JPH08255667A - Creeping discharge element for ozonizer and its manufacturing method - Google Patents

Abstract

PURPOSE: To provide a creeping discharge element which can keep high precision even when it is made into a large plate form or a laminated structure so as to improve the dimensional precision, and a method for manufacturing it. CONSTITUTION: An alumina green sheet 16 is subjected to a first baking under the atmosphere to form a dielectric layer 2. A linear corona discharge electrode 3 is printed on the upper surface of the dielectric layer 2 by use of a paste having an alloy powder mainly consisting of molybdenum dispersed therein, and a surface induction electrode 4 is also printed on the lower surface. A protecting layer 5 consisting of a paste having fine ceramic powder mixed thereto is adhered to the surface of the dielectric layer 2 including these electrodes 3, 4. The thus-formed discharge element material 18 is subjected to a second baking.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a creeping discharge element for an ozonizer and its manufacturing method. More specifically, it is a creeping discharge element equipped in an ozonizer for performing sterilization, deodorization, decolorization, etc. of gases, liquids and solids with ozone, and a creeping discharge element manufactured with high accuracy in terms of shape and dimensions, and its manufacturing method. Regarding

[0002]

Conventionally, a silent ozone generator using a glass discharge tube has been used as the ozonizer. However, since the silent ozone generator uses a glass discharge tube and has a large volume, if the capacity of the silent ozone generator is increased with an increase in the number of objects to be treated, the aggregate of glass discharge tubes becomes enormous. Further, the glass discharge tube needs to be cleaned and replaced due to stains and wear, and the creeping discharge type ozonizer is gradually used because of its low electrical efficiency.

This creeping discharge method enables high-frequency discharge and increases the acceleration energy of electrons, facilitating the ozonization reaction, and since the discharge is along the surface, it is easy to cool the discharge space. Furthermore, since the ceramics used for the dielectric layer are superior in mechanical strength and thermal shock characteristics to the above-mentioned glass, it is possible to operate under low temperature and pressure, and to improve efficiency. In addition, it has the advantage that the consumption of the discharge element is small.

However, as is known from the description in Japanese Patent Publication No. 22998/1990, the conventional creeping discharge element is provided with a corona discharge electrode and an induction electrode at the same time when firing fine ceramics for forming a dielectric. It is manufactured by baking.

That is, as shown in FIG. 3, first, the alumina powder 51, the binder 52, and the dispersion medium 53 are mixed by a ball mill 54 or the like. Then, after the vacuum defoaming process V, an alumina green sheet 55 is formed by doctor blade molding or the like. Then, one of the two alumina green sheets cut into the predetermined size
A corona discharge electrode 56 is printed on the upper surface of 5a with a paste containing tungsten, and a protective film 57 is attached to the upper surface of the same with a paste containing alumina powder. In addition, the induction electrode 58 is printed on the upper surface of the other side 55b by the same paste containing tungsten. Next, the other of the alumina green sheets 55b is connected to the one of the alumina green sheets 55 having the induction electrode 58.
The material 59 of the creeping discharge element is formed by adhering it to the back surface of a with a pressure press or the like so as to face it. This material 59
Since the metal electrodes are printed, the materials are heated and fired in the non-oxidizing atmosphere of the firing furnace 60.

The plate-shaped creeping discharge element 61 is thus completed. Alumina green sheet is dielectric layer 6
It becomes 2.

The tungsten is used as the electrode material because it has a shrinkage factor close to that of the alumina green sheets 55a and 55b, which are the materials for the dielectric layer, when it is fired.

[0008]

However, the creeping discharge element 61 manufactured as described above has the electrodes 56 and 58.
Alumina green sheets 55a, 5 with printed
Since 5b is integrally fired at a high temperature, it becomes difficult to adjust the strain, and there is a limitation in improving the dimensional accuracy.

As a result, for example, when manufacturing a discharge unit having a laminated structure in which a plurality of creeping discharge elements 61 are laminated, the joining method is limited and good sealing properties of the joining portion with the raw material gas introduction portion and the like are provided. Can not be expected. further,
When the size of the single creeping discharge element 61 is increased, the dimensional accuracy may be reduced proportionally.

For the above reasons, it is difficult to manufacture a high-precision and large-capacity ozonizer compactly.

The present invention has been made to solve the above problems, and since it is possible to improve the dimensional accuracy, it is possible to maintain a high accuracy even in the case of a large plate or a laminated structure. And its manufacturing method.

[0012]

A creeping discharge element according to the present invention is a creeping discharge element in which a linear corona discharge electrode and a planar induction electrode are formed with a dielectric layer interposed therebetween. The electrode is formed of one of the metals described in (1) and (2) below, (1) an alloy containing molybdenum as a main component, (2) an alloy containing silver and palladium, and the dielectric. The layer is formed of alumina porcelain, and is characterized in that a metallized layer is formed on the boundary surface between the corona discharge electrode and the dielectric layer by diffusion of both.

Further, it is preferable to form a protective layer on the surface of the corona discharge electrode, since it is possible to prevent the electrode from being worn due to discharge. Further, it is preferable to form a protective layer also on the surface of the induction electrode because it is more effective to prevent electrode wear due to discharge.

The method of manufacturing a creeping discharge element of the present invention comprises the steps of first firing a dielectric material made of fine ceramics to form a dielectric layer when manufacturing a creeping discharge element for an ozonizer, and the following (1) and A linear corona discharge electrode is printed on one surface of the dielectric layer and a planar induction electrode on the other surface with a paste in which a powder made of one of the metals described in (2) is dispersed. Printing step, (1) alloy containing molybdenum as a main component, (2)
The method is characterized by including an alloy of silver and palladium, and a step of performing second firing while leaving these electrodes as they are.

In the step of printing the corona discharge electrode and the induction electrode on the dielectric layer, a protective layer material made of fine ceramics or glass or a protective layer material made of resin is printed on the surface of the dielectric layer including each electrode after printing. It is preferable to add the step of applying, in the same manner as described above, in that the electrode can be prevented from being worn out due to discharge.

[0016]

According to the method for manufacturing a creeping discharge element of the present invention, the alumina green sheet before printing the electrodes is fired to form the dielectric layer. Therefore, for example, the dimension inspection of the dielectric layer is performed after the firing. By performing a grinding process as needed, a dielectric layer with high dimensional accuracy can be formed. In the baking (baking) of the printed electrode, which is a post-process, there is no need to worry about distortion of the dielectric layer because only a small amount of heat is applied at a lower temperature than when the alumina green sheet is baked, and skillfully Since the selected electrode material does not inadvertently shrink due to baking, a sound electrode is formed. In this way, a highly accurate creeping discharge element is manufactured.

Further, according to the present invention, since the quality check can be performed in the middle of the product manufacturing process after the dielectric layer is formed as described above, it is possible to allow the dimensional accuracy and the like until after the surface discharge element is completed as in the conventional case. There is no such thing as whether or not it is possible. Moreover, since the alumina green sheets are normally fired continuously in the furnace in the air atmosphere and the electrodes are fired batchwise in the furnace in the non-oxidizing atmosphere, the intermediate product is high before the batch treatment. The product yield is good because it is finished to dimensional accuracy. It has a great advantage as compared with the prior art in which the dimensional accuracy is confirmed after the batch firing (after the surface discharge element is completed).

Since it is possible to improve the dimensional accuracy of the creeping discharge element as described above, it is easy to make it large. Further, even when assembling such a creeping discharge element in a laminated structure, the joining method is not particularly limited, and the sealing property can be easily improved even in the joining portion with the raw material gas introduction portion, and the accuracy can be improved. A good discharge unit can be manufactured.

[0019]

Embodiments of the creeping discharge element and the manufacturing method thereof according to the present invention will be described below with reference to the accompanying drawings.

FIG. 1 (a) is a plan view showing an embodiment of the creeping discharge element of the present invention, and FIG. 1 (b) is an A of FIG. 1 (a).
FIG. 2 is a cross-sectional view taken along the line A, and FIG. 2 is an explanatory view showing an embodiment of a method of manufacturing the creeping discharge element of the present invention.

In FIG. 1, reference numeral 1 denotes a plate-shaped creeping discharge element having a linear corona discharge electrode 3 on its upper surface and a planar induction electrode 4 on its lower surface with a dielectric layer 2 in between. In this embodiment, the dielectric layer 2 is made of alumina porcelain, and both electrodes 3, 4 are made of molybdenum-containing metal. Molybdenum was used as the electrode material because the amount of heat applied at the time of baking the electrode is smaller than that at the time of firing the alumina green sheet, so that it contracts when the particles are sintered corresponding to the dielectric layer 2 which hardly contracts. This is because the metal needs to have a low rate. further,
Another purpose is to use a refractory metal as an electrode material in order to prevent damage to the electrodes due to discharge when the creeping discharge element 1 is used. From this point of view, other metals such as niobium, tantalum, or rhenium can be used as the counter electrode in the alumina porcelain dielectric layer.
On the contrary, if the conventional tungsten electrode is to be baked on the dielectric layer made of the fired alumina porcelain, the electrode itself may be distorted or easily peeled off due to the difference in shrinkage.

On the other hand, as the dielectric layer, aluminum nitride or the like can be used instead of alumina porcelain.

In the figure, reference numeral 5 is a protective layer formed to prevent the electrode from being worn away by electric discharge.

Metallized layers 6 and 7 are formed on the boundary surfaces between the electrodes 3 and 4 and the dielectric layer 2, respectively. In the metallized layers 6 and 7, a slight component in the alloy mainly composed of molybdenum of the electrodes 3 and 4 is contained in the dielectric layer 2.
Is a layer portion formed by diffusing into and reacting with the alumina porcelain, and has an effect of firmly fixing the electrodes 3 and 4 and the dielectric layer 2 to each other. Therefore, the electrodes 3 and 4 are not likely to peel off even during use of the creeping discharge element 1.

Next, a method of manufacturing the creeping discharge element 1 will be described with reference to FIG.

In FIG. 2, first, alumina powder 11, binder 12 and dispersion medium 13 are mixed by a ball mill 14 or the like to obtain a viscous fluid slurry (FIG. 2).
(A)).

Then, after vacuum defoaming treatment (FIG. 2B), an alumina green sheet 16 is formed by a doctor blade device 15 or the like (FIG. 2C).

Then, the alumina green sheet 16 cut into a predetermined size is heated and fired in the atmosphere of the first firing furnace 17. The finished product is the dielectric layer 2 (FIG. 2 (d)).

Although not shown, the dielectric layer 2 is dimensionally inspected as necessary, and as a result of the dimension inspection, the dimension and shape are adjusted by grinding or the like as necessary (strain relief). .

Next, a linear corona discharge electrode 3 (see FIG. 1A) is printed on the upper surface of the dielectric layer 2 with a paste mixed with an alloy powder containing molybdenum as a main component, and the same molybdenum is also formed on the lower surface thereof. The induction electrode 4 is printed with a paste containing an alloy powder whose main component is (FIG. 2).
(E)).

Then, a protective film 5 is adhered to the upper surfaces of the electrodes 3 and 4 by a paste containing fine ceramic powder to form a material 18 for the surface discharge element. (FIG. 2 (f)).

Thereafter, this material 18 is applied to the metal electrode 3,
In order to bake No. 4, it is heated in the non-oxidizing atmosphere of the second firing furnace 19 (FIG. 2 (g)). By this heating, the protective layer 5 is formed and the dielectric layer 2 and the electrodes 3, 4 are formed.
The metallized layers 6 and 7 (see FIG. 1B) are formed on the boundary surface between the metallized layers and. When heating by the second firing furnace 19,
Compared with the heating and firing in the first firing furnace 19, the temperature is, for example, 50 to 100 ° C. lower, so the amount of heat applied to the material 18 is much smaller than in the first firing furnace 17. Therefore, there is no possibility that the dielectric layer 2 will be distorted.

The plate-shaped creeping discharge element 1 is thus completed (FIG. 2 (h)).

[0034]

According to the present invention, since the dielectric layer has little distortion and has high dimensional accuracy, it is a high-precision creeping discharge element not only in the case of a small size but also in the case of a large plate. Further, even when assembling such a creeping discharge element into a laminated structure, the joining method is not particularly limited,
Further, it is possible to easily improve the sealing property even at the joint portion with the raw material gas introduction portion, and it is possible to manufacture the discharge unit with high accuracy.

Further, according to the manufacturing method of the present invention, since the quality check can be performed at an intermediate stage of the product manufacturing process after forming the dielectric layer, the product yield is good.

[Brief description of drawings]

1A is a plan view showing an embodiment of a creeping discharge element of the present invention, and FIG. 1B is a sectional view taken along the line AA of FIG. 1A.

FIG. 2 is an explanatory view showing an example of a method for manufacturing a creeping discharge element of the present invention.

FIG. 3 is an explanatory diagram showing an example of a conventional method for manufacturing a creeping discharge element.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Creeping discharge element 2 ... Dielectric layer 3 ... Corona discharge electrode 4 ... Induction electrode 5 ... Protective layer 6, 7 ... Metallized layer 11 ... Alumina powder 16 ...・ Alumina green sheet

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mr. Musashino Musashino 1-1 Kawasaki-cho, Akashi-shi, Hyogo Prefecture Kawasaki Heavy Industries Ltd. Akashi factory (72) Inventor Shozo Okazaki 1-1, Kawasaki-cho, Akashi-shi, Hyogo Kawasaki Heavy industry Akashi factory

Claims (5)

[Claims] 1. A creeping discharge element in which a linear corona discharge electrode and a planar induction electrode are formed via a dielectric layer, wherein the corona discharge electrode is described in the following (1) and (2). (1) an alloy containing molybdenum as a main component, (2) an alloy containing silver and palladium, and the dielectric layer is formed of alumina porcelain. A creeping discharge element for an ozonizer, wherein a metallized layer is formed on the boundary surface between an electrode and a dielectric layer by diffusion of both. 2. The creeping discharge element for an ozonizer according to claim 1, wherein a protective layer is formed on the surface of the corona discharge electrode. 3. The creeping discharge element for an ozonizer according to claim 2, wherein a protective layer is formed on the surface of the induction electrode. 4. When manufacturing a creeping discharge element for an ozonizer, a step of first firing a dielectric material made of fine ceramics to form a dielectric layer, and the metal described in the following (1) and (2). Printing a linear corona discharge electrode on one surface of the dielectric layer and a planar induction electrode on the other surface with a paste in which a powder consisting of one of the above is dispersed; ) An alloy containing molybdenum as a main component, (2) an alloy consisting of silver and palladium, and a step of performing second firing while leaving these electrodes as they are, and a method for producing a creeping discharge element for an ozonizer. 5. In the step of printing a corona discharge electrode and an induction electrode on the dielectric layer, a protective layer material made of fine ceramics or glass or a protective layer material made of resin is printed on the surface of the dielectric layer including each electrode after printing. The method for producing a creeping discharge element for an ozonizer according to claim 4, wherein a step of applying is added.