JPH07115960B2 - Method for joining ceramic member and metal member - Google Patents

Description

The present invention relates to a method for joining a ceramic member and a metal member.

[Prior Art] Generally, when a ceramic material and a metal member are filled with a brazing material and are fitted and joined, poor wettability of the brazing material results in poor filling efficiency between the two members, resulting in a decrease in bonding strength between the two members. Also, it becomes difficult to relax the stress by the brazing material.

Therefore, for example, as disclosed in Japanese Utility Model Laid-Open No. Sho 62-93343, the wettability of the brazing material is improved by plating a soft metal in advance on the fitting portion of the metal member before joining the ceramic member and the metal member, It is known to solve the above problems.

[Problems to be Solved by the Invention] Further, when a product obtained by generally combining a ceramic member and a metal member is used as a ceramic turbo rotor that is required to rotate at high speed in a high temperature atmosphere,
In order to obtain a bond strength that can be practically used, the plated soft metal preferably has a thickness in the range of 50 to 200 μm. Further, the thickness of the soft metal needs to be 200 μm or more in consideration of the dimensional tolerance, the shape tolerance and the like during machining of the mounting portion.

However, the thickness of the mating part of the metal member is 200 μm due to plating.
In order to form the above soft metal, a long time (15 to 25 hours) is required for the plating process, which is disadvantageous in terms of cost.

Here, the applicant and the applicant filed Japanese Patent Application 1-12
No. 3532 proposed a method of joining a ceramic member and a metal member. In this prior art, instead of forming the stress relaxation layer on the inner surface of the concave fitting portion of the metal member only by the plating layer, a build-up portion made of soft metal is formed, and the exposed surface of the build-up portion is machined. An inner peripheral processed surface is formed by scraping, and a plated portion is formed on the surface.

The plated portion according to the above-mentioned prior art can have a reduced thickness due to the presence of the build-up portion, the plating time is short, and the stress relaxation layer has a thickness capable of sufficiently relaxing localized concentrated stress. This is advantageous in terms of product cost because the process time for forming the is significantly reduced.
However, on the other hand, variations in film thickness and non-uniformity of the plated portion remain as the dimensions of the product, so that it is difficult to secure dimensional accuracy and shape tolerance.

The present invention provides a method for joining a ceramic member and a metal member that solves the above problems.

[Means for Solving the Problems] The applicant of the present application has studied and tested the cause of the deterioration of the wettability of the brazing material and the poor flow of the brazing material. As a result, for example, a concave fitting made of Incoloy used as a metal member It has been discovered that when the soft metal copper is welded to the inner surface of the joint to form the build-up portion, the iron content mixed in from the recessed fitting portion in the build-up portion has an adverse effect. The inventors have completed the present invention by finding that the amount of iron mixed in the surface portion of the built-up portion is 1% by weight or more and does not occur below this amount.

That is, the method for joining a ceramic member and a metal member of the present invention comprises a step of forming a stress relaxation layer made of a soft metal on the inner surface of the concave fitting portion of the metal member, and a convex portion of the ceramic member on the concave fitting portion of the metal member. Method for joining a ceramic member and a metal member, which comprises a step of inserting a concave fitting portion and a step of filling a gap between the concave fitting portion of the metal member and the convex fitting portion of the ceramic member with a brazing filler metal and coupling them. In the step of forming the stress relaxation layer, the first step of forming a build-up portion by welding the soft metal copper to the inner surface of the concave fitting portion of the metal member, and the exposed surface of the build-up portion The second step is to scrape off by machining to form an inner peripheral processed surface, and the amount of iron mixed in the build-up portion is 1% by weight on the surface portion (depth up to 20 μm from the surface). It is characterized by the following.

The first step and the second step are for forming a stress relaxation layer made of a soft metal on the inner surface of the concave fitting portion of the metal member. This stress relaxation layer is for relieving the stress of the joint when the convex fitting portion of the ceramic member is joined to the concave fitting portion of the metal member. That is, since a ceramic member generally has high rigidity and is brittle, a localized concentrated stress is generated, and the ceramic member is easily damaged from there. The stress relaxation layer relieves this localized concentrated stress.

In the first step, the amount of iron mixed in the build-up portion is set to 1 by forming a build-up portion by welding copper, which is a soft metal, in the concave fitting portion of the metal member while controlling heating conditions. It is set to not more than wt%. This overlay has a thickness of 200μ
m or more. Copper, which is used as a soft metal for forming the built-up portion, is formed as a ring-shaped material in advance, and the material is arranged along the inner surface of the concave fitting portion of the metal member, and then a high-frequency heating device and ultrasonic welding are used. It can be melted by an apparatus or the like under the above heating conditions, and can be welded and built up on the inner surface of the concave fitting portion.

The heating condition varies depending on the material of the metal member, but the heating temperature and the heating time are controlled to be predetermined conditions. For example, when a metal member made of Incoloy is used, the maximum heating temperature of copper is
By setting the maximum heating time at 1200 ° C. after copper is welded to 3 seconds or less, the amount of iron mixed in the build-up portion can be 1% by weight or less.

The reason for setting the amount of iron to 1% by weight or less is that the exposed surface of the build-up portion of the concave fitting portion is machined by the second step, the inner peripheral processed surface formed and the concave fitting portion are formed. Between the convex fitting portion of the ceramic member inserted in the joint,
When the molten brazing material is filled, the wettability of the brazing material with respect to the inner peripheral processed surface is good, and the flow of the brazing material is good, so that the filling efficiency is improved, and the concave fitting portion and the convex fitting portion are provided. This is because the bond strength with is sufficient. Since this makes the flow of the molten metal good in the related art, it is not necessary to form a copper plating layer on the inner peripheral processed surface formed by machining the exposed surface of the overlay portion.

In the second step, the amount of the built-up portion formed in the first step to be machined is preferably such that the thickness of the built-up portion after the cutting is 50 to 200 μm. Further, the machining can be performed using a processing device such as cutting or grinding.

[Operation] The method for connecting the ceramic member and the metal member according to the present invention is such that a soft metal is formed on the inner surface of the concave fitting portion of the metal member before the convex fitting portion of the ceramic member is inserted into and combined with the concave fitting portion of the metal member. Is performed when forming a stress relaxation layer consisting of
The first step and the second step are performed in this order.

In the first step, a ring-shaped build-up material made of copper, which is a soft metal, and a metal member having a concave fitting portion to be the build-up processing target formed in advance are prepared prior to the build-up processing. The build-up material is placed in the recessed fitting portion of the metal member, and while controlling the heating conditions, copper is welded to the inner surface of the recessed fitting portion to form the build-up portion and mix with the build-up portion. The amount of iron to be added is 1% by weight or less on the surface portion.

In the second step following the first step, the exposed surface of the overlay portion is machined to form an inner peripheral processed surface.

In this way, the stress relaxation layer made of copper, which is a soft metal, is formed on the inner surface of the concave fitting portion of the metal member. After this,
The convex fitting portion of the ceramic member is inserted into the concave fitting portion of the metal member, and both members are integrally joined by melting and filling the brazing material.

[Effect] In the stress relaxation layer formed on the inner surface of the convex fitting portion of the metal member by the joining method of the present invention, the amount of iron mixed in the surface portion of the overlay portion is 1% by weight or less. Even when a copper plating layer is not formed on the inner peripheral processed surface formed in two steps, when the molten brazing material is filled, the wettability of the brazing material with respect to the inner peripheral processed surface is good, and the flow of the brazing material flows. And the filling efficiency of the brazing material can be improved. Therefore, the coupling strength between the concave fitting portion of the metal member and the ceramic member becomes sufficient. Further, as a result, it is not necessary to form a plating layer for improving the flow of the molten brazing material in the concave fitting portion, and the manufacturing process and the manufacturing time can be shortened and the material can be saved accordingly. The cost can be reduced.

Furthermore, since the inner peripheral processed surface is formed by scraping off the exposed surface of the overlay portion by machining, the dimensional accuracy and shape tolerance are improved as compared with the plated one, and The bond strength is also improved.

[Embodiment] A method for connecting a ceramic member and a metal member according to an embodiment of the present invention will be described with reference to FIGS. 1 to 6.

As shown in FIG. 2, the method of connecting the ceramic member and the metal member is performed in the process of manufacturing the ceramic turbo rotor 6 which is composed of the metal member 1 and the ceramic member 4 and is required to rotate at a high speed in a high temperature atmosphere. Used.

The metal member 1 includes a rotating shaft 12 made of steel and a metal ring 14 made of Incoloy 903 integrally fixed to the tip of the rotating shaft 12 by welding.

The metal ring 14 has a concave fitting portion 15 as shown in FIG.
On the inner surface 16 thereof, a stress relaxation layer 2 made of copper is formed as a soft metal. This stress relaxation layer 2 has a metal ring 14 and a rotating shaft 12
It is formed by a first step and a second step which are sequentially performed before being integrally fixed to the tip of the.

In the first step, as shown in FIG.
The metal ring material 14a forming the coil is the coil 7 of the high frequency heating device.
It is placed inside a fixed mounting table (not shown). The shape of the metal ring material 14a is a bottomed tubular body having a through hole in the center bottom surface. Then, a ring-shaped build-up material 20 made of copper as a soft metal is placed on the inner surface 16 of the concave fitting portion 15. This overlay material 20 has a circular cross section with a diameter of 1.3 mm.
belongs to. And the heating maximum temperature is 1200 ° C. as the heating condition of the overlay material 20 by the high frequency heating device,
The maximum heating time after melting of the overlay material 20 was set to 1 second. As a result, the overlay material 20 is welded to the inner surface 16 of the concave fitting portion 15 of the metal ring 14b, and the overlay portion 21 is formed as shown in FIG.
Is formed. The amount of iron mixed in the overlay 21 is 0.33% by weight when the entire overlay 21 formed under controlled heating conditions is 100% by weight. Incidentally, in the built-up portion 21, Ni diffused from the concave fitting portion 15 and mixed in,
It is formed of a copper alloy containing Co, Al and Ti.

In the second step, with respect to the metal ring 14b taken out from the high-frequency heating device, the exposed surface 21a of the built-up portion 21 is machined to be flattened on the exposed surface side as shown by a chain double-dashed line in FIG. The inner peripheral processed surface 22 is formed (see FIG. 5). This second
The time required for machining in the process is about 35 seconds.

As a result, as shown in FIG. 1, the concave fitting portion 15 of the metal ring 14 is
On the inner surface 16 of the above, the stress relaxation layer 2 including the built-up portion 21 having the inner peripheral processed surface 22 is formed.

After the step of forming the stress relaxation layer 2 made of a soft metal and having a thickness t of 125 μm on the inner surface 16 of the concave fitting portion 15 of the metal ring 14 in this manner, the concave fitting portion 15 shown in FIG. The step of inserting the convex fitting portion 40 of the ceramic member 4 into the metal, and heating the concave fitting portion 15 of the metal ring 14 and the convex fitting portion 40 of the ceramic member 1 and melting the brazing material in the gap between them. 3 (BAg-8) is introduced and filled, and then the brazing material 3 is solidified to be joined, and the end surface of the tip end portion of the rotating shaft 12 brought into contact with the bottom outer wall surface 17 of the metal ring 14 shown in FIG. The ceramic turbo rotor 6 is formed by carrying out the step of integrally joining 12a and 12a.

In the present embodiment, the convex fitting portion 40 of the ceramic member 1 is formed without forming a copper plating layer on the inner peripheral processed surface 22 of the built-up portion 21 which is the exposed surface of the stress relaxation layer 2 of the metal ring 14. When the molten brazing filler metal 3 is flown into and filled in the gap between and, since the amount of iron mixed in the surface portion of the built-up portion 21 formed in the first step is 0.33 wt% as described above, The wettability of the brazing material 3 with respect to the circumferentially machined surface 22 is kept good, and the brazing material 3 can quickly move to every corner along the surface of the inner peripherally machined surface 22,
A packing efficiency of 95% or more was obtained.

Further, in the present embodiment, it is not necessary to form a copper plating layer on the inner peripheral processed surface 22 of the built-up portion 21 which is the exposed surface of the stress relaxation layer 2 of the metal ring 14, and the inner surface formed in the second step Since the peripheral processed surface 22 becomes the manufacturing dimension, it is difficult to secure the dimensional accuracy and the shape tolerance because the defect due to the formation of the plating layer, that is, the variation and unevenness of the plating film thickness remains as the product dimension. This can be solved, and dimensional accuracy and shape tolerance can be easily secured.

(Comparative example) For comparison, by setting the maximum temperature of the overlay portion by high-frequency heating to a high value and setting the holding time after the overlay material 20 has melted to be long, the iron content in the copper of the stress relaxation layer is set. Metal rings with different ratios were made and bonded to the ceramic member to compare the filling state of the brazing material. The results are shown in Table 1. With respect to the iron content of 1% or less in the copper of this example,
When the amount of iron mixed was more than that, the filling rate was low and good bonding could not be obtained.

The amount of iron shown in Table 1 is 20
It is in the range of μm.

The filling factor shown in Table 1 is expressed by the following equation.

Filling ratio = filled area / filled area × 100 = filled area / bonding area to be filled (= πdl) d: diameter of connecting portion l: connecting length In the present embodiment, the metal member 1 is As shown in FIGS. 1 and 2, after the metal ring 14 having the stress relaxation layer 2 formed on the concave fitting portion 15 is joined to the ceramic member 4, the metal rotary shaft 12 is welded to the outer peripheral end thereof. However, the present invention is not limited to this, and even when a metal rotary shaft integrally formed with the concave fitting portion 15 at one end in advance is used, The effect is the same.

[Brief description of drawings]

1 to 6 are explanatory views of the present embodiment, and FIG. 1 is a longitudinal sectional view showing a state in which a stress relaxation layer is formed in a concave fitting portion of a metal ring, and FIG. FIG. 4 is a partial vertical cross-sectional side view showing an example of use after the ceramic member and the metal member are joined together, and FIG. 3 is a vertical cross-sectional view showing a state in which a build-up material is arranged in a concave fitting portion of a metal ring. Is a vertical cross-sectional view showing a state in which a build-up portion is formed on the inner surface of the concave fitting portion of the metal ring, and FIG.
FIG. 4 is a vertical cross-sectional view showing a metal ring in which the built-up portion is machined to form an inner peripheral processed surface, and FIG. 6 is a convex fitting portion of a ceramic member inserted into a concave fitting portion of the metal ring. It is a partial expanded longitudinal cross-sectional view which shows the combined state. 1 ... Metal member, 2 ... Stress relaxation layer 3 ... Brazing material, 4 ... Ceramic member 14 ... Metal ring, 15 ... Concave fitting part 16 ... Inner surface of concave fitting part, 20 ... Overlay Material 21 …… Overlay part, 22 …… Inner peripheral processed surface 40 …… Convex fitting part

Claims (1)

[Claims] 1. A step of forming a stress relaxation layer made of a soft metal on an inner surface of a concave fitting portion of a metal member, a step of inserting a convex fitting portion of a ceramic member into the concave fitting portion of the metal member, In a method of joining a ceramic member and a metal member, which comprises filling a brazing material in a gap between a concave fitting portion of a metal member and a convex fitting portion of the ceramic member and joining the brazing material, forming the stress relaxation layer. Is a first step of forming a build-up portion by welding the soft metal copper to the inner surface of the concave fitting portion of the metal member while controlling the heating conditions, and the exposed surface of the build-up portion is machined off. And a second step of forming an inner peripheral processed surface, wherein the amount of iron mixed in the overlay portion is 1 at the surface portion.
A method of joining a ceramic member and a metal member, characterized in that the content is less than or equal to wt%.