JPH04325469A - Method for joining ceramics - Google Patents

Abstract

PURPOSE:To simplify the joining stage by brazing ceramics in which the faces to be joined are metallized by an Mo-Mn method in a hydrogen atmosphere having a specified dew point or in an atmosphere of a nitrogen-hydrogen mixed gas by copper. CONSTITUTION:The joined faces of an alumina ceramics rod, e.g. contg. 92% Al2O3 are coated with mixed metallic powder constituted of, by weight, 80% Mo and 20% Mn, which is burned at 1450 deg.C for 30min in a nitrogen-hydrogen atmosphere having 30 deg.C dew point to metallize the surfaces of the ceramics. Next, a pure copper plate is put between each other of the above metallized faces, which is heated at 1150 deg.C for 20min in a hydrogen atmosphere having 0 to 10 deg.C dew point or in an atmosphere of a nitrogen-hydrogen mixed gas, and brazing is executed. In this way, ceramics/ceramics or ceramics/metal can be joined without the need of improving the wettability by a brazing filler metal by applying plating to the Mo-Mn metallized faces.

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 ceramics, and more particularly to a method for joining ceramics to ceramics and ceramics to metals.

0002

2. Description of the Related Art FIG. 6 is a diagram of a conventional ceramic bonding process. Publications {Advances in Elect
ron Tube Tech. Vol. 2 No. 1
6 1963}, conventional methods have been used to bond ceramics, especially alumina ceramics, with Kovar, Ni-Fe alloys, iron, copper, stainless steel, etc.
The method shown in is known. That is, fine powders of molybdenum and manganese are applied to the ceramic bonding surface, and this is baked in a reducing atmosphere at 1300° C. to 1500° C. to metallize it. Next, nickel or copper plating is applied to this metallized surface, and heating called plating sintering is performed to further improve the adhesion of the plating. Thereafter, a eutectic solder of, for example, silver and copper (melting point: 779° C.) is placed between the mating metal and heated to about 800° C. in hydrogen gas, thereby achieving bonding between the ceramic and the metal.

0003

[Problem to be solved by the invention] In the conventional bonding process described above, plating is required to improve the wettability of the Mo-Mn metallized surface with the brazing material, and is necessary as long as the wettability is good. If this step can be omitted, the process will be simplified.

[0004] The present invention was made in order to solve this problem, and an object of the present invention is to provide a simplified method for joining ceramics.

[0005]

[Means for Solving the Problems] The method for joining ceramics of the present invention is to bond ceramics whose surfaces to be joined are metallized by the Mo-Mn method in a hydrogen atmosphere or a nitrogen-hydrogen mixed gas having a dew point of 0°C to 10°C. They are joined by brazing with copper in an atmosphere.

[0006]

[Operation] In this invention, if copper is used as a brazing material, it has good wettability on Mo-Mn, so plating is unnecessary, and bonding strength and airtightness comparable to those with plating can be obtained. . In addition, to prevent the components of the powder applied to ceramics from being reduced and blackened in a hydrogen atmosphere, the atmosphere must be limited to a hydrogen atmosphere or a nitrogen-hydrogen mixed gas atmosphere with a dew point of 0°C to 10°C. It was solved by

[0007]

【Example】

Example 1. As shown in FIG. 1, which is a process diagram of a ceramic bonding method according to an embodiment of the present invention, 92% Al2O
80% by weight of Mo and M
A mixed metal powder consisting of 20% by weight of n is applied and the dew point is 3.
The ceramic surface was metallized by firing at 1450°C for 30 minutes in a nitrogen-hydrogen atmosphere at 0°C. The thickness of the metallization layer was approximately 25 μm. Then 0 between these metallized surfaces
．． Place a 1mm thick pure copper plate and heat it with 50N2 with a dew point of 0.5℃.
Brazing was performed by heating at 1150° C. for 20 minutes in a -5OH2 atmosphere. The cross section of the copper brazed joint thus obtained was observed using a scanning electron microscope. FIG. 2 is a scanning electron micrograph showing the state of the metal structure at the joint of ceramics joined according to an embodiment of the present invention. As shown, it was confirmed that the copper solder adhered tightly to the metallized layer and did not damage the metallized layer. In addition, as shown in FIGS. 3, 4 and 5,
The joints of ceramics joined according to an embodiment of the present invention were examined using an X-ray microanalyzer.
This is also clear from the photographs showing the distribution state of each element. In addition, 3 ceramic rods were brazed as described above.
When the brazed joint strength was measured using the point bending method, it was found to be 1
It was 7.3Kg/mm2.

Comparative Example 1. In Example 1, the metal surface of the ceramic rod was plated with Ni to a thickness of about 0.5 μm, and sintered at 900° C. for 30 minutes in hydrogen with a dew point of −30° C. Next, a thickness of 0.1
mm of Ag-Cu eutectic solder was placed and brazed by heating at 800°C for 15 minutes in a hydrogen atmosphere with a dew point of -30°C. When the brazed joint strength of the brazed ceramic rods was measured using the three-point bending method, it was found to be 17.2.
Kg/mm2.

Example 2: An alumina ceramic cylinder containing 92% Al2O3, having an outer diameter of 50 mm, a wall thickness of 5 mm, and a height of 30 mm, the side surfaces of which were treated with a powder, was coated with Example 1 on the end surface that would be the joint surface. The metallization treatment was carried out in the same manner as above. A Kovar ring with a diameter of 46 mm and a wall thickness of 0.5 mm and a pure copper ring with a diameter of 1 mm are placed on top of this, and the dew point is 1.
It was heated at 1150°C for 20 minutes in a hydrogen atmosphere at 0°C. When the airtightness of this brazed joint was examined using a helium leak tester, the permissible value was 1 x 10-8 cc/se.
It was confirmed that it was below c. Under these brazing conditions, the brazing material exhibited the luster of metallic copper, and did not show any blackening even when a ceramic lacquer was applied.

Comparative Example 2. In Example 2, dew point -30
When the ceramics were joined in the same manner as in Example 2 except that the brazing was performed in hydrogen gas at .degree. This seems to be due to the strong reducing power of hydrogen gas at a high temperature of 1150°C. This condition is not desirable because it not only impairs the appearance of the product, but also affects performance such as electrical insulation.

[0011]

Effects of the Invention The present invention provides ceramics whose surfaces to be joined are metallized by the Mo-Mn method in a hydrogen atmosphere or a nitrogen-hydrogen mixed gas atmosphere with a dew point of 0°C to 10°C.
By brazing and joining with copper, a simplified method for joining ceramics can be obtained.

[Brief explanation of drawings]

FIG. 1 is a process diagram of a method for joining ceramics according to an embodiment of the present invention.

FIG. 2 is a scanning electron micrograph showing the state of the metal structure of a joint of ceramics joined according to an embodiment of the present invention.

FIG. 3 is a photograph showing the distribution state of Al element, which was obtained by examining a bonded portion of ceramics bonded according to an embodiment of the present invention using an x-ray microanalyzer.

FIG. 4 is a photograph showing the distribution state of Mo element, which was obtained by examining a bonded portion of ceramics bonded according to an embodiment of the present invention using an x-ray microanalyzer.

FIG. 5 is a photograph showing the distribution state of Cu element, which was obtained by examining a bonded portion of ceramics bonded according to an embodiment of the present invention using an x-ray microanalyzer.

FIG. 6 is a process diagram of a conventional ceramic bonding method.

Claims (1)

[Claims] 1. Ceramics whose surfaces to be joined are metallized by the Mo-Mn method and are joined by brazing with copper in a hydrogen atmosphere or nitrogen-hydrogen mixed gas atmosphere with a dew point of 0°C to 10°C. joining method.