JPH04300257A - Method of joining ceramics - Google Patents

Abstract

PURPOSE:To obtain ceramics joint parts having high bond strength and high airtightness by oxidizing ceramic members to be joined, using an inorganic joining material consisting essentially of SiO2, heat-treating the members in vacuum and joining. CONSTITUTION:At least two ceramic members to be joined, constituting a ceramics joined material, are oxidized. Then, the members are heat-treated with an inorganic joining material consisting essentially of SiO2 in vacuum and joined. By the joining method, since the ceramic members to be joined are oxidized before joining, the surface properties of the members to be joined, such as wetting to the joining material, are changed and hardening properties of the joining material are improved with the vacuum heat treatment to form joint part having few pores and no defects. In the heat treatment, the members to be joined are allowed to stand and treated in an oxygen-containing gas atmosphere, e.g. in air or an oxygen gas at about 800-1,000 deg.C for about 1-2 hours. In the operation, the whole ceramic members to be joined may be oxidized or only joining part of the ceramic members may be oxidized.

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 bonding method for forming a ceramic bonded portion with strong bonding strength and high airtightness at the bonded portion.

0002

[Prior Art] Ceramics, regardless of whether they are oxides or non-oxides, have a high degree of heat resistance and heat insulation, and have electrical and electronic properties such as insulation, conductivity, and magnetic and dielectric properties. It has excellent mechanical properties such as wear resistance and is already used as a material for various structures and is being researched and developed. When ceramics are used as a material for mechanical parts or structures, mechanical parts and structural members of various shapes are required.
In addition, combinations of various parts and members are required, and apart from those manufactured by integral molding, it is necessary to bond and fix ceramics.

[0003] Ceramic bonded bodies made by combining various ceramic members are often used as mechanical parts and structural members. In this method, a member in which a number of tubular bodies are fixed to a plate-like body is used. This method uses compression springs to mechanically join ceramic members on spherical surfaces, and FIG. 4 is an explanatory cross-sectional view of the joint part of the shell-and-tube heat exchanger shown in the publication, The spherical parts provided at the inner ends of the through holes X and X' of the plate-like bodies A and A', respectively, and the spherical part of the tubular body B are fixed by a spherical joint part Y by mechanical pressure. However, in this case, the tubular body may be damaged due to thermal stress during use, and gaps may be created in the spherical joint due to expansion and contraction, allowing dust, etc. in the circulating gas to leak, adhere to the joint, and cause damage to the tubular body. It was not possible to obtain good sealing performance.

[0004] Furthermore, a method has been proposed in which ceramic members are bonded using a bonding material. Conventionally, borosilicate glass containing a boron oxide (B2O3) component, known as Pyrex glass (registered trademark), a heat-resistant glass, is generally used as a bonding material for bonding ceramic members, and its powder or slurry is applied to the bonding part. It was applied to the surface and then heated in the air or in a vacuum for bonding. However, in ceramic bonding by this method, bonding defects such as pores and cracks are likely to occur in the bonded portion, and there are problems such as poor bonding strength and sealing performance.

[0005]

[Problems to be Solved by the Invention] In view of the above-mentioned conventional ceramic bonding technology, the present invention provides a method for bonding ceramic members that has higher sealing performance than mechanical bonding and is simpler in terms of equipment and operation. In ceramic bonding using a certain bonding material, the present invention was completed as a result of intensive studies aimed at forming a homogeneous bonded portion in order to obtain a ceramic bond with improved sealing performance and bonding strength.

[0006]

[Means for Solving the Problems] According to the present invention, at least two ceramic members to be joined constituting a ceramic joined body are oxidized and then subjected to heat treatment in vacuum using an inorganic joining material containing SiO2 as a main component. A ceramic bonding method is provided, which is characterized in that the ceramic bonding method is characterized in that the ceramic bonding method is performed by bonding.

[0007]

[Function] The present invention is constructed as described above, and by oxidizing the ceramic members to be joined prior to joining, the surface properties of the members to be joined, such as wettability with the joining material, are changed, It is presumed that, along with the vacuum heat treatment, the solidification properties of the bonding material are improved, and a defect-free bonded portion with fewer pores is formed.

The present invention will be explained in more detail below. The ceramics used in the present invention may be either oxide or non-oxide ceramics, and may be selected as appropriate depending on the type of structural member in which the joined body is used, mechanical strength, etc. good. For example, when used in industrial machinery, heat exchangers, etc., silicon nitride and silicon carbide, which have high strength and high heat resistance, are used. Further, each may be made of the same type of ceramic or different types of ceramics. In the present invention, the shape, thickness, and size of the ceramic members to be joined are not particularly limited. For example, it may be a simple joining between two flat surfaces, or a joining in which a tubular body is inserted into each hole of a perforated plate with many holes formed in the flat plate to form a continuous bonding layer between the flat plate surface and the hole. good. In this case, the tubular body may be circular, elliptical, rectangular, polygonal, star-shaped, etc., and the holes in the flat plate may be formed into a tapered shape, a stepped shape, a threaded structure, etc., and the end of the tubular body may be formed into a hole. It can also be formed to match the shape of.

In the oxidation treatment of the present invention, the bonding member is exposed to about 800 to 1
The treatment can be carried out by standing at 000° C. for about 1 to 2 hours. In this case, the entirety of each ceramic member of the materials to be joined may be oxidized, or only the joint portion may be oxidized. The bonding material used in the present invention may be selected depending on the functional properties of the type of ceramic used for each ceramic member to be bonded, and the usage conditions of the resulting bonded body. Preferably, an inorganic bonding material mainly composed of ceramics of the same type as those forming the objects to be bonded or SiO2, which is melted and fluidized by heating, is preferably used. Inorganic bonding materials containing SiO2 as a main component include bonding materials containing 50% by weight or more of SiO2, such as the above-mentioned borosilicate glass commonly used for ceramic bonding, aluminoborosilicate glass, aluminosilicate glass, Examples include glass bonding materials such as silicate glass. The above-mentioned inorganic bonding material is usually used as a powder in the form of a slurry or paste, using a solvent such as water or alcohol, and adding a binder if necessary. In this case, in order to obtain a homogeneous joint, the average particle size of the glass bonding material should be as fine as possible, preferably 1 μm or less.

[0010] The normal joining procedure in the present invention is to apply a bonding material paste to at least one of the joining surfaces of the two or more oxidized members to be joined, which constitute the joining part of the ceramic joined body, and to After joining the joint surfaces of the parts together, dry in the atmosphere at about 100 to 150°C for about 1 to 2 hours,
This can be carried out by further calcining at about 400 to 500[deg.] C. for about 0.5 to 3 hours, followed by heat treatment in vacuum under reduced pressure to melt the bonding material, and then cooling and solidifying. The heat treatment temperature and time in this case can be appropriately selected depending on the type of bonding material used and the shape and thickness of the bonded portion. Normally, heat treatment at 1150 to 1400°C for about 1 to 5 hours is sufficient. If the heat treatment temperature is lower than 1150°C, the entire applied bonding material forming the joint will not be melted uniformly, resulting in a homogeneous bond. can't get the part. In addition, if the temperature exceeds 1400°C, some of the components of the joining material and the parts to be joined will evaporate significantly, so the joint interface between the joint part and the parts to be joined will likely become porous, resulting in poor airtightness and reduced strength. This is not preferable because it lowers the temperature. The thickness of the bonding material to be applied is not particularly limited. Usually about 0.
The thickness may be 0.05 to 5 mm. It can be selected as appropriate depending on the shape and material of the joining member, the structure of the joining part, the strength required for the joining part, etc.

[0011]

Embodiments Below, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to this example. Example 1 (Preparation of bonding material) Approximately 60% by weight of water was added to commercially available powdered borosilicate glass powder, and the mixture was heated in a vibration mill using an alumina cobblestone for approximately 30% by weight.
The mixture was mixed and ground for a period of time to obtain fine borosilicate glass powder with an average particle size of 0.5 μm. The obtained finely 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 100 parts by weight of the obtained paste-like borosilicate glass and mixed to prepare a bonding material paste.

(Oxidation treatment of members to be joined) S of members to be joined
Two i3 N4 cylinders with a diameter of 20 mmφ and a height of 20 mm were oxidized by being left at about 1000° C. for 1 hour in an electric furnace in an oxygen atmosphere to obtain oxidized Si3 N4 members to be joined.

(Joining) Obtained oxidized Si3 N4
As shown in the cross-sectional diagram of FIG. 1, the two manufactured members to be joined are
Approximately 100 μm of the prepared paste-like bonding material was applied to the bottom surface of each member 1 to be bonded to form the bonded portion A, and the plate-like bodies were pressed together. After that, it was dried in an electric furnace at 120°C for about 1 hour, the temperature was further raised, and after calcining at about 500°C for about 1 hour, the inside of the electric furnace was evacuated and the temperature was further raised to about 1150°C. After being heat-treated for 1 hour, it was left to stand and cooled to obtain a bonded body. After cooling, take out the joined body and JIS
The bonding strength of the bonded portion at room temperature was measured according to R-1601. The results are shown in Table 1.

[0014]

[Table 1]

Comparative Example 1 A bonded body was obtained in exactly the same manner as in Example 1, except that the bonded members were used as they were without being oxidized and the heat treatment was performed in the atmosphere. The bonding strength of the bonded portion of the obtained bonded body was measured in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 2 A bonded body was obtained in exactly the same manner as in Example 1, except that the bonding members were used as they were without being oxidized. The bonding strength of the bonded portion of the obtained bonded body was measured in the same manner as in Example 1. The results are shown in Table 1.

Examples 2 to 4 A cylinder made of Si3N4 with a diameter of 6.5 mmφ and a height of 50 mm and a cylinder with a diameter of 18 mmφ and a height of 10 mm.
Each of the cylinders with a bottom, which has a hole in the center of the bottom into which the cylinder of one of the members to be joined can be inserted, was oxidized at a temperature of 8 mm.
Oxidation treatment S was performed in the same manner as in Example 1 except that the temperature was 00°C.
Three pieces of each member to be joined made of i3 N4 were obtained. The resulting oxidized Si3N4 member to be joined is shown in Figure 2.
As shown in the cross-sectional explanatory diagram, the cylinder 2 of the welded member is embedded in the hole at the bottom of the cylinder 3 with the bottom of the joining member, and around the bottom of the cylinder 3 with the bottom and the cylinder 2 orthogonal to the bottom, the cylinder 2 of Example 1 is embedded. The same bonding material paste was applied. The coating thickness of the bonding material was approximately 5 mm. Thereafter, the bonded bodies were dried and calcined in the same manner as in Example 1, and then processed in the same manner as in Example 1, except that each bonded body was heat-treated at the temperatures shown in Table 1 to obtain bonded bodies. The joint strength of the joints of each of the obtained joined bodies was measured by a cantilever bending test. In addition, in the leak test machine shown in FIG. 4, when the bonded body 10 was set in a predetermined bonded body support jig 11 and immersed in water, and the inside of the pipe 12 was pressurized at a pressure of 8 kg/cm2, the leakage occurred. A leak test was conducted by measuring the volume of bubbles per second (milliliter/second).
Sealing performance was measured. The results are shown in Table 1.

Example 5 A bonded body was obtained in exactly the same manner as in Example 1 except that the oxidation treatment temperature was 800°C and the vacuum heat treatment temperature was 1400°C. The bonding strength of the bonded portion of the obtained bonded body was measured in the same manner as in Example 1. The results are shown in Table 1.

Example 6 Three circular pipes made of Si3N4 with an outer diameter of 6.5 mmφ, an inner diameter of 4.5 mmφ and a height of 100 mm were used as members to be joined, and
Example 1 except that each of three bottomed cylinders with a diameter of 0 mm and a height of 10 mm and having three holes in the bottom into which the circular pipes of the members to be joined were inserted was oxidized at a temperature of 800° C. for 2 hours. Each member to be joined made of oxidized Si3N4 was obtained in the same manner as above. The obtained oxidized Si3N
As shown in the cross-sectional diagram of FIG.
One end of the three circular tubes 4 of the members to be joined is embedded in each hole in the bottom of the cylinder 5 with the bottom of the joining member, and the cylindrical tubes 4 of Example 1 are placed around the bottom of the cylinder 5 with the bottom and each circular tube 4 perpendicular to the bottom A similar bonding material paste was applied. The coating thickness of the bonding material was approximately 5 mm. Thereafter, it was dried and calcined in the same manner as in Example 1, and then
A bonded body was obtained in the same manner as in Example 1, except that the bonded body was heat-treated at the temperature shown in Table 1. The sealing properties of each of the obtained joined bodies were measured in the same manner as in Example 2. The results are shown in Table 1.

Comparative Example 3 A bonded body was obtained in exactly the same manner as in Example 6, except that the bonded members were used as they were without being oxidized and heat treated in the atmosphere at the temperatures shown in Table 1. The sealing performance of the joint portion of the obtained joined body was measured in the same manner as in Example 6. The results are shown in Table 1.

From the above Examples and Comparative Examples, it can be seen that the ceramic bonding of the present invention is excellent in strength, has no leakage at the bonded joints, etc., and has extremely high sealing performance. In addition, in Examples 2 to 4 and Example 6, the cylindrical portion of the cylinder 3 used as the member to be joined was subjected to vacuum heat treatment.
Even if the bonding material melts and fluidizes, the present invention has the advantage that the molten bonding material does not flow out to the outside, and the present invention is applied to ceramic bonding in which a large number of cylinders and pipes are bonded and fixed in the holes of a plate-shaped body. It is suitable for

[0022]

[Effects of the Invention] The ceramic bonding method of the present invention can produce a ceramic bonded body that has extremely few pores in the bonded area, is homogeneous throughout the bonded area, has high bonding strength, and has high sealing performance, and is extremely useful industrially. It is.

[Brief explanation of drawings]

FIG. 1 is an explanatory cross-sectional diagram showing a ceramic bonded body according to an embodiment of the present invention.

[Fig. 2] A cross-sectional explanatory diagram showing a ceramic bonded body according to an embodiment of the present invention.

FIG. 3 is an explanatory cross-sectional view showing a ceramic bonded body according to an embodiment of the present invention.

[Figure 4] Leak tester for evaluating the sealing performance of the joined body in the present invention

[Fig. 5] Cross-sectional explanatory diagram showing an example of conventional mechanical ceramic bonding

[Explanation of symbols]

A Joint part 1 Cylindrical member to be joined 2 Cylindrical member to be joined 3 Cylindrical member to be joined with perforated bottom 4 Circular pipe joined member 5 Cylindrical member to be joined with perforated bottom 10 Zygote 11　Joint body support jig 12 Pipe

Claims (1)

[Claims] Claim 1: After oxidizing at least two ceramic members constituting a ceramic joined body, SiO
1. A ceramic bonding method characterized by bonding by heat treatment in vacuum using an inorganic bonding material containing 2 as a main component.