JPH06101303B2 - Method of joining ceramics and metal - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a technique for joining ceramics and metal, and more particularly to improvement of a brazing method using an active metal.

[Conventional technology]

The joining of ceramics and metal is generally used for sealing an electron tube, but the electron tube has a wide variety such as a magnetron, an X-ray tube, and a transmission tube. Many of them use alumina as ceramics, and the joining method with the metal member is to apply a Mo-Mn paste to the joining surface of the alumina and fire it in a hydrogen furnace to form a metallized layer, and further perform Ni plating. A method of providing a joining layer by a so-called refractory metal method and joining a metal member by using a silver-copper eutectic brazing material as a brazing material is widely used.

As a specific example, a magnetron will be taken as an example to explain an example of joining ceramics and a metal member. FIG. 3 shows a cross section of a magnetron tube body used in a microwave oven or the like. 1 is a cathode which emits thermoelectrons, 2 is a cathode which forms a cavity resonator inside,
There are magnetic poles 3 and 4 for concentrating the magnetic field lines from the outside of the tube body in the working space formed by the cathode 1 and the anode 2, and the seal cylinders 5 and 6 are in contact with the cylindrical portion of the anode 2 so as to include them. It is touched. Further, ceramics as a sealing member holds the cathode 1 and, together with the cathode terminal 7 for supplying a cathode current,
Stem ceramics 8 bonded to the seal cylinder 5
And the antenna ceramics 12 that surrounds the anode 2 and the antenna 9 extending from a specific vane, and that the seal cylinder 6 and the exhaust pipe support 11 that holds the exhaust pipe 10 are joined to each other and serve as a radiation window of the generated microwave. is there.

Here, regarding the joint portion between the stem ceramics 8, the antenna ceramics 12 and the metal member, the stem ceramics 8 and the seal cylinder 5, the antenna ceramics 12 and the seal cylinder 6, and the exhaust pipe support 11 have the same joint structure. That is, as shown in the enlarged sectional view of the joint between the stem ceramics 8 and the seal cylinder 5 in FIG. 4, there is a metallized film 8a and a Ni plating layer 8b formed by the refractory metal method on the end surface of the stem ceramics 8, The seal cylinder 5 is brazed via a silver solder 13.

This structure is called so-called butt joint, and the seal cylinder 5
And the stress due to the difference in thermal expansion between the stem ceramics 8 is absorbed by the seal cylinder 5 having flexibility. This structure is also disclosed in JP-A-56-24733.

[Problems to be solved by the invention]

The metallization technology by the above high melting point metal method and the bonding structure are widely used because good bonding can be obtained because silver brazing metal has very good wettability.
On the other hand, the refractory metal method requires a long process of forming a metallized film, which leads to a high cost of the ceramic member, which is a major obstacle to obtaining a more inexpensive electron tube.

An object of the present invention is to provide an inexpensive and simple joining method for joining ceramics and metal.

[Means for solving problems]

The above-mentioned object is to perform the metallization and brazing in a single process without the two steps of once forming a metallized film on the surface of the ceramic and then brazing it in the step of joining the ceramics and the metal. It is achieved by doing it all at once.

[Action]

In the present invention, an active metal such as Ti or Zr containing a brazing material reacts with alumina of ceramics to form a reaction layer such as an alloy layer or a compound, and the brazing material is well wetted with the metal to form a strong bond. To get Here, in order to enhance the reaction between the brazing material and the ceramic, the surface of the ceramic has a finely uneven surface when viewed microscopically, and the brazing material containing the active metal is promoted by being adhered in a fine powder state.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. The figure is a cross-sectional view showing a seal portion between ceramics and a metal for sealing. In the figure, a fine powder of silver solder containing 2 to 5% by weight of an active metal such as Ti or Zr, a resin binder in the form of a paste is applied by printing or spraying to the end face of the ceramics 8 ', and dried and fixed. Coating film
20 is overlaid with a silver braze containing 1 to 2% by weight of an active metal such as Ti or Zr, or a foil brazing filler metal 21 formed from an ingot of eutectic silver braze, and the metal 5'is brought into contact with the brazing filler metal in a vacuum or
By heating in an inert atmosphere of Ar or N ₂ (about 85
Complete the brazing.

Here, as shown in the enlarged sectional view of FIG. 2, the coating film 20 of the paste-like brazing material is well adhered to the surface of the ceramic 8'having fine irregularities. The reaction with the active metal such as Ti in the coating film 20 proceeds sufficiently, and further, it is well melted with the foil-shaped brazing material 21 and brazed with the metal 5 '. As described above, the foil-shaped brazing material 21 may be a normal silver-copper eutectic brazing material, and it is more effective to reduce the content of the active metal contained in the coating film described above.

〔The invention's effect〕

According to the present invention, it is possible to firmly braze a ceramic and a metal by a single heat treatment, and it is not necessary to previously form a metallized film on the ceramic, which is inexpensive, An inexpensive joining method can be obtained.

[Brief description of drawings]

FIG. 1 is a partial view of a seal portion showing a combination state of ceramics and metal according to the present invention before joining, FIG. 2 is an enlarged sectional view of an essential part of FIG. 1, and FIG. 3 is a magnetron for explaining a conventional example. FIG. 4 is an enlarged sectional view of a seal portion showing a conventional example. 5 '... metal, 8' ... ceramics, 20 ... coating film, 21 ... foil brazing material.

Claims (2)

[Claims] 1. A method of joining ceramics and metal, in which a silver brazing filler metal containing an active metal is disposed between the ceramics and the metal, and heated in a vacuum or in an inert atmosphere to perform brazing and joining. Of the active metal-containing silver brazing fine powder is made into a paste with a liquid resin, and is applied to the bonding surface on the ceramics side and dried and fixed, and a foil-shaped eutectic silver solder or a silver solder containing an inert metal A method for joining a ceramic and a metal, which comprises stacking joining metals. 2. The active metal contained in the silver brazing fine powder is
The method for joining ceramics and metal according to claim 1, characterized in that the amount is larger than the amount of active metal contained in the foil-shaped silver solder.