JP2913201B2 - Spark rod - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

(1) Object of the Invention [Industrial application field] The present invention enables a spark rod body made of a conductive ceramic material to be detachable from the tip of a spark rod holder formed of a tough metal conductor. The spark rod body is formed such that the tip of the spark rod body protrudes into the combustion space of the flame stabilizer connected to the open end of the bottomed cylindrical metal pipe formed of a conductive ceramic material. The present invention relates to a spark rod for a radiant tube for generating a spark discharge. [Prior art] Conventionally, as a spark rod of this type, iron-
There has been proposed a structure formed entirely of a metal conductor such as a chromium-aluminum alloy (for example, "Kanthal" manufactured by Gadelius), but (i) the amount of heat generated by combustion of a combustion gas As the temperature of the radiant tube or the inside of the furnace increases and the temperature of the radiant tube or the combustion furnace increases, deterioration such as wear due to oxidation or curvature due to creep increases in a short period of time, and (ii) the service life is shortened. In addition, (iii) there is a disadvantage that the material efficiency cannot be improved because the whole must be replaced upon deterioration such as wear due to oxidation or curvature due to creep. Therefore, these disadvantages have been recently removed. For the purpose, the distal end (hereinafter, referred to as “spark rod body”) is formed of a conductive ceramic material, and the proximal end (hereinafter, “spark rod body”) is connected via a joint member. Now is proposed made by linked to removable relative) that Kuroddo holder ". [Problems to be Solved] However, in the conventional spark rod, the spark rod body has come to be formed of a conductive ceramic material, but it is not enough to increase the amount of heat generated by combustion of the combustion gas. (I) there is still a drawback that deterioration such as wear due to oxidation or curvature due to creep increases in a short period of time, and (ii) there is a drawback that the service life is shortened. (Iii) There is a drawback that the material efficiency must be improved because it must be replaced frequently when deterioration such as wear due to oxidation or curvature due to creep occurs. Therefore, the present invention is to provide a spark rod that can eliminate these disadvantages. (2) Configuration of the Invention [Means for Solving the Problems] The means for solving the problems provided by the present invention is as follows: "The tip of the spark rod holder made of a high toughness metal conductor is electrically conductive ceramic material. Of the spark rod body between the combustion chamber of the flame stabilizer connected to the open end of the bottomed cylindrical metal pipe made of conductive ceramics material A spark rod for a radiant tube for generating a spark discharge is provided so as to protrude, and 3 to 25% by weight of chromium silicide and 3 to 25%
It is produced by sintering a conductive ceramic material obtained by mixing aluminum oxide of 0% by weight, 0 to 6% by weight of carbon and the balance of silicon carbide at a temperature of 1700 to 2000 ° C. in an inert gas atmosphere. Spark rod body,
A plurality of combustion gas supply holes are formed in a disk-shaped peripheral portion made of a conductive ceramic material, and the combustion gas supply holes are connected to the inner peripheral surface of almost the middle portion of the flame stabilizer. A holding portion for holding the spark rod body via an insulating layer, a base end portion of the spark rod body is connected by insertion, and a joint member formed of a conductive metal and a distal end portion are screwed to the joint member. A spark rod, which is detachably connected by attachment and has a spark rod holder whose base end is attached to the center of the base of the metal pipe by an attachment member via an insulating layer. [Operation] The spark rod according to the present invention has a spark rod body of three as described in the above [Means for Solving the Problems].
A conductive ceramic material comprising -25% by weight of chromium silicide, 3-25% by weight of aluminum oxide, 0-6% by weight of carbon and the balance of silicon carbide is mixed under an inert gas atmosphere at 1700-2100. Since it is manufactured by sintering at a temperature of ° C., (i) the amount of heat generated by the combustion of the combustion gas increases and the effect of suppressing deterioration even at high temperatures is achieved, and (ii) Acts to prolong the useful life. Further, since the spark rod according to the present invention is formed by connecting the joint member to which the base end of the spark rod body is connected by insertion to the tip of the spark rod holder so as to be detachable, (Iii) The function of improving the electrical, thermal and mechanical connection between the spark rod body made of a conductive ceramic material and the spark rod holder made of a metal conductor. Furthermore, since the spark rod according to the present invention has a structure in which the spark rod body is supported by the holding portion and the spark rod holder is supported by the mounting member, (iV) the positioning is accurate and It works to suppress vibration of the part and prevent damage. Embodiment Next, a preferred embodiment of a spark rod according to the present invention will be described in detail with reference to the accompanying drawings. Here, an example of a flame stabilizer to which the spark rod according to the present invention is attached will be described in order to facilitate understanding of the configuration and the operation and effect of the spark rod according to the present invention. (Configuration of Embodiment) First, the configuration of an embodiment of a spark rod according to the present invention will be described in detail with reference to FIG. 30 is a spark rod according to the present invention,
The tip 31a is formed of a conductive ceramic material obtained by blending 25% by weight of silicon chromium, 3 to 25% by weight of aluminum oxide, 0 to 6% by weight of carbon, and the rest of silicon carbide, as described later. A spark rod body 31 functioning as a discharge region, and a spark rod body at one end.
A base member 31B of the base member 31 is connected by insertion, and a joint member 32 formed of an appropriate heat-resistant metal conductor (for example, a heat-resistant alloy or stainless copper) is provided. The portion 33a is detachably connected by screwing and functions as a holding means for the spark rod body 31 and a power supply means for the spark rod body 31, and is a tough metal conductor (for example, stainless steel, copper or brass). A spark rod holder 33 formed around the spark rod holder 33, an insulating layer 34 disposed on a peripheral surface near a base end 33b of the spark rod holder 33, and a spark rod holder disposed around the insulating layer 34 A mounting member 35 for appropriately holding 33 to a metal pipe 20 described below, and a spark rod holder
A power supply terminal 36 is formed for the base end 33b of the power supply 33, and is connected to a power supply line (not shown). Reference numeral 10 denotes a flame stabilizer to which the spark rod 30 according to the present invention is attached, which is formed of a suitable conductive ceramic material and is attached to an opening end of a metal pipe 20 to be described later; The combustion portion 12 is formed of a conductive ceramic material and is formed integrally with the cylindrical base 11, and the combustion portion 12 is formed of an appropriate conductive ceramic material and formed integrally with the cylindrical base 11. And a holding unit 13. By the way, flame stabilizer 10
A suitable conductive ceramic material (for example, a silicon carbide composite material) may be formed by sintering the formed body after forming it in a well-known manner, and is preferably impregnated with a heat-resistant material such as silicon. The flame stabilizer 10 is, in particular,
It is preferable that the spark rod body 31 is manufactured using the same conductive ceramic material as that used for forming the spark rod body 31. The cylindrical base 11 of the flame stabilizer 10 is inserted and attached at one end 11A to an opening end 21A of a metal pipe main body 21 included in a metal pipe 20 described later. The combustion gas (for example, natural gas) provided from the end 21A is guided toward the other end 11B. In the cylindrical base 11, the thickness of the one end 11A is reduced as desired. One end 11A of the cylindrical base 11 is inserted into the open end 21A of the metal pipe main body 21 and, when inserted and attached, engages the tip of the fixing screw 22 to stabilize the peripheral surface. At least one locking recess (which may be a locking hole) 11a is formed. A buffer member 11b such as a copper film may be arranged on the peripheral surface of the one end 11A of the tubular base 11 as required for the purpose of stabilizing the fixing by the tip of the fixing screw 22. At one end 11A of the tubular base 11, adhesive layers 11c and 11d made of a heat-resistant adhesive are provided within a range that does not block a conductive path between the metal pipe main body 21 and a heat-resistant adhesive. It may be formed. The combustion portion 12 of the flame stabilizer 10 is connected to the other end portion 11B of the cylindrical base 11, and combustion gas is burned in an internal space (also referred to as a combustion space). The combustion section 12 has at least one connection with a connection section to the other end section 11B of the cylindrical base section 11.
Two auxiliary agent supply holes 12a are formed. Combustion agent supply hole 1
When a plurality of 2a are formed, they are preferably held at equal angular intervals. The holding portion 13 of the flame stabilizer 10 is provided continuously with the inner peripheral surface of the other end portion 11B of the cylindrical base portion 11, and a desired number for supplying the combustion gas toward the internal space of the combustion portion 12. Combustion gas supply hole
13a are formed at a desired angular interval around the periphery, and the center of the holding hole 13b for holding the tip of the spark rod 30 according to the present invention (that is, the spark rod body 31) via the insulating layer 14 is located at the center. Have. The metal pipe 20 has a bottomed cylindrical shape, and has one end 11A of the cylindrical base 11 of the flame stabilizer 10 inserted and attached to the opening end 21A, and the opening of the metal pipe body 21. When screwed into a screw hole 21a formed on the peripheral surface of the end 21A, the tip presses the cushioning member 11b to engage the locking recess 11a, and the base 21B of the metal pipe main body 21. And a spark gas supply pipe 23 for supplying combustion gas from a combustion gas supply source (not shown), and a spark pipe according to the present invention, which is formed with respect to a base 21B of the metal pipe main body 21. It has a mounting hole 24 for mounting the mounting member 35 of the rod 30 appropriately (for example, by screwing). After the spark rod body 31 of the spark rod 30 according to the present invention is extended through the internal space of the cylindrical base 11 of the flame stabilizer 10 , the tip 31a of the spark rod main body 31 has the internal space of the combustion part 12 (that is, the combustion space). Projected against (Production Procedure and Assembly Procedure) Further, the production procedure of an embodiment of the spark rod according to the present invention will be briefly described with reference to FIG. The spark rod body 31 of the spark rod 30 according to the present invention is a mixture of 3 to 25% by weight of chromium silicide, 3 to 25% by weight of aluminum oxide, 0 to 6 parts by weight of carbon, and the balance of silicon carbide. The conductive ceramic material is processed in a known manner to form a molded body, and the molded body is sintered at a temperature of 1700 to 2100 ° C. in an inert gas atmosphere. The reason that the blending amount of chromium silicide is 3 to 25% by weight is that if the amount is less than 3% by weight, the electrical resistivity of the sintered body, that is, the spark rod body 31 is not sufficiently reduced, and if it exceeds 25% by weight, the firing is made. This is because the mechanical strength of the unit, that is, the spark rod body 31 is reduced and the spark rod body 31 is easily broken. The reason that the amount of aluminum oxide is 3 to 25% by weight is that if the amount is less than 3% by weight, the sintered body deteriorates and the mechanical strength of the sintered body, that is, the spark rod body 31 cannot be secured. If the content is more than 10% by weight, the mechanical strength of the sintered body, that is, the spark rod body 31 is reduced, and the sintered body is easily broken. The aluminum oxide need not always be added as a powder, but may be added as an aluminum alkoxide, an organic acid salt, etc., and converted into aluminum oxide before sintering. The basis for the carbon content of 0 to 6% by weight is as follows:
(I) The sintered body, that is, the spark rod body 31 can be formed without adding carbon, or the sinterability can be structured by adding 6% by weight or less of carbon, and the mechanical properties of the sintered body, that is, the spark rod body 31 The strength can be ensured, and (ii) addition of carbon exceeding 6% by weight results in deterioration of sinterability and deterioration of oxidation resistance. The carbon is preferably added as a resin having a high degree of carbonization (for example, a phenol resin). The basis for the sintering temperature of 1700-2100 ° C is (i)
If the temperature is lower than 1700 ° C., the mechanical strength of the sintered body, that is, the spark rod main body 31, cannot be secured. If the temperature exceeds 2100 ° C., the mechanical strength of the sintered body, that is, the spark rod main body 31, is reduced and the spark rod is easily broken. Is to become. The joint member 32 of the spark rod 30 according to the present invention usually cuts a pipe formed of an appropriate heat-resistant metal conductor to an appropriate length, and grinds an inner peripheral surface to a desired distance from one end, It is manufactured by grinding the inner peripheral surface to a desired distance from the other end to form a female screw. The spark rod holder 33 of the spark rod 30 according to the present invention has a male screw formed at the distal end of a rod or a tube formed of a tough metal conductor, and a power supply terminal 36 at a proximal end.
It is manufactured by disposing a mounting member 35 to the metal pipe 20 via an insulating layer 34 on the peripheral surface near the base end. The spark rod 30 according to the present invention is formed by winding an active metal braze around the spark rod body 31 and the joint member 32, for example, around the base end 31b of the spark rod body 31.
2 are connected to each other by being inserted into one end and subjected to heat treatment. After that, the other end of the joint member 32 is detachably connected to the tip 33a of the spark rod holder 33 by screwing. On the peripheral surface of the base end portion 33b of the spark rod holder 33, a mounting member 35 is previously disposed via an insulating layer 34. The flame stabilizer 10 is manufactured by processing a suitable conductive ceramic material in a known manner to form a molded body, and sintering the molded body in a known manner, and then forming the cylindrical base.
A heat-resistant adhesive (this forms the adhesive layers 11c and 11d) to dispose the cushioning member 11b on the peripheral surface of the one end 11A of the 11 and to prevent the leakage of the combustion gas to the front end surface and the step end surface Is inserted into the open end portion 21A of the metal pipe main body 21 in a state in which it is disposed. By screwing the fixing screw 22 into the screw hole 21a of the metal pipe main body 21, the tip of the fixing screw 22 presses the buffer member 11b and engages with the locking recess 11a. After that, the spark rod 30 according to the present invention is connected to its tip (ie, the tip 31a of the spark rod body 31).
Into the mounting hole 24 of the metal pipe 20 from the flame holder 10
Is inserted into the holding hole 13b formed in the holding portion 13 of FIG.
After that, the spark rod 30 according to the present invention, by appropriately mounting the mounting member 35 to the mounting hole 24,
Fixed. As described above, the spark rod 30 according to the present invention is attached to the flame stabilizer 10 . (Operation of Embodiment) In addition, the operation of an embodiment of the spark rod according to the present invention will be described in detail with reference to FIG. Flame holder 10, the guided combustion gas as shown by an arrow A ₂ after being fed as indicated by arrow A ₁ from the combustion gas supply by the combustion gas supply pipe 23, the opening end 21A of the metal pipe body 21 After guide to the holding member 13 by the receiving tubular base portion 11, supplied to the combustion space of the combustion section 12 as shown by arrow a ₃ via the combustion gas supply hole 13a formed in the peripheral edge portion of the holding member 13. In the combustion space of the combustion section 12, the combustion gas is supplied to the combustion aid supply hole.
After being mixed with a combustion aid (for example, combustion air) given as indicated by an arrow B from 12a, the tip of the spark rod 30 according to the present invention, that is, between the spark rod body 31 and the inner peripheral surface of the combustion part 12, is mixed. It is ignited and burned by the generated spark discharge. (Specific Example) In addition, an embodiment of the spark rod according to the present invention will be described with specific numerical values and the like in order to facilitate understanding of the configuration and the operation and effect. Example 1 A metal pipe made of stainless steel (Japanese Industrial Standard SUS310) having an inner diameter of 2.8 mm and an outer diameter of 4 mm was cut into a length of 22 mm,
Grind the inner peripheral surface to a distance of 10 mm from one end to
The joint member was manufactured by grinding the inner peripheral surface to 3.2 mm and a distance of 10 mm from the other end to form a female screw having a valley diameter of 3 mm and a pitch of 0.5 mm. On the other hand, 79 g of silicon carbide powder having an average particle size of 0.5 μm
5 g of chromium silicide powder with an average particle size of 3.0 μm and carbonization degree of 50% by weight
Was added to 150 ml of an acetone solution in which 8 g of the phenol resin was dissolved, followed by stirring and mixing using an alumina pot mill (that is, an alumina pot and balls) for 120 hours. After the solvent was removed by drying, the stirred mixture was granulated using a 60-mesh sieve to obtain granulated powder. The granulated powder contained only about 12 g of aluminum oxide that had fallen off from the pot wall and the balls and was mixed in because the pot mill was made of alumina. The granulated powder was formed by a room-temperature isostatic press to obtain a rod-shaped compact having a diameter of 4 mm and a length of 260 mm. The rod-shaped compact was housed in a graphite container and sintered at a temperature of 1900 ° C. in an argon atmosphere to form a sintered compact having a diameter of about 3.2 mm and a length of about 210 mm. The sintered body is
Both ends were cut to form a spark rod body having a diameter of about 3.2 mm and a length of 200 mm. Incidentally, the relative density, electrical resistivity and bending strength (the strength of three-point bending at room temperature, that is, room temperature; the same applies hereinafter) of the sintered body, that is, the spark rod body, were as shown in Table 1. . At the base end of the spark rod body, the outer surface is ground to a position of 10 mm in length, the outer diameter is 3 mm, the width is 10 mm and the thickness is 0.0
After 5 mm of a sheet-shaped active silver braze was wound twice, it was inserted into one end of the joint member. The spark rod body was housed in a carbon case with the base end inserted into the joint member, and maintained at 900 ° C. for 5 hours in a vacuum furnace under an atmosphere of about 10 ⁻⁵ mmHg. As a result, the spark rod main body was connected to the joint member to form a spark rod main body with a joint member. Incidentally, the composition of the active silver wax was 67 parts by weight of silver, 30 parts by weight of copper and 3 parts by weight of titanium. The spark rod body with the joint member was formed into a spark rod by screwing and connecting the tip of a spark rod holder made of stainless steel in advance to the other end of the joint member. The spark rod was used as an igniter for a radiant tube after being incorporated into a flame stabilizer. That is,
The spark rod uses natural gas as the combustion gas, uses air as the combustion aid, and raises the temperature inside the combustion furnace to 1150 ° C.
And used continuously for 3 months. The spark rod was stopped from supplying and supplying the combustion gas and the auxiliary agent, and was allowed to cool down to room temperature by natural cooling, and was then removed from the flame holder removed from the radiant tube. When the connection state between the spark rod main body and the spark rod holder and the joint member was observed, no abnormality was found in the spark rod. Example 2 74 g of silicon carbide powder having an average particle size of 0.5 μm
After addition of 10 g of chromium silicide powder having a particle size of 10 μm and 150 ml of an acetone solution containing 8 g of a phenol resin having a carbonization degree of 50% by weight, the mixture was stirred and mixed using an alumina pot mill (that is, an alumina pot and balls) for 120 hours. Was. After the solvent was removed by drying, the stirred mixture was granulated using a 60-mesh sieve to obtain granulated powder. The granulated powder contained only about 12 g of aluminum oxide that had fallen off from the pot wall and the balls and was mixed in because the pot mill was made of alumina. The granulated powder was formed by a room-temperature isostatic press to obtain a rod-shaped compact having a diameter of 4 mm and a length of 260 mm. The rod-shaped compact was housed in a graphite container and sintered at a temperature of 1900 ° C. in an argon atmosphere to form a sintered compact having a diameter of about 3.2 mm and a length of about 210 mm.
The sintered body is cut at both ends and has a diameter of about 3.2 mm and a length of 2
It was a 00 mm spark rod body. Incidentally, the relative density, electrical resistivity, and bending strength of the sintered body, that is, the spark rod body, were as shown in Table 1. The spark rod main body was attached to the joint member and the spark rod holder in the same manner as in Example 1, and then incorporated as a spark rod into a flame holder and used as an ignition device for a radiant tube. At this time, when the spark rod body and the connection state between the spark rod holder and the joint member were observed, no abnormality was observed. Example 3 69 g of silicon carbide powder having an average particle size of 0.5 μm
After adding 15 g of chromium silicide powder having a particle size of 15 μm and 150 ml of an acetone solution in which 8 g of a phenol resin having a carbonization degree of 50% by weight was dissolved, the mixture was stirred and mixed using an alumina pot mill (ie, an alumina pot and balls) for 120 hours. Was. After the solvent was removed by drying, the stirred mixture was granulated using a 60-mesh sieve to obtain granulated powder. The granulated powder contained only about 12 g of aluminum oxide that had fallen off from the pot wall and the balls and was mixed in because the pot mill was made of alumina. The granulated powder was formed by a cold isostatic press to obtain a rod-shaped compact having a diameter of 4.2 mm and a length of 250 mm. The rod-shaped compact was housed in a graphite container and sintered at a temperature of 1900 ° C. in an argon atmosphere to obtain a sintered compact having a diameter of about 3.3 mm and a length of about 220 mm.
The sintered body is cut at both ends to have a diameter of about 3.3 mm and a length of 2
It was a 00 mm spark rod body. Incidentally, the relative density, electrical resistivity, and bending strength of the sintered body, that is, the spark rod body, were as shown in Table 1. The spark rod main body was attached to the joint member and the spark rod holder in the same manner as in Example 1, and then incorporated as a spark rod into a flame holder and used as an ignition device for a radiant tube. At this time, when the spark rod body and the connection state between the spark rod holder and the joint member were observed, no abnormality was observed. Example 4 64 g of silicon carbide powder having an average particle size of 0.5 μm
After adding 20 g of chromium silicide powder of 20 μm and 150 ml of an acetone solution in which 8 g of a phenol resin having a carbonization degree of 50% by weight were dissolved, the mixture was stirred and mixed for 120 hours using an alumina pot mill (that is, an alumina pot and balls). Was. After the solvent was removed by drying, the stirred mixture was granulated using a 60-mesh sieve to obtain granulated powder. The granulated powder contained only about 12 g of aluminum oxide that had fallen off from the pot wall and the balls and was mixed in because the pot mill was made of alumina. The granulated powder was formed by a room-temperature isostatic press to obtain a rod-shaped compact having a diameter of 4 mm and a length of 260 mm. The rod-shaped compact is housed in a graphite container, and sintered at a temperature of 1900 ° C. in an argon atmosphere to have a diameter of about 1900 ° C.
The sintered body was 3.2 mm and the length was about 210 mm. The sintered body was cut at both ends into a spark rod body having a diameter of about 3.2 mm and a length of 200 mm. Incidentally, the relative density, electrical resistivity, and bending strength of the sintered body, that is, the spark rod body, were as shown in Table 1. The spark rod main body was attached to the joint member and the spark rod holder in the same manner as in Example 1, and then incorporated as a spark rod into a flame holder and used as an ignition device for a radiant tube. At this time, when the spark rod body and the connection state between the spark rod holder and the joint member were observed, no abnormality was observed. Example 5 78 g of silicon carbide powder having an average particle size of 0.5 μm
After adding 10 g of the chromium silicide powder of 10 μm and 150 ml of an acetone solution in which 4 g of vinyl acetate was dissolved, the mixture was stirred and mixed for 120 hours using a pot mill made of alumina (that is, pots and balls made of alumina). After the solvent was removed by drying, the stirred mixture was granulated using a 60-mesh sieve to obtain granulated powder. The granulated powder contained only about 12 g of aluminum oxide that had fallen off from the pot wall and the balls and was mixed in because the pot mill was made of alumina. The granulated powder was formed by a room-temperature isostatic press to obtain a rod-shaped compact having a diameter of 4 mm and a length of 260 mm. The rod-shaped compact is housed in a graphite container, and sintered at a temperature of 1900 ° C. in an argon atmosphere to have a diameter of about 1900 ° C.
The sintered body was 3.2 mm and the length was about 210 mm. The sintered body was cut at both ends into a spark rod body having a diameter of about 3.2 mm and a length of 200 mm. Incidentally, the relative density, electrical resistivity and bending strength of the sintered body, that is, the spark rod body, are as shown in Table 1. there were. The spark rod main body was attached to the joint member and the spark rod holder in the same manner as in Example 1, and then incorporated as a spark rod into a flame holder and used as an ignition device for a radiant tube. At this time, when the spark rod body and the connection state between the spark rod holder and the joint member were observed, no abnormality was observed. Comparative Example 1 After adding 84 g of silicon carbide powder having an average particle diameter of 0.5 μm to 150 ml of an acetone solution in which 8 g of a phenol resin having a carbonization degree of 50% by weight was dissolved, an alumina pot mill (that is, an alumina pot and balls) was added. With stirring for 120 hours. After the solvent was removed by drying, the stirred mixture was granulated using a 60-mesh sieve to obtain granulated powder. The granulated powder contained only about 12 g of aluminum oxide that had fallen off from the pot wall and the balls and was mixed in because the pot mill was made of alumina. The granulated powder was formed by a room-temperature isostatic press to obtain a rod-shaped compact having a diameter of 4 mm and a length of 260 mm. The rod-shaped compact is housed in a graphite container, and sintered at a temperature of 1900 ° C. in an argon atmosphere to have a diameter of about 1900 ° C.
The sintered body was 3.2 mm and the length was about 210 mm. The relative density, electrical resistivity and bending strength of the sintered body were as shown in Table 1, and particularly, the electrical resistivity was large and was unsuitable as a material for the spark rod body. Comparative Example 2 54 g of silicon carbide powder having an average particle size of 0.5 μm
After adding 30 g of chromium silicide powder having a particle size of 30 μm and 150 ml of an acetone solution in which 8 g of a phenol resin having a carbonization degree of 50% by weight was dissolved, the mixture was stirred and mixed using an alumina pot mill (that is, an alumina pot and balls) for 120 hours. Was. After the solvent was removed by drying, the stirred mixture was granulated using a 60-mesh sieve to obtain granulated powder. The granulated powder contained only about 12 g of aluminum oxide that had fallen off from the pot wall and the balls and was mixed in because the pot mill was made of alumina. The granulated powder was formed by a room-temperature isostatic press to obtain a rod-shaped compact having a diameter of 4 mm and a length of 260 mm. The rod-shaped compact is housed in a graphite container, and sintered at a temperature of 1900 ° C. in an argon atmosphere to have a diameter of about 1900 ° C.
The sintered body was 3.2 mm and the length was about 210 mm. The relative density, electrical resistivity, and bending strength of the sintered body were as shown in Table 1, and particularly, the bending strength was small and was unsuitable as a material for the spark rod body. (Modification) In the above description, the joint member 32 and the spark rod holder 33 are connected by screwing, but the present invention is not limited to this, and the connection is performed in another appropriate manner. Sometimes it is included. (3) Effect of the Invention As is clear from the above, the spark rod according to the present invention has the above-described structure.

As disclosed in the above, a spark rod body is composed of 3 to 25% by weight of chromium silicide, 3 to 25% by weight of aluminum oxide, 0 to 6% by weight of carbon and the balance of silicon carbide. Since it is manufactured by sintering a conductive ceramic material at a temperature of 1700 to 2100 ° C. in an inert gas atmosphere, (i) the amount of heat generated by combustion of the combustion gas increases and the temperature increases. It has the effect of suppressing deterioration even if it becomes, and (ii) has the effect of prolonging the useful life. Further, since the spark rod according to the present invention is formed by connecting the joint member to which the base end of the spark rod body is connected by insertion to the tip of the spark rod holder so as to be detachable, (Iii) The spark rod body made of a conductive ceramic material and the spark rod holder made of a metal conductor can be electrically, thermally, and mechanically connected. Furthermore, since the spark rod according to the present invention has a structure in which the spark rod body is supported by the holding portion and the spark rod holder is supported by the mounting member, (iV) the positioning is accurate and It has the effect of preventing damage by suppressing vibration of the part.

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment of a flame stabilizer according to the present invention. 10 flame stabilizer 11 cylindrical base 11A one end 11B other end 11a locking recess 11b cushioning member 11c, 11d adhesive layer 12 burning part 12a Combustion agent supply hole 13 ... Holder 13a ... Combustion gas supply hole 13b ... Holder hole 14 ... Insulating layer 20 ... Metal pipe 21 ... Metal pipe body 21A ... Open end 21B ... Base 21a ... Screw hole 22… Fixing screw 23… Combustion gas supply pipe 24… Mounting hole 30 … Spark rod 31… Spark rod body 32… Joint member 33… Spark rod holder 34… Insulating layer 35… Mounting member 36: Power supply terminal

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-56-1481 (JP, A) JP-A-63-282162 (JP, A) JP-A-1-215774 (JP, A) JP-A-1- 188470 (JP, A) Fully open 1987-131257 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01T 13/00-13/56 C04B 35/00 C04B 35/56 F23Q 3/00 102

Claims (1)

(57) [Claims] 1. A spark rod body made of a conductive ceramic material is detachably attached to a tip of a spark rod holder formed of a tough metal conductor, and is formed of a conductive ceramic material. For the radiant tube for generating spark discharge, the spark rod body is disposed so that the tip end thereof protrudes into the combustion space of the flame stabilizer connected to the open end of the bottomed cylindrical metal pipe. In the spark rod described above, a conductive ceramic material obtained by mixing 3 to 25% by weight of chromium silicide, 3 to 25% by weight of aluminum oxide, 0 to 6% by weight of carbon and the balance of silicon carbide is mixed with an inert gas. 1700-2100 under atmosphere
A spark rod body made by sintering at a temperature of ℃, and a plurality of combustion gas supply holes formed in a disk-shaped peripheral part made of conductive ceramics material and almost in the middle of a flame stabilizer The holding portion that holds the spark rod main body via the insulating layer in the center holding hole and the base end of the spark rod main body are connected to each other by insertion so that the conductive hole is electrically conductive. A joint member formed of a conductive metal and a distal end portion are detachably connected to the joint member by screwing, and a base end portion is attached to a central portion of the base of the metal pipe by an attaching member via an insulating layer. A spark rod comprising a spark rod holder.