WO2013035613A1

WO2013035613A1 - Bonded ceramic and process for producing same

Info

Publication number: WO2013035613A1
Application number: PCT/JP2012/071952
Authority: WO
Inventors: 井筒　靖久; 峻有馬; 近藤　直樹; 幹則堀田; 英紀北
Original assignee: 三井金属鉱業株式会社
Priority date: 2011-09-05
Filing date: 2012-08-30
Publication date: 2013-03-14
Also published as: JP5959170B2; KR20140071279A; JP2013053047A; CN103596903A

Abstract

A bonded ceramic obtained by bonding silicon nitride ceramic adherends to each other through a bonding portion comprising both silicon nitride particles and a silicon oxynitride glass. The bonding portion has a fine structure in which silicon nitride particles and a silicon oxynitride glass are observed. When a cross-section of the bonding portion is examined two-dimensionally, the ratio of the amount of the silicon oxynitride glass to the total amount of the silicon nitride particles and the silicon oxynitride glass, in the field of view, is 97:3 to 60:40. The silicon nitride particles contained in the bonding portion are columnar.

Description

Ceramic bonded body and manufacturing method thereof

The present invention relates to a ceramic joined body and a manufacturing method thereof.

Various methods for joining materials to be joined made of silicon nitride ceramics have been proposed. For example, (1) a method using a low-melting-point bonding material having several kinds of oxide glass compositions, (2) a method using physical pressing such as hot pressing in combination when using the same silicon nitride composition bonding material, (3) There has been proposed a method in which silicon metal is directly nitrided and integrated with a base material, or a low melting point metal is used as a brazing material.

Specifically, Patent Document 1 discloses silicon nitride ceramics containing Y ₂ O ₃ and Yb ₂ O ₃ as sintering aids, Y ₂ O ₃ , Al ₂ O ₃ , SiO ₂ and Si ₃ N _4. Joining with an oxynitride glass consisting of

In Patent Document 2, a silicon nitride rod is inserted into a hole of a disk-shaped silicon nitride perforated plate, and CeO ₂ , SrCO ₃ , MgO, Al ₂ O ₃ , SiO is inserted into a circular joint formed by the both. After applying a bonding agent composed of ₂ and Si ₃ N ₄ , heating at 1500 ° C. for 1 hour is described.

Patent Document 3 includes (a) a step of preparing a first raw material containing silicon particles, (b) a step of forming a molded body from the first raw material, and (c) silicon particles in the molded body. A step of reactive sintering, (d) a step of preparing a second raw material similar to the first raw material, (e) a step of preparing a slurry from the second raw material, and (f) a bonding material after The step of injecting the slurry into the gap between the formed members to be formed to form a bonding material, and (g) the silicon particles in the bonding material by the reaction sintering process similar to step (c). A joining method having a step of reactive sintering is described.

In Patent Document 4, a bonding agent mainly composed of glass containing aluminum, silicon, and yttrium is applied to one or both main surfaces of a pair of plate-like substrates made of a silicon nitride sintered body containing lutetium. A method for manufacturing a ceramic joined body is described, which includes a step and a step of joining the main surfaces of a pair of bases by heat treatment in a non-oxidizing atmosphere.

Japanese Patent Laid-Open No. 5-4876 JP-A-5-270933 JP 2010-138038 A JP 2010-150048 A

As described above, various joining methods have been proposed. However, when a low-melting-point joining material is used, the heat resistance and chemical reactivity resistance of the joining portion tend to be inferior. When physical press bonding such as hot pressing is used, a special large-sized manufacturing apparatus is required to manufacture a long tubular member. When a bonding material that directly nitrides silicon metal is used, silicon metal that is poor in heat resistance due to insufficient nitriding tends to remain in the bonding material.

Therefore, an object of the present invention is to provide a ceramic joined body that can eliminate the various drawbacks of the above-described prior art and a method for manufacturing the same.

The present invention is a ceramic joined body in which silicon nitride ceramics joined materials are joined via a joining part containing silicon nitride particles and silicon oxynitride glass,
In the two-dimensional cross-sectional observation of the microstructure of the bonding site, the ratio of silicon nitride particles to silicon oxynitride glass is 97: 3 to 60:40,
In addition, the present invention provides a ceramic joined body in which the silicon nitride particles contained in the joining portion are columnar.

Further, the present invention provides a method for producing a ceramic joined body as described above, wherein a silicon nitride ceramic material to be joined is joined to each other via a joining portion containing silicon nitride particles and silicon oxynitride glass. A method,
Between the materials to be bonded, a bonding material including a mixed powder having a composition capable of forming a bonding portion including silicon nitride particles and silicon oxynitride glass after heating is interposed,
The present invention provides a method for producing a ceramic joined body, in which the joining parts are heated under a state where the joining parts of the materials to be joined are pressurized.

The ceramic bonded body of the present invention has a bonding portion having a high bonding strength close to the strength of the material to be bonded. In addition, the bonded ceramic body of the present invention can maintain bonding strength even after it is exposed to a high-temperature oxidizing atmosphere.

FIG. 1 is a schematic diagram illustrating a state in which a material to be bonded is bonded using a bonding material made of a green sheet. 2A and 2B are schematic views showing a state in which the materials to be joined having a fitting structure are joined together. FIG. 2 is a schematic view showing a state in which the materials to be joined are joined using the inner sleeve. 4 (a) to 4 (d) are schematic views sequentially showing steps for producing a ceramic joined body using an apparatus suitably used for carrying out the production method of the present invention.

Hereinafter, the present invention will be described based on preferred embodiments thereof. The ceramic joined body of the present invention is formed by joining silicon nitride ceramic materials to be joined to each other through a joining portion. The two materials to be bonded that are bonded via the bonding site can take various shapes depending on the intended use of the ceramic bonded body. For example, it can take the shape of a hexahedron such as a rectangular parallelepiped or a cube, a rod-like body having a smooth end face, a tubular body, or the like. Further, the material to be joined may be either a solid body or a hollow body. However, it is preferable that the two materials to be joined have portions that are in surface contact with each other. By having the said part, the intensity | strength of the ceramic joined body in a joining part can fully be raised.

The two materials to be joined that are joined via the joining site may have the same shape or different shapes. Examples of the material to be joined having the same shape include a rod shape and a tubular shape. As the materials to be joined having different shapes, for example, as described in the background section, a disc-like shape having a perforated portion in the center and a rod-like shape having a cross-sectional shape that can be inserted into the perforated portion. Is mentioned.

As long as the main material is silicon nitride ceramics, the two materials to be bonded to each other through the bonding site may be of the same composition, or may contain a small amount of a third component such as a sintering aid. May be different.

The ceramic joined body of the present invention may be obtained by joining three or more materials to be joined according to the specific application. In that case, the ceramic bonded body may have two or more bonding sites.

In the ceramic joined body, it is preferable that the joining portion has a chemical composition and a microstructure that are continuous from a material to be joined that is a base material. In addition, it is desirable that there is little compositional difference between the bonding site and the material to be bonded around the bonding site. From these points of view, it is advantageous that the bonding portion has silicon nitride, which is the main material of the material to be bonded, as the main material of the crystal phase. It is known that at least one of α-silicon nitride and β-silicon nitride, which are two types of compounds having different crystal structures, is present in the silicon nitride contained in the bonding site. In addition, β-sialon, which is a substance in which a part of Si in β-silicon nitride is replaced by Al and a part of O is replaced by N may be present as a crystalline phase at the bonding site. In short, one or more kinds of α-silicon nitride, β-silicon nitride, and β-sialon are present as crystal phases at the bonding site. Regarding the description of the bonding sites described below, unless otherwise specified, “silicon nitride” means one or more of α-silicon nitride, β-silicon nitride, and β-sialon.

It is preferable from the viewpoint of increasing the strength of the bonded portion that the bonded portion contains at least a β-sialon crystal phase. In general, the proportion of β-sialon present in the bonding portion is lower than the proportion of silicon nitride present in the portion. However, the proportion of β-sialon present at the bonding site and the proportion of silicon nitride are not so important in achieving the object of the present invention. Furthermore, the joining site may contain a small amount of a third component such as a sintering aid.

Whether or not the bonding site contains α-silicon nitride, β-silicon nitride or β-sialon can be determined by identifying the crystal phase included in the bonding site, for example, by X-ray diffraction.

Since silicon nitride contained in the bonding site is a hardly sintered material, it is advantageous to add an oxide such as glass to the bonding site so that the glass fills the space between the silicon nitride crystal particles. is there. The glass existing between the silicon nitride crystal particles is silicon oxynitride glass in which a part of O in the SiO ₂ glass is incorporated into the silicon nitride crystal.

It is desirable that the bonding site has a structure in which silicon nitride, which is the main material of the material to be bonded, is used as the main material of the crystal phase, and silicon oxynitride glass is filled between the crystal particles. As described above, one or more of α-silicon nitride, β-silicon nitride, and β-sialon may be present as the silicon nitride crystal phase. In addition, the silicon oxynitride glass may contain one or more metal elements commonly used as a sintering aid for silicon nitride, such as Al, Y, Mg, Zr, and Yb. The ratio of silicon nitride particles to silicon oxynitride glass is preferably 97: 3 to 60:40, and more preferably 95: 5 to 65:35. By setting the ratio between the two in this range, a dense bonded portion can be easily obtained, and deterioration of the bonded portion, for example, strength after holding for a predetermined time in a high-temperature oxidizing atmosphere is hardly deteriorated. The ratio between the silicon nitride particles and the silicon oxynitride glass is obtained, for example, by image analysis of a two-dimensional cross-sectional structure observation image obtained by a scanning electron microscope (SEM) in which the bonding portion is enlarged by about 500 to 5000 times. be able to. For example, if various commercially available computer software are used for image analysis, this ratio can be easily obtained. By observing the structure of the bonding site, the difference between the silicon nitride crystal phase and the silicon oxynitride glass can be clearly distinguished.

The ceramic joined body has one of the characteristics in the microstructure of the joining portion. Specifically, columnar particles and spherical particles are observed as crystal grains at the bonding site when the bonding site is observed with a microscope. As described above, the joining portion is configured to include silicon nitride and β-sialon, and the columnar particles and spherical particles are configured to include silicon nitride and β-sialon as a crystal phase. Specifically, the columnar particles mainly contain β-silicon nitride and β-sialon as crystal phases. On the other hand, the spherical particles mainly contain α-silicon nitride as a crystal phase. As a result of studies by the present inventors on columnar particles and spherical particles, it has been found that the columnar particles mainly containing β-silicon nitride and β-sialon greatly contribute to the improvement of the strength of the bonded portion. When the present inventors further advanced the study, it was found that the balance between the presence of the columnar particles and the spherical particles in the joining site greatly affects the joining strength of the joining site. Specifically, when the joining portion includes columnar particles and spherical particles in a predetermined balance, the joining portion has a high joining strength close to the strength of the material to be joined. The columnar particles contained in the bonding part mean particles having an aspect ratio (major axis / minor axis) of 2 or more in the structure observation of the cross section of the bonding part.

Β-silicon nitride and β-sialon present at the bonding site are mainly contained in the columnar particles, and the average aspect ratio (major axis / minor axis) of the columnar particles is preferably 2 to 30, and more preferably 2. It is 7 to 20, more preferably 2.7 to 15. By causing the columnar particles having such an aspect ratio to exist at the bonding site, the bonding strength and fracture toughness of the bonding site can be easily increased. The long axis of the columnar particles refers to the line segment that has the longest line segment that crosses the columnar particles in a two-dimensional image of the columnar particles obtained by observing the bonding site with a microscope. The short axis refers to the component that is perpendicular to the long axis and has the shortest line segment across the columnar particle. The aspect ratio of the columnar particles can be determined by, for example, performing a two-dimensional cross-sectional structure observation with a scanning electron microscope (SEM) in which the bonding site is enlarged by about 500 to 5,000 times, and arbitrarily selecting particles within the observation field. Measure aspect ratio. Among the measured particles, the arithmetic average of the aspect ratio is obtained for 1000 or more particles having an aspect ratio of 2 or more.

The spherical particles present at the bonding site do not require that the two-dimensional image of the spherical particles obtained by observing the bonding site under a microscope is a perfect circle, but may be a circle that can be regarded as a perfect circle. When the spherical particles are not perfect circles, the aspect ratio (major axis / minor axis) of the spherical particles may be less than 2.

The balance between the columnar particles and the spherical particles at the bonding site may be set such that the ratio of the columnar particles to the total amount of the columnar particles and the spherical particles in the observation field is preferably 10 to 30%, more preferably 15 to 30%. As a result of the examination by the present inventors, it has been found that this is advantageous. This ratio is calculated by calculating the total area of the area of the two-dimensional image of the columnar particles and the area of the two-dimensional image of the spherical particles, which is measured by microscopic observation of the bonding site at a magnification of about 500 to 5000 times. Is divided by the total area and multiplied by 100. This ratio can be calculated, for example, by image analysis of a microscope observation image of the bonded portion.

The size of the silicon nitride particles present at the bonding site depends on the particle size of the mixed powder constituting the bonding material described later, and is generally equal to or larger than the particle size of the particles constituting the mixed powder. In particular, it is desirable that those having a particle diameter of 0.7 μm or more exist in an amount of 15% or more on a volume basis.

The thickness of the bonding site, that is, the distance between the two materials to be bonded should be 50 to 500 μm, particularly 50 to 300 μm, especially 50 to 100 μm, so that a uniform and high bonding strength bonding site can be formed. It is preferable from the viewpoint.

In order to form a bonded portion having the above microstructure, the ceramic bonded body of the present invention may be manufactured, for example, by the method described below.

In order to carry out the manufacturing method of the present invention, two silicon nitride ceramics that are materials to be joined are arranged so that their joint surfaces face each other. Further, a bonding material having a composition capable of forming a bonded portion including silicon nitride particles and silicon oxynitride glass after heating is interposed between the two bonded materials. By heating the bonding material sandwiched between the two materials to be bonded, a bonding site including silicon nitride particles and silicon oxynitride glass is formed, and the materials to be bonded are bonded.

The mixed powder described above preferably contains silicon nitride particles. From the viewpoint of production of silicon oxynitride glass, we are also preferred to include particles of silicon dioxide (SiO _2). From the viewpoint of production of sialon, it is also preferred to include particles of alumina (Al ₂ O _3). The proportion of silicon nitride contained in the mixed powder is generally preferably 20 to 35% by mass. The proportion of silicon dioxide is generally preferably 10 to 20% by mass. The proportion of alumina is generally preferably 5 to 15% by mass. In addition to these, the above-mentioned mixed powder may contain various oxides known as sintering aids, such as Y ₂ O ₃ , CaO, MgO, ZrO ₂ , Yb ₂ O _{3 and the} like. Good. In particular, Y is an element having a high effect of extending silicon nitride crystal grains in a columnar shape. These various oxides are generally preferably contained in the mixed powder in an amount of 35 to 55% by mass as a total amount.

The bonding material contains silicon nitride particles in excess relative to the amount of silicon oxynitride glass formed under high temperature heating for bonding, and part of the silicon nitride particles remain as solid phase particles in the silicon oxynitride glass. It is desirable to make such a composition. The remaining silicon nitride particles that are not completely dissolved in the silicon oxynitride glass change into columnar particles in the glass during heating and holding during bonding. As will be described later, when α-silicon nitride is used as the silicon nitride particles, almost all is converted to β-silicon nitride or β-sialon, but when the temperature is low and the holding time is short, a part of α-silicon nitride is used. May remain. Although α-silicon nitride may remain, α-silicon nitride has an equiaxed particle shape and is not advantageous for obtaining the strength of the binding site.

In particular, from the viewpoint of forming silicon oxynitride glass and from the viewpoint of generating columnar silicon nitride particles, nitrogen is contained in the mixed powder in an amount of 25 equivalent% or more, particularly 25 to 60 equivalent%, particularly 35 to 55 equivalent%. It is desirable. “Equivalent%” is a notation method that takes into account the valence of ions in the glass, and is often used to indicate the composition of silicon oxynitride glass. For each of the cation and the anion in the glass, the sum of the product of the number of atoms and the valence is expressed as 100%, and the total is 200%.

Particularly in this production method, it is advantageous to use α-silicon nitride as silicon nitride. As described above, it is known that silicon nitride includes α-silicon nitride and β-silicon nitride, which are two types of compounds having different crystal structures. Of these two types of silicon nitride, In the present invention, it is advantageous to use α-silicon nitride because it is possible to easily form the joint portion composed of the microstructure including both the columnar particles and the spherical particles described above. The reason for this is based on the knowledge of the present inventors that when α-silicon nitride is used as silicon nitride, a bonded portion having a dense structure can be formed as compared with the case where β-silicon nitride is used. In addition, the inventors' knowledge that when α-silicon nitride is used as silicon nitride, a bonded portion having a high bonding strength can be formed even when heated at a lower temperature than when β-silicon nitride is used. Is also based. However, in the present invention, it is not hindered to use β-silicon nitride as silicon nitride.

In this production method, the average particle size of the mixed powder used to form the bonded site is preferably 0.4 to 5.0 μm, more preferably 0.4 to 3.0 μm, and still more preferably 0.4 to It is also advantageous to use 2.0 μm. When a mixed powder having an average particle size within this range is used, the fluidity of the mixed powder becomes moderately high and exhibits good wettability when forming a bonded portion by heating. As a result of the study by the present inventors, it was found that the mixed powder spreads sufficiently between the two materials to be joined and the generation of gaps was reduced. If a mixed powder having a particle size smaller than the range of the average particle size is used, the fluidity of the mixed powder may not be sufficiently high, and the wettability may be low. Further, when a mixed powder having a particle size larger than the average particle size range is used, the bonded portion may not be sufficiently densified and the strength may not be obtained.

The average particle diameter of the mixed powder is measured using, for example, a particle size distribution measuring device by a laser diffraction method. In order to set the average particle diameter of the mixed powder within the above-described range, the mixed powder may be subjected to a treatment such as pulverization by a mill or the like using ceramic balls or the like as a medium.

高温 Excess silicon oxynitride glass contained in the bonded portion is diffused into the material to be bonded under high temperature heating for bonding. In addition, the β-silicon nitride or β-sialon crystal phase generated at the bonding site by high-temperature heating is elongated by the heating and holding under high temperature during bonding, and grain growth results in columnar particles. It is desirable from the viewpoint of obtaining the strength of the part. In order to reduce the composition difference between the bonding site and the material to be bonded around the bonding site and to elongate and grow β-silicon nitride or β-sialon columnar particles in the bonding site, the heating temperature can be increased, It is effective to increase the holding time. On the other hand, silicon nitride or silicon oxynitride glass decomposes and evaporates at a high temperature, and this occurs remarkably when the temperature exceeds 1750 ° C. in an atmospheric pressure nitrogen atmosphere. In addition, when performing bonding, in order to make it difficult for defective bonding to occur and to complete the bonding in a short time, mechanical pressure is applied in a direction orthogonal to the bonding surfaces of the bonded materials, It is effective to bring the bonding material into close contact.

The mixed powder used for forming the bonding site can be mixed with a liquid such as water or an organic solvent to prepare a slurry having a predetermined concentration, and the slurry can be applied to the bonding surface of the materials to be bonded. . Alternatively, a green sheet can be formed from the slurry, and the green sheet can be disposed on the joining surface of the materials to be joined. It is advantageous to use a green sheet from the viewpoints of ease of work, reliability of arrangement, and the like, and from the viewpoint of forming a joint portion having a uniform thickness. For example, as shown in FIG. 1, when joining the joining materials 2 made of mixed powder between the end faces with the end faces of the joined

materials

1a and 1b made of tubular bodies having the same shape facing each other, the joining material 2 An annular green sheet can be used.

In addition, as shown in FIGS. 2 (a) and 2 (b), when joining two materials to be joined 1a, 1b having a long shape in one direction such as a tubular body or a rod-like body, end faces of the materials to be joined 1a, 1b. However, when the end surfaces are brought into contact with each other so that the positions of the axes of the materials to be bonded 1a and 1b are aligned, it is easy to align the axes of the materials to be bonded 1a and 1b. It is preferable because it is possible. Specifically, as shown in FIG. 2 (a), the end surface 11a of one material to be bonded 1a is tapered, and the end surface 11b of the other material to be bonded 1b corresponds to the inclination angle of the tapered shape. It can be formed into a mortar shape having an inclination. Further, as shown in FIG. 2B, the end surface 11a of one material to be bonded 1a has a stepped shape having a convex portion, and the end surface 11b of the other material to be bonded 1b corresponds to the shape of the convex portion. It can be made into the shape which has the recessed part made. In FIGS. 2A and 2B, illustration of the bonding material is omitted.

Furthermore, when the material to be joined has a shape that is long in one direction, such as a tubular body or a rod-like body, an inner sleeve for aligning the axis of the material to be joined can also be interposed at the joining site. Even if it does in this way, since the axial center alignment of two to-be-joined materials can be made easy, it is preferable. The inner sleeve also has a role as a reinforcing material for the joint portion. For example, as shown in FIG. 3, when the two materials to be joined 1a and 1b are tubular bodies, the inner sleeve 3 that can be inserted into the materials to be joined 1a and 1b is joined to both the materials to be joined 1a and 1b. Intervene in the site. The inner sleeve 3 is tubular or rod-shaped, and has a protrusion 3a on the side surface in a substantially central region along the longitudinal direction. The protrusion 3 a is continuously formed over the entire area of the inner sleeve 3 in the circumferential direction. On the other hand, the end surfaces of the materials to be bonded 1a and 1b have a first end surface 12 located on the outer peripheral side and a second end surface 13 located on the inner peripheral side and lower than the first end surface 12. It has a step structure. When the first end surfaces 12 of the materials to be bonded 1a and 1b are brought into contact with each other, a thin portion is formed on the inner walls of the materials to be bonded 1a and 1b due to the step between the first end surface 12 and the second end surface 13. It is formed. By fitting the protruding portion 3a of the inner sleeve 3 into the thin portion, the two

materials

1a and 1b can be easily aligned with each other. Also in FIG. 3, illustration of the bonding material is omitted.

The material of the inner sleeve 3 may be the same as or different from the material of the base material. Further, the inner sleeve 3 may be made of a material that remains even after the joining portion is formed by heating, or may be made of a material that disappears by heating.

It should be noted that the fitting structure shown in FIG. 2A or 2B and the inner sleeve 3 shown in FIG. 3 can be used in combination.

The heating of the bonding material disposed between the two bonded

materials

1a and 1b is preferably performed in the range of 1500 to 1750 ° C., particularly 1550 to 1730 ° C., particularly 1600 to 1700 ° C. By heating at a temperature in this range, a bonded portion having a dense structure can be generated. The heating atmosphere is preferably a nitrogen atmosphere.

When the heating temperature is within the above range, the heating time is preferably set to 0.5 to 12 hours, particularly 1 to 6 hours. By heating for this time, the compositional difference between the bonded portion and the material to be bonded around the bonded portion decreases due to diffusion of the silicon oxynitride glass, and the β-silicon nitride or β-sialon columnar particles in the bonded portion are reduced. A desired balance is achieved, and a bonded portion having a composition and structure closer to the material to be bonded can be successfully formed.

During heating, it is advantageous to pressurize the two materials to be joined that are in contact with each other in a direction facing each other. By doing so, it is possible to successfully form a bonded portion having a dense structure. From this point of view, it is preferable that the pressurizing pressure is set to 0.01 to 5 MPa, particularly 0.1 to 5 MPa, particularly 1 to 5 MPa.

Further, during heating, the two materials to be joined are rotated in the same direction around the axis perpendicular to the joining surface of the materials to be joined, and the two materials are rotated at the same speed. It is preferable to keep it. This operation is effective when joining materials to be joined that are long in one direction in series in the longitudinal direction. By this rotation, the downward sag due to the gravity of the bonding material at a high temperature during heating is suppressed, and the bending of the bonded body can be prevented. In addition, it can suppress that a joining material flows out to the lower part side of a joined part. From the viewpoint of making this effect even more remarkable, it is preferable to set the rotational speed to a low speed of 1 to 5 rpm, particularly 3 to 5 rpm. If rotation is not performed, the bonding material may flow out, resulting in a defect of insufficient strength due to insufficient bonding material.

The formation of the bonding site by heating the bonding material may be completed by only one heating, or may be performed two or more times as necessary. In general, it is possible to form a bonded portion having a microstructure that is satisfactory only by one heating.

In the ceramic joined body obtained by the manufacturing method of the present invention, the strength of the joined portion is close to the strength of the workpiece to be joined. Specifically, in the ceramic joined body obtained by the manufacturing method of the present invention, the four-point bending strength of the joined portion is preferably 50% or more with respect to the four-point bending strength (JIS-R1601) of the material to be joined. More preferably, it is 60% or more, more preferably 70% or more.

Furthermore, in the ceramic joined body obtained by the manufacturing method of the present invention, even when this is repeated in an air atmosphere at 900 ° C. for 1 hour a plurality of times, a joining strength equivalent to that before the exposure is maintained at the joining site. . Specifically, the four-point bending strength after exposure is preferably 70% or more, more preferably 80% or more, and even more preferably 85% or more with respect to the four-point bending strength (JIS R1601) before exposure. Yes.

4 (a) to 4 (d) schematically show steps of manufacturing a ceramic joined body in order by an apparatus suitably used for carrying out the manufacturing method of the present invention. The apparatus shown in the figure is particularly preferably used for joining tubular or rod-like materials to be joined.

First, as shown in FIG. 4A, the two materials to be bonded 1a and 1b to be bonded are each gripped by the chuck 20. The gripping by the chuck 20 is performed so that the two

workpieces

1a and 1b are held horizontally. Each chuck 20 is slidably mounted on the pedestal 21. When the end surfaces of the materials to be bonded 1a and 1b are opposed to each other at a predetermined distance and the bonding material 2 is disposed between the end surfaces, one chuck 20 is moved in the direction indicated by the arrow in FIG. The bonding material 2 is sandwiched between the bonded

materials

1a and 1b.

When the

materials

1a and 1b to be joined have a shape such as a round tube or a round bar, the outer diameter thereof is 5 to 60 mm, particularly 10 to 45 mm, especially 10 to 30 mm. It is preferable from the point of reliable joining. In addition, when the materials to be joined 1a and 1b have a shape such as a round tube or a round bar, the joining can be performed even if the upper limit value of the length is 2000 mm. There is no limit to the lower limit of the length, and the shorter the length, the easier the joining.

Next, as shown in FIG. 4B, the

workpieces

1a and 1b are rotated around the axis by a rotation mechanism (not shown) provided in the chuck 20. Along with this rotation, the two chucks 20 are moved in the direction indicated by the arrows in the drawing, and the contact portions of the two materials to be joined 1 a and 1 b are introduced into the heating furnace 22. At this time, in order to prevent the joining material 2 from falling off, it is advantageous to pressurize the materials to be joined 1a and 1b in directions facing each other in the axial direction.

When the contact portions of the two materials to be bonded 1a and 1b are introduced into the heating furnace 22, the heating furnace 22 is heated while continuing to rotate the materials to be bonded 1a and 1b as shown in FIG. Starting, the bonding material 2 located at the contact portion is heated. During heating, the

materials

1a and 1b are continuously rotated. Further, during heating, the bonded

materials

1a and 1b are pressurized in a direction facing each other in the axial direction. By holding the materials to be bonded 1a and 1b horizontally and heating them while rotating around their axes, it is possible to form a bonded portion having a desired microstructure.

¡Heating is performed at a desired temperature and time, and when the target joining portion is formed, heating by the heating furnace 22 is stopped. However, the rotation of the materials to be joined 1a and 1b is continued even after the heating is stopped. When the heating furnace 22 is cooled to room temperature, the rotation of the

materials

1a and 1b to be joined is stopped, the chuck 20 is moved, and the joining portion is taken out of the heating furnace 22. In this way, a ceramic joined body is obtained. When it is desired to increase the length of the ceramic joined body, as shown in FIG. 4 (d), a material to be joined 1c is prepared, and the end surface of the material to be joined 1c and the end surface of the material to be joined 1b are predetermined. The bonding material 2 is disposed between both end faces so as to face each other at a distance. Thereafter, an operation similar to the above-described operation is performed to obtain a long ceramic joined body in which three materials to be joined 1a, 1b, and 1c are connected in series along their longitudinal directions. By repeating the above operation, a long ceramic joined body having a desired length can be obtained.

As described above, according to the method shown in FIG. 4, a material to be joined having a long shape extending in one direction such as a tubular shape or a rod shape can be easily manufactured with a compact facility.

The ceramic joined body thus obtained includes, for example, firing furnace members such as heater tubes, thermocouple protection tubes, rotary kiln furnace core tubes, roller hearth kiln rollers, lining materials, liners, stirring blade materials, steel plates It is useful in many applications such as wear-resistant mechanical device members such as transport rollers, and pipe members for transporting chemicals and slurries.

As mentioned above, although this invention was demonstrated based on the preferable embodiment, this invention is not restrict | limited to the said embodiment. For example, in the apparatus shown in FIG. 4, heating the

target materials

1a and 1b while rotating the

materials

1a and 1b around the axis orthogonal to the joining surfaces of the

materials

1a and 1b succeeds. Although it is advantageous from the viewpoint of forming well, heating may be performed while rotating in other directions.

Further, in the apparatus shown in FIG. 4, the materials to be bonded 1 a and 1 b are rotated so that the axes of the materials to be bonded 1 a and 1 b are located in a horizontal plane. You may rotate so that the axis | shaft of 1b may be located in a vertical plane.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the scope of the present invention is not limited to such examples.

[Example 1]
As a material to be joined, two silicon nitride pipes having an outer diameter of 28 mm, an inner diameter of 22 mm, and a length of 1000 mm were prepared. These two pipes had a fitting structure shown in FIG. Moreover, the inner sleeve shown in FIG. 3 was also used. The inner sleeve was made of silicon nitride, which is the same material as the pipe. As a bonding material, a mixed powder having the composition and average particle size shown in Table 1 below was used. This mixed powder was mixed with ethanol to prepare a slurry, and a green sheet was produced from the slurry by a conventional method. The green sheet was annular, and had an outer diameter of 30 mm, an inner diameter of 20 mm, and a thickness of 80 μm. Using these, a ceramic joined body was manufactured according to the apparatus and process shown in FIGS. 4 (a) to 4 (d). The manufacturing conditions are as shown in Table 2 below. And the evaluation shown in the following Table 3 was performed about the obtained ceramic joined body.

[Examples 2 to 12]
A ceramic joined body was obtained in the same manner as in Example 1 except that the conditions shown in Table 2 were used. The same evaluation as Example 1 was performed about the obtained ceramic joined body. The results are shown in Table 3.

[Examples 13 and 14]
As a material to be joined, a silicon nitride block having a length of 30 mm, a width of 20 mm, and a height of 20 mm was used. The 30 mm × 20 mm surfaces of the block were opposed to each other and heated under the condition that a bonding material was interposed between the surfaces to obtain a ceramic bonded body. Details of the manufacturing conditions are as shown in Table 2. The same evaluation as Example 1 was performed about the obtained ceramic joined body. The results are shown in Table 3.

[Comparative Examples 1 to 4]
A ceramic joined body was obtained in the same manner as in the above example except that the conditions shown in Tables 2 and 3 were used. The same evaluation as Example 1 was performed about the obtained ceramic joined body. The results are shown in Table 3.

As is clear from the results shown in the above table, it can be seen that the bonded parts of the ceramics obtained in each example have a high bonding strength close to that of the material to be bonded. It can be seen that the ceramic joined body obtained in each example can maintain the joining strength even after the ceramic joined body is exposed to a high-temperature oxidizing atmosphere.

Claims

A ceramic joined body in which silicon nitride ceramics joined materials are joined via a joining portion containing silicon nitride particles and silicon oxynitride glass,
In the two-dimensional cross-sectional observation of the microstructure of the bonding site, the ratio of silicon nitride particles to silicon oxynitride glass is 97: 3 to 60:40,
A ceramic joined body in which the silicon nitride particles contained in the joining portion are columnar.
The ceramic joined body according to claim 1, wherein an aspect ratio (major axis / minor axis) of the columnar particles in the joining portion is 2 to 30.
A method for producing a ceramic joined body in which silicon nitride ceramics joined materials are joined via a joining portion containing silicon nitride particles and silicon oxynitride glass,
Between the materials to be bonded, a bonding material including a mixed powder having a composition capable of forming a bonding portion including silicon nitride particles and silicon oxynitride glass after heating is interposed,
A method for manufacturing a ceramic joined body, comprising heating a joining part under a state where the joining parts of the materials to be joined are pressurized.
4. The method for producing a ceramic joined body according to claim 3, wherein the mixed powder includes silicon nitride particles having an average particle diameter of 0.4 to 5.0 μm.
Heating while rotating the material to be joined around an axis perpendicular to the joining surfaces of the materials to be joined,
And the manufacturing method of Claim 3 or 4 which rotates the said to-be-joined material so that the said axis | shaft may be located in a horizontal surface.
The manufacturing method according to any one of claims 3 to 5, wherein a green sheet including the mixed powder is used as the bonding material.
The said to-be-joined material is a pipe | tube or rod-shaped thing, The said joining material is interposed between the end surfaces of this to-be-joined material, and it heats, rotating this to-be-joined material around the axis | shaft of this to-be-joined material. The manufacturing method as described in any one of thru | or 6.
The manufacturing method according to claim 7, wherein the end surfaces of the materials to be bonded are fitted to each other when the end surfaces are brought into contact with each other, and the positions of the axes of the materials to be bonded are matched.
The manufacturing method according to claim 7, wherein an inner sleeve for performing alignment of the axis of the material to be joined is interposed in the joining portion.