JP2010225422A - Discharge electrode - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a discharge electrode applicable as an ionizer electrode or as various other discharge application electrodes having high ion generating efficiency, excellent durability with very long life, no trouble for occurrence of dust by interface peeling of a covered layer, and being capable of manufacturing with low-cost. <P>SOLUTION: The discharge electrode is a metal electrode 1 on a surface portion of which a diffusion-hardened layer of metal 11 is formed by a penetron treatment. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a discharge electrode suitable for various discharge applications such as an ionizer electrode, an electric discharge machining electrode, a glow lamp electrode, and a gas laser electrode used for static electricity removal.

  In general, in the manufacturing process of a semiconductor integrated circuit, a liquid crystal display, a precision electronic device, etc. performed in a clean space such as a clean room, the adhesion of fine particles to a workpiece due to electrostatic adsorption leads to a serious defect and An electrostatic charge eliminating device called an ionizer is used because the yield of the workpiece itself is reduced due to electrostatic breakdown of the circuit and the insulating layer. This ionizer generates a corona discharge by applying a high voltage between the needle-like electrodes to ionize gas molecules, and neutralizes the reverse polarity charge of the object to be neutralized by the generated positive and negative ions. Is.

  However, the needle electrode of the ionizer is gradually depleted with the discharge, but there is a concern that the ion generation efficiency is lowered due to the change of the tip shape due to this depletion, and the back contamination is caused by scattering of the electrode material. . In addition, the unit price of the acicular electrode is generally low, but when the lifetime is exhausted early due to depletion, it is very troublesome to replace the depleted electrode with a new one in the ionizer that is used in a large number for the liquid crystal process etc. There is also a problem that maintenance costs increase.

  Therefore, conventionally, as an ionizer electrode, the surface of the metal electrode is covered with a ceramic tube (Patent Document 1), a nickel plating layer (Patent Document 2), diamond (Patent Document 3), etc., in order to suppress the wear. A silicon oxide layer 12 on the outer peripheral surface of a rod made of silicon, a material using a titanium oxide-based conductive oxide (Patent Documents 4 and 5) or a carbide (Patent Document 6) such as silicon carbide as an electrode material. Proposed ones (Patent Document 7), those provided with a conductive layer on the outer peripheral surface of a rod made of polycrystalline silicon (Patent Document 8), etc. have been proposed, some of which have been put into practical use.

JP-A-3-230499 JP-A-5-21131 JP-A-2005-19164 JP-A-6-243951 JP 2001-217095 A JP 2006-108101 A JP-A-6-84581 JP-A-6-140127

  However, in the electrode in which the surface of the conventional metal electrode is covered with a ceramic tube, there is a problem that the ceramic tube is easily broken due to the difference in thermal expansion coefficient between the metal of the electrode and the ceramic. In addition, an electrode using a conductive oxide, carbide, silicon, polycrystalline silicon, or the like as an electrode material has a poor thermal diffusivity, so that the thermal deterioration progresses quickly and the durability is difficult. Furthermore, in the electrode in which the surface of the metal electrode is covered with a nickel plating layer or diamond (Patent Document 3), the progress of wear is slowed down by the coating layer, but the coating layer becomes thinner with time and part of the base metal At the stage of exposure, there is a problem that the wear proceeds at a stroke from the exposed part, and there is a problem that the coating layer peels off at the interface with the base metal at the peripheral part and generates dust, and the formation cost of the coating layer is high. There is also the difficulty of attaching.

  In view of the above-mentioned circumstances, the present invention has a high ion generation efficiency as a discharge electrode to be applied to various discharge applications including an ionizer electrode, and is excellent in durability and has a very long life, and An object of the present invention is to provide a product that does not cause the generation of dust due to interfacial peeling of the coating layer and can be manufactured at low cost.

  In order to achieve the above object, a discharge electrode according to claim 1 of the present invention is such that a metal diffusion hardened layer is formed on the surface of the metal electrode by penetron treatment.

  The invention according to claim 2 is the discharge electrode according to claim 1, wherein the electrode base material is a kind selected from titanium, tungsten, and stainless steel, and the diffusion metal of the diffusion hardened layer is titanium, tungsten, nickel, copper, It consists of a kind selected from gold.

  According to a third aspect of the present invention, in the discharge electrode according to the first aspect, the electrode base material is titanium, and the diffusion metal of the diffusion hardened layer is tungsten.

  According to a fourth aspect of the present invention, in the discharge electrode according to any one of the first to third aspects, the metal electrode is an ionizer electrode.

  The discharge electrode according to the invention of claim 1 has a metal diffusion hardened layer formed by penetron treatment on the surface portion of the metal electrode, and the diffusion hardened layer is densified (increased specific gravity) by the implanted metal. In addition, in a state where the implanted metal is diffused so as to decrease in density as it becomes deeper from the electrode surface, the implanted metal is completely integrated with the base material without forming an isolated interface with the base material. Therefore, according to this discharge electrode, since the entire surface including the surface portion is made of a metal material, high ion generation efficiency can be secured, and the diffusion hardened layer has high hardness and is not easily worn out. Even when the number of electrons popping out is the same as the case without the diffusion hardened layer, there is little change in shape due to wear due to the above densification, and rapid wear and tear even if the diffusion hardened layer becomes thinner over time Interfacial delamination that leads to dust generation does not occur, so it has a very long life, there is no fear of back-contamination due to scattering of the electrode material, and the electrode surface is extremely hard and is not damaged during handling. On the other hand, in the Penetron process for forming a diffusion hardened layer, the base metal is a negative electrode, and the negative electrode and the positive electrode made of a metal material to be diffused are separated from each other only by electromagnetic vibration in a state where a DC electric field is applied. Because the metal material on the positive electrode side is driven into the negative electrode side with the discharge between the two electrodes at the time to generate a diffusion hardened layer, it is extremely easy to operate and can be processed in a short time, and it can be coated by plating, CVD method, etc. Compared with the formation of the layer, the manufacturing cost of the discharge electrode is remarkably reduced and the production efficiency is greatly improved.

  According to the second aspect of the invention, since a specific metal material is used as the diffusion metal of the electrode base material and the diffusion hardened layer, the discharge electrode having the diffusion hardened layer on the surface portion can be reliably and easily manufactured by the penetron process. .

  According to the invention of claim 3, since the electrode base material is titanium and the diffusion metal of the diffusion hardened layer is tungsten, a discharge electrode having a high hardness surface portion of 1600 Hv is provided.

  According to the invention of claim 4, the ionizer electrode has high ion generation efficiency, is excellent in durability, has a very long life, and does not cause the generation of dust due to interface peeling of the coating layer, and is manufactured at a low cost. What you can do is provided.

It is a side view which shows an example of the electrode for ionizers to which this invention is applied. It is an axial direction sectional view of the tip side of the electrode for ionizers to which the present invention is applied. It is a rear view of the ionizer used for the discharge test in the Example of this invention. It is a correlation diagram which shows the relationship between the depth from the surface of the electrode for discharge which concerns on the Example of this invention, and hardness. It is an enlarged photograph figure of the tip side after the initial stage and 1 month progress of the electrode for discharge of the example in the same discharge test. It is the enlarged photograph figure of the front end side after the initial stage and 1 month progress of the electrode for discharge of the comparative example in the same discharge test. FIG. 6 is a photographic diagram further enlarging the photographic diagram of number 2 in FIG. 5. It is the photograph figure which expanded further the photograph figure of the number 4 in FIG.

  As described above, the discharge electrode of the present invention has a metal diffusion hardened layer formed by penetron treatment on the surface of the metal electrode. This diffusion hardened layer has a higher density (increased specific gravity) and higher hardness due to the implanted metal, and the base metal is diffused so that the density decreases as the implanted metal becomes deeper from the electrode surface. It is completely integrated with the base material without forming an isolated interface. Therefore, in this discharge electrode, since the entire surface portion including the surface portion is made of a metal material, high ion generation efficiency can be secured, and in addition to the surface portion being hard and difficult to wear out, it jumps out during discharge. Even if the number of electrons is the same as the case without the diffusion hardened layer, the shape change due to wear is reduced as much as the density is increased, and rapid wear is reduced even if the diffusion hardened layer becomes thinner over time. No interfacial delamination that leads to dust generation, extremely durable and long life, no fear of back contamination due to scattering of electrode material, and the electrode surface is extremely hard and will be damaged during handling There is nothing.

  The Penetron treatment for forming the diffusion hardened layer is also referred to as an electric discharge hardening treatment, and as a means to increase the hardness of the surface portion of metal cutting tools, metal forming dies, blades, etc., and extend the life. It's being used. In this penetron treatment, the object to be treated is a negative electrode, the metal material to be diffused is a positive electrode, and a DC electric field is applied between the two electrodes. With the discharge of time, the metal material of the positive electrode migrates and diffuses to the surface layer of the object to be processed of the negative electrode, and a diffusion hardened layer with extremely high hardness is formed. The treatment is generally performed in the atmosphere, but the discharge causes the negative electrode surface to be ionized at a local ultrahigh temperature (usually 15,000 ° C. or higher) to create an atmosphere that eliminates the action of oxidizing gas in the atmosphere. At the same time, the ionized positive electrode material is implanted and diffused between the atoms of the negative electrode material expanded at a local ultra-high temperature, and the implanted positive electrode material is transferred with cooling contraction to replace the negative electrode atoms.

  The discharge electrode of the present invention is a metal diffusion hardened layer formed on the surface of the metal electrode by performing the above Penetron treatment with the metal base material on the negative electrode side and the metal material to be diffused on the positive electrode side, Compared to forming a coating layer by plating, CVD, or the like, the diffusion hardened layer can be formed easily and in a short time, so that the production cost is remarkably reduced and the production efficiency is greatly improved.

  The base metal of the discharge electrode is not particularly limited because compatibility varies depending on the use of the electrode, but titanium, tungsten, and stainless steel are preferable. Similarly, the diffusion metal of the diffusion hardened layer is not particularly limited, but preferred examples include titanium, tungsten, nickel, copper, and gold. The base metal and the diffusion metal of the diffusion hardened layer may be the same. Thus, the ionizer electrode is most preferably configured with titanium as a base metal and tungsten as a diffusion metal.

  Penetron treatment conditions vary depending on the size and form of the discharge electrode, the electrode base material and the type of diffusion metal in the diffusion hardened layer, etc., but the output is about 0.5 to 2 mmA, the positive / negative electrode separation cycle Is generally in the range of about 10 to 200 Hz. The thickness of the diffusion hardened layer varies depending on the size of the discharge electrode, the electrode base material, the type of the diffusion metal of the diffusion hardened layer, etc., but the thickness from the electrode surface to the deepest diffusion portion is 1 to 1. About 50 μm is preferable.

  Note that the penetron treatment may cause unevenness and distortion of the tip of the electrode surface, but the treated electrode surface may be polished as a countermeasure.

  Next, an example in which the present invention is applied to an ionizer electrode will be specifically described in comparison with a comparative example.

  FIG. 1 shows an ionizer electrode of an example and a comparative example. The ionizer electrode 1 has a round shaft shape having a total length of 22 mm and a diameter of 2.0 mm, and a tip portion 1 a having a length of 6.5 mm is conical and is formed of titanium. Thus, with respect to the ionizer electrode of the example, with a Penetron device (manufactured by Unitool, Switzerland, power supply AC100 / 200V, 50/60 Hz), the titanium metal electrode was used as the negative electrode and the tungsten electrode as the positive electrode. By performing a penetron process at 0 mmA and a separation / contact cycle of 100 Hz, as shown in FIG. 2, the thickness from the electrode surface to the deepest diffusion portion is about 30 μm by implanting tungsten into the surface portion of the base material 10 made of titanium. A diffusion hardened layer 11 was formed.

  The relationship between the depth (mm) from the surface and the hardness (micro Pickers hardness Hv) of the ionizer electrode of the example in which the diffusion hardened layer 11 was formed was as shown in FIG. was gotten. As shown in FIG. 4, the hardness decreases with increasing depth from the surface, but the surface shows a high hardness of 1,600 Hv or more, and has a hardness of about 1,200 Hv even at a depth of about 50 μm.

[Electrode depletion test with ionizer]
As shown in FIG. 3, each of the four ionizer electrodes 1 of the above-described example (treated product) and comparative example (untreated product ... no penetron treatment) is used as a positive / negative pair. Installed around the vent 3 of the ionizer 2 (MKS Ionizer 5802) and with a setting of wind speed LOW, a positive or negative voltage of 5 to 6 V is constantly applied to each electrode to generate a corona discharge. Monthly continuous operation was performed, and changes in the tip shape of each electrode were examined.

As a result, the electrodes (numbers 1, 2, 5, and 6) of the processed products of the examples have no change in the tip shape even after one month for both the positive and negative electrodes, as shown in the photograph of FIG. It was found that there was almost no wear. On the other hand, in the unprocessed product electrodes (Nos. 3, 4, 7, and 8) of the comparative example, the tip shape after one month is larger than the initial shape as shown in the photograph of FIG. It was confirmed that the positive electrode (Nos. 4 and 8) had a large change, resulting in considerable wear. In addition, about the processed goods of the number 2 of an Example, and the unprocessed goods of the number 4 of a comparative example, when the amount of wear from the initial stage was computed based on the further enlarged (150 times) photograph shown in FIG.7 and FIG.8 The depletion amount of the treated product of No. 2 was about 0.01 mm ³ , whereas the depletion amount of the untreated product of No. 4 was about 0.07 mm ³ . 5 and 6, the electrodes are ultrasonically cleaned for 10 minutes before photographing.

  The discharge electrode of the present invention is particularly suitable as an ionizer electrode, but is not limited to this ionizer electrode and is used for various discharge applications such as an electric discharge machining electrode, a glow lamp electrode, and a gas laser electrode. obtain. And the size and form of the electrode for discharge can be variously set according to these uses.

DESCRIPTION OF SYMBOLS 1 Ionizer electrode 10 Base material 11 Diffusion hardening layer 2 Ionizer

Claims (4)

  A discharge electrode in which a metal diffusion hardened layer is formed on the surface of a metal electrode by penetron treatment.   2. The discharge electrode according to claim 1, wherein the electrode base material is one kind selected from titanium, tungsten, and stainless steel, and the diffusion metal of the diffusion hardened layer is one kind selected from titanium, tungsten, nickel, copper, and gold.   The discharge electrode according to claim 1, wherein the electrode base material is titanium, and the diffusion metal of the diffusion hardened layer is tungsten.   The discharge electrode according to any one of claims 1 to 3, wherein the metal electrode is an ionizer electrode.

Images