursor injected from the nozzle 600 collides with the plurality of heaters 100 and 200, since the reductant precursor evaporates immediately, it is possible to suppress the deposition of intermediates generated by the decomposition of the reductant precursor.

[0072] It is preferable that the heating member 2000 has the heating sections 30 of the plurality of heaters 100 and 200 electrically connected in parallel. That is, it is preferable that one end of the heating sections 30 of the plurality of heaters 100 and 200 is electrically connected to a power source, and the other end is electrically connected to the ground (for example, the cylindrical member 300). Further, the applied voltage from the power source is preferably 60 V or less. With such a configuration, it is possible to quickly and efficiently heat the reductant precursor to generate a reductant, and to suppress the deposition of intermediates on the inner wall surface of the cylindrical member 300.

Explanation of Reference Numerals

[0073] 10 First ceramic base material 20 Glass section 21 Closed pores 30 Heating section 40 Second ceramic base material 50 Terminal 60 Brazing material 70 Seal section 100,200 Heater 300 Cylindrical member 400 Insulating material 500 Bolt 600 Nozzle 1000, 2000 Heating member

Claims

1. A first ceramic substrate, a glass part provided on the first ceramic substrate, and a heating part embedded in the glass part, wherein the glass part has closed pores, and the heating part is a heater composed of a metal having a mass change rate of 700 °C with respect to the mass at 25 °C of 0.1% or less in an air atmosphere.

2. The heater according to claim 1, further comprising a second ceramic substrate provided on the glass part.

3. The heater according to claim 1 or 2, wherein the ceramic substrate is a cordierite substrate.

4. The coefficient of thermal expansion of the glass part is less than 2.0×10 -6 to 6.0×10 -6 / K, and the heater according to claim 1 or 2.

5. The heater according to claim 1 or 2, wherein the Young's modulus of the glass part is 5 to 50 GPa.

6. The heater according to claim 1 or 2, wherein the glass part contains boron and / or silicon and has a glass transition temperature of 600 to 1100 °C.

7. The heater according to claim 1 or 2, wherein the heating part has a volume resistivity change rate of 300 °C with respect to the volume resistivity at 25 °C of 10% or less.

8. The heater according to claim 1 or 2, wherein the heating part is composed of an alloy containing one or more selected from Ni, Fe, and Cr.

9. The heater according to claim 8, wherein the alloy is a Ni—Cr alloy and / or an Fe—Cr alloy.

10. The heater according to claim 1 or 2, further comprising a terminal connected to the heating part.

11. The heater according to claim 10, wherein the terminal is connected to the heating part by a brazing material.

12. The heater according to claim 1 or 2, which is used for heating exhaust gas.

13. A cylindrical member, a plurality of heaters according to claim 1 or 2 arranged along at least a part of the inner peripheral surface of the cylindrical member, and an insulating material arranged between the cylindrical member and the heater, wherein the heating parts of the plurality of heaters are heating members that can be electrically connected to a power source in series or in parallel.

14. A heating member according to claim 13, which is used for heating a reducing agent precursor to generate a reducing agent, wherein it is arranged on at least a part of the cylindrical member, and further comprises a nozzle capable of injecting the reducing agent precursor onto the inner peripheral surface of the cylindrical member, the heater is arranged on the inner peripheral surface of the cylindrical member where the reducing agent precursor is injected from the nozzle, and the cylindrical member is an exhaust pipe of a diesel engine.

15. ​ One end of the electric heating part of the heater is electrically connected to the power supply, and the other end is electrically connected to the cylindrical member. The heating member according to claim 14, wherein the applied voltage from the power supply is 80 V or less.

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