JP2755814B2 - How to join ceramic members - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for joining ceramic members.

[Conventional technology]

A conventional method of joining ceramic members will be described with reference to an example in which the mutually end surfaces of columnar ceramic workpieces 13 arranged on the left and right are joined together as shown in FIG.

In FIG. 3, a thin metal foil is sandwiched as a bonding foil 2 on the bonding surface, and a processed product 13 is a pressing device 10 (in FIG. 3,
(The case of using a vise is shown to show the simplest example).

A DC power supply circuit 1 in which a DC power supply, a capacitor, and a switch are connected in series is connected to the opposite ends of the bonding foil 2, and the switch is closed during the joining process to instantaneously flow a large current through the bonding foil 2. . As a result, the bonding foil 2 generates heat due to its electrical resistance, rises to a high temperature and melts, and then is cooled and solidified by opening the switch. During this time, a bonding structure was formed between the ceramic material processed products 13. .

[Problems to be solved by the invention]

The conventional joining method is relatively simple and practical as compared with other joining methods such as a hot isostatic pressing method and a method using an electric furnace, but has the following problems.

(1) It is necessary to tighten the processed product more tightly from the left and right in advance. However, when the bonding foil is melted (or re-solidified), thermal stress is locally generated due to thermal expansion, which leads to partial deformation or micro-destruction. However, the bonding strength of the entire bonding surface may be degraded.

(2) If the processed product is thin or weak in shape, it may be damaged by strongly tightening it. Further, as shown in FIG. 4, a processed product 23 such as a long thin flat plate is used.
In the case where the joint surface is large and the pressing point a is complicated, the points may be unbalanced and may be broken.

An object of the present invention is to solve the above-mentioned problems and to provide a method capable of favorably joining ceramic members.

[Means for solving the problem]

In the method for joining ceramic members of the present invention, a metal foil is provided and fixed on a joint surface of a plurality of ceramic members joined to each other, the weight is reduced, and a large direct current is applied to the metal foil to join the ceramic members. It is characterized by performing.

[Action]

In the above, the plurality of ceramic members joined to each other at the joint surface are pressed and fixed by a predetermined pressing force so that the respective joint surfaces are in close contact with each other. The ceramic member is put in a weightless state in the above state, a large direct current is applied to the metal foil, and the metal foil is melted.

The molten metal foil has a capillary constant of 10 ² to 10 ⁴ compared to the ground in a weightless state, and the distance of spreading along a solid surface in a narrow gap is 10 times that of a normal ground.
^{Since it is 2} to 10 ⁴ times, the inside of the narrow gap of the joining surface is sufficiently widened, and a good joining can be obtained with a small pressing force for fixing the ceramic member as compared with the conventional method.

As described above, since the joining of the ceramic members can be performed without performing the strong tightening, the occurrence of local thermal stress can be avoided, and the joining of the ceramic members having a thin or large joining surface is possible.

〔Example〕

 One embodiment of the present invention will be described with reference to FIG.

This embodiment shown in FIG. 1 is applied to the joining of a processed product 3 in which a thin-walled cylinder is half-split.

In FIG. 1, a processed product 3 is fixed on a stand 7 with a shoe 4 with the bonding foil 2 interposed therebetween. Next, the feed shaft 5 provided in the feed mechanism 6 is moved left and right by screw driving, and the shoe 4 is pressed against the workpiece 3 with a predetermined force via the piezoelectric element 8.

Further, a power supply circuit 1 in which a DC power supply, a capacitor, and a switch are connected in series is connected to opposite ends of the joining foil 2 sandwiched between the processed products 3. After the above assembly is completed, this is stored in a shock absorber and dropped using a weightless facility with a drop tower of about 30 m or more, and the power switch is closed by remote control to close the joint of the workpiece 3. Join.

In the above, the processed product 3 sandwiching the bonding foil 2 is fixed between the shoes 4 and pressed by the feed mechanism 6 with a predetermined force. In this case, tightening is performed while measuring the pressing force by the piezoelectric element 8, and the pressing force is set to a predetermined value designed from numerical values such as the surface roughness of the processed product and the thickness of the foil. This value is generally as small as one to two orders of magnitude in the conventional method.

The processed product 3 integrated with the feed mechanism 6 and the like by the above assembling operation is dropped by the drop tower, and a current is applied to the bonding foil 2 in a state where the weightless state is formed, and the processed product 3 is bonded.

The weightless state obtained by the drop tower is approximately at the level of the gravitational acceleration on the ground of 10 ⁻² to 10 ⁻⁴ , and at this time, the capillary constant is 10 ² to 10 ⁴ times that of the ground. This is because the distance over which the liquid spreads and spreads along the solid surface in a narrow gap such as the joint surface
10 ² to 10 ⁴ times.

FIG. 2 is a microscopic view of the bonding surface. The surface of the solid (processed product) 3 has irregularities of about several μm, and the solid bonding foil 2 is sandwiched between the two surfaces. In some cases, if the liquid gets wet and spreads in the gap d and spreads sufficiently, the bondability is good. In a weightless state, as described above, the capillary constant is significantly improved, and this has the effect of improving the bondability.

As described above, it is possible to join a processed product made of a ceramic material without performing a strong tightening, so that generation of local thermal stress can be avoided, and it becomes possible to join a processed product having a thin or large joint surface.

The above weightless state can be formed by an aircraft. In this case, the device shown in Fig. 1 is installed in the aircraft, and a weightless environment for about 20 to 30 seconds is created by parabolic flight of the aircraft. The bonding is performed during this time. The operation is manual or timer operation. In the case of the former, braking acceleration of about 10G at landing, in the case of the latter, usually 3
G, assuming an accident, it is necessary to endure an acceleration of about 10G, and it is necessary to provide a shock absorber.

〔The invention's effect〕

The method for joining ceramic members of the present invention includes a plurality of ceramic members fixed to each other with a metal foil interposed therebetween,
By joining the metal foil by applying a large direct current to the metal foil in a weightless state, it becomes possible to join the ceramic members without performing a strong tightening, so that the occurrence of local thermal stress can be avoided, and the thin or large joining can be achieved. It has become possible to join ceramic members having surfaces.

[Brief description of the drawings]

FIG. 1 is an explanatory view of one embodiment of the present invention, FIG. 2 is an enlarged sectional view of a joint portion according to the one embodiment, FIG. 3 is an explanatory view of a conventional method, and FIG. It is explanatory drawing of joining of the long thin flat plate which concerns on the method of. DESCRIPTION OF SYMBOLS 1 ... Power circuit, 2 ... Bonding foil, 3 ... Workpiece, 4 ... Shoe, 5 ... Feed shaft, 6 ... Feed mechanism, 7 ... Stand, 8 ... Piezoelectric element.

Claims (1)

(57) [Claims] The present invention is characterized in that a metal foil is provided and fixed on a bonding surface of a plurality of ceramic members to be bonded to each other, the weight is reduced, and bonding is performed by applying a large direct current to the metal foil. Method of joining ceramic members.