JP2008255437A - Conductive diamond coated net-like electrode, method of manufacturing the same and ozone water generator provided with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conductive diamond coated net-like electrode having a conductive diamond film formed by employing a plasma CVD method, a method of manufacturing the same and the like. <P>SOLUTION: The method of manufacturing the net-like electrode is carried out by applying the conductive diamond film on a net-like base material formed from a high melting point metal by the plasma CVD method. The conductive diamond film is applied on the net-like base material 1 by providing a mounting table 11 on which the net-like base material 1 is placed in a vacuum container 21, providing an outer frame 12 formed from the high melting point metal on the outer peripheral part of the mounting table 11 to surround the outer periphery of the net-like base material 1 placed on the mounting table 11 and supplying a gaseous starting material containing a carbon source into the vacuum container 21 and forming plasma so as to wrap the mounting table 11 and the outer frame 12. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a mesh electrode used in an electrolytic treatment apparatus such as an ozone water generation apparatus, a method for producing the same, and the like.

  Since ozone water in which ozone is dissolved has an excellent oxidizing power, it is widely used for cleaning and sterilization in the manufacture of semiconductor devices, the medical field, the food field, and the like. Ozone water can be easily manufactured with a relatively small processing apparatus, and the ozone concentration can be easily controlled. Therefore, ozone water is mainly manufactured by electrolyzing (electrolyzing) water.

  As an ozone water generating apparatus for producing ozone or ozone water by an electrolytic method, for example, as described in Japanese Patent No. 3375904 (Patent Document 1), an electrode sandwiched between a mesh-like anode electrode and a cathode electrode is used. Some have a direct-current power source that constitutes a cell and supplies direct-current power to the anode electrode and the cathode electrode. When water is passed while energizing the electrodes, the water is electrolyzed and ozone is generated on the anode side. Hydrogen ions generated at this time pass through a proton permeable membrane having ion permeability and reach the cathode, where electrons are received to generate hydrogen. The generated ozone is dissolved in the supplied water, and ozone water is obtained.

  In such an electrolytic treatment apparatus, in order to promote the generation of ozone, the electrode is formed in a net shape, and platinum is mainly used as a material from the viewpoint of safety and catalytic action. However, although platinum is a relatively stable electrode material, it is an expensive noble metal, and has a problem in terms of cost because it is eluted and consumed with electrolysis.

For this reason, as described in JP-A-9-268395 (Patent Document 2), a conductive diamond-coated network electrode in which a conductive substrate is coated with a conductive diamond film by a thermal CVD method is used as an anode electrode. It has been proposed. Such a conductive diamond-coated mesh electrode has the advantages of low electrical resistance, high efficiency in generating electrolytic ozone water, and reduced material costs compared to platinum electrodes. Japanese Patent Laid-Open No. 2005-336607 (Patent Document 3) does not cover a substrate with a conductive diamond film, but lasers a large number of through holes in a conductive diamond plate formed by a microwave plasma CVD method. A self-supporting conductive diamond porous electrode drilled by machining or electric discharge machining has also been proposed.
Japanese Patent No. 3375904 JP-A-9-268395 JP-A-2005-336607

However, the self-supporting conductive diamond porous electrode described in the cited document 3 needs to be formed in a thickness of 0.2 to 1.0 mm so that the conductive diamond becomes a self-solid, and the ideal performance is Even if it is obtained, the cost is very high and the practicality is poor. On the other hand, in the case of the conductive diamond-coated mesh electrode described in the cited document 2, since the conductive diamond film is coated by the thermal CVD method, active species are deposited on the surface of the mesh substrate facing the filament. Although the diamond film is well coated, it is difficult to form the diamond film because active species do not easily circulate on the back surface, and the front and back surfaces of the network substrate cannot be simultaneously coated with the conductive diamond film. For this reason, productivity is low and by extension, manufacturing cost becomes high. Further, as described in the cited document 2, the size of the substrate is limited to a very small size of about 1 cm ² .

  By the way, with respect to the thermal CVD method, the plasma CVD method described in the cited document 3 has high film forming efficiency, and by forming plasma so as to wrap the reticulated base material, active species are also present on the back surface side. The wraparound and the front and back surfaces can be simultaneously coated with the diamond film. However, if the plasma CVD method is applied to a substrate with an uneven and angular surface such as a mesh substrate, plasma may concentrate on the edge including the corner of the substrate or abnormal discharge may occur. Or the like occurs, and there is a problem that the outer peripheral edge of the substrate melts or a diamond film is formed only on a part of the substrate. For this reason, conventionally, the plasma CVD method has not been applied as a means for coating a mesh substrate with a conductive diamond film.

  In view of the above problems, the present invention provides a conductive diamond-coated mesh electrode to which a plasma CVD method is applied as a means for coating a conductive diamond film, a method for manufacturing the same, and an ozone water generation apparatus using the electrode. For the purpose.

  The production method of the present invention is a production method of a mesh electrode in which a conductive diamond film is coated on a mesh substrate formed of a refractory metal by a plasma CVD method, and the mesh substrate is placed in a vacuum vessel. A raw material including a carbon source in the vacuum vessel provided with an outer frame formed of a refractory metal so as to surround the outer periphery of the net-like base material placed on the mounting table. Gas is supplied, plasma is formed so as to wrap around the mounting table and the outer frame, and the mesh substrate is covered with a conductive diamond film.

  According to this manufacturing method, since the outer frame is arranged on the outer periphery of the mesh substrate placed on the mounting table, plasma concentration or abnormal discharge on the outer peripheral edge of the mesh substrate arranged on the inner side of the outer frame In addition, since the plasma wraps around the front and back surfaces of the reticulated base material, the outer peripheral edge of the reticulated base material is not melted or a diamond film is not formed on the entire front and back surfaces of the reticulated base material. Thus, the conductive diamond film can be efficiently coated at the same time. In addition, a conductive diamond film can be efficiently coated even on a reticulated substrate having a size larger than that capable of being formed by thermal CVD. For this reason, according to the production method of the present invention in which the conductive diamond film is coated by the plasma CVD method, the conductive diamond-coated mesh electrode can be efficiently produced, and the productivity is excellent.

  In the manufacturing method of the conductive diamond-coated mesh electrode, the mesh substrate is preferably formed of Ti or Mo. Since these metals have a high melting point and good workability, a reticulated substrate can be easily produced from a wire or a plate.

  The outer frame is preferably formed of a refractory metal having a melting point equal to or higher than the melting point of the refractory metal forming the network substrate. Plasma concentrates on the outer periphery of the outer frame, and the temperature is higher than that of the net-like base material placed on the placing table. For this reason, by forming the outer frame with a high melting point metal having a melting point equal to or higher than the melting point of the net-like base material, the outer frame can be prevented from melting and deforming, and excellent durability can be obtained.

  Moreover, it is preferable that the mounting table on which the net-like base material is mounted has an uneven surface on the mounting surface. Thereby, it becomes easy for the plasma to wrap around the back surface of the mesh substrate placed on the mounting table, and the coating of the conductive diamond film on the back surface can be promoted.

  The outer frame is preferably provided on the outer periphery of the mounting table via a gap. By providing such a gap, it is possible to suppress heat conduction from the outer frame to the network substrate, to prevent fluctuations in the processing temperature of the network substrate, and to improve the film formability of the conductive diamond film Can do.

  In addition, the conductive diamond-coated mesh electrode of the present invention is manufactured by the above manufacturing method, and can be efficiently manufactured using a plasma CVD method. In particular, the circle-like diameter of the wire portion of the mesh substrate is 50 to 500 μm, the coverage of the conductive diamond film on the entire front and back surfaces of the mesh substrate is 50 to 100%, and the mesh substrate coated with the conductive diamond film is used. The average film thickness of the conductive diamond film in the wire portion of the material is preferably 800 nm or less, whereby the durability of the conductive diamond film coated on the network substrate can be improved.

  Further, the ozone water generating apparatus of the present invention is an electrolytic treatment in which an anode electrode and a cathode electrode are arranged with a proton permeable membrane interposed therebetween, electrolyzing water to generate ozone and producing ozone water in which the ozone is dissolved. An apparatus using the conductive diamond-coated mesh electrode as at least the anode electrode. In particular, those satisfying the size of the wire portion of the mesh substrate, the coverage of the conductive diamond film, and the average film thickness are excellent in durability, so that the durability of the ozone water generator can be improved.

  According to the manufacturing method of the present invention, the outer frame is provided so as to surround the outer periphery of the mesh substrate placed on the mounting table, and the plasma is formed so as to wrap the mounting table and the outer frame. Plasma concentration and abnormal discharge generated at the corners and edges of the mesh substrate can be suppressed, and the conductive diamond film can be coated by the plasma CVD method. Can be manufactured efficiently, and is excellent in productivity. A conductive diamond-coated network electrode in which a conductive diamond film having a predetermined coverage and an average film thickness is coated on a network substrate having a wire portion of a predetermined size is coated with a conductive diamond film by a conventional thermal CVD method. Low in cost, less likely to peel off or break the membrane, and has excellent durability.

  Hereinafter, a method for producing a conductive diamond-coated mesh electrode according to an embodiment of the present invention will be described together with a plasma CVD apparatus used when the production method is carried out. First, the plasma CVD apparatus will be briefly described. As shown in FIG. 1, the plasma CVD apparatus includes a vacuum vessel 21, a processing table 22 constituting one electrode, the other flat plate electrode 23 arranged to face the processing table 22, and the processing table 22. A high-frequency plasma power source 24 for supplying plasma power to the flat plate electrode 23, an exhaust device (not shown) for evacuating the inside of the vacuum vessel 1 through an exhaust tube 25, and a gas supply tube 26 in the evacuated vacuum vessel 1 And a gas supply device (not shown) for supplying the raw material gas. A cooling water passage and a heater (not shown) are provided inside the processing table 22, and the table temperature is controlled by these. Reference numeral 27 denotes an observation window used for emission analysis or the like.

  When manufacturing the conductive diamond-coated mesh electrode, first, as shown in FIG. 1, the mounting table 11 on which the mesh substrate 1 is mounted on the processing table 22 and the outer periphery of the mounting table 11 are surrounded. The outer frame 12 is placed through the gap 13. Reference numeral 14 denotes a spacer for securing the gap 13.

  The net-like base material 1 means a flat shape in which a large number of holes are opened between wire portions, and a wire net formed by knitting a wire material vertically or horizontally, or a large number of slits are provided in a staggered manner. In addition to a lath net (expanded metal) in which the plate material is stretched in a direction perpendicular to the slit direction and the slits are greatly opened, a perforated plate in which a large number of holes are mechanically formed in the plate material is included.

  Since the reticulated substrate 11 is exposed to plasma, it is made of a high melting point metal having a melting point of 1300K or higher, such as Ti, Mo, Ta, Nb. In particular, Ti and Mo have good workability, and are easy to be processed into a net-like material by knitting a wire or expanding a plate material, and oxidized at the surface of a wire part not coated with a conductive diamond film at a high temperature. Although a film is formed and does not contribute to the electrolytic reaction, elution of the substrate can be prevented during the electrolytic treatment.

  The wire portion of the net-like substrate 1 preferably has an equivalent circle diameter of about 50 to 500 μm. The circle equivalent diameter means a diameter of a circle having an area equivalent to the area of the cross section of the wire portion. By setting the equivalent circle diameter to about 50 to 500 μm, the flexibility of the reticulated substrate can be ensured and can be easily adhered to the proton permeable membrane or the like without any gap. Note that the size of the wire portion is represented by a circle-equivalent diameter because the cross-sectional shape of the wire portion has various forms such as a circle and a square, and these are handled in a unified manner.

  The mounting table 11 on which the mesh substrate 1 is placed is formed of a refractory metal having a melting point higher than that of the refractory metal forming the mesh substrate 1 so as not to be welded to the mesh substrate 1 during the plasma CVD process. It is preferable to do. Moreover, it is preferable that the mounting surface (upper surface) of the mounting table 11 is a concavo-convex surface having a level difference of about 1 to 10 mm, which is equal to or greater than the thickness of the mesh substrate. By making the mounting surface uneven, the plasma easily wraps around the back surface (the mounting surface is the front surface) of the net-like substrate 1 mounted on the mounting surface during the plasma CVD process. The conductive diamond film can be easily coated on the mesh substrate 1 from the side.

  In FIG. 1, clog-like convex portions 16 of clogs are formed at equal intervals on the mounting surface of the mounting table 11, but the unevenness of the mounting surface is not limited to this, for example, as shown in FIG. 3. A large number of short columnar protrusions 17 may be provided. Moreover, although the said net-like base material 1 may be only mounted in the mounting base 11 mentioned above, you may make it fix to the mounting base 11 by spot-welding in the suitable location of a convex part.

  The outer frame 12 disposed on the outer periphery of the mounting table 11 so as to continuously surround all of the outer periphery of the mesh substrate 1 and the mounting table 11 intentionally concentrates the plasma during the plasma CVD process. This is intended to prevent the plasma from concentrating on the outer peripheral edge including the corners of the reticulated base material 1 and the occurrence of abnormal discharge. For this reason, it is preferable to form the high melting point metal having a melting point higher than that of the net-like base material 1 so as not to melt due to plasma concentration or abnormal discharge. For example, when the reticulated substrate 1 is formed of Ti (melting point: 1675 ° C.), the mounting table 11 and the outer frame 12 are Mo (melting point: about 2622 ° C.), Nb (melting point: 2467 ° C.), Ta (melting point: 2977 ° C.), W ( It is preferable to use a high melting point metal such as a melting point of 3382 ° C.).

  As shown in FIG. 2, the width W1 of the outer frame may be about 3 to 10 mm. Further, by providing the gap 13 between the mounting table 11 and the outer frame 12, heat conduction from the outer frame 12 to the mounting table 11 is cut off, and the processing temperature of the net-like substrate 1 mounted on the mounting table 11. Fluctuations are prevented. The width W2 of the gap 13 may be about several mm to 10 mm. In order to easily secure the gap 13, a spacer 14 formed of a refractory metal or ceramic having a melting point higher than that of the net-like substrate 1 is interposed between the mounting table 11 and the outer frame 12 as shown in the figure. It is preferable to provide it. The upper surface of the outer frame 12 is preferably set so as to be flush with or higher than the upper surface of the mesh substrate 1 placed on the placing table 11. When the net-like base material 1 is higher, the plasma may be concentrated on the net-like base material side.

  After placing the mounting table 11 and the outer frame 12 on which the mesh substrate 1 is placed on the processing table 22 as described above, the vacuum vessel 1 is evacuated and energized while injecting the source gas into the vacuum vessel 1. Plasma is generated so as to wrap the outer frame.

As the source gas, a mixed gas of a carbon source gas (for example, methane gas, carbon monoxide gas) and hydrogen gas is used, and a trace amount of boron source gas (for example, diborane (for example, diborane) is used to impart conductivity to the diamond film. B ² H ⁶ ), trimethylboron (B (CH ₃ ) ₃ )) are added. The ratio of the carbon source gas to the hydrogen gas is usually about 0.1 to 10 vol%, and the ratio of the boron source to the carbon source may be about 0.1 to 10 ⁵ ppm. Boron may be added by placing solid boron in the plasma CVD apparatus. By performing plasma CVD using such a film forming gas, a conductive diamond thin film containing a trace amount of boron as an impurity in the diamond thin film is formed on the surface of the substrate.

  Further, the film thickness of the conductive diamond film can be adjusted by adjusting the processing temperature and processing time of the reticulated substrate 1, and the film forming rate increases as the processing temperature increases, and the film increases as time increases. The thickness becomes thicker. The processing temperature of the reticulated substrate 1 can be adjusted by controlling the power supplied to the plasma CVD apparatus and the temperature of the processing table. The film thickness can also be controlled by adjusting the distance between the net-like substrate and the plasma. The distance between the reticulated base material and the plasma can be adjusted by moving the processing table on which the base material is placed up and down in the vacuum container. In addition, the coverage of the conductive diamond film (coverage of the entire front and back surfaces) can be adjusted by adjusting the treatment time, and the coverage increases as the treatment time increases. The coverage can also be adjusted by pretreatment (diamond nucleation promotion treatment) of the reticulated substrate.

  The coverage of the conductive diamond film is preferably 50 to 100%, and the average film thickness of the conductive diamond film in the wire portion of the network substrate coated with the conductive diamond film is preferably 800 nm or less. When the coverage is less than 50%, the coating area becomes too small, and the electrolysis effect as an electrode for electrolysis is lowered. On the other hand, when a conductive diamond film is formed by plasma CVD, a compressive residual stress is inevitably generated in the film due to a difference in thermal expansion coefficient with the base material, but the average film thickness should be 800 nm or less. As a result, the film can be prevented from being peeled off or damaged when the equivalent-circle diameter of the wire portion is 50 to 500 μm, and the durability as an electrode for electrolysis can be improved. In the case of a high-melting point metal such as Ti or Mo that is easily oxidized as the reticulated substrate 1, an oxide film is formed in the wire portion not covered with the conductive diamond film during the plasma CVD process so that it does not contribute to the electrolytic reaction. Therefore, elution during electrolytic treatment is also suppressed.

  The conductive diamond-coated mesh electrode manufactured by the above-described manufacturing method can be suitably used as an electrode of various electrolytic treatment apparatuses, for example, an ozone water generating apparatus, particularly an anode that is likely to be eluted into an electrolytic solution.

  Here, an embodiment of the ozone water generator will be described with reference to FIG. The ozone water generating apparatus includes a proton permeable membrane (ion exchange membrane) 31, an anode electrode 32 and a cathode electrode 33 that are closely arranged so that no gap is formed on both surfaces of the proton permeable membrane 31, and a casing 34 that encloses these. And a DC power source 35 for applying a DC voltage to the anode electrode 32 and the cathode electrode 33. The casing 34 is provided with a water supply port 37 at one end (lower end in the illustrated example) on the anode side and the cathode side, an ozone water outlet 38 at the other end (upper end) on the anode side, and hydrogen at the other end on the cathode side. A containing water outlet 39 is provided.

  The conductive diamond-coated mesh electrode is used as the anode electrode 32, while a platinum mesh electrode is used as the cathode electrode 33, for example. The cathode electrode 33 is not limited to a platinum electrode, and a conductive diamond-coated mesh electrode may be used, or another noble metal mesh electrode may be used. A water supply pipe (not shown) is connected to the water supply port 37, and water is supplied through the water supply pipe. The supplied water is preferably pure water, but tap water can also be used as raw water. In this case, it is preferable to remove chlorine and impurities through a filtration layer such as an activated carbon layer. Further, the water supply pipe can be provided with a flow rate control valve for controlling the amount of supplied water.

  According to the ozone water generator, the water supplied from the water supply port 37 is electrolyzed on the anode side to generate ozone and protons. The ozone is dissolved in water and discharged from the ozone water outlet 38. On the other hand, protons pass through the proton permeable membrane 31 and receive electrons from the cathode to become hydrogen, and dissolve in water to become hydrogen-containing water. The hydrogen-containing water is discharged from the hydrogen-containing water outlet 39 to the outside.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated more concretely, this invention is not limitedly interpreted by this Example.

  A rectangular (56 × 18 mm) mesh substrate was collected from a titanium wire mesh (thickness 1 mm, mesh opening 300 μm square) prepared by knitting a titanium round wire having a wire diameter of 30 to 1000 μm vertically and horizontally. This net-like base material was mounted on a mounting table having substantially the same planar shape, and this mounting table was set together with the outer frame on the processing table 22 of the vacuum vessel 1 of the microwave plasma CVD apparatus as shown in FIG. Then, a conductive diamond film was coated on the mesh substrate by plasma CVD so that the plasma was wrapped, and a conductive diamond-coated electrode was manufactured. For comparison, the plasma CVD method was applied to only some of the reticulated substrates using only the mounting table without using the outer frame. The planar size of the mounting table 11 used was 60 × 18 mm, and claw-like convex portions of clogs having a height of 0.8 mm were formed on the mounting surface at a pitch of 1 mm. Further, as shown in FIG. 2, the width W1 of the outer frame 12 is 5 mm, and the gap W2 with respect to the mounting table 11 is 3 mm. Further, the upper surface of the outer frame 12 was made to be flush with the reticulated base material placed on the placing table 11.

In the plasma CVD process, after evacuating the inside of the vacuum vessel, a raw material gas obtained by adding a small amount of trimethylboron as a boron source to a mixed gas obtained by diluting methane (CH ⁴ ) as a carbon source with hydrogen (H ² ) is used as the vacuum vessel. Then, the film was formed by controlling the gas pressure in the vacuum vessel to 5 × 10 ³ to 1 × 10 ⁴ Pa. At this time, the film thickness of the conductive diamond film was adjusted by adjusting the plasma power to adjust the treatment temperature of the mesh substrate to 900 to 1100K. Further, the coverage was adjusted by adjusting the treatment time.

  When the outer film was used during the plasma CVD process, the film formation state was observed. As a result, plasma was concentrated on the outer frame surface to light purple, and the entire area of the reticulated substrate was orange. On the other hand, in the case where no outer frame is used, only the outer peripheral edge of the net-like base material is heated in orange.

  After the plasma CVD treatment, the average film thickness and the coverage (the coverage of the entire front and back surfaces) of the conductive diamond film coated on the mesh substrate were measured. The average film thickness was determined as follows. At the central part in the width direction of the net-like base material, the wire part coated with the diamond film is collected from five places at almost equal intervals along the length direction, the cross section is observed with a microscope, and the cross-sectional photograph is image-analyzed. Thus, the film thickness at each sampling site was measured, and the average value was obtained. The coverage was determined by image analysis of photographs of the front and back surfaces of the treated reticulated substrate. These survey results are also shown in Table 1. Sample No. 13 of the comparative example was formed at the same substrate processing temperature (1100 K) and processing time as Sample No. 5 with a coverage of 80%. Moreover, about the comparative example, since the coverage was very low, the film thickness measurement was abbreviate | omitted.

  Further, when the surface of the conductive diamond film was observed with an electron microscope for Sample No. 4 (base material processing temperature 900 K) and Sample No. 5 (base material processing temperature 1100 K), FIG. 5 (A) shows Sample No. 4 In (B), a surface morphology peculiar to CVD diamond was observed as shown in Sample No. 5). Further, when the conductive diamond film of sample No. 5 was subjected to Raman spectroscopic analysis, as shown in FIG. 6, a spectrum peculiar to conductive diamond was observed.

In addition, the conductivity of the conductive diamond film coated on the network substrate cannot be directly measured due to the influence of the network substrate, but by measuring the boron atom density in the conductive diamond film, The conductivity can be evaluated from the electrical resistance of a diamond film containing the same amount of boron formed on an insulating substrate (eg, quartz). When the boron atom density of the conductive diamond film of sample No. 5 is measured by secondary ion mass spectrometry, it is 8 × 10 ²⁰ to 2 × 10 ²¹ cm ⁻³ , and the boron atom density formed on the insulating substrate is the same. Since the electric resistance of the conductive diamond film of about 10 is about 10 ⁻³ Ωcm, it was confirmed that the conductive diamond film has this level of conductivity.

Next, each sample of the conductive diamond-coated electrode was used as an anode electrode, and an ozone water generation test was performed using the ozone water generation apparatus shown in FIG. As the cathode electrode, a platinum mesh electrode having the same thickness and opening size as the anode electrode was used. As the proton permeable membrane, “Nafion” (trade name) manufactured by DuPont was used. The water flow rate was about 2 Liter / min, and the current density during electrolysis was about 2.0 A / cm ² . In addition, the sample No. 13) of the comparative example formed without using the outer frame was not subjected to the ozone water generation test because the coverage was very low.

By this test, the peeling rate of the diamond film of the conductive diamond-coated mesh electrode after 100 hours of operation was determined. The peeling rate was calculated from the following formula when the coverage after 100 hr operation was C2% and the initial coverage was C1%.
Peeling rate = (C1-C2) / C1 × 100 (%)

  Further, the content of ozone water after 100 hours of operation was measured to evaluate the ozone water generation performance. The case where the ozone amount in the ozone water after the predetermined time operation was 2 ppm or more was judged as “good”, and the case where it was 1 ppm or more and less than 2 ppm was judged as “good”. These measurement results are summarized in Table 1.

  From Table 1, among the conductive diamond-coated electrodes of the invention example, the wire diameter (equivalent circle diameter) of the mesh substrate is 50 to 500 μm, the coverage of the conductive diamond film is 50 to 100%, and the average film thickness is 800 nm or less. This mesh electrode was particularly excellent in durability as an electrode.

Furthermore, using the conductive diamond-coated electrodes of Sample No. 4 and No. 5 according to the invention example as the anode electrode of the ozone water generator, electrolysis is performed while passing water at a flow rate of 1.5 to 2 Liters / min. The current to be energized during electrolysis was controlled in a constant current stepwise within a range of 0.05 to 3.0 A / cm ² , and the ozone concentration of the obtained ozone water was measured while observing the voltage required for energization. FIG. 7 shows the results, showing the relationship between the applied voltage, current density, and ozone concentration. In the figure, “Sample A” is Sample No. 4 in Table 1, and “Sample B” is Sample No. 5.

From FIG. 7, the required applied voltage increased or decreased in the range of 6 to 21 V depending on the current density, and ozone water was obtained at an ozone concentration of 0.2 to 24 ppm depending on the current density. In particular, it was confirmed that ozone water was generated even in a low current density region (0.05 to 0.3 A / cm ² ), which was conventionally difficult to obtain with a platinum electrode.

It is sectional explanatory drawing of the plasma CVD apparatus used in order to implement the manufacturing method of the electroconductive diamond covering mesh electrode which concerns on embodiment. It is a top view of the mounting base and outer frame which were used with the manufacturing method concerning an embodiment. It is a perspective view which shows the other example of a mounting base. It is a section explanatory view of the ozone water generating device concerning an embodiment. It is an electron micrograph of the surface of the electroconductive diamond film which concerns on an Example. It is a Raman spectrum of the conductive diamond film which concerns on an Example. It is a graph which shows the relationship between the applied voltage between electrodes in the ozone water production | generation which concerns on an Example, a current density, and ozone concentration.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Reticulated base material 2 Mounting stand 3 Outer frame 21 Vacuum container

Claims (8)

A method for producing a conductive diamond-coated network electrode in which a conductive diamond film is coated on a network substrate formed of a refractory metal by a plasma CVD method,
Provide a mounting table on which a mesh substrate is placed in a vacuum vessel, and an outer frame formed of a refractory metal so as to surround the outer periphery of the mesh substrate placed on the mounting table on the outer periphery of the mounting table A conductive diamond-coated network, in which a source gas containing a carbon source is supplied into the vacuum vessel, plasma is formed so as to wrap the mounting table and the outer frame, and the mesh substrate is coated with a conductive diamond film Electrode manufacturing method. The manufacturing method according to claim 1, wherein the reticulated substrate is formed of Ti or Mo. The manufacturing method according to claim 1, wherein the outer frame is formed of a refractory metal having a melting point equal to or higher than a melting point of the refractory metal forming the network substrate. The manufacturing method according to any one of claims 1 to 3, wherein the mounting table has an uneven surface on which the mesh electrode is mounted. The manufacturing method according to claim 1, wherein the outer frame is provided on the outer periphery of the mounting table via a gap. A conductive diamond-coated network electrode in which a conductive diamond film is coated on a network substrate formed of a refractory metal,
A conductive diamond-coated mesh electrode manufactured by the manufacturing method according to any one of claims 1 to 5. The equivalent circle diameter of the wire portion of the mesh substrate is 50 to 500 μm, the coverage of the mesh substrate on the front and back surfaces of the mesh diamond substrate is 50 to 100%, and the conductive diamond film is coated. The conductive diamond-coated network electrode according to claim 6, wherein an average film thickness of the conductive diamond film in the wire portion of the network substrate is 800 nm or less. An ozone water generating device in which an anode electrode and a cathode electrode are disposed with a proton permeable membrane interposed therebetween, and ozone is generated by electrolyzing water and producing ozone water in which the ozone is dissolved in water,
An ozone water generator using the conductive diamond-coated mesh electrode according to claim 6 or 7 as at least the anode electrode.