JPH03252078A - Corona discharge electrode and manufacture thereof - Google Patents

Abstract

PURPOSE:To improve the adhering force between a plating layer and an electrode core material and improve discharge characteristic by providing a diffusion layer formed on the electrode core material surface and the plating layer formed on the diffusion layer. CONSTITUTION:A diffusion layer 2 by metal diffusion formed on the surface of an electrode core material 1 and a plating layer 3 by metal plating formed on the diffusion layer 2 are provided. As the core material 1 of the electrode, tungsten, molybdenum and alloys thereof can be used. The metal materials used in the diffusion layer 2 and the plating layer 3 include noble metals such as gold and platinum and alloys thereof. In this way, the interposition of the diffusion layer 2 by forming the metal diffusion layer 2 on the core material 1 surface of the electrode, and plating the metal material on the diffusion layer 2 allows the prevention of plating peeling in drawing work, and the surface state of the plating layer 3 is made fine, resulting in an improvement in smoothness. Hence, the adhesion between the electrode core material and the plating layer can be improved, and discharge characteristic can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention (Field of Industrial Application) The present invention relates to a corona discharge electrode and a method for manufacturing the same.

(Prior Art) Corona discharge is a state in which a partially sustained gas discharge occurs due to an unequal electric field, such as an electric field caused by an electrode with a sharp tip.

In this state, ionization of neutral molecules occurs and the material exhibits considerable electrical conductivity.

Tungsten is often used as a material for corona discharge electrodes because it has excellent mechanical strength and is inexpensive. However, when using tungsten as a corona discharge electrode, a uniform and stable discharge can only be sustained for a short period of time.In order to maintain a stable corona discharge for a certain amount of time, the following corona discharge electrode has been proposed. has been done.

For example, Japanese Utility Model Application Publication No. 58-1+8787 describes a corona discharge electrode having a two-layer structure in which a core material such as tungsten is coated with a noble metal such as platinum by plating or vapor deposition.

According to Japanese Patent Application Laid-Open No. 59-204051i, a core material such as tungsten is covered with a vibrator such as platinum, and this is drawn to a predetermined wire diameter to improve the adhesion between the core material and the coating material and the smoothness of the wire surface. A cladding method has been described that improves discharge characteristics by using corrosion resistance of platinum or the like.

(Problem to be Solved by the Invention) However, the double-structured corona discharge electrode described above has a problem in that the coating material peels off during discharge because the adhesion between the core material and the coating material is insufficient. However, the discharge characteristics were not significantly improved.

Further, the two-layer structure electrode has a problem in that the surface smoothness is not good, which is an impediment to improving electrical characteristics.

Furthermore, in the cladding method using a vibrator made of platinum or the like mentioned above, not only is the vibrator made of platinum or the like highly hard, but it is also necessary to prevent the core material from being exposed during wire drawing in order to prevent deterioration of discharge characteristics. Since a certain amount or more is required for the thickness of the coating material, it is difficult to reduce costs, and it is also undesirable from the point of view of material efficiency.

Therefore, the challenge was to improve the adhesion between the core material of the corona discharge electrode and the metal material formed on this core material to improve the discharge characteristics, and to improve the surface smoothness of the formed coating layer. There is.

The present invention has been made to solve these problems, and an object of the present invention is to provide a corona discharge electrode that improves the adhesion between the core material and the coating layer of the electrode and has excellent discharge characteristics, and a method for manufacturing the same. shall be.

[Structure of the Invention] (Means for Solving the Problems) The corona discharge electrode of the present invention includes a linear core material, a diffusion layer formed on the surface of the core material by metal diffusion, and a diffusion layer formed on the surface of the core material. It is characterized by having a plating layer formed by metal plating.

The method for manufacturing a corona discharge electrode of the present invention also includes the steps of applying metal plating to the surface of a linear core material, heat-treating the core material to form a metal diffusion layer on the surface of the core material, and forming a metal diffusion layer on the surface of the metal diffusion layer. The method is characterized by comprising a step of applying metal plating to form a metal plating layer, and a step of wire bowing the core material on which the metal diffusion layer and the metal plating layer are formed.

In the present invention, tungsten, molybdenum, or an alloy thereof can be used as the core material of the electrode, and tungsten is particularly suitable from the viewpoint of mechanical strength.

Metal materials used for the diffusion layer and plating layer of the present invention include noble metals such as gold and platinum, and alloys thereof.

This diffusion layer can be formed as follows. First, metal plating with a thickness of 0.1 to 0.3 μm, such as gold plating, is applied to the surface of the linear core material by electroplating.

Next, in a heating furnace with a heat zone of 200 mm,
In a hydrogen atmosphere, at a temperature of about 41) O''C to soo''c, the core material is passed through at a drawing speed of 3f]0 to 809c/■in.

As a result, a gold diffusion layer is formed on the surface of the core material.

The thickness of the diffusion layer varies depending on the diameter and thickness of the core material, but
．． The diffusion layer is 0.75 for the core material of 09 +iui
It is preferable to form the film with a thickness of about 2 μm.

Next, gold plating is applied on this diffusion layer to form a plating layer.

After forming the plating layer, cold drawing force is applied using a die or the like.

In the wire drawing process, the wire drawing is repeated 17 while reducing the diameter of the wire by 1/1o00 to the diameter of the wire immediately after the plating layer is formed, thereby improving the adhesion between the gold plating layer and the diffusion layer.

After increasing the adhesion between the diffusion layer and the plating layer to a certain extent, it is possible to draw the wire without peeling the plating layer even if the wire diameter is reduced in units of 1/100 1 m. can.

(Function) According to the present invention, a metal diffusion layer is formed on the surface of the core material of a corona discharge electrode, and a metal material for improving discharge characteristics is plated on this diffusion layer.

By using this diffusion layer, the adhesion of the plating layer is improved and peeling during wire drawing is prevented.

Furthermore, the surface condition of the plating layer becomes more dense and smoothness improves, resulting in improved discharge characteristics.

(Example) Next, an example of the present invention will be described using the drawings.

Example 1 FIG. 1 is a sectional view showing an example of a corona discharge electrode according to the present invention.

In the figure, a diffusion layer 2 made of gold and having a thickness of 1.5 μm is formed on the surface of a core material 1 made of a pure tungsten wire with a diameter of 0.09 mm.

A plating layer 3 made of gold and having a thickness of 1.0 μm is further formed on the surface of the diffusion layer 2.

Such a corona discharge electrode can be produced as follows.

First, a pure tungsten wire with a diameter of 0.09-1 whose surface has been cleaned is plated with Au to a thickness of 0.3 μm.

After that, the tungsten wire was heated 5 cm/2 in the heating furnace of heat zone 20al11 under hydrogen atmosphere and 700°C.
The tungsten is passed through at a speed of min to diffuse and infiltrate Au into the tungsten surface.

After this diffusion treatment, the tungsten wire has an E
PMA (Electron Probe Mic
As is clear from the results of RO Analyzer),
An Auft scattering layer with a thickness of 1.5 μm was formed.

EPMA is a device that scans the sample surface with an electron beam to observe the two-dimensional distribution of elements, and the horizontal axis in Figure 2 is the cross-sectional direction;
The vertical axis indicates the intensity of the wavelength for detecting tungsten (ν) and gold (Au).

8.983 people detected tungsten, 5.8 people detected gold.
40 different wavelengths were used, and the thickness of the diffusion layer was determined by the inflection width of ^U.

On the surface of this diffusion layer, a new layer of Au with a thickness of 1.0 μl was added.
A plating layer is formed by a normal electroplating method.

Thereafter, the wire is subjected to cold wire drawing using a die 2 until the final wire diameter becomes 0.06 vm.

In this wire drawing process, first, wire drawing is repeated three times while decreasing the diameter by 1/1000 mm with respect to the wire diameter after U plating, and then the wire diameter is reduced to 1/10 (1/1000 mm).
The wire diameter is decreased in units of s to a predetermined final wire diameter.

The gold-coated tungsten electrode thus produced could be wire-drawn without peeling of the gold plating layer, had high adhesion between gold and tungsten, and had significantly improved surface smoothness.

Furthermore, when the corona discharge electrode obtained in this example was operated by applying a DC voltage of 7 KV, stable corona discharge could be maintained for a long time.

Example 2 Same diameter as the tungsten wire used in Example 1, 0.09
An 11 m long pure tungsten wire was coated with 0.3 μm thick ^U plating.

Thereafter, the tungsten wire was heated at 5 m/si in a hydrogen atmosphere at 500°C in a heating furnace with a heat zone of 200 cm.
It was passed at a speed of n to diffuse and infiltrate the tungsten surface.

After this diffusion treatment, the tungsten wire is coated with EP as shown in Figure 3.
As is clear from the MA results, the thickness is 0.75μ■^
A U diffusion layer was formed.

After that, under the same conditions as in Example 1, this person was placed on the υ diffusion layer.
Form a plating layer and the final wire diameter is 0.01ilI1
The wire was drawn until it reached m.

The gold-coated tungsten electrode thus produced could be wire-drawn without peeling of the gold plating layer, had high adhesion between gold and tungsten, and had significantly improved surface smoothness.

Furthermore, when the corona discharge electrode obtained in this example was operated by applying a voltage of 5 KV AC, stable corona discharge could be sustained for a long time.

Example 3 Same diameter as the tungsten wire used in Example 1, 0.09
O+i pure tungsten wire was coated with 0.3 μm thick ^U plating.

Thereafter, the tungsten wire was heated at 5 m/min in a hydrogen atmosphere at 600°C in a heating furnace with a heat zone of 200 am.
It passed at a speed of gin to diffuse and infiltrate the tungsten surface.

After this diffusion treatment, the tungsten wire is coated with EP as shown in Figure 4.
As is clear from the MA results, A with a thickness of 1.25 μ-
A u-diffusion layer was formed.

After that, Au was deposited on this Aυ diffusion layer under the same conditions as in Example 1.
A plating layer was formed, the wire was drawn until the final wire diameter was 0.0611, and when a voltage of 8 KV AC was applied and activated as a corona discharge electrode, stable corona discharge was sustained for a long time. was completed.

Example 4 Same diameter as the tungsten wire used in Example 1, 0.09
Au plating with a thickness of 0.3 μm was applied to m- pure tungsten wire.

Thereafter, the tungsten wire was passed through a heating furnace of Heat Zone 2001■ in a hydrogen atmosphere at a temperature of 800° C. at a rate of 5 layers/1 n to diffuse and infiltrate the tungsten surface.

After this diffusion treatment, the tungsten wire is coated with EP as shown in FIG.
As is clear from the MA results, 2.0μ thick Au
A diffusion layer was formed.

After that, Au was deposited on this ^U diffusion layer under the same conditions as in Example 1.
A plating layer was formed, the wire was drawn until the final wire diameter was 0.06 mm, and when a DC voltage of 4 KV was applied and activated as a corona discharge electrode, stable corona discharge was maintained for a long time. I was able to do it.

In this way, by forming a metal diffusion layer on the surface of the electrode core material and plating the metal diffusion layer, it was possible to increase the adhesion of the plating layer and improve the surface smoothness.

Further, the corona discharge electrodes obtained in these Examples had strength equivalent to that of a tungsten wire of the same diameter, and it was possible to reduce costs.

[Effects of the Invention] As explained above, according to the present invention, since the electrode has a diffusion layer formed on the surface of the core material and a plating layer formed on the diffusion layer, the plating layer and the core material are It is possible to improve the adhesion of the material, and to obtain a corona discharge electrode with excellent discharge characteristics at low cost.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing one embodiment of the corona discharge electrode of the present invention, and FIGS. 2, 3, 4, and 5 are EPMA diagrams showing the relationship between the diffusion treatment temperature and the gold diffusion layer. It is a schematic diagram of a photograph. 1... Core material 2... Diffusion layer 3... Plating layer

Claims (2)

[Claims] (1) A corona discharge characterized by having a linear core material, a diffusion layer formed on the surface of the core material by metal diffusion, and a plating layer formed on the diffusion layer by metal plating. electrode. (2) A step of applying metal plating to the surface of the linear core material and heat-treating the core material to form a metal diffusion layer on the surface of the core material, and applying metal plating to the surface of the metal diffusion layer to form a metal plating layer. A method for manufacturing a corona discharge electrode, comprising: forming the metal diffusion layer and the metal plating layer; and drawing the core material on which the metal diffusion layer and the metal plating layer are formed.