JPH0256314B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for electrically bonding ceramics using electrical energy.

[Prior Art] For example, when non-conductive ceramics are to be bonded, the applicant interposes an adhesive that is conductive at high temperature on the bonding surface of the non-conductive ceramics,
We proposed an electrical bonding method for ceramics that heats the bonding surface and applies high DC or AC voltage to both ends of the bonding surface.

FIG. 2 is an electrical connection diagram of a device for carrying out a conventional electrical bonding method for ceramics, in which a commercial AC power source 1 short-circuits the secondary winding 2b of a welding transformer 2, which has drooping characteristics, for example. It is connected to the primary winding 3a of the step-up transformer 3 via the primary winding 2a, and discharge electrodes 4a, 4b are connected to both ends of the secondary winding 3b of the step-up transformer 3. A high voltage can be applied, and by changing the reactor of the welding transformer 2, an arbitrary current can be applied. Next, after interposing the adhesive 5, which is conductive at high temperatures, on the joint surface of the non-conductive ceramics 6a, 6b, the jet ports of the blowpipe 7a, 7b and the discharge electrodes 4a, 4b are directed toward the joint surface, and the discharge electrode The gaps between the tips of 4a and 4b and both ends of the joint surface are each about 2 mm.

Now, the joint surfaces are heated with combustible gas flame from blowpipe 7a, 7b installed on both sides of ceramics 6a, 6b.
At the same time as heating to 850°C to 900°C, heat is applied between the discharge electrodes 4a and 4b at a temperature of 1000°C to
When an AC voltage of 10,000 V is applied, the conductivity of the adhesive 5 improves with the heating described above, and arc discharge occurs between the discharge electrodes 4a, 4b and both ends of the bonding surface, resulting in an electric current of several tens of mA or more. current is applied to the adhesive 5. For example, in ceramics with a junction width of 17 mm, when a voltage of 6000 V is applied, a current of about 0.5 A flows. As a result, the adhesive 5 is heated to a high temperature by the Joule heat, melts in a short time, and is firmly bonded to the ceramics 6a, 6b.

If the area of the joint is large, the entire surface may be joined while moving the ceramic or blowpipe using an appropriate moving means (not shown). Further, by providing a plurality of pairs of blowpipe, a wide area can be joined at the same time.

Here, adhesives that have conductivity at high temperatures include 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, yttrium, molybdenum, manganese, tungsten, iron,
Examples include known adhesives containing metals such as copper, silver, nickel, tin, and zinc, and fluorides such as calcium fluoride and sodium fluoride. Further, as the combustible gas, combustible gases such as city gas, propane gas, hydrogen, oxygen gas, etc. may be used alone or in combination as appropriate.

In addition, when applying a DC voltage, a rectifier circuit may be added between the secondary winding 3b of the step-up transformer 3 and the discharge electrodes 4a, 4b.

[Problems to be Solved by the Invention] When the voltage applied to both ends of the bonding surfaces of ceramics to be bonded through an adhesive that is conductive at high temperatures is a commercial frequency AC voltage, arc discharge may occur. There is a risk that the arc may fail to re-ignite near the zero point of the current flowing in the adhesive, and in order to activate the electrical protection, the bond width should be 17 mm, for example.
For ceramics, a high voltage of 6000V or more must be applied. Therefore, applying a high voltage is not preferable from the viewpoints of work, safety, and increase in input power. On the other hand, in the case of DC voltage, there is a risk that the airflow generated in the adhesive will change due to high temperature explosion of the adhesive, which may interrupt the discharge. Under the above-mentioned conditions, a high voltage of 5000 V or more is applied, which is not preferable from the viewpoint of work, safety, and increase in input power.

[Means for Solving the Problems] In order to solve the above problems, in the present invention, a high-frequency voltage is superimposed on an AC voltage or a DC voltage as the voltage applied to both ends of the bonding surfaces of the ceramics to be bonded. It is characterized by what it did.

[Function] When the temperature of the adhesive described above is raised to 850°C to 900°C, the molecules are thermally ionized into electrons and positive ions.
In such a thermally ionized state, by applying a high voltage necessary to sufficiently move electrons and positive ions, the electrons and positive ions are accelerated and 1/10
It is known that the amount of electrons and positive ions increases in a short time of ⁴ to ^1/10 seconds, and that the amount of electrons and positive ions is sufficiently maintained even if the voltage is lowered immediately thereafter. In other words, once generated electrons and positive ions are prevented from recombining by a slight ionization effect, the arc discharge once generated continues.

For example, when applying a commercial frequency AC voltage of 6000V, the recombination time is usually shorter than the 1/10 ³ to 1/10 ⁵ seconds near the voltage zero point, and the voltage is higher than the AC voltage mentioned above, for example 10000V. Superimposing a high frequency voltage prevents the recombination of electrons and positive ions that have been generated at least once, so that the electrons and positive ions are maintained at a certain value. Then, for example
Even at a potential of about 1000V, electrons and positive ions are multiplied by this electric field, so the above-mentioned AC voltage can be reduced to 700 to 2000V.
Even when the AC voltage is reduced in this way, the arc can be re-ignited reliably by superimposing the high-frequency voltage on the AC voltage near the zero point of the current flowing through the adhesive. On the other hand, a similar phenomenon can occur when applying a DC voltage, so
By superimposing a high frequency voltage at startup, the applied voltage can be reduced, and by continuously superimposing a high frequency voltage, if the arc breaks for some reason, re-ignition is reliably performed.

[Example] The present invention will be described below with reference to the drawings. 1st
The figure is an electrical connection diagram of an apparatus for implementing the ceramic electrical bonding method of the present invention, and the same components as in FIG. 2 are given the same reference numerals. In the figure, a commercial AC power supply 1 short-circuits a secondary winding 2b of a welding transformer 2, which has a drooping characteristic, and passes the primary winding 3a of a step-up transformer 3 through this primary winding 2a. A bypass capacitor 8 is connected to both ends of the secondary winding 3b. Furthermore, a high frequency generator 10 is connected to the primary winding 9a of the air core transformer 9 at one end, and connected to the discharge electrode 4a via the secondary winding 9b, and the discharge electrode 4a is connected to the other end. 4b is connected. That is,
The high-frequency voltage generated from the high-frequency generator 10 becomes a high voltage in the secondary winding 9b of the air-core transformer 9, and this high-voltage high-frequency voltage is superimposed on the secondary output voltage of the step-up transformer 3, and the discharge electrodes 4a, 4b are superimposed on the secondary output voltage of the step-up transformer 3. applied in between. Next, after interposing the adhesive 5, which is conductive at high temperatures, on the joint surfaces of the non-conductive ceramics 6a, 6b, the spouts of the blowpipe 7a, 7b and the discharge electrodes 4a, 4b are directed toward both ends of the joint surface. Deploy.

Now, the joint surfaces are heated with combustible gas flame from blowpipe 7a, 7b placed on both sides of ceramics 6a, 6b.
While heating to 850℃~900℃, for example, the bond width
In the case of 17 mm ceramics, when a voltage obtained by superimposing a high frequency voltage of 10000 V on a commercial frequency AC voltage of about 1000 V is applied between the discharge electrodes 4a and 4b,
Arc discharge occurs between the discharge electrodes 4a, 4b and both ends of the joint surface. After that, welding transformer 2
By adjusting the reactor, the adhesive 5 is energized with the same current as when only a commercial frequency AC voltage of 6000 V is applied. At this time, the current due to the high frequency voltage flows through the bypass capacitor 8. As a result, the adhesive 5 is heated to a high temperature and melts, thereby firmly joining the ceramics 6a and 6b. Here, the high-frequency voltage may be generated continuously, but in the configuration described above, the phase of the energizing current is delayed by approximately 90 degrees with respect to the applied AC voltage. It is more effective if it is set near the zero point of .

In the above explanation, the type of applied voltage was commercial frequency AC voltage, but in the case of DC voltage, a rectifier circuit must be added between the secondary winding 3b of the step-up transformer 3 and the bypass capacitor 8. Bye.

Further, by forming the blowing pipes 7a, 7b into a partially raised shape, the blowing pipes 7a, 7b can be used as discharge electrodes.

[Effects of the Invention] As described above, according to the present invention, by superimposing a high frequency voltage on the voltage applied to the adhesive,
Since the applied voltage can be reduced compared to conventional methods, it is possible to improve the safety of electric power equipment and the human body, and improve work efficiency.Also, even when the applied voltage is reduced, the arc cannot be re-ignited. This has the effect of ensuring that the process is carried out reliably.

[Brief explanation of drawings]

FIG. 1 is an electrical connection diagram of an apparatus for implementing the ceramic electrical bonding method of the present invention, and FIG. 2 is an electrical connection diagram of an apparatus for implementing the conventional ceramic electrical bonding method. 1... AC power supply, 3... Step-up transformer, 4a, 4
b...Discharge electrode, 5...Adhesive, 6a, 6b...
Ceramics to be joined, 7a, 7b...Blowpipe, 1
0...High frequency generator.

Claims (1)

[Claims] 1. Butt ceramics to be joined that are conductive at high temperatures or with an adhesive that is conductive at high temperatures, heat both ends of the joining surfaces with a gas flame, and 1. A method for electrically bonding ceramics in which a DC or AC voltage is applied to a portion of the ceramics, and a voltage obtained by superimposing a high-frequency voltage on the DC or AC voltage is applied.