JPH0222998B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to an ion source in an object charging device,
Ion sources in static eliminators for charged objects, ozone generation discharge elements in creeping discharge ozonizers, or
This invention relates to a creeping corona discharge element used as a discharge element for plasma chemical reactions in NO _x and SO _x oxidation equipment.

More specifically, the present invention relates to improvements in a creeping corona discharge element in which a linear corona discharge electrode and a planar induction electrode are integrally opposed to each other via a dielectric layer, and a method for manufacturing the same.

[Prior Art] Conventionally, there is an electric field device for an electric field curtain in which a plurality of linear electrodes are provided in parallel on the surface of a dielectric layer, and a planar induction electrode is provided on the back surface of the dielectric layer. 57-6835), which forms an electric field curtain consisting of an unequal alternating electric field on the surface of the dielectric layer, generates an electrodynamic reaction repulsion force against the charged fine particles, and utilizes this. In this case, in order to obtain an effective repulsion force, it is necessary to apply a low-frequency AC voltage in the range of 10 to 200 Hz between the linear electrode and the planar induction electrode, and this can be used as is in the above-mentioned ion source. When a high frequency and high voltage is applied to the dielectric layer, the linear electrode may peel off from the surface of the dielectric layer due to the heat generated, become oxidized, or cause sputtering due to ion bombardment.

Further, the electric field is concentrated near each electrode in the dielectric layer, and this electric field concentration portion is locally degraded by ion collisions.

Therefore, when this electric field device is used as an ion source, its lifespan is extremely short and it cannot actually withstand long-term use.

[Problems to be Solved by the Invention] This invention solves the problems when using a conventional electric field device as an ion source, and obtains an inexpensive creeping corona discharge element that can be practically used for a long period of time. The purpose is to Here, creeping corona discharge refers to a streamer discharge that extends from a corona discharge electrode along the surface of a dielectric, and is more accurately called creeping discharge.

Another purpose is to prevent linear corona discharge electrodes from peeling off from the surface of the dielectric layer due to thermal stress even if severe temperature changes occur repeatedly during long-term use due to the nature of creeping corona discharge elements. , or wear and tear due to oxidation or ion collision.

Another purpose is to prevent the dielectric layer from being partially degraded by electric field concentration.

[Means for Solving the Problems] A creeping corona discharge element of the present invention has a linear corona discharge electrode made of tungsten and a planar induction electrode integrally provided through a dielectric layer made of alumina porcelain. A protective layer such as a glaze or an alumina insulating film is formed on the surface of the linear corona discharge electrode, and the interface between the linear corona discharge electrode and the dielectric layer is made of a metallized layer formed during firing. It is fixed together in layers.

The method for manufacturing a creeping corona discharge device of the present invention is to form an upper raw material sheet with a fine ceramic dielectric material such as fine alumina powder and a binder, and to form a linear corona discharge electrode on the upper surface of the raw material sheet and a flat surface on the lower surface. A lower raw material sheet made of the same dielectric material as the upper raw material sheet was polymerized onto the lower surface of the upper raw material sheet, pressure bonded, and then fired. In this case, a boundary layer made of a metallized layer is integrally formed at the interface between the upper raw material sheet and the linear corona discharge electrode.

[Operation] Both terminals of a high frequency, high voltage power supply are connected to the linear corona discharge electrode and the planar induction electrode, and a high frequency and high voltage is applied between the two electrodes via a dielectric layer made of alumina porcelain. A high-frequency creeping corona discharge is generated widely along the surface of the dielectric layer from the edge of the linear corona discharge electrode, generating abundant positive and negative ions, as well as causing ozone generation, oxidation of NO _x and SO _x , etc. It causes a plasma chemical reaction.

At this time, unipolar ions are taken out from the positive and negative ions in the high-frequency creeping corona discharge area that widely occurs along the surface of the dielectric layer, that is, the creeping discharge area, to charge the object, or It is possible to supply a charged object to the region where positive and negative ions exist in the discharge region to eliminate static electricity, or to fluidly supply air or pure oxygen to the creeping discharge region to turn it into ozone gas, or to convert it into _{ozone gas.} The system supplies contaminated gases containing gases to the same area and oxidizes them to turn them into clean gases.

In addition, the creeping corona discharge heats the dielectric layer and both electrodes to a high temperature, and even if they expand thermally, the expansion coefficients of tungsten and alumina porcelain are almost equal to each other, so both expand and contract, and there is a gap between them. Even if no thermal stress occurs, and even if there is an internal temperature gradient that creates thermal stress at the boundary between the linear corona discharge electrode and the dielectric, this interface will be affected by the metallization that occurs during sintering of tungsten and alumina porcelain. Since the linear corona discharge electrode and the surface of the dielectric layer are firmly fixed together through the layers, no peeling occurs between the linear corona discharge electrode and the surface of the dielectric layer.

Furthermore, a raw material sheet made of fine alumina powder and a binder, and a linear corona discharge electrode and a planar electrode printed with ink with tungsten powder dispersed on both the top and bottom surfaces of the sheet have high melting points, so they can be fired at the same time. At that time, both of them diffuse into each other to form a metallized layer.

[Example] Examples of the creeping corona discharge element of the present invention will be described with reference to the accompanying drawings.
As shown in the figure, through a dielectric layer 20 formed into a flat plate of high-purity alumina porcelain with a purity of 90% or more,
Linear corona discharge electrode 3 made of tungsten,
4, 5 and a planar induction electrode 9 are integrally sintered, and the surfaces of the linear corona discharge electrodes 3, 4, 5 are coated with protective layers 3a, 4 such as glaze or alumina insulating film.
a, 5a, and the linear corona discharge electrodes 3,
4 and 5 and the dielectric layer 20 are integrally fixed through a boundary layer consisting of metallized layers 3b, 4b, and 5b formed by mutual reaction during sintering. Such metallized layers 3b, 4b, 5b are produced by firing the corona discharge electrodes 3, 4, 5 and the alumina dielectric layer 20 in contact with each other at a high temperature, for example, when the purity of alumina is 92%. In this case, it is heated to 1500℃ for a certain period of time in a hydrogen furnace.

Further, an embodiment of the method for manufacturing a creeping corona discharge element of the present invention will be explained with reference to FIGS. 1A to 1E. The upper raw material sheet 1 is pre-pulverized into a dielectric material made of fine alumina powder or the like of several microns or less. The raw material sheet 1 is bonded with a binder and formed into a plate shape.
Linear corona discharge electrodes 3, 4, and 5 are printed on the upper surface 2 by using thick film printing technology such as screen printing to a width of about 1 mm and a thickness of about 1 mm using an ink containing tungsten powder dispersed therein.
A common conducting wire 6 and a terminal conducting wire 7 to be connected to these linear corona discharge electrodes 3, 4, 5 are printed at the same time, and a planar induction electrode 9 is printed on the lower surface 8 of the raw material sheet 1. is printed using thick film printing technology such as screen printing using ink that disperses the same tungsten powder, and a hole with a diameter of about 1 mm is formed in the center of the lower raw material sheet 10 formed of the same dielectric material as the upper raw material sheet 1. 12 is drilled through it, the hole 12 is filled with the ink to form a conductor, and the lower raw material sheet 10 is
A disk-shaped contact conductor portion 13 with a diameter of approximately 10 mm is formed using the same ink on the upper surface of the contact hole 12 centered on the hole 12 described above. Also, in the same manner, a terminal conductor 7a to be connected to the terminal conductor 7 is printed on the edge.

Further, a disk-shaped contact conductor part 15 with a diameter of about 10 mm is formed on the lower surface 14 of the lower raw material sheet 10 with the above-mentioned hole 12 at its center, and with the same ink,
A terminal conducting wire 17 connected to the terminal conducting wire 7a and a disk-shaped contact conductor portion 16 having a diameter of about 10 mm connected thereto are formed using the same ink.

The lower raw material sheet 10 thus formed was stacked on the lower surface 8 of the upper raw material sheet 1 and bonded by thermocompression, so that the planar induction electrode 9 was airtightly sandwiched between both raw material sheets 1 and 10 like a sandwich. After forming into a shape, it is fired in a hydrogen furnace to form both raw material sheets 1 and 10 into a single dielectric substrate 18. At this time, at the interface between the upper raw material sheet 1 and the linear corona discharge electrodes 3, 4, 5, a small amount of impurity SiO ₂ in the alumina porcelain is present at the grain boundaries of tungsten.
MgO and Al ₂ O ₃ diffuse and react to form a glass phase part (this is called a metallized layer), and it becomes as if roots have grown into the tungsten, forming the upper raw material sheet 1. linear electrode 3,
4 and 5 are firmly fixed.

At the same time, the planar induction electrode 9 fuses with the disc-shaped terminal conductor part 13 and is electrically connected to the disc-shaped terminal conductor part 15 on the lower surface 14 of the lower raw material sheet 10 through the conductor in the hole 12. Further, the linear corona discharge electrodes 3, 4, 5 on the surface 2 of the upper raw material sheet 1 are connected to the disc-shaped terminal conductor portion 16 on the lower surface 14 of the lower raw material sheet 10 via the common conductor 6 and the terminal conductors 7, 7a. Ru.

Figure 1E shows a cutaway of a part of the creeping corona discharge element as an ion source manufactured in this way.When using this as an ion source, a linear corona discharge electrode is shown in Figure 1F. 3,
Both terminals of a high frequency high voltage power supply 19 are connected to the electrodes 3, 5 and the planar induction electrode 9, respectively.
A high frequency high voltage is applied between 5 and 9 through the dielectric layer 20 which is a part of the dielectric substrate 18, and a high frequency creeping corona discharge is induced from each edge of the linear corona discharge electrodes 3, 4, 5. Surface 2 of body layer 20
It is generated widely along the ridge and generates an abundance of positive and negative ions.

At this time, only positive or negative unipolar ions are removed by the action of the DC electric field among the positive and negative ions generated in the area of high-frequency creeping corona discharge widely occurring along the surface 2 of the dielectric layer 20, that is, in the creeping discharge area. It can be used to charge objects by striking them, or to eliminate static electricity by supplying charged particles to the region where these positive and negative ions are generated.
or by supplying air or pure oxygen in a fluid manner,
These gases are converted into ozone gas, or contaminated gases containing NO _x and SO _x are similarly supplied to oxidize and convert them into clean gases.

Examples of the present invention will be described as follows.

Experimental example 1 0.5mm thick made of 92% pure alumina porcelain
After printing ink containing tungsten powder dispersed on one side of the flat dielectric layer, a linear corona discharge electrode is formed by sintering, and a planar corona discharge electrode is formed on the other side of the flat dielectric layer. A creeping corona discharge element formed with an induction electrode is used as an ozonizer, and a
By applying a voltage of 10 KHz and 10 KVpp (peak to peak), a creeping discharge was generated on one side of the flat dielectric, and dry air and pure oxygen were supplied thereto to generate ozone, which lasted for 4000 hours each. Even during use, the linear corona discharge electrode did not peel off from one side of the flat dielectric.

When ozone was generated by supplying raw air with a humidity of 80% instead of the dry air described above, the linear corona discharge electrode did not peel off from the flat dielectric material even after 1000 hours of use.

Furthermore, even if this creeping discharge element is dropped from a height of 1 meter onto a concrete floor, it will not be destroyed, and even if this creeping discharge element is red-hot to 900 degrees Celsius and placed in water at 0 degrees Celsius, it will not crack or peel off. There is no, and the temperature is even below zero.
It could be used as an ozonizer even at 100℃.

Experimental Example 2 A protective layer with a thickness of 10 μm was formed using 99% pure alumina porcelain on the surface of the linear corona discharge electrode of the creeping corona discharge element shown in Experimental Example 1 above, and the protective layer was placed under the same conditions as described above. When ozone was generated, when dry air and pure oxygen were supplied as raw material gases, the lifespan was extended by 2000 hours compared to when no protective layer was formed.

Furthermore, when raw air with a humidity of 80% was supplied as the raw material gas, the lifespan was further extended by 1000 hours compared to the case without a protective layer.

The above is an example of the creeping corona discharge element of the present invention and its manufacturing method, and the present invention is not limited thereto. For example, in the above example, the lower raw material sheet 10 is polymerized on the lower surface 8 of the upper raw material sheet 1. However, if necessary, the polymerization of the lower raw material sheet 10 may be omitted.

Further, although the dielectric layer 20 in the above embodiment is flat, a cylindrical dielectric layer 26 may also be used as shown in FIGS. 2 to 5. In each of these drawings, the same parts as the drawing numbers of the above-mentioned embodiments have the same names and functions.

In FIG. 2, the upper raw material sheet 1 shown in FIGS. 1A and 1B is bent around the longitudinal direction so that the upper surface 2 is on the outside, and a dielectric layer 26 in the shape of a hollow cylinder 25 is formed and then sintered. In this case, a high frequency corona discharge is generated on the outer surface of the cylindrical dielectric layer 26 to generate ions there.

FIG. 3 shows a modification of the one shown in FIG. 2, in which linear corona discharge electrodes 3, 4, and 5 are arranged on the surface of a cylindrical dielectric layer 26 in a direction perpendicular to its generatrix direction.

FIG. 4 shows that the upper raw material sheet 1 shown in FIGS. 1A and 1B is bent with its longitudinal direction as an axis so that its upper surface 2 is inward, and then sintered to form a hollow cylindrical dielectric layer 26. A creeping corona discharge element is constructed, and in this case, a high frequency creeping corona discharge is generated on the inner surface of the cylindrical dielectric layer 26 to generate ions there.

FIG. 5 shows a modification of the one shown in FIG. 4, in which the linear corona discharge electrodes 3, 4, and
It is arranged on the inner surface of the plane in a direction perpendicular to its generatrix direction.

6 to 9 show the linear corona discharge electrodes 3, 4, 5 in the embodiment of FIG. 1E in a dielectric layer 191.
A particularly long electric transmission line 187 is arranged on the surface of the line, and between the terminal 178 of the linear corona discharge electrode 187 and the terminal 179 of the planar induction electrode 9, a high frequency high voltage power source with a pulse width of about 1NS to 1000NS is connected. The corona discharge generated in this case has a particularly active chemical action and is suitable for the production of ozone and the oxidation of NO _x and SO _x .

In FIG. 6, linear corona discharge electrodes 187 are provided in a zigzag pattern on the surface of a dielectric layer 18 on a flat plate, a planar induction electrode 9 is embedded inside the electrodes, and a dielectric layer 18 is interposed between the two electrodes. This generates creeping corona discharge. Note that arrows 188, 189, 190 in the figure
indicates the traveling direction of the traveling wave high voltage.

FIG. 7 shows a cylindrical dielectric layer 192 formed by bending the top surface of the creeping corona discharge element shown in FIG. A cylindrical dielectric layer 193 is formed by bending the dielectric layer 193 with its longitudinal direction as an axis, and creeping corona discharge is generated inside and outside the cylinder, respectively.

FIG. 9 shows a linear corona discharge electrode 18 in the generatrix direction formed on the surface of the cylindrical dielectric layer 193 shown in FIG.
7 is replaced with a spiral linear corona discharge electrode 194.

[Effects of the Invention] The present invention provides a creeping corona discharge element in which a linear electrode and a planar induction electrode are integrally provided via a dielectric layer, in which the dielectric layer is formed of alumina porcelain, and the linear corona discharge The electrode is made of tungsten, and the boundary surface between the linear corona discharge electrode and the dielectric layer is integrally fixed through a boundary layer consisting of a metallized layer formed when they are fired. Even if the surface of the dielectric layer and the linear corona discharge electrode are heated to a high temperature by the creeping corona discharge that occurs there, and they are each thermally expanded, the expansion coefficients at that time are almost equal to each other, so both expand and contract at the same time. , no thermal stress is generated between them, and even if thermal stress occurs due to a temperature gradient between the surface of the dielectric layer and the linear corona discharge electrode, there will be no thermal stress between the linear corona discharge electrode and the dielectric. The linear corona discharge electrodes and the surface of the dielectric layer are fixed together through a boundary layer made of a metallized layer generated during sintering, so that the roots of the linear corona discharge electrode and the surface of the dielectric layer are mutually connected. No peeling occurs between them. That is, these two phenomena work together to further ensure that the linear corona discharge electrode is prevented from peeling off from the surface of the induction electrode.

Furthermore, since the dielectric layer of the present invention is formed of alumina porcelain, there is no risk of local deterioration of the electric field concentration portion of the dielectric layer when the creeping corona discharge occurs due to the characteristics of the alumina porcelain. do not have.

Further, in the combined invention of the present invention, the linear corona discharge electrode is formed of tungsten in the above-mentioned creeping corona discharge element, and a protective layer is formed on the surface of the linear corona discharge electrode. Even though the linear corona discharge electrode is made of tungsten, which is susceptible to wear as described above, there is no risk of wear due to oxidation or ion collision when corona discharge occurs.

Furthermore, in the method for manufacturing a creeping discharge element, which is another combined invention of the present invention, linear corona discharge electrodes are printed on the upper surface of the upper raw material sheet and these are simultaneously fired in that state, so that the firing temperature and fine of the tungsten are controlled. The temperature is the same as that of the ceramic dielectric,
At these interfaces, a small amount of impurities SiO ₂ , MgO, and AI ₂ O ₃ diffuse into the grain boundaries of tungsten and react to form glass phase portions at the grain boundaries (this is called a metallized layer). It will be like tungsten roots extending into each other.

Therefore, the fine ceramic dielectric and the linear corona discharge electrode are firmly fixed to each other.

[Brief explanation of drawings]

1A to 1D are perspective views showing an embodiment of the method for manufacturing a creeping corona discharge element of the present invention, in which FIG. 1A shows the upper surface of the upper raw material sheet, and FIG.
The figure shows its underside. FIG. 1C shows the upper surface of the lower raw material sheet, and FIG. 1D shows its lower surface. Fig. 1E is a perspective view showing an embodiment of the creeping corona discharge element of the present invention, Fig. 1F is a cross-sectional view showing its usage state, and Figs. 2 to 9 are perspective views of other embodiments of the invention. be. DESCRIPTION OF SYMBOLS 1... Upper raw material sheet, 2... Upper surface of upper raw material sheet, 3... Linear corona discharge electrode, 3a... Protective layer, 3b... Metallized layer, 4... Linear corona discharge electrode, 4a... Protection Layer, 4b...metalized layer,
5... Linear corona discharge electrode, 5a... Protective layer, 5b
... Metallized layer, 8 ... Lower surface of upper raw material sheet, 9 ... Planar induction electrode, 10 ... Lower raw material sheet, 12 ... Hole, 13 ... Disc-shaped contact conductor part,
14... Disc-shaped contact conductor part, 16... Disc-shaped terminal conductor part, 18... Dielectric plate, 19... High frequency high voltage power supply, 20... Dielectric layer, 26... Cylindrical dielectric layer .

Claims (1)

[Claims] 1. In a creeping corona discharge element in which a linear corona discharge electrode and a planar induction electrode are integrally provided via a dielectric layer, the dielectric layer is formed of alumina porcelain, and the linear corona A creeping surface characterized in that the discharge electrode is made of tungsten, and a boundary layer consisting of a metallized layer formed during firing is integrally formed on the interface between the linear corona discharge electrode and the dielectric layer. Corona discharge element. 2. In a creeping corona discharge element in which a linear corona discharge electrode and a planar induction electrode are integrally provided via a dielectric layer, the dielectric layer is formed of alumina porcelain, and the linear corona discharge electrode is formed of tungsten. In addition, a protective layer is formed on the surface of the linear corona discharge electrode, and a boundary layer consisting of a metallized layer formed during firing is integrated at the interface between the linear corona discharge electrode and the dielectric layer. A creeping corona discharge element characterized in that it is formed as follows. 3 A linear corona discharge electrode is disposed on the upper surface of a highly flexible upper raw material sheet made of a fine ceramic dielectric material such as fine alumina powder and a binder, and a planar induction electrode is disposed on the lower surface of the tungsten powder. A creeping surface characterized by printing with ink and simultaneously firing them in that state to integrally form a boundary layer made of a metallized layer at the interface between the upper raw material sheet and the linear corona discharge electrode. Method for manufacturing a corona discharge element.