JP2000072559A - Ceramic joint structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reliable ceramic bonding structure in which a bonding layer in which a bonding composition is solidified has a low expansion property and a sufficient bonding strength can be maintained even when a use temperature exceeds 600 ° C. I do. SOLUTION: The inside of a cylindrical joint 3 is threaded, and the fitting is performed while turning a filter tube 1 or a filter tube 2 threaded outward. For this reason, the position of the tubular joint 3 does not shift from the joint of the two filter tubes. When the thread is cut and fitted, the gap between the screws can be reduced. The gap is filled with a cordierite ceramics bonding composition with a thickness of 0.5 mm or less and solidified.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic bonding structure, and more particularly, to a bonding layer in which a bonding composition is solidified has a low expansion property, and is capable of maintaining sufficient bonding strength even when a use temperature exceeds 600.degree. The present invention relates to a ceramic bonding structure having a characteristic.

[0002]

2. Description of the Related Art A filter tube made of cordierite ceramics having a low thermal expansion, which has a porosity of 30% or more and has practical strength even at a high temperature of 600 ° C. or more, has been proposed as a filter for removing high-temperature dust-containing gas. (Japanese Unexamined Patent Publication
-68411).

Further, a method for producing a low expansion cordierite aggregate used as a main raw material of a cordierite ceramics filter tube has been proposed (Japanese Patent Laid-Open No. 6-151).
281). The average thermal expansion coefficient of the cordierite aggregate at room temperature and 1000 ° C. by this production method is 22 to 26 × 10 ⁻⁷ / ° C. for the ordinary cordierite aggregate, and the cordierite crystal grain size is 50 μm or more. 10 × 1
There is a feature that the temperature can be ^{reduced to} 0 ⁻⁷ / ° C. or less.

Here, the length of a cordierite filter tube manufactured by the method described in Japanese Patent Application Laid-Open No. 3-68411 is limited due to manufacturing restrictions. The filter tube is difficult to manufacture because it is deformed by its own weight during firing. However, considering the economics of a dust collector for removing high-temperature dust-containing gas, it is advantageous to use a long filter tube, and to use a short filter tube (for example, 710).
mm) filter tubes (for example, three) are used.

[0005] In this case, in order to ensure the reliability of the filter tube, the joint portion of the filter tube also needs to have sufficient joint strength and reliability. That is, it is caused by residual stress generated during firing and cooling, mechanical shock applied when the filter tube is attached to the dust removal device, thermal shock and thermal stress caused by temperature rise and fall of high temperature dust-containing gas to be removed, vibration generated during use, and the like. It is necessary that the joint is not damaged by stress or the like.

In this regard, Japanese Patent Application Laid-Open No. 7-138081 proposes a low thermal expansion ceramic bonding composition and a bonding method which stably exhibit high bonding strength. The object to be bonded at this time was a cordierite filter tube manufactured by the method described in JP-A-3-68411. The filter tube had an average thermal expansion coefficient between room temperature and 1000 ° C of 1.
8 × 10 ⁻⁷ / ° C. or less.
The thermal expansion coefficient is almost the same as that of the bonding composition shown in (1), and the bonded portion has been used stably without the residual strain generated during firing and cooling and the thermal stress generated during high temperature use.

In order to improve the reliability of this filter tube, cordierite aggregate, which is a main raw material, is prepared by using Japanese Patent Publication No. Sho 57-2.
The average thermal expansion coefficient at room temperature and 1000 ° C. shown in FIG.
From cordierite aggregate of 8 × 10 ^-7 / ° C.
The filter tube was replaced with a low-expansion cordierite aggregate having an average coefficient of thermal expansion at room temperature and at 1000 ° C. of 10 × 10 ⁻⁷ / ° C. or lower as shown in −151281 to improve the reliability of the filter tube.

By replacing cordierite aggregate with low expansion, the average thermal expansion coefficient between room temperature and 1000 ° C. of the filter tube is from 18 × 10 ⁻⁷ / ° C. to 12 × 10 ⁻⁷ / °.
When the temperature fell below ℃, the thermal shock or thermal stress generated in the filter tube was reduced, and the reliability of the filter tube could be improved.

Similarly, for the tubular joint, by replacing cordierite aggregate with low-expandable cordierite aggregate, the average thermal expansion coefficient between room temperature and 1000 ° C. of the filter tube is 18 × 10 ^−7. / ° C to 12 × 10
^As a result, the thermal shock or thermal stress generated was reduced, and the reliability was improved.

[0010]

By the way, when a low-expansion filter tube is joined with an adhesive shown in the conventional Japanese Patent Application Laid-Open No. 7-138081, a difference in thermal expansion occurs between the joining layer and the filter, and the cooling of the sintering of the joining portion. In the process, tensile stress is generated in the bonding layer having a large thermal expansion coefficient, and residual stress is generated.

Also, the joined filter tube is 900
When used for a long time at a high temperature of about ℃, the thickness of the bonding layer becomes 4
mm or more, the bonding layer changes with time, and further generates stress. Further, if the stress value exceeds the strength value of the joint, cracks may occur in the joint, and eventually there is a risk that the joint may be damaged from the joint to the tube.

The present invention has been made in view of such a conventional problem, and a bonding layer in which a bonding composition is solidified has a low expansion property, and has a sufficient bonding strength even when a use temperature exceeds 600 ° C. It is an object of the present invention to provide a reliable ceramic bonding structure that can be maintained.

[0013]

SUMMARY OF THE INVENTION Therefore, the present invention (Claim 1) provides a first device made of cordierite ceramics.
A first filter tube having at least a lower portion threaded, a second filter tube having at least an upper portion threaded, and a ceramic joining structure in which the filter tube and the second filter tube are joined in series. A cylindrical joint made of cordierite ceramics having female threads from both ends so as to be screwed with both male screws was provided.

The first and second filter tubes are filter tubes containing low-expansion cordierite having a particle diameter of 0.1 mm or more crystallized from glass. And, since it contains 50% or more of low-expansion cordierite aggregate disclosed in Japanese Patent Application Laid-Open No. 6-151281, it is an excellent filter tube with low expansion and high strength. For this reason, there is sufficient strength to perform thread cutting on the outside of the filter tube.

The cylindrical joint attached to the joint between the first filter tube and the second filter tube also prevents the generation of cracks due to a difference in thermal expansion between the filter tube and the first joint.
Japanese Patent Laid-Open Publication No.
51281 low expandable cordierite aggregate
Those used at 0% by weight or more are used.

The inside of the tubular joint is threaded, and the first filter tube or the second filter threaded outside is threaded.
Is fitted while rotating the filter tube, so that the position of the tubular joint does not deviate from the joint of the two filter tubes.
When threading and fitting are performed in this manner, the gap between the filter pipe and the tubular joint can be reduced.

Further, according to the present invention (claim 2), the first filter pipe and / or the second filter pipe and the tubular joint are formed with a tapered screw having a taper angle of 1/3 to 1/24. It is characterized by doing.

The screw where pressure is applied and where sealing is required is preferably tapered. When the thread having the tapered thread is fitted, the rotation stops when the diameters of the external thread and the internal thread coincide with each other, and at this point, there is no gap between the external thread and the internal thread, so that the sealing property is improved. If the taper is too small, it is necessary to increase the length of the threaded portion in order to provide sealing properties. If the taper is too large, the thickness of the filter tube at the distal end becomes thin, so the taper angle is reduced to 1/3. Up to 1/24, even 1/1
2 to 1/18 is preferred.

Further, according to the present invention (claim 3), the male screw has a pitch of 0.5 to 10 mm, a hook height of 1 to 6 mm, and a length of the screw portion of 20 to 70 mm. .

The shape of the screw that affects the degree of engagement (degree of engagement) between the male screw provided on the first filter pipe and the second filter pipe and the female screw provided on the cylindrical joint is mainly a screw. Pitch, thread height, and thread length. When the pitch is smaller than 0.5 mm, the aggregate particles of both filter tubes or tubular joints are reduced to 0.
Since it is about 5 mm, there is a possibility that a part of the aggregate particles may be scraped off at the time of processing, and the processing accuracy is not improved. Further, when the pitch is 10 mm or more, it is necessary to increase the length of the screw portion in order to increase the degree of engagement (the degree of engagement) between the male screw and the female screw. Therefore, the pitch of the screws is preferably 0.5 to 10 mm, more preferably 3 to 7 mm.

On the other hand, if the height of the snag is smaller than 1 mm, the degree of snag becomes small and sufficient bonding strength cannot be obtained. Further, since the thickness of the filter tube is about 14 mm, it is preferable that the catch height is smaller than about 6 mm which is about half the thickness. Therefore, the hook height is preferably 1 to 6 mm, more preferably 2 to 4 mm. Further, when the length of the screw portion is 20 mm or less, the degree of engagement is not sufficient, and when the length is 70 mm or more, the length of the tubular joint becomes longer by that much.

Further, the present invention (claim 4) provides a method for bonding cordierite ceramics between the first filter tube and the tubular joint and between the second filter tube and the tubular joint. It is characterized by being filled with a thickness of 0.5 mm or less and solidified.

In the conventional joining method, the thickness of the joining layer is 4 m
m, which is greatly affected by the change with time due to the use time of the bonding layer. On the other hand, when the threaded filter pipe and the tubular joint are joined, the clearance between the filter pipe and the tubular joint is 0.5 mm at the maximum, and the influence of the temporal change during use of the joining layer is reduced. If the thickness of the bonding layer is larger than 0.5 mm, there is a possibility that the influence of a change with time due to the use time of the bonding layer, and a stress due to a difference in thermal expansion between the tubular joint and the bonding layer or between the filter tube and the bonding layer may occur.

Since the gap between the screws is small, when an adhesive is used, the strength required for the adhesive is sufficient if the adhesive is strong enough to prevent the screws from rotating. Therefore, in extreme cases, the joining composition is not used in the gap between the thread of the filter tube and the tubular joint, and the joining is performed at the step at the boundary between the filter tube and the tubular joint in order to prevent rotation of the screw. The composition for use may be merely added.

Further, since the amount of thermal expansion of the entire bonding layer is reduced by reducing the thickness of the bonding layer, thermal stress generated between the bonding layer and the member to be bonded is also reduced, and cracks in the bonding layer and its surroundings are reduced. Can be avoided. In addition, the construction is easy and the joining process is simplified.

Furthermore, the present invention (claim 5) provides that the cordierite ceramics bonding composition has a particle size of 10 to 1
50 μm cordierite aggregate at least 25 parts by weight, silica powder having a particle size of 0.1 μm to 1 μm 6 to 17 parts by weight, and powder having a particle size of less than 75 μm and mostly cordierite particles Characterized in that the silica sol is mixed with 4 to 10 parts by weight in terms of silica component with respect to 100 parts by weight of the mixture consisting of

In order to inject the bonding composition into the clearance of 0.5 mm or less, it is preferable that the particle size of the aggregate of the bonding composition is small. However, if the aggregate becomes too fine, cracks will be formed in the bonding layer during drying or firing.

When cordierite aggregate having a particle size of 10 to 150 μm is contained in the mixture in an amount of 25 parts by weight or more, shrinkage and heat shrinkage due to drying and solidification of the bonding layer are reduced, and cracks are generated in the bonding layer. Can be suppressed. As the above-mentioned aggregate, it is preferable to use a mixture obtained by melting and vitrifying a mixture containing a cordierite composition and then crystallizing the cordierite. Further, by adding cordierite aggregate having fine particles of less than 75 μm, a joined body having high strength can be obtained.

The bonding composition of the present invention includes JP-A-57-
It is preferable to use cordierite aggregate proposed in 20269 or JP-A-6-151281.
The cordierite aggregate disclosed in JP-A-57-20269 has no particle size dependence, and the average coefficient of thermal expansion between room temperature and 1000 ° C. is 18 × regardless of the particle size of the cordierite aggregate used. 10 to -7 ^/ in the range of ° C., the particle size of the Japanese average thermal expansion coefficient of the proposed cordierite aggregate in No. 6-151281 has a particle size-dependent aggregate 50μ
m or more, the average thermal expansion coefficient can be reduced to 10 × 10 ⁻⁷ / ° C. or less, and further to 300 μm or more, it can be reduced to 6 × 10 ⁻⁷ / ° C. That is, when the crystal grain size of the aggregate increases,
Fine cracks are generated in the crystal grain boundaries or in the grains, and the cracks absorb the thermal expansion, so that the coefficient of thermal expansion can be reduced.

However, when this aggregate is used as an aggregate in the bonding composition, the silica sol in the bonding composition blocks the crack and reacts, so that the effect of low expansion cannot be exhibited. Therefore, it is desirable that the particle diameter of all cordierite aggregates used in the joining composition be 150 μm or less.

The particle size of the silica powder to be added is 0.1.
By setting the thickness to 1 μm to 10 μm, appropriate fluidity and plasticity are imparted to the joining composition at the time of construction, and the joining composition easily enters the gaps between the screws, thereby facilitating the joining operation. Further, the addition of the silica powder allows the bonding composition to be well blended with the surface of the object to be bonded, and allows the bonding composition to easily enter even small dents on the surface of the object to be bonded, thereby obtaining high bonding strength. The silica powder is preferably fumed silica. The fumed silica particles are fine and spherical, and can impart properties such as fluidity to the bonding composition.

The reason why the weight of the silica powder is 6 to 17 parts by weight is that if it is less than 6, the fluidity and dispersibility become insufficient.
If the number is more than 17, the workability of the joining operation is deteriorated. Further, when the fine powder of silica is increased, the amount of shrinkage due to drying or firing increases, and cracks are easily generated in the bonding layer.

It should be noted that the reason why the silica sol is added in an amount of 4 to 10 parts by weight in terms of a silica component with respect to 100 parts by weight of the mixture in the composition is that if it is less than 4 parts by weight, the bonding strength becomes insufficient and When the amount is more than the weight part, a large amount of moisture causes a crack in the bonding layer at the time of drying.

Further, the present invention (Claim 6) provides a method for applying or impregnating an organic binder to a threaded surface of the first filter tube, the second filter tube, and / or the cylindrical joint in advance, and then joining the ceramic binder. The first filter tube, the second filter tube, and the tubular joint are joined by a composition for use.

Assume that a cordierite filter tube used for dust removal of high-temperature gas such as a combustion gas of a pressurized fluidized-bed boiler or a synthesis gas of a coal gasifier is joined.
The average thermal expansion coefficient between room temperature and 1000 ° C. is preferably 12 × 10 ⁻⁷ / ° C. or less because the filter tube is subjected to repeated thermal stress. The use of cordierite aggregate as the main raw material of the filter tube as proposed in JP-A-6-151281 is possible.

However, since the filter tube using the above-mentioned aggregate has a porosity of 30% or more, the water absorption is high. Therefore, the liquid component in the bonding composition for bonding the filter easily permeates. The above-mentioned aggregate has a crystal grain size of 50 μm or more, and a fine crack is generated in a crystal grain boundary or a crystal grain,
Since these absorb thermal expansion, the thermal expansion coefficient is small.

When the silica sol penetrates these grain boundaries,
Because of the reaction, the portion of the filter tube impregnated with silica sol, which is a liquid component in the bonding composition, has an increased thermal expansion coefficient. For this reason, it is preferable to apply an organic binder to the filter tube in advance at the time of construction and to suppress the permeation of the silica sol before joining. The organic binder is preferably an aqueous solution of polyvinyl alcohol.

When the organic binder is impregnated in advance into the threaded surface as the part to be joined, the silica sol in the joining composition does not permeate into the part to be joined, and the performance of the filter tube as the part to be joined is threatened. It can be joined without any. In addition, since the organic binder burns and disappears during firing, the conditions for infiltration are not so severe.

[0039]

Embodiments of the present invention will be described below. FIG. 1 shows an overall configuration diagram of an embodiment of the present invention. In FIG. 1, the lower part of the filter tube 1 is provided with a male screw. The same male screw is also provided on the upper part of the filter tube 2. The cylindrical joint 3 is internally threaded so as to be screwed with these male threads. The cut length l of the female screw is the length of the screw portion. Then, the filter pipe 1 and the filter pipe 2 are connected by the tubular joint 3. FIG. 2 shows a partially enlarged view of the threaded portion of the male screw and the female screw. In the figure, a is the height of the hook, and b is the pitch.

Next, the operation will be described. The filter tube 1, the filter tube 2, and the tubular joint 3 are sintered bodies containing cordierite aggregate crystallized from cordierite glass and having a particle size of 0.1 mm or more and 60% by weight or more. The average coefficient of thermal expansion between room temperature and 1000 ° C. is 12 × 10
⁻⁷ / ° C. or less, average room temperature strength is 150 kg / cm ² or more. The dimensions of the filter tube are outer diameter 170mm, inner diameter 1
It is 40 mm long and 710 mm long. The dimensions of the cylindrical joint 3 are 190 mm in outer diameter and 170 mm in inner diameter, and the room temperature strength is 150 kg / cm ² or more.

FIG. 3 shows a method for threading the filter tubes 1 and 2. Although a screw-threading machine is not shown, the screw-threading of the filter tubes 1 and 2 was performed using a diamond wheel whetstone 4 with a shaft which was a lathe modified for ceramics processing. The outer diameter of the shaft of the rotary grindstone 4 is 6 mm. As a cutting tool, a diamond rotating grindstone 4 that rotates at a constant speed is installed outside the filter tube 1, and the diamond rotating grindstone 4 is fed in the axial direction of the filter tube 1 in synchronization with the rotation speed of the filter tube 1. Was given.
FIG. 4 shows the outer shape of the diamond rotary grindstone 4. The outer diameter of the diamond wheel 4 used is 40 mm and the thickness is 5 m
m.

Similarly, as shown in FIG. 5, the screwing of the cylindrical joint 3 was also performed by installing a diamond rotating grindstone 4 which rotates at a constant speed as a cutting tool inside the cylindrical joint 3. In the screw shape, the pitch b is 7 mm, the hook height a is 4 mm, and the length 1 of the screw portion is 40 mm.

Next, the effect of the thread shape applied to the filter tube on the strength of the ceramic joined body will be described.
As shown in Table 1, the filter tube is subjected to various shapes of thread cutting. And cut this filter tube into strip shape,
The screw-shaped surface was bent at three points so that tensile stress was applied, and the bending strength was measured. Table 1 shows the results.

[0044]

[Table 1]

From Table 1, it can be seen that the higher the thread caught height a, the thinner the filter tube thickness and the lower the three-point bending strength. In particular, when the hook height a exceeded 6 mm, the strength was low. Also, the larger the pitch b, the higher the bending strength tends to be.

Next, the gap between the filter pipe 1 or the filter pipe 2 and the tubular joint 3 was filled with the bonding composition of Example 12 shown in Table 5 and bonded, and the bonding strength after firing was measured. Table 2 shows the results.

[0047]

[Table 2]

Each joint was cut to a length of 260 mm, and the tubes at both ends of the joint were pulled to measure the tensile strength of the joint (see FIG. 6). In addition, the joint is cut to a length of 700 mm, both ends are fixed, a belt is placed 200 mm from the fixed both ends, a weight is placed under the belt, and the joint is broken in the manner of four-point bending. A test was performed (see FIG. 7).

When the pitch b was smaller than 0.5 mm, the degree of catching was small, and the pulling strength was weak. Also, because the thread processing was not finished precisely,
The fitting did not work. When the pitch b increases,
In order to increase the degree of engagement, the height of the engagement a
From the results in Table 2, when the catch height a is larger than 6 mm, the thickness of the filter tube is reduced and the strength is reduced, so that the pitch b is 12 mm.
In this case, the hook height a was 6 mm.

Next, the bonding composition will be described. The bonding composition is obtained by melting and vitrifying a mixture having a cordierite composition, and then, cordierite aggregate having a particle size of 10 to 150 μm crystallized into cordierite, and a particle size of 0.1 mm to 1 μm. Silica powder and particle size 75μ
Powders of less than m and mostly cordierite particles and silica sol were prepared according to the formulations in Tables 3-5. Mixing was performed with a universal mixer for 3 minutes.

[0051]

[Table 3]

[0052]

[Table 4]

[0053]

[Table 5]

First, the threaded filter tube 1 is impregnated with a 10% aqueous solution of polyvinyl alcohol. Then, the joining composition is applied to the place, and the threaded tubular joint 3 is inserted while rotating until it stops. Then
By inserting the filter tube 2 into the tubular joint 3 in the same procedure, a ceramic joined body is obtained.

The thus-obtained ceramic joined body was allowed to stand in a room for 24 hours and then solidified in an electric furnace at a heating rate of 100 ° C./hour for 24 hours at 1000 ° C. The joining layer of the joined body of the obtained filter tubes and the periphery thereof were observed to confirm the presence or absence of cracks. In addition to the presence or absence of this crack, the evaluation
The bonding strength and the strength of the bonding composition alone were also determined (Tables 3 to 5).

FIG. 8 is a cross-sectional view when the bonding strength between the tube and the adhesive is measured using the bonding composition. Regarding the bonding strength, the prepared bonding composition was sandwiched between two test pieces made of a filter material of 25 × 40 × 10 mm, pressed until the thickness became approximately 1 mm, and after removing the excess bonding composition, 1000 parts were removed. The sample was baked at 24 ° C. for 24 hours and cut into strips as shown in FIG.

The strength of the bonding composition alone was 4
Pour the bonding composition prepared in a mold of 0 × 150 × 15 mm, air-dry for 2 days and night, and remove from the mold at 1000 ° C.
3 hours at room temperature for the sintered body that was heat treated for 24 hours.
The point bending strength was measured. The results are shown in Tables 3-5.

Table 3 shows the effect of changing the particle size of cordierite aggregate. Table 4 shows the effect of changing the amount of silica powder added. Table 5 shows the effect of changing the amount of silica sol added. In addition, Table 6 shows the effect of different treatment methods applied to the characteristics of the filter tube in order to prevent the liquid of the ceramic bonding composition from penetrating into the filter tube during bonding.

[0059]

[Table 6]

In Table 6, when the filter tube was joined without any treatment, the average thermal expansion coefficient of the filter tube was 12 because silica sol in the joining composition permeated the filter tube.
The temperature rises from × 10 ⁻⁷ / ° C. or less to 15 × 10 ⁻⁷ / ° C.
On the other hand, if the impregnation treatment is performed in advance with the PVA aqueous solution, the silica sol in the bonding composition does not penetrate into the filter tube, so that the bonding can be performed without changing the thermal expansion coefficient.

[0061]

As described above, according to the present invention, when low thermal expansion ceramics are joined by threading joining, a highly reliable ceramic joined body can be obtained without cracks or the like occurring at the joints. In addition, since the filter tubes can be connected in series, it is easy to increase the length of the filter tube, and it is possible to provide a junction filter tube having a large practical value that can be used for high-temperature dust removal.

Further, the joined cordierite ceramics filter tube is attracting attention as a next-generation coal energy utilization technology, such as a dust removing device for removing dust in a synthesis gas of a coal gasifier and a pressurized fluidizer. It is suitable for a dust removal device that removes dust in the combustion gas sent to the gas turbine of a power plant using a floor combustion boiler. The value is enormous.

[0063]

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of an embodiment of the present invention.

FIG. 2 is a partially enlarged view of a threaded portion of a male screw and a female screw.

FIG. 3 is a diagram showing a method of threading a filter tube.

Fig. 4 Outline of diamond wheel

FIG. 5 is a view showing a method of threading a cylindrical joint;

FIG. 6 is a diagram showing a method for measuring the tensile strength of a joint.

FIG. 7 is a diagram showing a fracture test method of a joint portion;

FIG. 8 is a diagram showing a method for measuring the bonding strength between a tube and an adhesive.

FIG. 9 is a diagram showing a three-point bending measurement of a sample cut into a strip shape.

[Explanation of symbols]

 1, 2 filter tube 3 tubular joint 4 diamond rotating whetstone a hook height b pitch l screw length

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Shotaro Okumiya 1150 Hazawa-cho, Kanagawa-ku, Yokohama-shi, Kanagawa Prefecture F-term within Asahi Glass Co., Ltd. 4D019 AA01 BA05 BA07 BB06 CA03 CB06 CB10 4D058 JA02 JB06 KA03 KA11 KA12 KA23 KB15 SA20 4G026 AA02 AB02 AC01 AD05 AE02 AF01 AG16

Claims (6)

[Claims] 1. A ceramic joining structure in which a first filter tube and a second filter tube made of cordierite ceramics are joined in series, the first filter tube having at least a lower portion threaded, and A ceramic joining structure, comprising: a second filter tube having an externally threaded upper portion; and a cylindrical joint made of cordierite ceramics, which is internally threaded from both ends so as to be screwed with the both external threads. 2. The taper angle of the first filter tube and / or the second filter tube and the cylindrical joint is 1/3 to 1/3.
2. The ceramic bonding structure according to claim 1, wherein the ceramic bonding screw is a 1/24 tapered screw. 3. The male screw has a pitch of 0.5-1.
0mm, hook height 1-6mm, screw length 2
The ceramic bonding structure according to claim 1 or 2, wherein the thickness is from 0 to 70 mm. 4. A cordierite ceramic bonding composition having a thickness of 0.5 mm or less is filled between the first filter tube and the tubular joint and between the second filter tube and the tubular joint. The ceramic joint structure according to claim 1, 2 or 3, wherein the ceramic joint structure is solidified. 5. The cordierite ceramics bonding composition according to claim 1, wherein the cordierite aggregate has a particle size of 10 to 150 μm, at least 25 parts by weight, and a silica powder having a particle size of 0.1 to 1 μm, 6 to 17 parts by weight. Wherein the silica sol is converted to a silica component in an amount of 4 to 10 parts by weight, based on 100 parts by weight of a mixture comprising a powder having a particle size of less than 75 μm and mostly cordierite particles. Item 6. A ceramic bonding structure according to Item 4. 6. An organic binder is applied or impregnated in advance to the threaded surface of the first filter tube, the second filter tube and / or the cylindrical joint, and then the first filter is formed by the ceramic bonding composition. The tube, the second filter tube, and the tubular joint are joined to each other.
Or the ceramic joining structure according to claim 5.