JPH04270178A - Production of long ceramic pipe - Google Patents

Abstract

PURPOSE:To easily produce a long ceramic pipe in high accuracy. CONSTITUTION:A plurality of short tubular members 11 consisting of sintered ceramic pipes produced by conventional forming process are joined together using a ceramic adhesive. In the above process, an aligning rod 12 for joint part is inserted into the tubular members at a position including the joint 13 of the tubular members and the joint part is bonded with the above ceramic adhesive by heat-treating at least at the joint part while pressing the tubular members with each other. A long ceramic pipe having high accuracy can be produced by using short tubular members having high shape stability and joining the members in well-aligned state.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for obtaining a long ceramic tubular body with high precision.

0002

BACKGROUND OF THE INVENTION Ceramic tubular bodies have conventionally been generally manufactured by a pressure extrusion method. That is, the ceramic raw material is supplied to an extruder equipped with an annular die, and the ceramic raw material is discharged from the annular die using uniaxial pressure to shape it, which is then cut into appropriate lengths and then directly fired. be. As described above, the pressure extrusion method is a suitable method for obtaining a molded article having a simple cross-sectional shape such as a tubular body. However, although the ceramic raw materials used in this pressure extrusion method are given a certain degree of shape retention by adding organic binders, etc., this is not sufficient, and it is difficult to obtain long molded bodies. As a result, the distortion and deformation would become large.

Furthermore, ceramic tubular bodies can also be manufactured by slip casting, cold isostatic pressure (CIP) molding, and the like. In the slip casting method, a ceramic slurry is injected into a hollow mold at one end and then discharged. A ceramic layer is formed on the inner surface of the mold. This operation is repeated several times until the desired thickness is achieved, which is then dried and fired. It is something to do. In addition, in the CIP method, ceramic powder is filled around a hard mandrel placed inside a rubber bag, hydrostatic pressure is applied from the outside of the bag, the ceramic powder is compressed around the mandrel, and then The base material (shiraji, [green]) obtained by removing the CIP mold is fired. However, even with the slip casting method and the CIP method, it is technically difficult to obtain a long molded body, and this simply results in an increase in manufacturing costs.

0004

SUMMARY OF THE INVENTION Therefore, it is an object of the present invention to provide a method for accurately manufacturing long ceramic tubular bodies from short ceramic tubular bodies obtained by various molding methods. be.

[0005]

[Means for Solving the Problems] The above objects are such that a plurality of short tubular members made of a ceramic sintered body are arranged in series along the axial direction of the tubular members, and at least one of the plurality of tubular members is arranged in series along the axial direction of the tubular members. A ceramic adhesive is applied to the connecting end surfaces of the tubular members by heating at least the connecting portions of the tubular members while applying pressure along the axial direction so as to press the tubular members into contact with each other from the extreme ends of the tubular members. A method for manufacturing a long ceramic tubular body by joining tubular members to each other, wherein during the above operation, a connecting portion alignment rod is inserted into the interior of the tubular member to connect at least the tubular members to each other. This is achieved by a method for manufacturing a long ceramic tubular body, which is characterized in that the rod is present at a position that includes the section.

[0006]

[Operation] In this way, in the present invention, when a plurality of short ceramic tubular members are joined together to obtain a long ceramic tubular body, a rod for connecting portion alignment is inserted into the tubular member and this rod is inserted into the tubular member. Since the bonding end surfaces of the tubular members are placed at a position that includes at least the connecting portion between the tubular members, alignment of the joining end surfaces of the tubular members is achieved, and a long ceramic tubular body can be obtained with high precision.

The material constituting the connecting portion alignment rod used in the manufacturing method of the present invention is a ceramic adhesive that is sufficiently stable at the heating temperature during bonding, or a ceramic sintered body constituting the ceramic tubular member. There is no particular limitation, and various metals, ceramics, etc. can also be used as long as they have no reactivity with the material and have a coefficient of thermal expansion comparable to that of the ceramic sintered body constituting the ceramic tubular member. but is preferably graphite. Graphite has good processability and is also economically advantageous. Particularly, when the ceramic tubular member is made of silicon nitride ceramics as described later, graphite is preferable because it has a coefficient of thermal expansion comparable to that of silicon nitride ceramics.

[0008] Furthermore, it is necessary that the connecting portion alignment rod has an outer diameter slightly smaller than the inner diameter of the ceramic tubular member to which it is connected. That is, if the outer diameter of the connecting portion alignment rod is too small compared to the inner diameter of the ceramic tubular member, the alignment of the joint end surfaces in connecting the ceramic tubular members will deteriorate. It also depends on the difference in coefficient of thermal expansion between the ceramic sintered body that makes up the ceramic tubular member and the material that makes up the connecting rod, or the diameter of the ceramic tubular member. When this rod for connecting portion alignment is inserted inside, the clearance between the inner surface of the ceramic tubular member and the outer surface of the rod for connecting portion alignment is 0.3 to 0.5 mm, more preferably 0.1 to 0.2 m.
It is about m.

The ceramics constituting the elongated tubular body obtained by the manufacturing method of the present invention are not particularly limited, and include, for example, non-oxide ceramics based on silicon nitride and silicon carbide, alumina, silica,
Examples include oxide ceramics such as zirconia and ferrite, and composite ceramics such as whisker or fiber reinforced ceramics, among which silicon nitride ceramics (including sialon) are particularly desired from the viewpoint of their uses. That is, the high wear resistance, heat resistance, and corrosion resistance of silicon nitride ceramics are suitable for fields that handle various chemical products or molten metals. For example, when manufacturing various chemical products from molten metal such as when obtaining AlCl3 from molten aluminum, molten metal supply pipes in die casting to obtain large castings, gas injection nozzles in molten metal scouring, and even thermoelectric Applications include twin pipes and supply pipes in gas combustion systems.

Hereinafter, the manufacturing method of the present invention will be explained in more detail by taking as an example the case where a plurality of elongated tubular bodies made of silicon nitride ceramics are joined together as described above.

[0011] In the present invention, the short tubular member used can be produced by various known molding methods such as extrusion molding, slip casting, and CIP. A base material having a desired shape is obtained by such various molding methods, and then fired according to a conventional method. Note that it is possible to further perform secondary processing before and after firing, if necessary. Furthermore, the joining end surface of such a short tubular member has an Rmax of less than 10 μm, more preferably 8 μm.
It is desirable that the thickness be less than μm in order to achieve better bonding.

In the present invention, a ceramic adhesive is then applied to at least one of the joining end surfaces of the plurality of tubular members to be joined. The ceramic adhesive can be applied to the joint end face by mixing the ceramic adhesive (powder) with a suitable developing solvent to form a slurry, and applying the slurry by spraying, dipping, or brushing.

As described above, a plurality of short ceramic tubular members 11 are coated with a ceramic adhesive on their joint end surfaces.
are then arranged in series as shown in FIGS. 1 and 2. At this time, in the present invention, the connecting portion alignment rod 12 is inserted into the ceramic tubular member 11 as described above. As shown in FIGS. 1 and 2, the connecting portion alignment rod 12 may be disposed at a position that includes at least the connecting portions 13 between the tubular members, and does not need to be present over the entire length of the plurality of tubular members 11. do not have. Furthermore, in the case where three or more ceramic tubular members 11 are arranged in series and there are a plurality of connection parts 13, there may be a plurality of connection part alignment rods 12, although not shown. I don't mind. It should be noted that this connecting portion alignment rod 12 is preferably made of graphite as described above, but the surface of this connecting portion alignment rod 12 is further coated with boron nitride powder, talc (talc), etc., in the form of a ceramic tube. It is desirable to attach the rod 12 for connecting portion alignment before inserting it inside the member 11, thereby making the reaction between the rod 12 for connecting portion aligning and the adhesive or the ceramics constituting the tubular member 11 more effective. can be prevented.

[0014] Subsequently, with the connecting portion alignment rods 12 disposed inside as described above, the plurality of tubular members 11 to be connected are pressurized along the axial direction so as to press against each other. As shown in FIG.
Alternatively, as shown in FIG. 2, a plurality of tubular This can also be achieved by pressing and moving the endmost abutting members 16 and 17, which are the abutting surfaces of both members 11, toward the center of the plurality of tubular members 11, respectively. Note that this pressing force depends on the type of ceramic and ceramic adhesive used to make up the tubular member 11, but if the tubular member 11 is made of silicon nitride ceramic, it is 10 to 30 kgf/. It is desired that the pressing force be about 10 to 20 kgf/cm2, more preferably about 10 to 20 kgf/cm2. Note that even if a relatively large force is applied in the direction of pressing the plurality of tubular members 11 to each other in this way, the presence of the connecting portion alignment rod 12 causes the connecting portions 13
The consistency of the joining end surfaces of each ceramic tubular member 11 is confirmed.

[0015] While maintaining this pressurized state,
The connecting portion 13 is heated to the bonding temperature of the ceramic adhesive applied to the connecting portion 13. As a method for this heat treatment, as shown in FIG. ), or as shown in FIG. 2, using a heating furnace (not shown) having a relatively small hot zone 19, to locally heat only the vicinity of the joint 13 of the tubular members 11. It is also possible to use either. The former method is advantageous when connecting a plurality of relatively short tubular members 11, for example, 300 mm or less in length, while the latter method is advantageous when connecting relatively long tubular members 11, for example, 300 mm or less in length. This is advantageous when connecting two or three tubular members 11 that go over each other. In addition, in the method of heating the entire plurality of connected tubular members 11 as shown in FIG. 1, the endmost abutting members 14 and 15 are also exposed to this heat treatment. It is required to have heat resistance and not to exhibit reactivity with the ceramics constituting the tubular member 11 under this heating condition, and is preferably made of, for example, graphite. In the method of locally heating as shown in FIG. 2, the endmost contact members 16 and 17 are not directly exposed to heat treatment, so these members 16 and 17 are made of, for example, steel. It works well even though.

Further, the conditions for such heat treatment depend on the type of ceramic constituting the tubular member 11 and the ceramic adhesive used. For example, if the tubular member 11 is made of silicon nitride ceramic, 1500 in a nitrogen atmosphere
It is desirable to maintain the temperature at about 1700°C.

Furthermore, in the manufacturing method of the present invention, particularly in the embodiment shown in FIG.
As described above, not only those obtained by molding methods such as extrusion molding, slip casting, and cold isostatic pressure (CIP) molding, but also short tubular members 11 obtained by these molding methods are used. For example, it is also possible to further use a material obtained by joining one end as shown in FIG. 1. Therefore, the length of the ceramic tubular body obtained by the manufacturing method of the present invention is limited only by the size of the place where the heating furnace used for joining is placed.
For example, a ceramic tubular body with a length exceeding 2 m can be manufactured easily and with high precision by the manufacturing method of the present invention.

Furthermore, in the method of manufacturing a long ceramic tubular body of the present invention, for example, when the diameter of the tubular member 11 to be connected is small, a jig having a structure as shown in FIGS. 3 or 4 may be used. By using this method, it becomes possible to simultaneously obtain a plurality of elongated ceramic tubular bodies in one operation.

In the jig shown in FIG. 3, a plurality of graphite connecting portion alignment rods 12 have their lower ends inserted into a plurality of through holes 26 provided in a bottom holding plate 24, respectively. On the other hand, similarly, the connecting part alignment rod 1
A plurality of through holes 27 provided in the upper holding plate 25 fit into the upper end portions of the upper holding plate 25, respectively. In addition, the bottom holding plate 24
Loading rams 28 and 29 are in contact with the outer side of the upper holding plate 25, respectively, for applying pressure toward the center along the axial direction of the connecting portion alignment rod 12. Note that both of the through holes 26 and 27 have a diameter slightly larger than the outer diameter of the connecting portion alignment rod 12, and specifically, the clearance between the two is 0.3 to 0.5.
mm, more preferably about 0.1 to 0.2 mm. In this jig, when the lower ends of the plurality of connection part alignment rods 12 are respectively inserted into the plurality of through holes 26 provided in the bottom holding plate 24, the connection part alignment rods 12 are inserted into the plurality of through holes 26 provided in the bottom holding plate 24.
The connecting portion alignment rod 12 is installed exactly at the bottom holding plate 24 and is prevented from further advancing at a position where the lower end surface of the rod 12 contacts the upper surface of the loading ram 28 which contacts the bottom holding plate 24 outwardly. It appears to be fixed. In this state, the plurality of tubular members 11 are inserted into each of the plurality of connecting portion alignment rods 12 as shown in FIG. The lowermost end surfaces of the plurality of tubular members 11 abut against the upper surface of the bottom holding plate 24 around the outer periphery of the connecting portion alignment rod 12 . Here, the upper holding plate 25 is inserted so that the upper end portions of the plurality of connecting portion alignment rods 12 are respectively inserted into the plurality of through holes 27.
descend from above. The uppermost end surfaces of the plurality of tubular members 11 come into contact with the lower surface of the upper holding plate 24 around the outer periphery of the connection part alignment rod 12, so that the plurality of tubular members 11 inserted through each connection part alignment rod 12 It is held between the holding plate 24 and the upper holding plate 25. Therefore,
When pressure is applied toward the center by both loading rams 28 and 29, the plurality of tubular members 11 receive this pressure and are brought into pressure contact with each other. On the other hand, since the upper end of the connecting portion alignment rod 12 does not come into contact with the upper loading ram 29, the connecting portion aligning rod 12 does not receive this pressing force. Then, while maintaining the plurality of tubular members 11 in pressure contact with each other in this manner, the heat treatment is performed as described above. Note that the jig shown in FIG. 3 has a relatively large hot zone 1 as in the case shown in FIG.
The bottom holding plate 24, the top holding plate 25, and the loading rams 28 and 29 are all made of graphite in order to heat the entire plurality of connected tubular members 11 using a heating furnace (not shown) having It is configured.

In the jig shown in FIG. 4, a holding hole 30 (corresponding to the through hole 26 of the jig shown in FIG. ) does not pass through the bottom holding plate 24, and the lower end of the connecting part alignment rod 12 is held in contact with the bottom holding plate 24, but the jig has almost the same configuration as the jig shown in FIG. and is used in the same way. Note that in the jig shown in FIG. 4, a heating furnace (not shown) having a relatively small hot zone 19 is used to locally heat only the vicinity of the connection part 13, as in the case shown in FIG. Since the bottom holding plate 24, the top holding plate 25, and the loading rams 28 and 29 are not directly exposed to heat, they are all made of steel.

[0021]

[Examples] Next, the present invention will be explained in more detail with reference to Examples. Example 1 Length 3 obtained by sintering after molding by uniaxial extrusion method
A long tubular body was obtained from a short tubular member made of Sialon with a diameter of 0 mm, an outer diameter of 19 mm, and a wall thickness of 2 mm using a jig as shown in Fig. 3 having 60 graphite connection alignment rods. . The 10 short tubular members, each of which has adhesive applied to each joining end surface, are inserted into each of the connection alignment rods of this jig, and each tubular member has a load of 10 kgf/
While applying a total load of 642 kgf from the loading rams at both ends so as to apply a pressure of cm2, the jig was heated at 1600°C for 20 minutes in a nitrogen atmosphere in a hot press heating furnace with a hot zone surrounding the entire jig to perform bonding. Ta. As a result, 60 sialon tubular bodies each having a length of about 300 mm could be manufactured at one time. Note that the deviation of the joints in these sialon tubular bodies was 0.25 mm on average.

Example 2 Two sialon tubular bodies each having a length of about 300 mm obtained in Example 1 were connected to each other as shown in FIG. The same connecting operation was then repeated five times to obtain a Sialon tubular body with a length of 2.1 m. The adhesive, pressure, and heat treatment conditions used in the connection operation were the same as in Example 1, except that the heating in the connection operation was performed locally using a hot press heating furnace with a relatively small hot zone. did. The deviation of the joint in the sialon tubular body thus obtained was 0.6 mm on average.

Example 3 Inner diameter 70 mm and outer diameter 70 mm obtained by CIP method
Two sialon tubular members each having a length of 700 mm were connected to each other as shown in FIG. 2 to obtain a sialon tubular body having a length of 1.4 m. Note that the adhesive, pressure, and heat treatment conditions used in this connection operation were the same as in Example 2. The deviation of the joint in the sialon tubular body thus obtained was 0.3 mm on average.

Example 4 Inner diameter 150 mm and outer diameter 170 mm obtained by CIP method
Three sialon tubular members with a length of 250 mm, and C
Inner diameter 150mm, outer diameter 170m obtained by IP method
Figure 2 shows one sialon tubular member with a length of 200 mm.
They were successively connected to each other as shown in Figure 3, and a sialon tubular body having a length of 950 mm was obtained by performing the connecting operation three times. The adhesive, pressure, and heat treatment conditions used in these connection operations were the same as in Example 2. The deviation of the joint in the sialon tubular body thus obtained was 0.5 mm on average, and was extremely accurate, requiring almost no secondary processing.

[0025]

[Effects of the Invention] As described above, according to the present invention, it is possible to easily manufacture long ceramic tubular bodies, which have been difficult to manufacture using conventional methods such as pressure extrusion, slip casting, and CIP. , a short tubular member whose shape such as wall thickness can be easily controlled is obtained using a conventional molding method, and these are connected with high consistency by using a joint alignment rod. The tubular body has a uniform wall thickness throughout its entire length without being affected by its length, and is free from distortion and deformation.

[Brief explanation of the drawing]

FIG. 1 is a drawing schematically showing a joining step in an embodiment of the method for manufacturing a long ceramic tubular body of the present invention;

FIG. 2 is a drawing schematically showing a joining step in another embodiment of the method for manufacturing a long ceramic tubular body of the present invention;

FIG. 3 is a drawing schematically showing a joining step in yet another embodiment of the method for manufacturing a long ceramic tubular body of the present invention;

FIG. 4 is a drawing schematically showing a joining step in yet another embodiment of the method for manufacturing a long ceramic tubular body of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 11... Tubular member, 12... Connecting part alignment rod, 13... Connecting part, 14, 15, 16, 17... Endmost part abutting member, 18
, 19... Hot zone, 24... Bottom holding plate, 25... Upper holding plate, 26, 27... Through hole, 28, 29... Loading ram, 30... Holding hole.

Claims (2)

[Claims] 1. A plurality of short tubular members made of a ceramic sintered body are arranged in series along the axial direction of the tubular members, and these tubular members are inserted from the outermost end of at least one of the plurality of tubular members. At least the connecting portions of the tubular members are heat-treated while applying pressure along the axial direction so as to bring them into pressure contact with each other, and the tubular members are bonded to each other using a ceramic adhesive applied to the connecting end surfaces of the tubular members. A method for manufacturing a long ceramic tubular body, wherein during the above operation, a connecting portion alignment rod is inserted into the interior of the tubular member so that the rod is present at a position that includes at least the connecting portions between the tubular members. A method for manufacturing a long ceramic tubular body, characterized in that it is left to stand. 2. The method for manufacturing a long ceramic tubular body according to claim 1, wherein the connecting portion alignment rod is made of graphite.