JPS6177676A - Silicon nitride bonded body and bonding method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Technical Field] The present invention relates to a bonded body and a bonding method for a silicon nitride body, which is a type of heat-resistant, high-strength ceramic, and more specifically to a metallized layer of aluminum or aluminum alloy on the surface of a silicon nitride body. The present invention relates to a bonded body and a bonding method in which a bonded body is formed and bonded through at least this metallized layer.

"Prior art and its problems" Recent technological developments regarding heat-resistant and high-strength ceramics such as silicon nitride bodies and silicon carbide bodies have been remarkable, and high heat-resistant materials such as turbochargers, turbine blades, radiant tubes, and high-temperature heat exchangers have been developed. , its application to fields that require high corrosion resistance, high strength, etc. is being actively considered.

When using these ceramics for various purposes,
It is necessary to bond a metal member such as a metal shaft to ceramics. Generally, in order to join ceramics to each other or ceramics to a metal body, it is necessary to metallize the surface of the ceramics and then fusion weld the parts to be joined through this metallized layer, metal brazing, or soldering. It is being done.

Conventionally, as a method for joining a silicon nitride body and stainless steel, titanium was ion-blated to a thickness of 2 to 4 gm on the surface of the silicon nitride body, and then an aluminum foil was sandwiched between the stainless steel and the silicon nitride body was bonded in an argon gas atmosphere. A method of joining by heating to about 670° C. is known (see summary of general lectures at the Autumn Conference of the Japan Institute of Metals, 1981, p. 542).

However, in this joining method, since titanium is ion-blated, there are problems in that work efficiency is poor and costs are high.

Furthermore, it is also possible to metallize the surface of a ceramic such as a silicon nitride body using CVO, pVD, or the like.

However, these methods have problems such as slow formation of a precipitate layer, low adhesion, and difficulty in partially plating only the bonded area, making them unsuitable for subsequent bonding with metal objects or ceramics. Met.

``Object of the Invention'' The object of the present invention is to provide a bonded body and a bonding method for silicon nitride bodies, which enable bonding of silicon nitride bodies and metal bodies, ceramics, etc. with a strong bonding force and by relatively simple means. It's about doing.

"Structure of the Invention" A joined body of silicon nitride bodies according to the present invention is a joined body in which at least one of a pair of members to be joined is a silicon nitride body,
A metallized layer of aluminum or aluminum alloy is formed on the surface of the silicon nitride body, and the other member to be joined is joined via at least this metallized layer.

Further, the method for joining silicon nitride bodies according to the present invention is a joining method in which at least one of a pair of members to be joined is a silicon nitride body, and the silicon nitride body is coated with aluminum or an aluminum alloy in a molten state at 900 to 1400°C. This is a method in which a metallized layer is formed on the surface by contacting the two members, and the other member to be joined is joined via at least this metallized layer.

As described above, in the present invention, a metallized layer of aluminum or an aluminum alloy is directly formed on the surface of a silicon nitride body, and other members to be joined are bonded via this metallized layer.

Silicon nitride bodies have excellent corrosion resistance against molten aluminum or aluminum alloys, and have thus far been used in aluminum melting crucibles, stirring jigs, and the like. For this reason, there has never been an example in which aluminum or an aluminum alloy has been positively applied as a metallizing material for a silicon nitride body. Incidentally, since the aluminium photomelting crucible made of silicon nitride is used in the atmosphere at a temperature of around 700° C. at most, a preferable aluminum metallized layer is not formed on the surface of the crucible.

The present inventors have discovered that it is possible to metallize aluminum or an aluminum alloy on the surface of a silicon nitride body by bringing aluminum or an aluminum alloy into contact with the silicon nitride body in a molten state at 900 to 1400°C, and that it is possible to form metallization in this manner. They discovered that an extremely strong bonding force can be obtained by bonding metal bodies, ceramics, etc. through the metallized layer, which led to the completion of the present invention.

As described above, the reason why aluminum or aluminum alloy can be directly metallized on a silicon nitride body and strong bonding strength can be obtained according to the present invention is thought to be that the following reaction occurs at the bonding interface at high temperatures.

5i3N 4 + 4Al→3 Si+4
AlN3 5in2 +4 At→3 Si+2
A1203 (when the surface is oxidized) Si3N4 + Al→Al-Si alloy + N25i0
2 + Al → Al-9i alloy +02 The silicon nitride body used in the present invention is a silicon nitride body to which a sintering aid is added, which is sintered by a sintering method such as normal pressure sintering, real press, or hot isostatic pressing. ; Reactive sintered silicon nitride body without a sintering aid sintered by a reactive sintering method; Or a silicon nitride body made by sintering a reactive sintered silicon nitride body with a sintering aid added at a higher temperature to make it denser. It is.

Furthermore, the aluminum used in the present invention has a purity of 98.0.
% or more, and the aluminum alloy may contain copper, silicon, manganese, magnesium, zinc, nickel, chromium, titanium, bismuth, etc. in a total amount of 10% or less, preferably 5% or less.

Methods for bringing molten aluminum or aluminum alloy into contact with the silicon nitride body include immersion method (immersing the silicon nitride body in a bath of molten aluminum, etc.), overlaying method (placing a piece of solid aluminum etc. on the silicon nitride body) put,
(heating to bring them into molten contact), a method that utilizes capillary action (metallizing and bonding are performed simultaneously by placing the silicon nitride body and the other member to be joined side-by-side with a slight gap and bringing them into contact with a bath of molten aluminum, etc.) ) etc. can be adopted.

The metallization temperature is set in a temperature range of 900 to 1400°C, and if it is lower than 900°C, the adhesion of the metallized layer will be weak, and if it exceeds 1400°C, the aluminum or aluminum alloy will evaporate rapidly and the g content will increase. arise.

A vacuum or neutral atmosphere is suitable for the metallization, but metallization is possible even in the air by using a flux to prevent oxidation on the molten metal.

Hereinafter, specific examples of the present invention will be described with reference to the drawings.

As shown in FIG. 1, a silicon nitride body 1 is prepared by the method described above.
A metallized layer 12 of aluminum or an aluminum alloy is formed on the surface of the substrate 1. In the present invention, the members to be joined are joined through at least this metallized layer 12.

In the specific example shown in FIG. 2, silicon nitride bodies 11 and 11 are fusion-welded to each other with a metallized layer 12 interposed therebetween. Such a joined body has aluminum or aluminum alloy interposed between the silicon nitride bodies 11 and 11, and
Obtained by heating to ℃.

In the specific example shown in FIG. 3, a metal body 14 is bonded to a metallized layer 2 formed on the surface of a silicon nitride body 11 via a metal solder 13.

In the specific example shown in FIG. 4, metallized layers 12 and 12 formed on the surfaces of silicon nitride bodies It and 11 are bonded to each other via a metal solder 13.

In the specific example shown in FIG. 5, a metal layer is added on the metallized layer 12 formed on the surface of the silicon nitride body 11! 5 is formed, and a metal body 14 is bonded to all eight layers 15 via solder 8. In this case, the metal layer 15 can be formed by electrolytic plating of copper, nickel, brass, lead-tin alloy, etc., or by dry copperizing treatment at high temperature using, for example, cuprous chloride or hydrocarbon.

In the specific example shown in FIG. 6, metal layers 15.15 are formed on the metallized layers 12.12 formed on the surface of the silicon nitride body 11.11, and these metal layers 15,
□15 are joined to each other via solder 1θ.

The specific example shown in FIG. 7 is a further application of the example shown in FIG.
A metal electrode 17 is inserted between the two and bonded.

Note that the present invention can also be applied to bonding a silicon nitride body and other ceramics.

“Embodiments of the invention” Example 1 Pressure-sintered silicon nitride body (10 ma+
0mm) (7) Tip part 5+m in vacuum at 1300℃
was immersed in molten aluminum for 1 minute to form an aluminum metallized layer. Vaseline was applied thinly onto this metallized layer, and then cuprous chloride powder was evenly applied, followed by holding in a furnace at 450° C. in the atmosphere for 20 minutes to form a copper layer. Then, a copper alloy body (10mm x 1oaa+X 20ma+
) was called solder to obtain a bonded body of a silicon nitride body and a metal body.

The bending strength of this joined body was 8 kg/ma+2, and the fracture location was within the solder layer.

Example 2 Silicon nitride body sintered by hot isostatic pressing (]0■X i
6 with a thickness of 0.5 mm between the end faces of
A bonded body of silicon nitride bodies was obtained by sandwiching the 061 aluminum alloy plates and holding them at 1200° C. for 130 seconds in an argon atmosphere of 10 Torr. The bending strength of this joined body was 18 kHz/■2, and the fracture location was inside the aluminum alloy layer.

"Effect of the Invention J As explained above, according to the present invention, aluminum or aluminum alloy is added to the silicon nitride body to
By contacting them in a molten state at 0°C, a metallized layer is formed on their surfaces, and the metal bodies and ceramics are bonded at least through this metallized layer, so a bond with extremely strong adhesive force can be achieved by a relatively simple means. You can get a body.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view showing a state in which a metallized layer of aluminum or aluminum alloy is formed on the surface of a silicon nitride body, and Figures 2, 3, 4, 5, 8, and 7 are FIG. 4 is a cross-sectional view showing different specific examples of the joined body according to the present invention. In the figure, 11 is a silicon nitride body, 12 is a metallized layer, 13 is a metal solder, 14 is a metal body, 15 is a metal layer, 1B is solder,
17 is a metal electrode.

Claims (12)

[Claims] (1) In a bonded body in which at least one of a pair of members to be joined is a silicon nitride body, a metallized layer of aluminum or an aluminum alloy is formed on the surface of the silicon nitride body, and at least one of the members to be joined is connected to the other member to be joined through the metallized layer. A joined body of silicon nitride bodies, characterized in that members are joined. (2) A bonded body of silicon nitride bodies according to claim 1, wherein both of the members to be joined are silicon nitride bodies, and the silicon nitride bodies are fusion-welded to each other via the metallized layer. (3) In claim 1, the members to be joined are a silicon nitride body and a metal body, and the metal body is attached to the metallized layer formed on the surface of the silicon nitride body through a metal solder. A bonded body of silicon nitride bodies. (4) In claim 1, the members to be joined are all silicon nitride bodies, and the metallized layers formed on the surfaces of these silicon nitride bodies are joined to each other via a metal solder. A bonded body of silicon nitride bodies. (5) In claim 1, the members to be joined are a silicon nitride body and a metal body, and a metal layer is further formed on the metallized layer formed on the surface of the silicon nitride body, and A bonded body of a silicon nitride body, in which the metal body is bonded to a metal layer via solder. (6) In claim 1, each of the members to be joined is a silicon nitride body, and a metal layer is further formed on each of the metallized layers formed on the surfaces of these silicon nitride bodies, A bonded body of silicon nitride bodies in which these metal layers are bonded to each other via solder. (7) In a joining method in which at least one of a pair of members to be joined is a silicon nitride body, a metallized layer is formed on the surface by bringing aluminum or an aluminum alloy into contact with the silicon nitride body in a molten state at 900 to 1400°C. A method for joining silicon nitride bodies, characterized in that the other member to be joined is joined through at least this metallized layer. (8) In claim 7, each of the members to be joined is a silicon nitride body, and aluminum or an aluminum alloy is interposed between these silicon nitride bodies.
A method for joining silicon nitride bodies by heating to 00 to 1400°C. (9) In claim 7, the members to be joined are a silicon nitride body and a metal body, the metallized layer is formed on the surface of the silicon nitride body, and the metal body is metal-brazed to the metallized layer. A method for joining silicon nitride bodies. (10) In claim 7, each of the members to be joined is a silicon nitride body, the metallized layer is formed on the surface of these silicon nitride bodies, and the metallized layer is metallized to each other. How to join the body. (11) In claim 7, the members to be joined are a silicon nitride body and a metal body, the metallized layer is formed on the surface of the silicon nitride body, and a metal layer is further formed on the metallized layer. . A method for joining a silicon nitride body, in which the metal body is soldered to the metal layer. (12) In claim 7, each of the members to be joined is a silicon nitride body, the metallized layer is formed on the surface of these silicon nitride bodies, and further a metal layer is formed on each of the metallized layers. and a method of joining silicon nitride bodies in which these metal layers are soldered together.