Classifications

• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F1/00—Treatment of water, waste water, or sewage
  • C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
  • C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
  • C02F1/46104—Devices therefor; Their operating or servicing
  • C02F1/46109—Electrodes
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
  • C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
  • C25B11/02—Electrodes; Manufacture thereof not otherwise provided for characterised by shape or form
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F1/00—Treatment of water, waste water, or sewage
  • C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
  • C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
  • C02F1/46104—Devices therefor; Their operating or servicing
  • C02F1/46109—Electrodes
  • C02F2001/46133—Electrodes characterised by the material
  • C02F2001/46138—Electrodes comprising a substrate and a coating
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F1/00—Treatment of water, waste water, or sewage
  • C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
  • C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
  • C02F1/46104—Devices therefor; Their operating or servicing
  • C02F1/46109—Electrodes
  • C02F2001/46152—Electrodes characterised by the shape or form

Definitions

• the present invention relates to a large electrode.
• Such electrodes are used industrially in large electrolysis cells intended, in particular, for organic or inorganic syntheses or for the depollution of waste water by oxidation of the contaminants which they contain.
• the electrodes of these installations have dimensions ranging from 20 x 25 cm to 100 x 200 cm.
• the object of the present invention is to overcome this difficulty by proposing a silicon-diamond electrode structure on a support, which has the dimensions of the large existing metal electrodes but remains roughly flat and, at the very least, flexible in any condition.
• the installations can thus benefit from the significant advantages which the silicon-diamond electrodes provide without suffering from their disadvantages.
• the invention relates to a large electrode, characterized in that it comprises: - a metal support plate, - a plurality of tiles fixed to one face of said plate in electrical relation to it and each comprising a silicon substrate made conductive, with, on the plate side, a bonding layer and, on the opposite side, a layer of diamond made conductive; and - an insulating layer covering both the portions of said face which are not covered by the tiles and the sides thereof.
• the metal constituting the support plate is chosen from aluminum, titanium, zirconium, niobium or any metal capable of being passive by forming, on its surface, an insulating, waterproof and stable layer obtained. by chemical or electrochemical oxidation.
• the substrate of the tiles is preferably made of silicon or silicon carbide made conductive by doping using a metal such as titanium, zirconium or niobium.
• the bonding layer of the tiles to the support plate is advantageously made of aluminum, aluminum-silicon, silver, platinum or platinum-silver, while a titanium bonding sublayer is interposed between the substrate of the tiles and this tie layer.
• the diamond layer of the tiles is made conductive by doping using boron and / or nitrogen.
• the insulating layer is advantageously an oxide of the metal of the support plate.
• the invention also proposes several methods of fixing the tiles to the support plate, which are presented below:
• the bonding layer of the tiles is silver and is fixed to the support plate by means of a polymerizable paste based on silver;
• the bonding layer of the tiles is silver, the face of the support plate is covered with a layer of silver and these two layers are welded together directly by heating;
• the bonding layer of the tiles is silver, the face of the support plate is covered with a layer of silver and these two layers are welded together by means of a tin-lead alloy;
• the bonding layer of the tiles is made of aluminum and is welded directly to the support plate;
• the bonding layer of the tiles is made of aluminum and is fixed to the support plate by welding using an aluminum-silicon alloy;
• the bonding layer of the tiles is made of aluminum and is fixed to the support plate by means of a central silicon mini-plate, the two faces of which, covered with an aluminum layer, are respectively welded directly to the bonding layer and to the plate;
• the bonding layer of the tiles is made of aluminum and is fixed to the support plate by means of a central silicon mini-plate, the two faces of which are covered with a layer aluminum, are respectively welded to the bonding layer and to the plate by means of an aluminum-silicon alloy.
• FIG. 2 is a sectional view, on an enlarged scale, of one of the tiles of the electrode of Figure 1;
• FIG. 3 to 9 illustrate different ways of fixing the tiles on a metal support plate.
• Figures 1a and 1b show, at 10, a metal support plate having, typically, a thickness of 5 mm, a length of 100 cm and a width of 60 cm.
• the metal constituting this plate is chosen from aluminum, titanium, zirconium, niobium and, in general, any metal capable of being passive by forming on its surface an insulating layer obtained by chemical or electrochemical oxidation.
• the upper face 12 of the plate 10 receives a mosaic of tiles 14, advantageously having a square shape of 5 to 25 mm on a side, with a thickness of approximately 2 mm. These tiles are regularly aligned in rows and columns with a space between them of 100 ⁇ m to 1 mm. As shown in FIG. 1 b, the portions of the face 12 not covered by the tiles 14, as well as the sides thereof, are covered with an insulating layer 16 formed, as already mentioned, by oxidation once the tiles were fixed on the plate 10. This insulating layer can be covered, in turn, in order to reinforce its sealing, by an additional film of polyvinyledifluoride (PVDF), polyepoxide or another polymer.
• PVDF polyvinyledifluoride
• FIG. 2 shows that each pane 14 comprises a substrate 18, made of silicon or silicon carbide which has been doped, by known methods of the skilled person, so as to reduce its resistivity to a value which, typically, is of the order of 1 to 3 m ⁇ cm.
• the upper face of the substrate 18 is covered with a layer of diamond 20 made conductive by doping using boron, nitrogen or a mixture of the two according to a process which is described, for example, in the application for Patent EP 00810147.9 of February 22, 2000.
• the underside of the substrate 18 is metallized by depositing a bonding layer 22 of titanium and then, on the latter, of a bonding layer 24 of aluminum, aluminum-silicon, silver, platinum or platinum-silver.
• the substrate 18 has a thickness of 0.5 to 2 mm, the diamond layer 20 a thickness of 0.1 to 3 ⁇ m, the bonding layer 22 a thickness of 10 to 200 nm and the tie layer 24 a thickness of 100 nm to 2 ⁇ m.
• connection between the tiles 14 and the support plate 10 must ensure both their mechanical connection and their electrical connection.
• Figures 3 to 9 illustrate different ways of making this connection.
• the support plate 10 can be produced in all the metals mentioned above, with the exception of aluminum, while, in the embodiments of FIGS. 6 to 9, the plate 10 is made of previously deoxidized aluminum or one of the metals mentioned above.
• the bonding layer 24 is silver.
• the connection between the tile 14 and the plate 10 is then carried out by a paste 26 formed from a mixture of silver and epoxy resin, the polymerization of which is ensured by heating to an appropriate temperature.
• the bonding layer 24 is still made of silver and the upper face of the plate 10 is covered with a layer of silver 28, structured to the dimensions corresponding to those of the tiles to be received. These two layers are welded together by simple heating in an oven at a temperature not exceeding 550 ° C.
• the bonding layer 24 is always in silver and the upper face of the plate 10 covered with a structured silver layer 28. These two layers are welded together by means of an alloy tin-lead 30 by heating to a temperature of up to 350 ° C.
• the connecting layer 24 is made of aluminum and the connection between the pane 14 and the support plate 10 made of aluminum is carried out by direct vacuum welding at a temperature of 500 to 600 ° C.
• the bonding layer 24 is made of aluminum and the bonding between it and the support plate 10 is carried out by means of an aluminum-silicon paste 32, such as that sold under the name Castolin190AI .
• the operation is carried out under vacuum at a temperature of 500 to 600 ° C.
• the bonding layer 24 is always made of aluminum and the bonding is carried out by means of a silicon mini-plate 34, the two faces of which are covered with a layer of aluminum.
• This plate is placed in the center of the tile 14 and the assembly is carried out by direct vacuum welding at a temperature of 500 to 600 ° C.
• the mini-wafer 34 is advantageously square in shape. It typically has a thickness of 0.5 to 1 mm and a side of 2 to 10 mm.
• the bonding layer 24 remains of aluminum and the bonding is carried out by means of the mini-wafer 34 of FIG. 8. But, in this case, the welding is done the aluminum-silicon paste 32 used in the production of FIG. 7.
• the parts of the support plate between the tiles must also be passivated. This can be achieved by chemical or electrochemical oxidation which occurs during the first use or, still, by a selective deposition of PVDF, PTFE, polyepoxide or any other suitable polymer.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• Organic Chemistry (AREA)
• Water Supply & Treatment (AREA)
• Hydrology & Water Resources (AREA)
• Environmental & Geological Engineering (AREA)
• Life Sciences & Earth Sciences (AREA)
• General Chemical & Material Sciences (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Electrodes For Compound Or Non-Metal Manufacture (AREA)
• Water Treatment By Electricity Or Magnetism (AREA)
• Electrolytic Production Of Metals (AREA)
• Photovoltaic Devices (AREA)

Priority Applications (1)

Applications Claiming Priority (4)

Publications (1)

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Family Cites Families (3)

• 2001
  • 2001-01-31 EP EP01810099A patent/EP1229149A1/de not_active Withdrawn
• 2002
  • 2002-01-24 EP EP02737614A patent/EP1356135A2/de not_active Withdrawn
  • 2002-01-24 WO PCT/CH2002/000037 patent/WO2002061181A2/fr not_active Ceased

Non-Patent Citations (1)

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