JP2843450B2 - 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 ceramic members made of ceramics. More specifically, the present invention relates to a ceramic joining method for forming a ceramic joint having high joint strength and high airtightness of the 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 excellent mechanical properties such as abrasion resistance. It 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 fix and fix the ceramics.

[0003] Ceramic joints obtained by combining various ceramic members are often used as mechanical parts and structural members. For example, ceramic joints for industrial furnaces proposed by the applicant in Japanese Patent Application Laid-Open No. 60-62592 have been used. A member in which many tubular bodies are fixed to a plate-like body is used. In this method, a ceramic member is mechanically joined to a spherical surface by using a compression spring. FIG. 5 is a sectional view showing a joint of a shell-and-tube heat exchanger shown in the publication. The spherical portions provided at the inner ends of the through-holes X and X 'of the plate-like members A and A' and the spherical portion of the tubular member B are fixed by a spherical joint Y by mechanical pressing. However, in this case, the tubular body may be damaged by thermal stress during use, and a gap is generated in the spherical joint due to expansion and contraction, dust and the like in the flowing gas leak, and adhere to the joint sufficiently. A good sealing property could not be obtained.

[0004] A method of joining ceramic members with a joining material has also been proposed. Conventionally, as a bonding material used for bonding ceramic members, boron oxide (B) known as Pyrex glass (trade name of so-called heat-resistant glass) is used.
Borosilicate glass containing a ₂ O ₃ ) component is generally used, and its powder or slurry is applied to a joint and heated in air or vacuum to join. However, in the ceramic joining by this method, there is a problem that joining defects such as pores and cracks are apt to occur in the joining portion, and the joining strength and the sealing property are poor.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a method for joining ceramic members, in which, in view of the above-mentioned conventional ceramic joining technology, the sealing property is higher than mechanical joining, and the apparatus and operation are simple. In ceramic joining using a certain joining material, as a result of earnestly studying for the purpose of forming a uniform joining portion in order to obtain a ceramic joining with improved sealing properties and joining strength, the present invention was completed.

[0006]

According to the present invention, at least two ceramic members constituting a ceramic joined body are oxidized and then subjected to a nitrogen atmosphere using an inorganic joining member mainly composed of SiO _2. A ceramic bonding method is provided, wherein the ceramic bonding method is performed by heat treatment.

[0007]

The present invention is configured as described above, and oxidizes the ceramic member to be joined prior to joining, and performs a joining heat treatment in a nitrogen atmosphere, thereby allowing the member to be joined to, for example, a joining material. In addition to changing the surface properties such as wettability, the heat treatment in a nitrogen atmosphere improves the solidification properties of the bonding material to form a joint having few pores and no defects. Oxynitride glass, and the oxidation treatment of the ceramic member to be joined and the joint heating in a nitrogen atmosphere act synergistically to obtain a ceramic joined body with high sealing properties, large joint strength and excellent heat resistance. It is estimated that it is possible.

Hereinafter, the present invention will be described in more detail. The ceramics used in the present invention may be any ceramics such as oxides and non-oxides, and may be appropriately selected according to necessary use conditions such as the type of structural member used for the joined body, mechanical strength, and the like. Good. For example, when used for industrial machines and heat exchangers, silicon nitride or silicon carbide having high strength and high heat resistance is used. Further, they may be made of the same or different ceramics. In the present invention, the shape, thickness, and size of the ceramic member to be joined are not particularly limited. For example, it may be a simple joining of flat surfaces, or a joining in which a tubular body is inserted into each hole of a perforated plate having a large number of holes formed in a flat body to form a continuous joining layer on the surface of the flat plate and the holes. Good. In this case, the tubular body may be any of a circle, an ellipse, a rectangle, a polygon, a star, and the like, and a flat plate hole is formed in a tapered shape, a stepped shape, a screw structure, or the like, and the end of the tubular body is a hole. It can also be formed according to the shape.

In the oxidation treatment of the present invention, the member to be joined is placed in an oxygen-containing gas atmosphere, for example, in air or oxygen gas, for about 800 to
The treatment can be carried out at 1000 ° C. for about 1 to 2 hours. In this case, the entire ceramic member of the member to be joined may be oxidized, or only the joined portion may be oxidized. The joining material used in the present invention may be selected according to the functional properties of the type of ceramic used for each ceramic member to be joined, the usage conditions of the obtained joined body, and the like. It is preferable to use the same type of ceramics constituting the member to be bonded or an inorganic bonding material mainly composed of SiO ₂ which is melted and fluidized by heating. The inorganic bonding material containing SiO ₂ as a main component is a bonding material containing 50% by weight or more of SiO _2. For example, the above-mentioned borosilicate glass, aluminoborosilicate glass, and aluminosilicate generally used for ceramics bonding are used. Glass bonding materials such as glass and silicate glass can be used. The above-mentioned inorganic bonding material is usually used in the form of a slurry or a paste by using a powder thereof, for example, using a solvent such as water or alcohol and adding a binder if necessary. In this case, in order to obtain a uniform joint, it is preferable that the average particle size of the powder of the glass joining material is as fine as possible, and preferably 1 μm or less.

The general joining procedure in the present invention is as follows. A joining material paste is applied to at least one of the joining surfaces of the two or more oxidized members to be joined constituting the joint of the ceramic joined body. After joining the joining surfaces of the members, it is dried in the air at about 100 to 150 ° C for about 1 to 2 hours, and calcined at about 400 to 500 ° C for about 0.5 to 3 hours, and then heated in a nitrogen atmosphere. The treatment can be carried out by melting the joining material and then cooling and solidifying it. In this case, the heat treatment temperature and time can be appropriately selected depending on the type of the bonding material to be used and the shape and thickness of the bonding portion. For example, when using borosilicate glass,
It is preferable to stand at about 1500 to 1600 ° C. for about 1 to 3 hours. In this case, if the heat treatment temperature is less than 1500 ° C., the entire joining material forming the joining portion is not uniformly melted, so that a uniform joining portion cannot be obtained.
If the temperature exceeds 1600 ° C., some of the components of the joining material and the member to be joined are significantly evaporated, so that the joining interface between the joining portion and the member to be joined tends to be porous, the airtightness is poor, and the strength is reduced. Is not preferred. The thickness of the joining material to be applied is not particularly limited. Usually about 0.0
The thickness may be 5 to 5 mm. It can be appropriately selected according to the shape and material of the joining member, the structure of the joining portion, the strength required for the joining portion, and the like.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings. However, the present invention is not limited to this embodiment. Example 1 (Preparation of bonding material) Water of about 60% by weight was added to powder of commercially available powdered borosilicate glass, and the mixture was pulverized for about 3 hours with a vibrating mill using alumina boulders to obtain an average particle size of 0.5 μm. Of borosilicate glass was obtained. The obtained fine powdered borosilicate glass and water were mixed at a ratio of 1: 1 to form a paste. Further, 4 parts by weight of a binder was added to and mixed with 100 parts by weight of the obtained paste-like borosilicate glass to prepare a bonding material paste.

(Oxidation treatment of the member to be joined)
Two cylinders made of i ₃ N ₄ with a diameter of 20 mmφ and a height of 20 mm,
It was left to stand at about 800 ° C. for 1 hour in an electric furnace in an oxygen atmosphere to be oxidized, thereby obtaining an oxidized Si ₃ N ₄ joined member.

(Joining) The obtained two members to be joined made of oxidized Si ₃ N ₄ were prepared on the bottom surface of each member 1 to be joined, as shown in the cross-sectional explanatory view of FIG. About 100 μm of the paste-like joining material was applied, and the respective plate-like bodies were pressed together to be joined. Then, after drying in an electric furnace at 120 ° C. for about 1 hour, further raising the temperature and calcining at about 500 ° C. for about 1 hour, setting the electric furnace in a nitrogen atmosphere and further raising the temperature to about 1500
After heating to 1 ° C. for 1 hour, the mixture was left as it was and cooled to obtain a joined body. After cooling, remove the joined body
The bonding strength at room temperature of the bonded part was measured according to ISR-1601. The results are shown in Table 1. Furthermore, the joined body was subjected to an oxidation test at 800 ° C. for 10 hours in the air, and the change in joint strength was measured thereafter. The results are shown in Table 1.

[0014]

[Table 1]

Comparative Example 1 A joined body was obtained in exactly the same manner as in Example 1 except that the joining member was used without being oxidized, and the heat treatment was performed at 1150 ° C. in vacuum. In the same manner as in Example 1, the bonding strength of the obtained bonded body was measured before and after the oxidation test.
The results are shown in Table 1.

Comparative Example 2 A joined body was prepared in exactly the same manner as in Example 1 except that the joining member was used without oxidation treatment and the joining heat treatment temperature was 1150 ° C. Could not.

Example 2 A member to be joined was made of Si ₃ N _{4 having} a diameter of 6.5 mmφ and a height of 50 mm.
And a bottomed cylinder having a diameter of 18 mmφ, a height of 10 mm, and a hole at the center of the bottom in which a cylinder of one of the members to be inserted can be inserted, except that the oxidation temperature was set to 800 ° C. Thus, each member to be joined made of the oxidized Si ₃ N ₄ was obtained. As shown in the cross-sectional explanatory view of FIG. 2, the member to be joined made of the oxidized Si ₃ N ₄ is embedded in the cylinder at the bottom of the cylinder 3 with the member to be joined. The same bonding material paste as in Example 1 was applied to the bottom surface and the periphery of the cylinder 2 perpendicular to the bottom surface. The applied thickness of the bonding material was about 5 mm . Thereafter, drying and calcination were performed in the same manner as in Example 1, and then heat treatment was performed in the same manner as in Example 1.
A conjugate was obtained. The joining strength of the joining part of the obtained joined body is
Each was measured before and after the oxidation test in the cantilever bending test. Further, in the leak tester shown in FIG. 4, when the joined body 10 is set on a predetermined joined body supporting jig 11 and immersed in water, and the inside of the pipe 12 is pressurized at a pressure of 8 kg / cm ² , Volume of bubbles generated per second (milliliter /
Second), a leak test was performed before and after the oxidation test, and the sealability was measured. The results are shown in Table 1.

Example 3 A joined body was obtained in exactly the same manner as in Example 1 except that the temperature of the oxidation treatment was 800 ° C. and the temperature of the heat treatment in a nitrogen atmosphere was 1600 ° C. The joint strength of the obtained joint was measured before and after the oxidation test in the same manner as in Example 1. The results are shown in Table 1.

Example 4 An outer diameter of 6.5 mmφ and an inner diameter of Si ₃ N _{4 of the} member to be joined were 4.0 mm.
Each of three cylindrical tubes of 5 mmφ and length of 100 mm and two bottomed cylinders having a diameter of 40 mmφ and a height of 10 mm and having three holes at the bottom into which the circular tube of the member to be joined can be inserted is oxidized. Each member to be joined made of oxidized Si ₃ N ₄ was obtained in the same manner as in Example 2 except that the processing time was changed to 2 hours. The resulting oxidized Si ₃ N ₄ manufactured workpieces as shown in cross-sectional view of Figure 3, the three workpieces one end of the circular tube 4 to the holes in the bottom of the joint member bottomed cylindrical 5 The same bonding material paste as in Example 1 was applied around the bottom surface of the embedded and bottomed cylinder 5 and around each of the circular tubes 4 orthogonal to the bottom surface. The applied thickness of the bonding material was about 5 mm. Thereafter, drying and calcination were performed in the same manner as in Example 1, and then heat treatment was performed in the same manner as in Example 1.
A conjugate was obtained. The sealability of the obtained joined body was measured before and after the oxidation test in the same manner as in Example 2. The results are shown in Table 1.

Comparative Example 3 A joined body was obtained in the same manner as in Example 4, except that the joining member was used without being oxidized and subjected to a heat treatment at 1150 ° C. in the air. The obtained joined body was treated in the same manner as in Example 4,
The sealability of the joint was measured before and after the oxidation test, respectively. The results are shown in Table 1.

Comparative Example 4 A joined body was obtained in the same manner as in Comparative Example 2, except that the heating temperature during joining was changed to 1500 ° C. In this case, unlike in Comparative Example 2, a joint was formed. The joint strength of the obtained joint was measured before and after the oxidation test in the same manner as in Example 1. The results are shown in Table 1.

From the above Examples and Comparative Examples, it can be seen that the ceramic joint of the present invention is excellent in strength, there is no leakage at the joints such as burying, and the sealing property is extremely high. In addition, the ceramic joint of the present invention was found to be suitable for long-term use with little change in joint strength and sealability even when left at high temperature in the air, with little deterioration due to oxidation, and comparative examples. It can be seen that the bonding obtained by the conventional bonding method of Example 1 is severely deteriorated by oxidation and is not suitable for long-term use. In the second and fourth embodiments, the cylindrical portion of the cylinder 3 used as the member to be joined has an advantage that the molten joining material does not flow out even when the joining material is melted and fluidized in the vacuum heating process. The present invention is suitable for applying the present invention to ceramic joining in which a large number of columns or tubes are joined and fixed to holes of a plate-like body.

[0023]

According to the ceramic joining method of the present invention, it is possible to obtain a ceramic joined body having extremely small porosity at the joint, uniform homogeneity of the joint, high joint strength, high sealing property, and excellent heat resistance. It is very industrially useful.

[Brief description of the drawings]

FIG. 1 is an explanatory sectional view showing a ceramic joined body according to one embodiment of the present invention.

FIG. 2 is a sectional explanatory view showing a ceramic joined body according to one embodiment of the present invention.

FIG. 3 is an explanatory sectional view showing a ceramic joined body according to one embodiment of the present invention.

FIG. 4 is a leak tester for evaluating the sealing performance of a joined body according to the present invention.

FIG. 5 is an explanatory sectional view showing an example of a conventional mechanical ceramic joint.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS A Joining part 1 Cylindrical member to be joined 2 Cylindrical member to be joined 3 Cylindrical member to be joined with a perforated bottom 4 Cylindrical member to be joined 5 Cylindrical member to be joined with a perforated bottom 10 Joint body 11 Joint support jig 12 Pipe

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁶ , DB name) C04B 37/00

Claims (1)

(57) [Claims] At least two ceramic members constituting a ceramic bonded body are oxidized, and then heated and bonded in a nitrogen atmosphere using an inorganic bonding member containing SiO ₂ as a main component. Ceramic bonding method.