JP2003176183A - Inorganic joining member and production method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inorganic joining member which has high reliability by joining sintered compacts with different compositions and/or fine structures utilizing the characteristics of gel casting. <P>SOLUTION: Gel casting slurry is cast into a frame mold having ruggedness, and is solidified, and is released from the mold to form ruggedness on the surface of the solidified body. The gel casting slurry with a different composition and/or a different fine structure is cast into the surface of the solidified body, solidified, and thereafter released from the mold. The solidified body is then sintered, so that the firmly integrated inorganic joining member is produced. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an inorganic joining member using a gel casting method and a method for producing the same, and more specifically, to a different composition and / or
Further, the present invention relates to an inorganic bonding member in which sintered bodies having different microstructures are bonded to each other at an interface having irregularities, and a manufacturing method thereof.

[0002]

2. Description of the Related Art The constituent material of the inorganic bonding member according to the present invention is composed of ceramics such as alumina, magnesia, silicon carbide, etc., various metals, or a combination thereof. Includes dense bodies that do not contain to porous bodies that have interconnected pores.

Next, as a method for joining sintered bodies having different compositions and / or different microstructures, a method utilizing joining or thermal spraying is conventionally known. As an example, in joining, a method is known in which an interface between metal and ceramics, which is found in a turbine shaft, is combined with metallizing and fitting techniques.

[0004]

However, in the joining of dissimilar materials by the conventional method, peeling at the interface at the time of fabrication and breakage during use are likely to occur. Examples of the cause thereof include the following, in addition to the difference in the coefficient of thermal expansion between the target base materials. One is the composition of the interface, and the bonding material as "glue" has a lower melting point than the base material, and at the same time, the mechanical strength is low.
In terms of the shape of the interface, if the interface has a smooth shape with no irregularities, the anchoring effect due to the "cutting in" of the bonding material or the mating base material does not contribute to the destruction. Of course, the wettability between the base materials, the wettability between the base material and the bonding material, and the like also affect the generation of defects at the interface. Ideally, the bonding interface contains nothing but the intended base metal component, and
It is preferable that the above-mentioned mechanical properties and the like are not impaired at the joint surface, and further, that the shape of the joint surface is not restricted. However, for example, when the ceramics are bonded to each other via a metal, there is a possibility that the high temperature strength and the high rigidity which are the characteristics of the ceramics may be impaired.
Also, when joining metals by laser,
The resulting interface is limited to a plane. In addition, in the joining method using explosion impact, there are large restrictions on applicable dimensions and shapes.

Next, in the case of obtaining a composite material by thermal spraying, unless the hardness of the base material which is the target of thermal spraying is relatively low, it is difficult to absorb the impact at the moment when the thermal spraying material collides,
Since the adhesive strength at the interface is low and peeling easily occurs, it is particularly difficult to use dense ceramics as a base material. Further, since the temperature change is large when the components to be sprayed reach the surface of the base material, there is a problem that when the layer thickness is increased in spraying, defects such as peeling due to residual strain are likely to occur.

In order to solve the above problems, a joining method is desired in which the target components are in close contact with each other without interposing different components at the interface and the interface shape is arbitrary. The present invention has been made in view of the above problems, and utilizes a gel casting slurry method to obtain different compositions and / or
It is another object of the present invention to provide a technique capable of reliably obtaining an inorganic bonding member in which sintered bodies having different microstructures are bonded to each other at an interface having irregularities and which is firmly integrated.

[0007]

The above-mentioned object of the present invention is an inorganic joining member obtained by joining sintered bodies having different compositions and / or different microstructures at an interface having irregularities. This is achieved by an inorganic bonding member characterized in that the bonded body is obtained by sintering a solidified body obtained by the gel casting method. Further, an object of the present invention is to cast the gel casting slurry into a mold having an uneven surface, to remove the mold after solidification to form the unevenness on the surface of the solidified body, and to the surface of the solidified body on which the unevenness is formed. Gel casting slurry with different composition and / or different microstructure, and then demolding after solidification to obtain different composition and / or
Also achieved by a method for producing an inorganic bonding member characterized by including a step of obtaining a solidified body in which solidified bodies having different microstructures are bonded at an interface having irregularities, and a step of sintering the solidified body. To be done.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below. The slurry used in the gel casting method according to the present invention is obtained by mixing ceramic powder or metal powder as an inorganic skeleton material with a dispersion medium such as water or an organic solvent and a predetermined gelling agent. here,
In the present invention, the gel casting method is used.
This is because after pouring the slurry into the mold, it can be solidified as it is to obtain a solidified body. As a result, if a desired shape is formed on the mold, it becomes possible to easily obtain a solidified body that retains the shape. Further, the solidified body obtained by gel casting can be made into an integral molded body by using another gel casting slurry on the surface without drying. This has the effect of reducing the interfacial stress that occurs with drying shrinkage.

As the gelling agent, for example, a water-soluble epoxy resin or the like can be used, but it is desirable to use a component which constitutes a polymer by reactive crosslinking in view of handling of the slurry and the molded product. This is because the viscosity of the slurry becomes high when using components that make up the polymer from the beginning such as agar and polyvinyl alcohol, and it is necessary to increase the dispersion medium in order to ensure sufficient handleability, and as a result,
This is because the solid content is low and cracks are likely to occur during degreasing and firing. In addition, it is possible to increase the adhesive strength of the interface by using the component that solidifies by the reaction, and particularly, by using the gelling agent component that belongs to the same category, the effect can be enhanced.

Therefore, it is desirable to add it as a monomer or a low polymer in the slurry, and to cross-link it by a heat or the like in a mold to form a polymer. In addition to the above epoxy resin, The compounds included in the categories of acrylic resin, urea-amide resin, phenol resin and the like are listed, but many of them have excellent heat resistance and relatively high decomposition and burning temperatures.

Further, it is possible to obtain a porous body by adding a pore-forming material that forms pores by burning out or by impregnating the slurry with the pore-forming material.
Examples of such a pore-forming material include synthetic resin beads such as polyethylene and polystyrene, and particulate or fibrous organic substances such as starch and carbon. Also, fine pores can be formed by adding a binder component in a larger amount than that required for molding and utilizing the disappearance mark of the binder component. Of course, without using such a pore-forming material,
Only the independent pores may be present in the portion where the fibrous polymer pore-forming material is not present, or the pores may be dense.

The mold for gel casting is made of a material that does not absorb the dispersion medium in the gel casting slurry. However, since the gel casting slurry is completely solidified by, for example, leaving it standing or heating it to a predetermined temperature, the mold does not need to be absorbent. The material of the formwork is synthetic resin such as acrylic resin, polycarbonate resin, Teflon (registered trademark) resin, natural oils and fats such as wax, inorganic glass, metal, gypsum and synthetic treated so as not to absorb the slurry dispersion medium. Although wood can be used, it is preferable to select it in consideration of durability and maintainability, especially those properties in surface unevenness processing.

In the present invention, it is proposed to cast the gel casting slurry into a mold having an uneven surface, but the shape and size of the unevenness imparted to the mold are arbitrary and are appropriately selected depending on the application. It Further, various methods can be applied to the applying method, for example, inorganic glass can be chemically processed by hydrofluoric acid or physically processed by sandblasting. It is possible to perform physical processing, chemical processing, or physical processing after molding on the metal mold which is the molding frame of. The depth of the unevenness due to the chemical processing is typically as fine as several to several tens of microns, and is uniformly formed, whereas the unevenness due to the physical processing is relatively several hundred microns to several mm. It tends to be coarse. The greater the depth of the unevenness, and the more complicated the shape becomes, the more the anchoring effect between the base materials increases, but at the same time, the anchoring effect between the mold and the molded body also occurs at the time of molding, making it a “octopus”. An interface having a space larger in diameter than the diameter of the opening in the base material, which can be likened to, cannot be formed by transfer from the mold. In addition, even if the depth of the unevenness is large, the distance between the closest convex portions or concave portions, that is, the pitch of the unevenness becomes large and the contribution of the anchoring effect becomes small. It is desirable not to exceed the average depth, but when the reaction that does not impair the properties of the base materials progresses and the composition and microstructure are graded, the joint strength at the interface is Is improved and residual stress is reduced, so that the degree of freedom in the shape and size of the unevenness is increased.

Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to the examples. (Example 1) 100 parts by weight of yttria-stabilized zirconia powder, 4 parts by weight of gelling agent (water-soluble acrylic resin), and 160 parts by weight of ion-exchanged water were mixed in a ball mill to prepare a gel casting slurry (A). Next, 100 parts by weight of alumina powder, 7 parts by weight of gelling agent (water-soluble acrylic resin) and 250 parts by weight of ion-exchanged water were mixed in a ball mill to prepare a gel casting slurry (B). 70 × 70m for 100 × 100mm glass plate by treating the slurry contact surface with hydrofluoric acid
An uneven surface was provided in the surface range of m. When measured with a contact surface roughness meter, the average depth of the uneven surface was about 50 microns, and the average pitch was 40 microns. Face this glass plate with a glass plate of the same size that has not been treated as above and has a smooth surface, and make them 10 mm thick and 15 mm wide.
The space formed by fixing with a clamp through the silicone resin was used as a mold. The gel casting slurry (A) was cast into the mold, and liquid paraffin was poured to seal the mold. This is heated to 60 ℃ in a constant temperature bath, 70 × 70 × 10m
A solidified product of m was obtained. Remove the glass plate with the uneven surface and put it inside the solidified body around the outside with a size of 100 x 100 x 60 mm.
A silicone resin having a cutout of 70 × 70 × 60 mm was installed around the solidified body. Next, the gel casting slurry (B) is poured into a mold formed by the surface of the solidified body on which the silicone resin and the uneven surface are transferred, and liquid paraffin is further poured into the lid to form a lid to evaporate the dispersion medium at the time of heating and solidification. I tried to prevent it. Next, the gel casting slurry (B) was heated to 60 ° C. to be solidified and demolded. After the obtained bonded solidified body was frozen at 25 ° C. under zero, a dried body was obtained by vacuum degassing so as to keep it at 1 Torr or less, which was degreased in air at 450 ° C. and then calcined at 1500 ° C. . In this way, an inorganic bonding member was obtained, one of which was a yttria-stabilized zirconia sintered body and the other of which was an alumina sintered body, which were bonded to each other at the uneven interface. Five bending test pieces were cut out from the inorganic bonding member so that an interface was included perpendicularly to the axial direction, and a three-point bending test was performed at room temperature. The bending strength was as large as 430 Mpa on average.

(Example 2) 100 parts by weight of alumina powder, 14 parts by weight of gelling agent (water-soluble acrylic resin), 10 parts by weight of acrylic resin beads, and 270 parts by weight of ion-exchanged water were mixed in a ball mill to perform gel casting. The slurry (A) was used. Next, 100 parts by weight of alumina powder, 7 parts by weight of gelling agent (water-soluble acrylic resin), and 250 parts by weight of ion-exchanged water were mixed in a ball mill to prepare a gel casting slurry (B). After freeze-drying the bonded solidified body obtained in the same manner as in Example 1, after degreasing in air at 450 ° C. and baking at 1500 ° C., one is made of a dense body and the other is made of a porous body. An inorganic joining member joined at the uneven interface was obtained. No defects such as peeling were observed at the interface of the obtained bonded member, and a strongly integrated bonded body could be obtained.

Comparative Example 1 A yttria-stabilized zirconia / alumina bonding member was produced in the same manner as in Example 1 except that a smooth glass plate was used as the frame. Five bending test pieces were cut out so that the interface was included perpendicularly to the axis, and a three-point bending test was performed at room temperature. The average was 105 MPa, which was low.

Comparative Example 2 An inorganic joining member was produced in the same manner as in Example 2 except that a smooth glass plate was used as the mold. Peeling occurred at the interface of the obtained bonded member, and an integrated bonded body could not be obtained.

[0018]

From the above results, according to the manufacturing method of the present invention, it is possible to bond sintered bodies having different compositions and microstructures in a good bonding state by utilizing the characteristics of gel casting. There is an effect that a highly reliable inorganic joining member can be provided.

Claims (2)

[Claims] 1. An inorganic joining member, comprising sintered bodies having different compositions and / or different microstructures, which are joined together at an interface having irregularities, wherein the sintered bodies are solidified bodies obtained by a gel casting method. An inorganic joining member characterized by being sintered. 2. A step of casting the gel casting slurry on a mold having an uneven surface, demolding after solidification to form the unevenness on the surface of the solidified body, and a step different from the above on the surface of the solidified body on which the unevenness is formed. A step of casting a gel casting slurry having a different composition and / or different microstructure, demolding after solidification, and obtaining a solidified body in which solidified bodies having different compositions and / or different microstructures are joined at an interface having irregularities. And a step of sintering the solidified body.
A method for producing the inorganic bonding member as described above.