JPS6227035B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of adhering composite sintered ceramics and metal.

Semitics have excellent heat resistance and oxidation resistance, so they are attracting attention as heat-resistant components and structural materials for machinery. However, the difficulty in its practical application is that ceramics are generally brittle, so their reliability as a material is lower than that of metal materials, and although they have high strength, they are brittle and hard, so their workability is generally extremely poor. That's true. It is said that widespread practical application of ceramics will be difficult unless these two drawbacks are overcome. On the other hand, there is an idea to improve the brittleness of ceramics by dispersing and compounding fibers with high strength and excellent heat resistance into ceramics. Among these, composite ceramics made of fibrous silicon carbide single crystals (generally called silicon carbide whiskers) not only have high strength, but also have reduced brittleness due to the action of the silicon carbide whiskers they contain.
The present inventors have discovered that the reliability of strength is improved compared to the original matrix ceramic alone. Furthermore, it has been found that this composite ceramic is advantageously electrically conductive due to the silicon carbide whiskers contained therein, and therefore allows extremely complex machining by electrical discharge machining. For this reason, this silicon carbide whisker composite ceramic is expected to have future applications in various fields, and the present applicant has already applied for a patent for such ceramics. However, at the practical stage, when applying such composite ceramics to mechanical parts, etc., as long as they function together with other metal materials in some way, they can be firmly bonded to metal materials, and there is no simple bonding method. needs to be developed.

Conventionally, various methods have been developed for bonding ceramics and metals, such as the Telefunken method, active metal method, hydride method, copper sulfide method, metal oxide method, powder compression method, hot press method, and solder glass method. has been done. All of these conventional bonding methods involve the presence of a third component between ceramics and metal. This is because ceramics and metals have significantly different coefficients of thermal expansion, so it was thought that an intermediate layer was always necessary. However, in these various conventionally known methods, it is necessary to heat the intermediate layer in a vacuum or in a reducing atmosphere while preventing oxidation of the intermediate layer. Therefore, in the conventional method, not only various complicated operations are required to form the intermediate layer, but also extra and complicated steps and operations are required to adjust the heating atmosphere. Moreover, the adhesive strength of the resulting adhesive is not necessarily satisfactory.

In view of this, the present inventor has conducted intensive research on bonding methods for the composite ceramic and metal, and has developed a high-strength product that skillfully utilizes the properties of the composite ceramic, without requiring the complicated operations of conventional methods. This led to the invention of an adhesive method. That is, the present invention uses oxides, nitrides, or carbides of group elements or group elements as a matrix, and uniformly disperses fibrous silicon carbide single crystals in the range of 5 to 50% of the total weight in ceramics. A method for bonding a composite sintered ceramic containing a metal to a metal, the method comprising depositing a metal film on the surface of the composite sintered ceramic by electroplating, and then adhering a target metal onto the metal film. The present invention relates to a method of adhering composite sintered ceramics and metal.

The composite sintered ceramics in the present invention include the group:
The parent phase is an oxide, nitride or carbide of a group element, and 5 to 50% of the total weight is contained in ceramics.
It contains silicon carbide whiskers dispersed within a range of 1.5% and has high electrical conductivity, so it can be electroplated.

The length and thickness of the fibrous silicon carbide (SiC) single crystal used in the present invention are not particularly limited, but the length is usually 10 to 500 μm, preferably about 50 to 500 μm, and the thickness is usually 0.1 to 10 μm, preferably It is best to use a material with a diameter of about 0.5 to 3 μm. When the length becomes extremely short than 10 μm, a large amount of addition is required to increase the electrical conductivity to the extent that electrical discharge machining is possible, as is the case when granular SiC is added and molded, and the original characteristics of the ceramic are lost. There is a tendency for it to be damaged. The thickness of fibrous SiC is 0.1μm
More extreme thinning tends to cause the fibers to break during molding, a result similar to when using granular SiC. On the other hand, if the thickness is extremely thicker than 10 μm, the rigidity of the fibers increases, so that densification by sintering tends to become difficult. The amount of fibrous SiC single crystals dispersed in the ceramic is preferably 5 to 50% of the total weight. When the amount of SiC fibers is less than 5%, the electrical conductivity of the sintered body is not sufficiently improved, while when it exceeds 50%, the densification of the ceramic tends to decrease. The amount of the fibrous SiC single crystal added is more preferably 10 to 40% of the total weight.

In the present invention, oxides, nitrides, or carbides of group elements are used as the matrix. A wide variety of known oxides, nitrides, or carbides of group elements can be used. Examples of oxides include alumina, zirconia, magnesia, ferrites such as Fe ₂ O ₃ , single oxides such as uranium oxide, thorium oxide, etc.
Various spinel type compounds such as MgAl ₂ O ₄ , NiFeO ₄ , NiCrO ₄ , MgFe ₂ O ₄ and perovskite structure
Composite oxides such as LaCrO ₃ , LaSrCrO ₃ and SrZrO ₃ can be mentioned, examples of nitrides include silicon nitride, aluminum nitride, boron nitride, etc., and examples of carbides include silicon carbide, boron carbide, titanium carbide, etc. . In the present invention, these may be used in combination.

The SiC composite sintered ceramic of the present invention is manufactured as follows. After adding and mixing a predetermined amount of fibrous SiC single crystal to oxide, nitride, or carbide powder and dispersing it uniformly, a binder of about 0.1 to 2% of the weight of the mixture is added, and after molding and drying, it is sintered. As a result, a composite ceramic containing the single crystals uniformly dispersed without directionality is obtained. As the binder, preferably used is a solution of polyvinyl alcohol, acrylic resin, cellulose, sodium alginate, etc. in water, alcohol, or other organic solvent. A paste consisting of an oxide, nitride or carbide, SiC, and a binder is molded into a predetermined shape by injection molding, extrusion molding, etc.
The obtained molded body is predried under heat or reduced pressure, and then heated to 600° C. or lower to remove the binder. Next, the dried molded body is preferably sintered at a temperature of about 1300 to 1800° C. under pressure or without pressure.
Note that, if necessary, a sintering aid such as a small amount of MgO may be added to Al ₂ O ₃ in combination.

In the present invention, the type of metal film to be deposited on the composite sintered ceramics by electroplating is not particularly limited, and widely known types can be used, for example, only single metal types such as copper, silver, nickel, and chromium can be used. Instead, various alloys such as brass (Cu-Zn), bronze (Cu-Sn), lead-tin, etc. can be used. These may be appropriately selected depending on the type of metal to be bonded to the ceramics and the bonding method between the metal and metal film. The metal material to be bonded is not particularly limited, and a wide variety of materials can be used, from ordinary iron to cemented carbide containing nickel, chromium, etc., such as stainless steel, Inconel, etc.

The bonding method between the metal film and the metal is not particularly limited, and for example, silver brazing, soldering, arc welding, etc. can be used.

Bonding of the composite ceramic and metal in the present invention is performed as follows. That is, the surface of the composite ceramic to be bonded is washed with a suitable organic solvent to remove surface stains. With this at an appropriate concentration,
It is immersed in an electrolytic plating solution containing the desired metal ions, and a plating operation is performed under normal conditions to deposit a plating film. The thickness of the film is not particularly limited, but in order to obtain stronger adhesive strength,
A thickness of 10 μm or more is desirable. However, if the metal plating film is too thick and the particle form of the precipitated metal is too coarse, the disadvantageous result will be that the composite ceramic and the metal film will peel off. Therefore, it is preferable to select electroplating conditions such that a dense plating film of an appropriate thickness can be obtained. After electrolytic plating, cleaning and drying are performed, and then the target metal to be bonded and the composite ceramic may be bonded together using a conventionally known appropriate bonding method such as silver solder, solder, arc welding, or the like. Depending on the type of plating metal, it is possible to increase the adhesion between the plating film and the composite ceramic by heat-treating the composite ceramic in a reducing atmosphere after electrolytic plating, but this is not always necessary. It's not something you do.

As described above, according to the present invention, composite ceramics and metal can be easily bonded together. This method is different from other ceramic metallization methods,
It is possible to obtain a metal film without heating the sample to high temperatures, and because it does not use a glassy intermediate layer, it not only provides high adhesive strength, but also
Possible to bond with high heat resistance.

This will be explained in more detail below with reference to Examples.

Example 1 A silicon nitride sintered body containing silicon carbide whiskers uniformly dispersed at 30% of the total weight is used as a composite ceramic, and after degreasing and cleaning, it is immersed in an electrolytic plating solution and electroplated. As an electrolyte, 1 part water
A solution containing 200g of copper sulfate was used. The electrolytic plating conditions were a current density of 10 mA/cm ² and copper was used as a counter electrode. After about 2 hours of plating, the thickness of about
A 50 μm copper plating film was deposited on the surface. This copper coating surface and a copper plate as a material to be bonded were bonded together by soldering. When the bending strength was measured centering on the adhesive surface, it was found to be 600 Kg/cm ² .

Example 2 As a composite ceramic, an alumina sintered body containing silicon carbide whiskers uniformly dispersed at 40% of the total weight was used and bonded to a copper plate in the same manner as in Example 1. When the bending strength was measured centering on the adhesive surface, it was found to be 570 Kg/cm ² .

Example 3 Sialon (Si ₃ N ₄ :Al ₂ O ₃ =1:1) containing 30% of silicon carbide whiskers based on the total weight was used as the composite ceramic, and as in Example 1, the thickness was approximately A 100 μm copper plating film was deposited on the composite ceramic. Thereafter, the composite ceramic was bonded to an iron plate with silver solder at 650°C. When the bending strength was measured centering on the adhesive surface, the average strength was 1100 Kg/cm ² (with a variation of ±100 Kg/cm ² ).

Comparative Example Silicon carbide fibers (manufactured by Nippon Carbon Co., Ltd., trade name "Nicalon", multi-fiber silicon carbide spun yarn with approximately 500 fibers per tow, average fiber diameter of 10 to 12 μm) were used at 30% of the total weight. A silicon nitride sintered body containing 40% of the total weight and an alumina sintered body containing 40% of the total weight were prepared.
The fabrication was carried out using the hand lay-up method. A silicon nitride sintered body with the above content was made by arranging fibers in one direction and laminated with a matrix, and a nitride sintered body with the above content was made by arranging fibers at right angles of 0°/90° and laminating with a matrix. A silicon sintered body, an alumina sintered body with the above content in which fibers are arranged in one direction and laminated with a matrix, and
Four types of alumina sintered bodies having the above content were obtained by arranging fibers at right angles of 0°/90° and laminating them with a matrix.

Next, electroplating was performed on each of these four types of sintered bodies under the same conditions as in Example 1, and then an attempt was made to bond a copper plate with silver solder. However, in both cases, the electroplating plated only the electrically conductive fibers, and the plating peeled off when adhering with silver solder, so that no adhesion could be achieved in the end.

Claims (1)

[Claims] 1. Composite sintered material containing an oxide, nitride or carbide of a Group, Group or Group element as a matrix and containing fibrous silicon carbide single crystals uniformly dispersed within the range of 5 to 50% of the total weight in ceramics. A method for bonding ceramics and metal, the method comprising depositing a metal film on the surface of the composite sintered ceramic by electroplating, and then bonding a target metal onto the metal film. A method of bonding ceramics and metal.