JPH0262517B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for joining ceramics, in which ceramics are joined while being pressed together or brought close to each other.

[Prior Art] The present applicant has proposed a technique for joining ceramics, for example, by interposing an adhesive that is conductive at high temperature in the joint of non-conductive ceramics, heating the joint, and applying a high voltage to the joint. proposed a method.

FIG. 5 is a schematic diagram of an apparatus for carrying out a conventional method for joining ceramics, and shows a case in which pipe-shaped ceramics are arranged one above the other and joined together. 1a and 1b are pipe-shaped non-conductive ceramics, 2 is an adhesive applied to the joint surface of the ceramics 1a and 1b, 3 is a high-voltage power source, 4a and 4b are blowpipe tubes, and 5a and 5b are electric discharges connected to the power source 3. The electrodes are arranged facing each other so that the distance between them and the joint portion is approximately 2 mm. 6 is a turntable on which the ceramics 1a and 1b are mounted, 7 is a turntable 6
This is the motor that drives the.

In such a configuration, a paste-like adhesive 2, for example, is interposed between the ceramics 1a of the upper member and the ceramics 1b of the lower member, which are not restrained in the vertical direction, and are mounted on the rotary table 6. While the pipe-shaped ceramic is rotated at 30 to 200 rpm by the motor 7 around the center thereof, the joint including the adhesive 2 is uniformly heated to 850 to 900°C with the combustible gas flame from the blowpipe 4a, 4b. moreover,
When a voltage of 1,000 to 10,000 V is applied between the discharge electrodes 5a and 5b depending on the inner diameter, outer diameter, material, number of electrodes, etc. of the ceramic, the conductivity of the adhesive 2 increases with the heating, and the discharge electrode 5a, 5b
A discharge occurs between the adhesive 2 and the adhesive 2, and a current of several 100 mA or more is passed through the adhesive 2. As a result, the adhesive 2 is heated to a high temperature by the Joule heat and melts, and only the force due to the weight of the ceramics 1a of the upper member is applied to the ceramics 1b of the lower member to complete the bonding.

Here, the adhesive having conductivity at high temperatures is mainly composed of glass components such as kaolin, Al ₂ O ₃ and SiO ₂ , and oxides and sulfides such as copper, nickel, manganese, indium, molybdenum, and zinc. chlorides, oxides of rare earth elements such as lanthanum, indium, vanadium, holmium, ittrim, molybdenum, manganese, tungsten, iron, copper,
Examples include known adhesives containing metals such as silver, nickel, tin, zinc, and fluorides such as calcium fluoride and sodium fluoride. In addition, combustible gases include city gas, propane gas, hydrogen,
Combustion gas such as oxygen gas may be used alone or in combination as appropriate.

[Problems to be Solved by the Invention] First, if the non-conductive ceramic of the upper member described above is extremely heavy, heating the bonded part containing the adhesive with a gas flame, and then starting heating it with electricity. , the adhesive begins to melt and its ability to be pushed out of the bond increases significantly. Therefore, the thickness of the melted part of the ceramic bonded part via the adhesive becomes extremely narrow, and the cross-sectional area of the current-carrying path due to heating and melting decreases, making it impossible to obtain a sufficient heat-melted cross-sectional area in the joint. There was a problem that sufficient adhesive strength could not be obtained.

Next, if the non-conductive ceramic of the upper member is extremely light, the adhesive will begin to melt due to the heating described above, but in this case, there is almost no action of pushing it outward, so a current-conducting path is secured. , the adhesive will fully react and be bonded. However, because the upper member is light, the gas molecules contained in the adhesive expand due to high-temperature reactions, or gas molecules are generated due to physical and chemical reactions at the joint, remaining as so-called blowholes, resulting in insufficient bonding. There was a problem that the strength could not be obtained. For example, since the components contained in the adhesive are oxidized by heating, the joint contains a large amount of oxide. Therefore, when the bonded body is used at high temperatures for a long period of time, there is a problem in that the bond strength decreases as the bonded portion changes over time.

On the other hand, when bonding ceramics that are conductive at high temperatures, it is possible to bond them without using the adhesive described above, but the high temperature heating generates oxidized molten parts, causing the upper member to become extremely If it is light, the bonded portion after bonding will contain a large amount of oxide, resulting in the same problem of reduced bonding strength as described above.

[Means for Solving the Problems] In order to solve the above problems, the first invention provides a first invention in which the heating current is applied when the ceramics are joined by applying a heating current to the joint portion where the ceramics are butted. Immediately before or after the end of energization, the pressure at the joint is P1, and just before or after the end of energization, the pressure is P2.
, and P1 > P2.
The second invention is that when a heating current is applied to a joint where ceramics are abutted to join them, the thickness of the molten part is set to L1 immediately before or immediately after the end of the application of the heating current, and Hereafter, the thickness of the melted part is set to L2, and the characteristics are that L1>L2.

[Function] For example, by heating a joint where ceramics are butted together with an adhesive between them using a gas flame and electricity, do not pressurize or approach the ceramics unnecessarily in the joining direction until the adhesive has sufficiently reacted. Try not to let it happen. When the adhesive has sufficiently reacted, the gas contained in the adhesive can be removed by actively pressurizing or approaching the ceramics in the joining direction to maintain the thickness of the molten part after joining to an appropriate value as small as possible. A joint with high joint strength can be obtained by suppressing the occurrence of blowholes at the joint by squeezing molecules or by extruding oxides. On the other hand, it is also possible to aim for the effect of promoting the bonding effect based on the thermal diffusion effect between ceramic molecules in the bonding reaction, and more effective bonding can be obtained.

[Example] The present invention will be described below with reference to the drawings. 1st
The figure is a schematic diagram of an apparatus for carrying out the bonding method of the first invention, and shows the case where pipe-shaped ceramics are arranged one above the other and bonded together, similar to FIG. 5, and also shows the same constituent parts. The same reference numerals are used for the same reference numbers. FIG. 2 is a diagram showing a pressurizing pattern when applied to the embodiment of FIG. 1, in which the horizontal and vertical axes represent the elapsed bonding time T and the pressurizing force P, respectively. In Figure 1, 1a', 1
b' is a pipe-shaped conductive ceramic, 3 is a high-voltage power source, 4a and 4b are blowpipe 5a and 5b are discharge electrodes connected to the power source 3, and the distance between them and the joint is about 2 mm. is placed opposite to. 6 is a rotary table on which the ceramics 1a' and 1b' are mounted; 7 is a motor for driving the rotary table 6; 8 is, for example, an air cylinder for pressurizing the upper member ceramics 1a' in the welding direction; 9 is an upper member 1a'. 10 is a rotary head for transmitting the force generated by the air cylinder 8 to the chuck 9 without any trouble; 11 and 12 are first and second solenoid valves.

In this configuration, the lower ceramic member 1b' is mounted on the rotary table 6, the upper ceramic member 1a' is placed thereon, and the upper part of the ceramic member 1a' is gripped by the chuck 9. Here, when applying a heating current to the joint between the ceramics 1a' and 1b', which will be described later, it is necessary to secure a current conduction path near the joint surface while suppressing creeping discharge at the joint surface. At the welding start point Ta shown in the figure, the first solenoid valve 11 is opened and the second solenoid valve 12 is closed, and a small pressurizing force P1 is applied to the upper member ceramic 1a' and the lower member ceramic 1 through the air cylinder 8.
so that it is added between b′. Here, the pressure
A suitable value for P1 is, for example, 0.5 g/mm ² to 10 g/mm 2 .
Next, while rotating at 30 to 200 rpm around the center of the pipe-shaped ceramics with the motor 7,
Gas flame from blowpipe 4a, 4b heats the joint to 850-900℃
Heat evenly. Furthermore, ceramics 1a′,
For example, the outer diameter and inner diameter of 1b' are 15mmφ and 11mm, respectively.
In the case of φ, when a voltage of 6000 V is applied between the discharge electrodes 5a and 5b, the conductivity near the joint surface increases with the above heating, so that the discharge electrodes 5a and 5b are connected to the vicinity of the joint surface at time Tf. A discharge occurs between the two, and a heating current of about 0.5A flows through this part.
As a result, this part is heated to a high temperature by Joule heat and begins to melt, but the initial pressure P1
The solenoid valve 11 is further energized while maintaining the heating current until the bonding surface is in a state suitable for bonding, and the solenoid valve 11 is turned on at the optimum time point Tn at which the heating current ends, at the time Tm immediately before the end of the energization, or at the time To immediately after the end of the energization. At the same time as closing, the solenoid valve 12 is opened. Thereafter, a large pressurizing force P2 is applied between the ceramics 1a' of the upper member and the ceramics 1b' of the lower member, and the pressure welding is completed. Here, the appropriate pressing force P2 is 2 to 50 times that of P1. Note that it is desirable that the pressing forces P1 and P2 have a relationship of P1<P2.

FIG. 3 is a schematic diagram of an apparatus for carrying out the joining method of the second invention, and shows a case in which pipe-shaped ceramics are arranged one above the other and joined together, similar to FIGS. 1 and 5. The same components are given the same reference numerals. Figure 4 shows the third
It is a diagram showing a displacement pattern of the joining member applied to the example shown in the figure, in which the horizontal and vertical axes represent the joining elapsed time T and the thickness L of the fused portion, respectively. In FIG. 3, 3, 4a, 5a, 5b,
6, 7, and 10 are the same as those in FIG. 1, so their explanations will be omitted. 1a and 1b are non-conductive ceramics, 2 is an adhesive, 13 is a plate cam that can move the upper member ceramic 1a in any pattern, 14 is a roller that rotates along the pattern of the plate cam, and 15 is a support. The tool 16 is a connecting rod.

In such a configuration, a paste adhesive 2, for example, is interposed between the ceramics 1a of the upper member and the ceramics 1b of the lower member, and is mounted on the rotary table 6, and the upper part of the ceramics 1a is placed on the chuck 9. grip by. Here, when applying a heating current to the adhesive 2, which will be described later, it is necessary to ensure a sufficient cross-sectional area of the current-carrying path in this part.
First, at the joining start point Ta shown in FIG. 4, the roller 14 is set at position A shown in FIG. The cam 13 is moved in the X direction. Next, while the motor 7 rotates the ceramic pipe at 30 to 200 rpm around the center thereof, the joint containing the adhesive 2 is uniformly heated to 850 to 900°C using gas flames from the blowpipe 4a and 4b. Furthermore, when the outer and inner diameters of the ceramics 1a and 1b are, for example, 15 mmφ and 11 mmφ, respectively, when a voltage of 6000 V is applied between the discharge electrodes 5a and 5b, the conductivity of the adhesive 2 increases with the heating. By this, the discharge electrodes 5a, 5 at time Tf
A discharge occurs between b and the adhesive 2, and a heating current of about 0.5 A flows through this part. As a result, this part is heated to a high temperature by Joule heat and begins to melt, but while maintaining the thickness L1 of the melted part, electricity is further applied until the adhesive 2 is in a state suitable for joining, and this heating current is applied. At the optimum energization end time Tn, the time Tm immediately before the energization end, or the time To after the energization end, the roller 14 is at the position B shown in FIG.
The plate cam 13 is moved so that it reaches . Thereafter, by moving to position C, the thickness L of the fused portion between the upper member ceramic 1a and the lower member ceramic 1b is set to a value as small as possible, for example, L2 = 5μ.
The joining is completed as m. In addition, the thickness of the melted part
It is desirable that L1 and L2 have a relationship of L1>L2.

In the above explanation, an example was shown in which pressure is applied in the case of conductive ceramics, and an example in which pressure is applied in the case of non-conductive ceramics, but conversely, in the case of conductive ceramics, it is applied close to each other, and in the case of non-conductive ceramics, pressure is applied. It is also possible to join while applying pressure. Furthermore, it is also possible to join by a combination of approach and pressurization.

[Effects of the Invention] As described above, according to the present invention, by applying a weak pressurizing force to the joint part or maintaining the thickness of the molten part at an appropriate value until the end of the approximately optimal heating current, It is possible to secure a cross-sectional area of the current-carrying path for the heating current at the joint. In addition, by applying a strong pressure to the joint after the end of the approximately optimum current flow, or by reducing the thickness of the molten part as much as possible, the variation in joint strength can be reduced.
Moreover, a bonded body with high strength can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an apparatus for carrying out the joining method of the first invention, FIG. 2 is a diagram showing a pressure pattern when applied to the embodiment of FIG. 1, and FIG. FIG. 4 is a diagram showing the displacement pattern of the upper member when applied to the embodiment shown in FIG. 3; FIG. 5 is a schematic diagram of an apparatus for implementing the conventional ceramic bonding method. It is a diagram. 1a, 1b, 1a', 1b'...ceramics, 2
...Adhesive, 3...High voltage power supply, 4a, 4b...Blowpipe, 5a, 5b...Discharge electrode.

Claims (1)

[Claims] 1. Ceramics that are electrically conductive at high temperatures are butted together, or ceramics are butted together with an adhesive that is electrically conductive at high temperatures, and the bonded portion is heated with a gas flame and a voltage is applied to the bonded portion. A method of joining ceramics by applying a heating current to the ceramics, wherein the ceramics are joined while applying pressure in the joining direction. 2. The method of joining ceramics according to claim 1, wherein the pressing force is P1 immediately before or immediately after the heating current ends, and P2 immediately before or after the end of the heating current, and P1<P2. . 3. Butting ceramics that are conductive at high temperatures, or butting ceramics with an adhesive that is conductive at high temperatures, heating the joint with a gas flame, and applying a voltage to the joint to generate a heating current. A method of joining ceramics by applying an electric current to the ceramics, in which the ceramics are brought close to each other in the joining direction and joining is performed while changing the thickness L of the molten part. 4. The ceramic according to claim 3, wherein the thickness L of the melted portion is L1 immediately before or immediately after the heating current ends, and L2 immediately before or after the end of the heating current, and L1>L2. joining method.