JP2802013B2 - Ceramic joining method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for joining ceramics, which can easily and stably obtain a ceramic joined body having excellent airtightness and joint strength at a joint.

[0002]

2. Description of the Related Art Ceramics have a high degree of heat and heat insulation irrespective of the composition of oxides and non-oxides, and have electrical and electronic properties such as insulation, conductivity, magnetic and dielectric properties. It has a function and also has excellent mechanical properties such as abrasion resistance, and has already been used as a material for various structures and has been researched and developed. When ceramics are used as mechanical part materials or structural materials, mechanical parts and structural members of various shapes are required, and combinations of parts and members are also required. As a result, it is necessary to bond and fix ceramics in all parts.

[0003] Among various parts and members, a joined body in which a plate-shaped member and a member having another shape are combined is often used as a mechanical part or a structural member. There are many examples to use. For example, in a ceramic heat exchanger of an industrial furnace as disclosed in Japanese Patent Application Laid-Open No. 60-62592 by the applicant, a member in which a number of ceramic tubular bodies are fixed to a plate-like body is used.

As described above, many attempts have been made to use ceramics as parts and members of a heat exchanger. As a method of inserting a ceramic tubular body into a hole formed in a ceramic plate and fixing the same, there are two methods. JP-A-60-6
As disclosed by the applicant in No. 2592, a method of spherically joining by mechanical pressing using a compression spring, or preparing an inorganic joining material containing borosilicate glass or the like as a paste, and applying this to a joint portion A method of coating and heating and bonding is generally used. In addition, a plate having a hole is formed into a green body such as a green body or a calcined body, and a tubular body of a sintered body is inserted into the green body and fired, and the difference in firing shrinkage between the two is utilized. Also known is a method of joining them together.

[0005]

However, among the above-mentioned joining methods, in the method of joining spherical surfaces using a compression spring, a gap is formed in the spherical joint portion due to breakage due to thermal stress during use and expansion or contraction. And it cannot maintain sufficient airtightness. In addition, in the joining method using an inorganic joining material, it is necessary to prepare and apply the joining material in a paste form at the time of joining, so that workability is poor and joining defects such as pores and cracks are easily generated, There were problems with the airtightness and strength of the joint.

[0006] In the joining method utilizing the difference in firing shrinkage, a complicated operation such as preparation of the above-mentioned joining material is not required.
In order to obtain good bonding strength and airtightness, set the value (so-called interference) by subtracting the diameter of the perforated hole of the plate when heating and firing with nothing inserted from the outer diameter of the tube. Is important. However, in the related art, a technique specifically mentioning the set value of the interference is not known, and a desired bonded body having excellent airtightness and bonding strength has not always been stably manufactured.

The present invention has been made in view of such a conventional situation, and an object thereof is to provide a ceramic body having a cylindrical or cylindrical shape and a hole for inserting and joining these ceramic bodies. It is an object of the present invention to provide a joining method capable of easily and stably obtaining a joined body excellent in hermeticity and joining strength of a joined portion in joining utilizing a difference in firing shrinkage rate with a ceramic body having a joint.

[0008]

According to the present invention, a first ceramics unsintered body having a perforated hole and a second ceramics sintered body having a cylindrical shape or a columnar shape are separated from each other by the first ceramics sintered body.
The second ceramic sintered body is inserted into the perforated hole of the ceramic non-sintered body, and is heated and fired without using a bonding material.
In the joining method for joining integrally, the first ceramic
The green body and the second ceramic body are silicon nitride or
Is silicon carbide, and the diameter of the perforated hole of the first ceramics unsintered body is 0.1 to 1.
Set to be 0 mm smaller to prevent leakage from the joint
The present invention provides a method for joining ceramics, which is stopped .

[0009]

According to the present invention, the second ceramics sintered compact having a small firing shrinkage is inserted into a perforated hole of the first ceramic having a high firing shrinkage, and the difference in firing shrinkage is utilized. In this method, when the first ceramic green body is heated and fired in a state where nothing is inserted, the diameter of the perforated hole of the first ceramic green body is larger than the outer diameter of the second ceramic sintered body by 0.3 mm. It is characterized in that it is set to be smaller by 1 to 1.0 mm, that is, the so-called interference is limited to the range of 0.1 to 1.0 mm. This limited range was obtained by various experiments by the inventors, and in this range, it was confirmed that a bonded body excellent in both bonding strength and airtightness could be stably obtained.

On the other hand, if the interference is less than 0.1 mm,
The bonding force is weak, and a gap is likely to be formed at the bonding portion. If this gap is a through hole extending from the upper end to the lower end of the joint, the airtightness will be extremely poor. Further, if the interference exceeds 1.0 mm, joint defects such as cracks will occur.

In the present invention, the ceramics used for the first ceramic green body and the second ceramic sintered body
As such, silicon nitride or silicon carbide having high strength and high heat resistance is adopted in consideration of use in engines, industrial machines, heat exchangers, and the like . The shape, thickness, and size of the first ceramic green body are not particularly limited, and may be selected according to the purpose of use and conditions. For example, when used in a heat exchanger, Since the sealing effect increases as the joining distance of the joining portion increases, it is preferable to have a thickness of 3 mm or more. The number of perforated holes in the first ceramic green body is not particularly limited, and may be a single-hole plate having only one perforated hole or a perforated plate having a plurality of perforated holes. Furthermore, as long as the interference is in the range of 0.1 to 1.0 mm, the diameter and arrangement of the perforated holes of the first ceramic green body,
There is no particular limitation on the outer diameter or length of the second ceramic sintered body. The perforation hole of the first ceramic green body may be provided at the same time as molding or may be formed after molding.

[0012]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

(Example 1) 1% by weight of Y ₂ O ₃ , 1% by weight of MgO, 1% by weight of ZrO ₂
Was added and added in an amount of 0.5% by weight (all of which were externally added). The mixture was pulverized by an attritor, and then dried and granulated. A molded article was obtained. A hole having a diameter of 7 mm was formed by punching, and dried at 110 ° C. for 10 hours.
The binder was calcined at 00 ° C. for 5 hours to produce a first ceramic green body. In addition, a cylindrical rod was formed by extrusion using the same raw materials used in the production of the first ceramics green body, and dried and binder calcined under the same conditions as in the first ceramics green body. After performing, baking at 1650 ° C for 1 hour in a nitrogen atmosphere, diameter 6mm, length 50mm
Was obtained.

Next, as shown in FIG. 1, the second ceramic sintered body 3 is inserted into the perforation hole 4 of the first ceramic green body 2.
Is inserted so that the end of the second ceramics unsintered body 3 coincides with one surface of the first ceramics unsintered body 2, and in this state, is heated and fired at 1650 ° C. in a nitrogen atmosphere to be joined and integrated. Thus, a joined body 1 as shown in FIG. 2 was obtained. In this connection, the interference (the outer diameter of the second ceramic sintered body—the diameter of the perforated hole of the first ceramic unsintered body after the heating and sintering in the case where the heating and sintering in a state where nothing is inserted) is 0 in this joining. .2 mm.

With respect to the obtained joined body, the airtightness of the joined portion was examined using an airtightness test apparatus shown in FIG. In FIG. 3, the joined body 1 is held by a holding jig 7 installed in a water tank 6, and the space between the holding jig 7 and the joined body 1 is sealed by an O-ring 9. And in this state, 7kg
/ Cm ² air is applied to the joint through the air passage 10,
Air leaked from the joint was collected by a measuring cylinder, and the volume was measured.

Further, the bonding strength was measured using a bonding strength test apparatus shown in FIG. In FIG. 4, the joined body 1 is fixed to a rotating machine 11, and a load cell 12 is mounted on the top of the joined body 1.
, And the bending strength of the rotating cantilever was measured. Note that the maximum load weight of the load cell 12 is 500
kg. In addition, the presence or absence of a joint defect observable with the naked eye was examined by appearance observation. Table 1 shows the results.

(Example 2) A joint was produced and an evaluation test was performed in the same manner as in Example 1 except that the interference was set to 0.6 mm. Table 1 shows the results.

Example 3 A joined body was produced and an evaluation test was performed in the same manner as in Example 1 except that the interference was set to 0.1 mm. Table 1 shows the results.

(Example 4) A bonded body was produced and an evaluation test was performed in the same manner as in Example 1 except that the interference was set to 1.0 mm. Table 1 shows the results.

(Example 5) A first ceramic green body was obtained by using the same raw material, molding method, and perforated hole forming method as in Example 1, and had a diameter of 20 mm, a thickness of 3 mm, and one perforated hole. Was dried and calcined under the same conditions as in Example 1 and then calcined at 1350 ° C. for 3 hours in a nitrogen atmosphere. The second ceramic sintered body was obtained in the same manner as in Example 1 except that the shape was a tube having an outer diameter of 6 mm, an inner diameter of 4 mm, and a length of 50 mm. The obtained first ceramic unsintered body and the second ceramic sintered body are set with a tightening margin of 0.
Joining was performed in the same manner as in Example 1 except that the thickness was 4 mm, and an evaluation test of the joined body was performed. Table 1 shows the results.

Example 6 A first ceramic green body was obtained by extrusion molding using the same raw materials as in Example 1.
Twenty holes were punched out of a square plate-shaped body having a size of 90 mm and a thickness of 20 mm, and then dried and calcined under the same conditions as in Example 1. The second ceramic sintered body was obtained in the same manner as in Example 1 except that the shape of the second ceramic sintered body was a tube having an outer diameter of 6 mm, an inner diameter of 4 mm, and a length of 50 mm. . The obtained first ceramic unsintered body and the second ceramic sintered body were joined in the same manner as in Example 1 except that the interference was set to 0.4 mm, and an evaluation test of the joined body was performed. Table 1 shows the results.

(Example 7) A first ceramic green body was obtained by using the same raw material, molding method, and perforated hole forming method as in Example 1, and had a diameter of 20 mm, a thickness of 2 mm, and one perforated hole. Was obtained by drying and calcining the binder under the same conditions as in Example 1. The second ceramic sintered body was obtained in the same manner as in Example 1. The obtained first ceramic green body and the second ceramic sintered body were joined in the same manner as in Example 1 except that the interference was 0.6 mm, and an evaluation test of the joined body was performed.
Table 1 shows the results.

Example 8 1.5% by weight of B ₄ C and 1% by weight of C were added to a raw material powder of silicon carbide as a sintering aid (all external amounts), and these were mixed and pulverized with an attritor. After that, a raw material obtained by dry granulation was used to obtain a square plate-shaped molded body having a size of 60 × 60 mm and a thickness of 10 mm by press molding. In this, a hole having a diameter of 6.7 mm was formed by punching seven holes.
After drying at 10 ° C. for 10 hours, the binder was calcined in a nitrogen atmosphere at 500 ° C. for 5 hours to produce a first ceramic green body. Also, the same raw material as that used for the first ceramic green body was extruded to a diameter of 6 mm and a length of 5 mm.
After forming a cylindrical rod of 0 mm and drying and calcining the binder under the same conditions as in the first ceramic green body,
It was fired at 2000 ° C. for 3 hours in an argon atmosphere to obtain a second ceramic sintered body. On the joining surface of the obtained sintered body,
Cutting was performed. These were placed in an argon atmosphere for 200
Heating and sintering at 0 ° C. for 3 hours were performed to join and integrate. In this connection, the interference was set to 0.4 mm. An evaluation test was performed on the obtained joined body in the same manner as in Example 1. Table 1 shows the results.

(Comparative Example 1) A first ceramic green body was obtained by using the same raw material, molding method, and perforated hole forming method as in Example 1, and had a diameter of 20 mm, a thickness of 5 mm, and one bored hole. Was obtained by drying and calcining the binder under the same conditions as in Example 1. The second ceramic sintered body was obtained in the same manner as in Example 1 except that the joint surface was cut after firing. Example 1 Example 1 was repeated except that the interference between the obtained first ceramic unsintered body and the second ceramic sintered body was 0.05 mm.
In the same manner as described above, and an evaluation test of the joined body was performed. Table 1 shows the results.

(Comparative Example 2) A joined body was manufactured and evaluated in the same manner as in Comparative Example 1 except that the interference was 1.2 mm. Table 1 shows the results.

(Comparative Example 3) The first ceramic green body obtained in the same manner as in Example 1 was further subjected to 1650 in a nitrogen atmosphere.
C. for 1 hour to obtain a sintered body. The second ceramic sintered body has an outer diameter of 6 mm, an inner diameter of 4 mm, and a length of 50 mm.
It was obtained in the same manner as in Example 1 except that the tube was formed into a mm-shaped tube, and the joined surface was cut after firing. Next, CeO ₂ : 34.5% by weight, MgO: 2
7.6% by weight, SiO ₂ : 13.8% by weight, SrCO ₃ :
10.3 wt%, Al ₂ O _3: 6.9 wt%, Si ₃ N _4:
A bonding material having a composition of 6.9% by weight is applied in the form of a paste, and the bonding surfaces are adjusted.
For 3 hours to obtain a joined body. An evaluation test was performed on the obtained joined body in the same manner as in Example 1. Table 1 shows the results.

[0027]

[Table 1]

As shown in Table 1, the joined body of the embodiment according to the present invention was excellent in both the hermeticity of the joint and the strength of the joint. No measurement of joint strength due to multi-tube shape). On the other hand, Comparative Example 1 in which the interference is below the lower limit of 0.1 mm of the present invention, Comparative Example 2 in which the upper limit of the present invention exceeds 1.0 mm, and Comparative Example 3 in which the joining material is used for bonding In each of the bonded bodies, a defect occurred in the bonded portion, and both the airtightness and the bonded portion strength were poor.

[0029]

As described above, the present invention utilizes the difference in firing shrinkage between a ceramic body having a cylindrical or cylindrical shape and a ceramic body having a hole for inserting and joining the ceramic body. In joining, by limiting the interference, which is an important factor for obtaining an excellent joined body, to a predetermined range, it is possible to easily and stably obtain a joined body having excellent airtightness and joining strength of a joined portion. .

[Brief description of the drawings]

FIG. 1 is an explanatory cross-sectional view showing a combined state of a first ceramic green body and a second ceramic sintered body before joining in an example.

FIG. 2 is a side view showing an example of a ceramic joined body obtained by the present invention.

FIG. 3 is an explanatory view showing an airtightness test device.

FIG. 4 is an explanatory view showing a bonding strength test device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Joined body 2 1st ceramic unsintered body 3 2nd ceramics sintered body 4 Drilled hole 6 Water tank 7 Holding jig 9 O-ring 10 Vent path 11 Rotary machine 12 Load cell

Claims (3)

(57) [Claims] A first ceramic unsintered body having a perforated hole and a second ceramic sintered body having a cylindrical or columnar shape are inserted into the perforated hole of the first ceramic unsintered body. (2) In a joining method of inserting a ceramic sintered body, heating and firing without using a joining material, and integrally joining, the first ceramic unsintered body and the second ceramic
When the sintered body is silicon nitride or silicon carbide and the diameter of the perforated hole of the first ceramic unsintered body is heated and fired in a state where nothing is inserted, the outer diameter of the second ceramic sintered body is set to more 0.1~1.0mm decreases, bonding
A method for joining ceramics, wherein leakage from a part is prevented . 2. The first ceramic green body having a thickness of 3
The joining method according to claim 1, wherein the diameter is not less than mm. 3. A bonding method according to claim 1 or 2 wherein said first ceramic green body is porous plate having a plurality of drilled holes.