JP2010052966A - Method for manufacturing ceramic pipe - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a ceramic pipe where a bent ceramic pipe is easily manufactured and airtightness is held. <P>SOLUTION: The method for manufacturing the ceramic pipe includes: a forming step to form formed bodies of an upper half part 1a, a lower half part 1b and a holding body 2 respectively; a calcining step to calcine the upper half part 1a ceramic formed body and the lower half part 1b ceramic formed body obtained from the forming step at a specified temperature respectively and to calcine the holding body 2 ceramic formed body at a lower temperature than the calcination temperature of the upper half part 1a ceramic formed body and the lower half part 1b ceramic formed body; an assembly step to hold a ceramic pipe calcined body where an upper half part 1a calcined body and a lower half part 1b calcined body obtained from the calcining step are united with a holding body 2 calcined body; and a baking step to bake the ceramic pipe calcined body from the assembly step at a higher temperature than the calcination temperature. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a ceramic tube, for example, a method for manufacturing a ceramic tube suitable for manufacturing a ceramic tube having a bent portion.

Conventionally, ceramic tubes have been used for thermocouple protection tubes as described in Patent Document 1, gas introduction tubes for introducing gas into a reaction furnace, etc., and linear ceramic tubes are generally used. It has been.
This linear ceramic tube can be manufactured by being fired after being formed into a predetermined dimension by a mold, and can be manufactured relatively easily.

  On the other hand, the bent ceramic tube can be manufactured by the method described in Example 2 of Patent Document 2, for example. That is, a molded body extruded into a pipe shape by a vacuum kneading extruder is loaded into an L-shaped blow mold, one end of the molded body is sealed, compressed air is sent from the other end to the molded body, Thus, the extruded product is expanded and blow molded into an L shape. And the obtained molded object is baked and an L-shaped gas introduction nozzle (tube) can be manufactured.

Further, when manufacturing a bent L-shaped ceramic tube, as shown in FIG. 6 (a), first, two linear ceramic tubes 30, 31 are connected to the side walls of the ceramic tubes 30, 31. Through-holes 30a and 31a are formed.
Then, as shown in FIG. 6B, the ceramic tube 31 is fitted into the through hole 30a of the ceramic tube 30, and the ceramic tube 30 and the ceramic tube 31 are connected to manufacture an L-shaped ceramic tube. .

In addition, as shown in FIG. 7, when manufacturing a bent U-shaped ceramic tube, the three linear ceramic tubes 32, 33, and 34 are formed in the same manner as the manufacturing method of the L-shaped ceramic tube. Are manufactured by fitting together.
In order to prevent leakage from the joined portion A joined with the ceramic tube or intrusion of outside air, an adhesive or a coating material is applied to the joined portion A to achieve airtightness.
JP-A-10-67582 JP-A-11-274149

As described above, in the manufacturing method shown in Patent Document 2, since blow molding is performed after extrusion molding, there is a technical problem that it takes time and effort to manufacture and cannot be manufactured easily and inexpensively. It was. Further, in the case of a more complicated shape than the L-shape, there is a technical problem that extrusion molding and blow molding cannot be performed and the manufacturing cannot be performed.
On the other hand, in the case of a manufacturing method for connecting linear ceramic tubes, there is a technical problem that a plurality of ceramic tubes must be connected, which takes time and effort to manufacture, and cannot be manufactured easily and inexpensively. In addition, since the composition of the adhesive or coating material is different from the composition of the ceramic tube, there is a technical problem that the adhesive or coating material is peeled off from the joint due to the difference in thermal expansion coefficient when heat is applied, and the airtightness cannot be maintained. there were.

  In view of the above circumstances, the inventors of the present invention connect a linear ceramic tube by extrusion molding and then blow-molded ceramic tube by blow molding, and apply an adhesive or coating material to the joint. As a result of radically changing the conventional manufacturing method and studying a method of forming a bent ceramic tube compact, the present invention has been completed.

  The present invention has been made to solve the above technical problem, and an object of the present invention is to provide a method of manufacturing a ceramic tube that can easily manufacture a bent ceramic tube and maintain airtightness.

  A method of manufacturing a ceramic tube according to the present invention, which has been made to solve the above-described problems, includes an upper half of a tube made of ceramic having a semicircular cross-section, which extends along the axis of the tube, and an axis of the tube. And a tube lower half part made of ceramics, which is formed in a semicircular shape in cross section and is combined with the upper half part of the pipe to form one cylindrical pipe. A method of manufacturing a ceramic tube, comprising: an upper half portion of a pipe that covers the outer periphery of an upper half portion and a lower half portion of the pipe; and a holding body made of ceramics that holds the lower half portion of the pipe, A forming process for forming a ceramic molded body of the half, a ceramic molded body of the lower half of the pipe, and a ceramic molded body of the holding body, and the upper half ceramic molded body and the lower half of the pipe obtained by the molding process Each ceramic molded body at a predetermined temperature Obtained by calcining and calcining the holding ceramic molded body at a temperature lower than the calcining temperature of the upper half ceramic molded body and the lower half ceramic molded body, and the preliminary calcining step. The obtained tube upper half calcined body and tube upper half calcined body are combined into a single tubular calcined body, and then the tubular calcined body is held by the holder calcined body, and the ceramic tube It includes an assembly process for assembling as a pre-fired body, and a firing process for firing the ceramic tube pre-fired body that has undergone the assembly process at a temperature higher than the pre-sintering temperature.

A ceramic tube according to the present invention includes an upper half of a tube made of a ceramic having a semicircular cross section extending along the axis of the tube, and a semicircular ceramic having a semicircular cross section extending along the axis of the tube. The lower half of the pipe is united and the combined upper half of the pipe and lower half of the pipe are held by a holding body to form one cylindrical pipe.
That is, since the upper half of the tube and the lower half of the tube are so-called halved, the ceramic molded body of the upper half of the tube and the ceramic molded body of the lower half of the tube can be easily manufactured.

And after carrying out temporary baking of this holding body ceramic molded body at a temperature lower than the temporary baking temperature of the said tube upper half ceramic molded body and the tube lower half ceramic molded body, the said tube upper half temporary fired body and tube The upper half calcined body is combined to form one tubular calcined body, and then the tubular calcined body is held by the holder calcined body and assembled as a ceramic tube calcined body.
By firing the assembled ceramic tube temporary fired body at a temperature higher than the temporary firing temperature, the holding body temporary fired body is smaller than the shrinkage amount of the tube upper half temporary fired body and the tube upper half temporary fired body. Therefore, the upper half of the tube and the lower half of the tube are firmly held by the holding body and formed as one ceramic tube.
In the case of such a manufacturing method, since the conventional joint portion is not formed, it is not necessary to apply an adhesive or a coating material, and airtightness is maintained.

  Here, in the method of manufacturing a ceramic tube in which a part of the upper half of the tube covers a part of the lower half of the tube, in the temporary firing step, the upper half ceramic molded body is It is desirable to perform temporary firing at a temperature lower than the temporary firing temperature of the lower half ceramic molded body.

  In the preliminary firing step, it is desirable that the upper half ceramic molded body is temporarily fired at 1000 ° C., the lower half ceramic molded body is 1200 ° C., and the holder ceramic molded body is temporarily fired at 900 ° C.

  Furthermore, it is desirable that the upper half of the tube, the lower half of the tube, and the holding body have the same composition. The holding body is preferably a ring body that covers the outer periphery of the combined upper half and lower half of the pipe and holds the upper half and lower half of the pipe.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the ceramic tube which can manufacture a bent ceramic tube easily and can maintain airtightness can be obtained.

  Next, an embodiment of a method for manufacturing a ceramic tube according to the present invention will be described with reference to FIGS. 1 is a plan view of a ceramic tube manufactured by the method for manufacturing a ceramic tube according to the present invention, and FIG. 2 is a cross-sectional view taken along the line II of FIG.

  This ceramic tube 1 has a semi-circular tube upper half 1a extending along the tube axis L, and extends along the tube axis L, and has a semicircular cross section. The tube upper half 1a is joined to cover the outer periphery of the tube lower half 1b forming one cylindrical ceramic tube 1 and the tube upper half 1a and tube lower half 1b. A ring body 2 that holds the upper half 1a and the lower half 1b of the pipe is provided.

A concave portion 1a2 is formed along the axis L of the tube on the inner side of the opposed surface 1a1 of the lower half 1b of the upper half 1a. On the other hand, a concave portion 1b2 is formed along the axis L of the tube on the outer side of the facing surface 1b1 of the upper half 1a of the tube lower half 1b.
And the outer side part of the opposing surface 1a1 of the upper pipe half 1a is fitted into the recess 1b2 of the lower pipe half 1b, and the inner part of the opposing face 1b1 of the lower pipe half 1b is the concave part of the upper pipe half 1a. It is configured to fit into 1a2 and be formed into an integrated tube.

In the method for manufacturing a ceramic tube according to the present invention, a molded body of the upper half 1a, a molded body of the lower half 1b, and a molded body of the ring body 2 are manufactured. The ring body molded body is temporarily fired at a temperature lower than the temporary firing temperature of the lower half molded body.
Then, the tube upper half calcined body and the tube upper half calcined body are combined to form one tubular calcined body, and the ring calcined body is inserted. Thereafter, the assembled ceramic tube is characterized in that it is fired at a temperature higher than the pre-baking temperature.

As described above, the upper half 1a and the lower half 1b of the pipe are extended along the axis L of the pipe and are formed in a semicircular cross section, so that the ceramic pipe 1 is bent. In addition, the molded body of the upper half 1a and the lower half 1b of the tube can be easily manufactured.
Further, since the molded body of the ring body 2 is temporarily fired at a temperature lower than the temporary firing temperature of the molded body of the upper half 1a and the molded body of the lower half 1b, the assembled ceramic tube 1 is When fired, the amount of shrinkage of the temporarily fired body of the ring body 2 becomes larger than the amount of shrinkage of the temporarily fired body of the upper half portion 1a and the temporarily fired body of the lower half portion 1b.
As a result, the upper half 1a and the lower half 1b of the tube are clamped by the ring body 2 and held as an integrated ceramic tube 1.

Here, as shown in FIG. 2, the outer side of the facing surface 1a1 of the upper half 1a of the tube is fitted into the recess 1b2 of the lower half 1b of the tube, and the inner side of the facing surface 1b1 of the lower half 1b of the tube is In the case where the ceramic tube 1 is formed by fitting into the concave portion 1a2 of the upper half 1a of the tube, the molded body of the upper half 1a is formed into the lower half 1b in the temporary firing step. It is necessary to calcine at a temperature lower than the calcining temperature of the body.
Thus, since the molded body of the upper half 1a of the tube is temporarily fired at a temperature lower than the temporary firing temperature of the molded body of the lower half 1b of the tube, when the assembled ceramic tube is fully fired, The shrinkage amount of the pre-fired body of the half portion 1a becomes larger than the shrinkage amount of the pre-fired body of the lower half portion 1b, and a ceramic tube in which both are firmly fitted can be formed.
The inner diameter of the outer side of the facing surface 1a1 of the upper half 1a of the tube and the outer diameter of the inner side of the facing surface 1b1 of the lower half 1b of the tube are the same as the dimensions of the calcined body, or the upper half 1a. It is preferable that the inner diameter of the outer surface of the facing surface 1a1 is slightly larger than the outer diameter of the inner portion of the facing surface 1b1 of the lower pipe half 1b.
By adopting such a dimensional shape, the outer side of the facing surface 1a1 of the upper half 1a of the tube tightens the inner side of the facing surface 1b1 of the lower half 1b of the tube by contraction of the upper half 1a.

The upper half 1a, the lower half 1b, and the ring body 2 can be manufactured by a general method of manufacturing a ceramic molded body.
For example, 100 parts by weight of an alumina raw material powder having an average particle size of 5 μm, 20 parts by weight of ion exchange water, a small amount of ammonium polyacrylate as a dispersant, and 1 part by weight of polyvinyl alcohol as a binder are mixed in a pot mill to prepare a slurry. To do.
The obtained slurry is granulated using a spray dryer, and the obtained granulated powder is CIP and is 2 ton / cm ² pressure, 9 mm in diameter, 6 mm in inner diameter, semi-cylindrical L shape with a predetermined length. The molded product of the upper half of the tube and the molded product of the lower half of the tube are manufactured.
Similarly, the obtained slurry is granulated using a spray dryer, and the obtained granulated powder is obtained using CIP at a pressure of 2 tons / cm ² with a diameter of 12 mm, an inner diameter of 9.3 mm, and a width of 2 mm. A molded body of a ring-shaped ring body is manufactured.

  Then, the molded body of the upper half of the tube, the molded body of the lower half of the tube, and the molded body of the ring body are fired to obtain a temporarily fired body. As shown in FIG. 2, the outer side of the facing surface 1a1 of the upper pipe half 1a is fitted into the recess 1b2 of the lower pipe half 1b, and the inner side of the facing face 1b1 of the lower pipe half 1b is the upper pipe half. When formed into an integrated tube fitted in the recess 1a2 of 1a, the molded body of the upper half 1a is fired at 1000 ° C. in the atmosphere, and the molded body of the lower half 1b is 1200 ° C. in the atmosphere. And the molded body of the ring body 1 is fired at 900 ° C. in the atmosphere to obtain respective temporary fired bodies.

Further, the pre-fired body of the upper half 1a, the pre-fired body of the lower half 1b, and the pre-fired body of the ring body 2 are assembled into a pre-fired body of one ceramic tube.
At this time, in order to improve accuracy, if necessary, the pre-fired body of the upper half 1a, the pre-fired body of the lower half 1b, and the pre-fired body of the ring body 2 are machined and assembled. May be.

Then, the temporarily fired body of the assembled ceramic tube is fired at 1800 ° C. in the atmosphere to obtain a fired body.
At this time, the temporary firing temperatures of the upper half 1a of the tube, the temporary firing body of the lower half 1b of the tube, and the temporary firing temperature of the ring body 2 are different. That is, the amount of shrinkage is the smallest for the temporarily fired body of the lower pipe half 1b and the largest for the temporarily fired body of the ring body 2.
As a result, a tightening force due to contraction acts between the upper half 1a and the lower half 1b of the tube, and between the ring body 2, the upper half 1a and the lower half 1b of the tube, and the integrated ceramics. Formed as tube 1.

As described above, since the ceramic tube 1 has a so-called half-divided shape, it is possible to easily obtain the molded body of the upper half of the tube and the molded body of the lower half of the tube.
Further, when the molded body is pre-fired and then main-fired, the shrinkage amount of the holding body pre-fired body is larger than the shrinkage amount of the upper half-fired body and the upper half-fired body of the tube, The upper half and the lower half of the tube are firmly held by a holding body, and are formed as a single ceramic tube.
In the method of manufacturing a ceramic tube in which a part of the upper half of the tube covers a part of the lower half of the tube, in the temporary firing step, the upper half ceramic molded body is Temporary baking is performed at a temperature lower than the temporary baking temperature of the half ceramic molded body.
In the case of such a manufacturing method, even a bent ceramic tube does not have a conventional joint, so there is no need to apply an adhesive or coating material, and airtightness is reliably maintained. It is possible to prevent leakage and intrusion of outside air.

Next, the modification concerning this invention is demonstrated based on FIG. 3, FIG. 3 and 4 are diagrams corresponding to FIG.
In the modification shown in FIG. 3, the ring body 2 as the holding body shown in FIG. 2 is formed so as to cover the entire outer periphery of the upper half 1a and the lower half 1b of the pipe. 2 is formed in a circular arc shape in cross section. Thus, even when the holding body 2 is formed in an arc shape in cross section, it is formed so as to cover at least the fitted portion of the upper half 1a and the lower half 1b of the tube. preferable.

In the modification shown in FIG. 4, in the case where the holding body 2 is formed in a circular arc shape, the protrusion 1 a 3 extending along the axis L is opposed to the outer peripheral surface of the upper half 1 a of the pipe. Is formed. On the other hand, a concave portion 4a is formed on the holding body 4 so as to face each other, and the projection 1a3 is fitted.
Thus, even the ceramic tube having the structure shown in FIGS. 3 and 4 can obtain the same effects as those of the ceramic tube shown in FIGS.

According to the manufacturing method of the present invention, since a bent ceramic tube can be manufactured, as shown in FIG. 5, the thermocouple protection tube 11 of the thermocouple device 10 is integrally formed in an L shape. Can do. In the figure, reference numeral 12 denotes a ring body 12 for the thermocouple protection tube 11.
This thermocouple device 10 produced a pre-fired body of the upper half of the tube, a lower half of the tube, and a pre-fired body of the ring body, and when assembling the pre-fired body of these members, an alumina insulator was provided inside the tube. It can be manufactured by installing a thermocouple and then sintering at a predetermined temperature.
Therefore, in the case of this manufacturing method, the thermocouple can be installed inside the so-called half-divided upper half of the tube and the lower half of the tube (thermocouple protection tube 11), and the installation work can be easily performed. it can.

In the above embodiment, alumina has been described as an example of ceramics. However, the present invention is not limited to this, and other types of ceramics may be used.
Moreover, the structure of the fitting part of the pipe upper half 1a and the pipe lower half 1b is not limited to the structure shown in FIG. In particular, in order to reliably leak and prevent outside air from entering, it is desirable to machine the surface accuracy of the fitting portion to the degree of composition.
Furthermore, the upper half of the tube, the lower half of the tube, and the holding body (ring body) are preferably formed with the same composition. When these members are formed with the same composition, the amount of shrinkage can be easily calculated, and the tightening force between the members can be easily set to an appropriate force.

It was confirmed by the following experiments 1 and 2 that the present invention has a predetermined effect.
(Experimental example 1)
A slurry is prepared by mixing 100 parts by weight of an alumina raw material powder having an average particle size of 3 μm, 25 parts by weight of ion exchange water, a small amount of ammonium polyacrylate as a dispersant, and 1 part by weight of polyvinyl alcohol as a binder in a pot mill.
The obtained slurry is granulated using a spray dryer, and the obtained granulated powder is formed into a molded body of the upper half of the U-shaped pipe and the lower half of the pipe as shown in FIG. 7 by a slip casting method. Was made.
Then, the upper half of the pipe and the lower half of the pipe are temporarily fired at 1000 ° C. and 1200 ° C., and the upper half of the U-shaped pipe and the lower half of the pipe (so-called half-pipe as shown in FIG. 7). Split pipe: a pre-fired body having a straight body portion of 200 mm, a tip portion of 100 mm, an outer diameter of 20 mm, an inner diameter of 14 mm, a wall thickness of 3 mm, and a concave portion width of 1.5 mm).
Similarly, a ring-shaped ring body molded body shown in FIG. 2 was manufactured using the same slurry.

Then, the molded body of the ring body was temporarily fired at 900 degrees to obtain a temporary fired body of a ring-shaped ring body (outer diameter 15 mm, inner diameter 11 mm, wall thickness 2 mm, width 2 mm) as shown in FIG. Thereafter, the pre-fired bodies of the upper half of the tube and the lower half of the pipe were combined, and further, the pre-fired bodies of the ring bodies were set at intervals of 40 mm.
Further, a sealing alumina tube for closing one end of the U-shaped tube was set and sintered in a furnace at 1700 degrees to obtain an integral structure.
Evacuation set resulting sintered body in a vacuum furnace was subjected to leakage check, give ultimate vacuum 1.2 Pa, the leakage amount 4 × 10 ^-9 to ^{[Pa · m 3 / sec]} .

  As described above, in the case of the manufacturing method according to the present invention, even a ceramic tube bent in a U-shape does not have a joint portion as in the conventional case, so it is necessary to apply an adhesive or a coating material. It was confirmed that the airtightness was reliably maintained.

(Experimental example 2)
Using the same materials as in Experimental Example 1, a pre-fired body of the upper half of the tube, a lower half of the tube, and a pre-fired body of the ring body were manufactured. And when assembling the temporary calcination body of these members, the thermocouple provided with the alumina insulator inside the pipe was installed.
Thereafter, similarly to Experimental Example 1, sintering was performed at 1700 degrees to obtain an integral structure.
When the leak check of this ceramic tube was performed, the ultimate vacuum was 1.4 Pa, the leak amount was 4.0 × 10 ⁻⁹ [Pa · m ³ / sec], and there was no problem with the operation of the thermocouple. It was confirmed.

FIG. 1 is a schematic configuration diagram showing an example of a ceramic tube manufactured by the method for manufacturing a ceramic tube according to the present invention. FIG. 2 is a cross-sectional view taken along the line II of the ceramic tube shown in FIG. FIG. 3 is a view corresponding to FIG. 2 and showing a modified example of the holding body. FIG. 4 is a view corresponding to FIG. 2 and showing another modified example of the holding body. FIG. 5 is a view showing a thermocouple device using a ceramic tube manufactured according to the present invention as a protective tube. FIG. 6 is a side view showing a conventional method for manufacturing an L-shaped ceramic tube. FIG. 7 is a side view showing a conventional bent U-shaped ceramic tube.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ceramics tube 1a Upper half part 1b Lower half part 2 Ring body (holding body)
3 Holding Body 4 Holding Body 10 Thermocouple Device L Ceramic Tube Axis

Claims (5)

An upper half of the tube made of ceramic with a semicircular cross section, extending along the axis of the tube;
A tube lower half made of ceramics, which extends along the axis of the tube, has a semicircular cross section, and merges with the tube upper half to form one cylindrical tube;
A method of manufacturing a ceramic tube comprising an outer periphery of the combined upper half and lower half of the tube, and a holding body made of ceramic that holds the combined upper half and lower half of the tube ,
Forming step of forming each of the ceramic molded body of the upper half of the tube, the ceramic molded body of the lower half of the tube, and the ceramic molded body of the holding body;
Each of the upper half ceramic molded body and the lower half ceramic molded body obtained by the molding step is temporarily fired at a predetermined temperature, and the upper half ceramic molded body and the lower half ceramic molded body are formed. A preliminary firing step of temporarily firing the holding ceramic molded body at a temperature lower than the preliminary firing temperature of
The tube upper half calcined body and the tube upper half calcined body obtained by the calcining step are combined to form one tubular calcined body, and then the tubular calcined body is used as the holder calcined body. An assembly process for holding assembling as a ceramic tube temporary fired body,
And a firing step of firing the ceramic tube temporary fired body that has undergone the assembly step at a temperature higher than the temporary firing temperature. In the method of manufacturing a ceramic tube in which a part of the upper half of the tube covers a part of the lower half of the tube,
2. The ceramic tube production according to claim 1, wherein in the pre-baking step, the upper half ceramic molded body is pre-fired at a temperature lower than the pre-baking temperature of the lower half ceramic molded body. Method.   In the temporary firing step, the upper half ceramic molded body is preliminarily fired at 1000 ° C, the lower half ceramic molded body is 1200 ° C, and the holder ceramic molded body is 900 ° C. 2. A method for producing a ceramic tube as described in 2.   The method for manufacturing a ceramic tube according to any one of claims 1 to 3, wherein the upper half portion, the lower half portion, and the holding body have the same composition.   The said holding body is a ring body that covers the outer periphery of the combined pipe upper half and lower pipe half and holds the upper pipe half and the lower pipe half. A method for manufacturing ceramic tubes.

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