JPH0262518B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method of brazing ceramics and metal.

Conventional technology For example, when the inside of a cylinder is placed in a high temperature or corrosive environment, ceramics with excellent heat resistance and corrosion resistance are used on the inner surface of the cylinder, and metal with excellent toughness, workability, and economic efficiency is used on the outer surface. It is possible to do so. By the way, the coefficient of linear expansion of metal is usually larger than that of ceramics, so even if the dimensions are such that the metal cylinder and ceramic cylinder are in close contact at room temperature, when the temperature rises, the metal will expand more and the metal cylinder and ceramic cylinder will A space is created between the cylinder and the cylinder. In this state, if pressure is applied to the inner surface of the ceramic cylinder, the pressure will not be transmitted to the metal cylinder, and the ceramic cylinder may crack. Therefore, it is necessary to bond the ceramic cylinder and the metal cylinder to each other.

By the way, brazing is one of the most reliable joining methods for joining metal and ceramics. When joining large and small cylinders together using this brazing method, as shown in Fig. 11, both cylinders 2
After inserting the brazing material 24 into the gap 23 between 1 and 22, brazing was performed by heating to a high temperature.

Problems to be Solved by the Invention According to the conventional brazing method described above, unless the gap between the inner cylinder and the outer cylinder (brazing gap) is approximately 0.1 mm or less, the molten brazing material will be transferred to the brazing surface due to capillary action. It cannot be held in its entirety. That is, as shown in FIG. 12, if the gap 23 between the surfaces 21 and 22 is large, the brazing filler metal 24 will flow downward due to gravity, causing a shortage of brazing filler metal 24 in the upper part and causing defects. When this brazing method is applied to join a metal cylinder and a ceramic cylinder, heating to the brazing temperature will cause the gap between the two cylinders to
There is a problem in that the gap becomes quite wide, and the molten brazing filler metal flows to the bottom, causing the above-mentioned defects. For example, when joining a copper cylinder to the outer surface of zirconia ceramics with an outer diameter of approximately 100 mm, even if the brazing gap is 0.1 mm at room temperature, the brazing temperature is approximately
When heated to 800℃, it expands to about 0.4mm.

Therefore, an object of the present invention is to provide a method of brazing ceramics and metal that can solve the above problems.

Means for Solving the Problems In order to solve the above problems, the method of brazing ceramics and metal of the present invention is a method of brazing a metal cylinder to the outer surface of a ceramic cylinder, in which the inner surface is formed into an inverted conical shape. At the same time, the ceramic cylinder is placed in a holding jig, and each divided piece of the metal cylinder, which has been divided into multiple pieces in the circumferential direction, is placed along the outer surface of the ceramic cylinder with a brazing material sandwiched between them, and then the above-mentioned This method involves installing a plurality of spherical bodies between the inner surface of the holding jig and the outer surface of each divided piece, and then heating the spherical bodies to a brazing temperature while applying a predetermined pressing force to the upper part of the spherical bodies.

Effect According to the above method, the metal cylinder is divided into a plurality of pieces to be joined to the outer surface of the ceramic cylinder, and when the brazing filler metal placed between the two cylinders is heated, each divided piece of the metal cylinder is separated through the spherical body. Since it is pressed against the ceramic cylinder side, the gap between the two cylinders does not widen when the brazing filler metal is heated, so that the entire gap can be uniformly filled with the brazing filler metal, resulting in a good bond.

Embodiment Hereinafter, an embodiment of the present invention will be described based on the drawings.

First, as shown in FIGS. 3 and 4, a metal cylinder 2 made of copper to be joined to the outside of a ceramic cylinder 1 made of ceramic is equally divided into a plurality of pieces, for example eight pieces, in the circumferential direction. Next, the first
As shown in the drawings and FIG. 2, a steel holding jig 5 having a space 4 having an inner surface shaped like an inverted cone is placed on a base 3. Next, in this space 4,
A state in which the divided pieces 2a of the metal cylinder 2 are arranged on the outer surface of the ceramic cylinder 1 with the brazing material 6 in between (the third
4), after being placed, a plurality of ceramic balls (spherical bodies) 7 are filled into the annular groove between each divided piece 2a and the inner surface of the holding jig 5. At this time, the ceramic ball 7 is placed so that the top surface of the ceramic ball 7 is higher than the top surfaces of both cylinders 1 and 2. Next, a weight 8 is placed on the top surface of the ceramic ball 7. Then, the pressing force is transmitted to each divided piece 2a via the ceramic ball 7, and each divided piece 2a is pressed against the ceramic cylinder 1. In this state, the whole is heated to the melting temperature of the brazing filler metal 6. Then, the brazing filler metal 6 melts and is pressed by the weight 8 through each divided piece 2a, so that it sufficiently spreads between the two divided pieces 2a. Thereafter, the bonding is completed by cooling (see FIGS. 5 and 6).

Although ceramic balls were used as the spherical bodies in the above embodiments, metal balls may also be used if the heating temperature is low.

In addition, if you want to further strengthen the above,
The copper metal cylinder may be brazed to the outer surface of the outer copper metal cylinder without dividing it, as it is, by a conventional method.

Here, the size of the ceramic ball, the width d of the annular groove, and the inclination angle θ of the inner surface of the inverted conical space 4 are
Explain the relationship between

When a ceramic ball is placed in an annular groove, the state shown in FIG. 7 is good. In other words, three or more ceramic balls are not lined up on the same horizontal plane, and one or two ceramic balls are inserted below the annular groove, so that the pressing force F by the weight 8 is efficiently applied to the metal cylinder 2 side. In order to transmit the pressing force P well, it is necessary to make the frictional force between the ceramic balls as small as possible. Therefore, the diameter D of the ceramic ball is preferably 2/3 to 2 times the width d of the annular groove, and the inclination angle θ of the inner surface is 70.
~85° is good.

As shown in Figure 8, when the diameter of the ceramic balls is small, the number of ceramic balls increases and the contact area between the ceramic balls increases, resulting in a large frictional force.For example, below the annular groove, the pressing force against the metal cylinder increases. decreases. Conversely, as shown in FIG. 9, when the diameter of the ceramic balls is increased, the number of ceramic balls decreases, and the pressing force becomes uneven in the vertical direction. Furthermore, as shown in Fig. 10, if the inclination angle θ of the inner surface is smaller than 70°,
When the number of ceramic balls increases and the angle is small, the rate at which vertical pressing force is converted into horizontal pressing force decreases.

Next, an experimental example comparing the method of the present invention and a conventional method will be shown.

In this experiment, the outer diameter was 80 mm, the thickness was 5 mm, and the height was 30 mm.
A copper cylinder with a thickness of about 2 mm was bonded to the outer surface of a zirconia ceramic cylinder.

First, in the conventional case, the brazing gap between the ceramic cylinder and the copper cylinder was set to about 0.15 mm, and a 0.1 mm thick brazing metal (Ag-Cu-Ti brazing metal) was applied to both cylinders. It was heated to about 850°C. Then, when we examine the joint surface after brazing, we find that
As expected, the upper part was not soldered due to lack of solder. This is because the gap after heating was considerably wider than that before heating.

Next, in the case of the present invention, each divided piece of the copper cylinder divided into eight parts in the circumferential direction is placed on the outer surface of the ceramic cylinder with a brazing material sandwiched therebetween, and a ceramic ball with a diameter of 6 mm is placed on the outside thereof. After that, a weight of about 6 kg was placed above the ceramic ball and heated to perform brazing. When we examined the cross section of the joint, we found that enough brazing metal had entered between the two cylinders, and the joint was complete. by the way,
As a trial, we divided a copper cylinder into 8 parts in the same way as above, and attached a nichrome wire (0.5
mm diameter), and brazing was performed, but since each divided piece was not pressed uniformly, the brazing material did not penetrate sufficiently between the two cylinders, and a complete joint could not be obtained. Note that hot isostatic pressing (HIP) is a method for pressing each divided piece, but it requires expensive equipment.

Effects of the Invention According to the above-mentioned brazing method of the present invention, the metal cylinder to be joined to the outer surface of the ceramic cylinder is divided into a plurality of pieces, and when the brazing filler metal placed between the two cylinders is heated, the metal is transferred through the spherical body. Since each divided piece of the cylinder is pressed against the ceramic cylinder side, the space between the two cylinders does not widen when the brazing material is heated, and therefore the entire space can be uniformly filled with the brazing material, resulting in a good result. A bond is obtained.

[Brief explanation of drawings]

1 to 10 show an embodiment of the present invention, in which FIG. 1 is an overall sectional view, FIG. 2 is a plan view of the same,
Fig. 3 is a side view showing the state before heating, Fig. 4 is a plan view of Fig. 3, Fig. 5 is a side view showing the state after heating, Fig. 6 is a plan view of Fig. 5, and Fig. 7 is a side view showing the state before heating. 10 are side views showing the relationship between the ceramic ball and the annular groove, and FIGS. 11 and 12 are sectional views showing a conventional example. 1... Ceramics cylinder, 2... Metal cylinder, 2
a... Divided piece, 3... Base, 4... Space part, 5...
... Holding jig, 6... Brazing metal, 7... Ceramic ball, 8... Weight.

Claims (1)

[Claims] 1. A method of brazing a metal cylinder to the outer surface of a ceramic cylinder, in which the ceramic cylinder is placed in a holding jig whose inner surface is shaped like an inverted cone, and
Each divided piece of the metal cylinder, which is divided into multiple pieces in the circumferential direction, is placed along the outer surface of the ceramic cylinder with a brazing material sandwiched between them, and then between the inner surface of the holding jig and the outer surface of each divided piece. 1. A method for brazing ceramics and metal, which comprises arranging a plurality of spherical bodies, and then heating the spherical bodies to a brazing temperature while applying a predetermined pressing force to the upper part of the spherical bodies.