JPH06297139A - Brazed joined body - Google Patents

Abstract

PURPOSE:To obtain a joining material which is provided with a brazing filler metal layer with the thickness of a value set for a purpose, and to improve the performance and the reliability by providing a means for holding the thickness of a brazing filler metal layer at the part of the brazing filler metal layer between the surfaces to be joined. CONSTITUTION:First, a prescribed film like brazing filler metal is placed concentrically on a joining surface 2a of a metallic member 2. Then, the brazing filler metal is tack-welded by spot welding to the joining surface 2a of the metallic member 2 nearly on the same circumference at three places nearly at the same angle interval. As the result, the joining surface 2a of the metallic member 2 corresponding to the welded part is partially melted to form a thickened part of a prescribed height. Next, in a state to hold the tack-welded brazing filler metal, a ceramic member 3 is loaded and pressurized, and an adequate pressure is imparted mutually to the joined surfaces 2a, 3a. In this state, the joined surface is held in vacuum at 780 deg.C for 30 minutes and cooled through N2 inert gas replacement. Thus, after it is cooled and solidified, a brazed joined body 1 is obtained which is provided with a brazing filler metal layer 4 of a desired thickness T.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brazed joint body such as a ceramic / metal joint body.

[0002]

2. Description of the Related Art Generally, it is said that a brazed joint (hereinafter also simply referred to as a joint) cannot obtain a uniform joint strength when the brazing material layer has a thickness of 3 μm or less. There is. On the other hand, when the thickness is several hundred μm, the bonding strength is significantly reduced. However, depending on the thickness of the brazing material layer, it has a merit that it acts as a cushioning material and that residual stress can be reduced when joining members with different shrinkage amounts. ), The thickness of the brazing material layer has a very important meaning such as having a great influence on its performance.

For example, in the case where the joined body is required to have strength such as an engine tappet, the brazing material layer has an appropriate thickness of 5 to 20 μm. With this setting, when the thickness of the brazing material layer exceeds 20 μm, the brazing material layer itself undergoes plastic deformation due to impact load,
This is because there is a risk that the crowning formed on the portion (ceramic member) that will be the sliding surface of the cam will disappear.

As described above, the brazed joint body has an optimum brazing material layer thickness according to its purpose, use and function, and how to accurately approach the set (total) value. is important. Under these circumstances, conventionally, this thickness control is based on the amount of brazing material used, the thickness of the brazing material foil, or the so-called low temperature such as the brazing temperature (time) and the pressing force (weight) between the joint surfaces. This has been done by adjusting the attachment conditions to appropriate ones according to the purpose of the bonded body and the brazing material used.

[0005]

However, in the technique depending on the brazing condition, it is difficult to adjust the thickness of the brazing material layer according to the set value because the respective elements have large variations. It was In addition, in this type of joint, generally, in order to push out the blowholes and impurities in the brazing material to obtain a highly reliable joint, the joining surface is loaded with a larger amount of brazing material than necessary ( In the heating brazing process, excess brazing material is positively pushed out from the outer peripheral edge of the joint surface. As can be seen from this, it is difficult to accurately control the thickness of the brazing material layer to the set value in the above-mentioned conventional technique, and therefore, the thickness is generally in a relatively large allowable range (10 to 10). 50 μm), which was one of the causes of the deterioration of the performance of the bonded body. The present invention is
The present invention has been devised in order to solve such a problem, and an object thereof is to provide a brazed joined body provided with a brazing material layer having a thickness according to a set value.

[0006]

In order to achieve the above-mentioned object, the present invention provides a brazed joined body in which a plurality of members are joined by a brazing material, and a brazing material layer is formed between the joining surfaces. The brazing material layer thickness holding means for holding the thickness of the brazing material layer is provided. In this case, the brazing material layer thickness holding means can be provided by forming a convex portion on the joint surface, or can be provided by interposing an inclusion between the joint surfaces.

[0007]

In the joined body according to the present invention, since the brazing material layer thickness holding means is provided at the portion of the brazing material layer between the joint surfaces, the brazing material layer has a thickness of the brazing material layer. The thickness is held substantially at the same height as the holding means. Therefore, it is possible to reduce the variation in the thickness and to obtain a joined body including the brazing material layer having a thickness almost equal to the set value.

[0008]

EXAMPLE An example in which the joined body according to the present invention is embodied will be described in detail with reference to FIG. However, the bonded body 1 in this example is composed of the metal member 2 and the ceramic member 3, and the metal member 2 is JIS SNCM630.
The diameter is 30 mm, the length is 50 mm, the joint surface 2a is polished to Ra (center line average roughness) 0.2, and the ceramic member 3 is used.
Is a silicon nitride (90 wt% Si3 N4, the balance sintering aid) sintered body having a diameter of 30
It is a disk having a thickness of 3 mm and a thickness of 3 mm. In this example, the portion of the brazing material layer 4 between the joining surfaces 2a and 3a, and the joining surface 2a on the metal member 2 side is provided with a height substantially the same as the thickness T of the brazing material layer 4. A minute convex portion (protrusion) 5 as a brazing material layer thickness holding means is formed by means described later. However, although not shown in detail, the protrusions 5 are formed in three places on the circumference of the joint surface 2a at substantially equal angular intervals. The height of the convex portion 5 from the joining surface 2a (set thickness of the brazing material layer) is 30 μm.

Therefore, the joined body of this example is manufactured (joined) as follows. First, the joining surface 2a of the metal member 2
Then, a predetermined foil-shaped brazing material is concentrically placed. However, the brazing material in this example has a diameter of 30 mm and a thickness of 0.0
In-Ti-Cu-Ag system (I
n; 12.5%, Ti; 1.5%, Cu; 27%, A
g; 60%). Then, the brazing material is temporarily attached to the joining surface 2a of the metal member 2 by spot welding at three locations on the same circumference at substantially equal angular intervals. Then,
The joining surface (front surface) 2a of the metal member (base material) 2 corresponding to the welded portion (point) is partially melted and becomes a swell of a predetermined height. In this example, this bulge is a convex portion. Incidentally, this height of 30 μm is the one when spot welding is performed under the conditions of 200 V and 4 watt · sec. The reason why the number of the convex portions 5 is three is to make the thickness T of the brazing material layer 4 uniform, but it goes without saying that an appropriate number of them may be provided. Next, the ceramic member 3 is placed and pressed while sandwiching the temporarily attached brazing material, and an appropriate pressure is applied to the joint surfaces 2a and 3a. Then, under this condition, in vacuum at 780 ° C., 30
Hold for a minute and cool with N2 gas displacement. In this way, after the cooling and solidification, the brazed joined body 1 including the brazing material layer 4 having the desired thickness T can be obtained.

In this brazing process, the brazing material that has begun to melt by heating is crushed by the pressure between the joining surfaces 2a and 3a, and the excess brazing material is removed from the joining surfaces 2a and 3a.
It flows out from the peripheral edge of 3a. When the tip end surface 5a of the convex portion 5 on the joint surface 2a of the metal member 2 and the joint surface 3a of the ceramic member 3 come into contact with each other, the brazing material is not crushed any more, and at that time, the thickness T of the brazing material layer 4 is reduced. Is held constant. In addition, when the thickness T of the brazing material layer 4 was measured by longitudinally cutting the bonded body (20 samples) in this example with a metallurgical microscope, it was confirmed that it was in the range of 30 to 35 μm, Therefore, it has been proved that the tolerance of the set value can be a unit of several μm. This means that the convex portion 5 is effectively acting as a means for maintaining the thickness T of the brazing material layer. The height of the convex portion 5 in this example can be set to an appropriate size depending on conditions such as a current value during tack welding of the brazing material.

In the above-mentioned embodiment, the convex portion as the brazing material layer thickness holding means is formed in association with the temporary attachment of the brazing material (foil). It is also possible to separately form a suitable number in advance.
In this case, the brazing material (foil) is sandwiched between the joining surface of the metal member and the joining surface of the other member as in the conventional case,
Heating brazing may be performed under that. As an example of the method of forming this type of convex portion, the bulge of the hole edge from the reference surface (joint surface) formed on the periphery of the indentation (hole) formed when the indenter is pressed by the Vickers Katasa test or Rockwell Katasa test A technique using (height) can be mentioned. This is a technique utilizing the fact that the ridge (height) of the hole edge is constant if the test conditions such as the test object are the same. That is, the rising height of the hole edge is checked for each material and surface roughness of the metal member or for each test load,
The height of the convex portion is selected by selecting them according to the set thickness of the brazing material layer. By the way, the metal member (test object) was JIS SNCM630 and the joint surface was polished to Ra 0.2 by the Rockwell Katasa test method (JIS B7726, Z2245), and the test load was 150.
The height (protrusion) height of the peripheral edge of the impression at the time of kgf is
It is in the range of 30 to 33 μm. In any of the above embodiments, since the convex portion as the brazing material layer thickness holding means is provided integrally (integrally) on the joint surface of one member, separate and independent components are not required. When one of the members to be joined is a metal member, its formation is relatively simple and preferable.

In the above example, the brazing material layer thickness holding means of the present invention is formed of the same material as or the same body as the members to be joined. However, the present invention can be embodied in the following manner. it can. That is, it can be embodied by adhering another independent member to the joint surface or by interposing it as an inclusion between the joint surfaces without adhering. The inclusions may be made of a material having physical properties that do not melt or change with respect to the temperature at the time of brazing and the pressure (pressing pressure) on the joint surface, and a wire (bar) with a minute outer diameter. Body, ring, board (foil)
Examples include a body, a fine powder or granules. Regardless of the form, any one may be used as long as it can form a minute gap of a predetermined size between the joint surfaces as the set brazing material layer thickness. Since the joining member is a non-metal member such as ceramic, it is difficult to form the convex portion as in the above-described embodiment, or the thickness of the brazing material layer is positively adjusted in order to act as a cushioning material. It is suitable when it is desired to increase the size.

The brazing material layer thickness holding means in the present invention comprises:
As is clear from the above description, it suffices that a predetermined minute gap corresponding to the thickness of the brazing material layer set for each bonded body is maintained between the bonded surfaces during brazing. Incidentally, the thickness of the brazing material layer is suitable to be 10 to 60 μm in the case where the joined body is a tool, and is suitable to be 50 to 100 μm in the case of jigs where the strength is not so required. . Note that the present invention is not limited to a joined body of a metal member and a ceramic member, but a widely brazed joined body (engine parts, tools, electronic parts, regardless of the material of the joined body such as metal members or ceramic members). It can be used for parts etc.). In addition, as a matter of course, the bonded body (structure) according to the present invention is made up of two members, as well as three members.
It can also be applied to a composite structure consisting of the above members,
As the brazing material, not only active brazing material but also brazing material having various compositions according to the bonded body can be used.

[0014]

In the joined body according to the present invention, since the brazing material layer thickness holding means is provided in the portion of the brazing material layer between the joint surfaces, the brazing material layer has a low thickness. The height of the material layer is maintained at approximately the same height as that of the means for maintaining the thickness. That is, by adjusting the height of the brazing material layer thickness holding means to the set value of the brazing material layer thickness set according to the purpose for each joined body, the brazing material having a thickness almost equal to the set value can be obtained. Since the joined body including the material layer can be obtained, its performance and reliability can be remarkably improved. In a joined body in which the thickness of the brazing material layer has a great influence on the performance such as durability like an engine tappet, there is a remarkable effect.

[Brief description of drawings]

FIG. 1 is a front view and a partially enlarged sectional view of an embodiment of a brazed joined body embodying the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bonded body 2 Metal member 2a Bonding surface of metal member 3 Ceramic member 3a Bonding surface of ceramic member 4 Raw material layer 5 Convex part (raw material layer thickness holding means)

Claims (3)

[Claims] 1. A brazing material formed by joining a plurality of members with a brazing material, wherein brazing material layer thickness holding means for holding the thickness of the brazing material layer is provided between the joining surfaces. A brazed joint characterized by being provided. 2. The brazed joint body according to claim 1, wherein the brazing material layer thickness holding means is a convex portion formed on the joint surface. 3. The brazed joint body according to claim 1, wherein the brazing material layer thickness holding means is an inclusion interposed between the joint surfaces.