EP0027051B1 - Beschichtete Metallelektrode mit Sperrschicht und Verfahren zu deren Herstellung und Verwendung - Google Patents

Beschichtete Metallelektrode mit Sperrschicht und Verfahren zu deren Herstellung und Verwendung Download PDF

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Publication number
EP0027051B1
EP0027051B1 EP80303526A EP80303526A EP0027051B1 EP 0027051 B1 EP0027051 B1 EP 0027051B1 EP 80303526 A EP80303526 A EP 80303526A EP 80303526 A EP80303526 A EP 80303526A EP 0027051 B1 EP0027051 B1 EP 0027051B1
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Prior art keywords
substrate
barrier layer
film
metal
electrode
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English (en)
French (fr)
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EP0027051A1 (de
Inventor
Henri Bernard Beer
Jean Marcel Hinden
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De Nora SpA
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Eltech Systems Corp
Diamond Shamrock Corp
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Classifications

    • 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
    • C25B11/04—Electrodes; Manufacture thereof not otherwise provided for characterised by the material
    • C25B11/051—Electrodes formed of electrocatalysts on a substrate or carrier
    • C25B11/055—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the substrate or carrier material
    • C25B11/057—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the substrate or carrier material consisting of a single element or compound
    • C25B11/061—Metal or alloy
    • 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
    • C25B1/00—Electrolytic production of inorganic compounds or non-metals
    • C25B1/01—Products
    • C25B1/34—Simultaneous production of alkali metal hydroxides and chlorine, oxyacids or salts of chlorine, e.g. by chlor-alkali electrolysis
    • 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
    • C25B11/04—Electrodes; Manufacture thereof not otherwise provided for characterised by the material
    • C25B11/051—Electrodes formed of electrocatalysts on a substrate or carrier
    • C25B11/055—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the substrate or carrier material
    • C25B11/069—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the substrate or carrier material consisting of at least one single element and at least one compound; consisting of two or more compounds
    • 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
    • C25B11/04—Electrodes; Manufacture thereof not otherwise provided for characterised by the material
    • C25B11/051—Electrodes formed of electrocatalysts on a substrate or carrier
    • C25B11/073—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material
    • C25B11/091—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material consisting of at least one catalytic element and at least one catalytic compound; consisting of two or more catalytic elements or catalytic compounds
    • C25B11/093—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material consisting of at least one catalytic element and at least one catalytic compound; consisting of two or more catalytic elements or catalytic compounds at least one noble metal or noble metal oxide and at least one non-noble metal oxide
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D17/00—Constructional parts, or assemblies thereof, of cells for electrolytic coating
    • C25D17/10—Electrodes, e.g. composition, counter electrode

Definitions

  • the invention relates to electrodes for use in electrolytic processes, of the type having a substrate of a film-forming metal such as titanium, tantalum, zirconium, niobium, tungsten, aluminium and alloys containing one or more of these metals as well as silicon-iron alloys, coated with an electrocatalytic coating containing one or more platinum-group metals or their oxides possibly mixed with other oxides.
  • a film-forming metal such as titanium, tantalum, zirconium, niobium, tungsten, aluminium and alloys containing one or more of these metals as well as silicon-iron alloys
  • film-forming metal is meant one which has the property that when connected as an anode in the electrolyte in which the coated anode is subsequently to operate, there rapidly forms a passivating oxide film which protects the underlying metal from corrosion by the electrolyte.
  • passivating oxide film which protects the underlying metal from corrosion by the electrolyte.
  • the invention is more particularly concerned with dimensionally-stable electrodes provided with an improved barrier or intermediate layer between the film-forming metal substrate and the electrocatalytic outer coating.
  • a titanium electrode with a coating of platinum group metal was provided with an inert barrier layer of titanium oxide in the porous places of the coating, this barrier layer preferably being formed or reinforced by a heat treatment.
  • the inert barrier layer of titanium oxide was preformed by electrolytically treating or heating the titanium substrate in an oxidizing atmosphere prior to application of the platinum goup metal. The preforming of such a barrier layer was also advocated in U.K. Patent Specification 1 147 422 with a view to improving the anchorage of an active coating consisting of or containing platinum group metal oxides.
  • the invention concerns an electrode with a film-forming metal substrate having a porous outer electrocatalytic coating containing at least about 2 g/m 2 (as platinum group metal per projected surface area of the substrate) of at least one platinum group metal and/or oxide thereof possibly mixed with other metal oxides, and an improved non-passivating barrier layer between the substrate and coating.
  • this barrier layer is a preformed surface oxide film grown up from the film-forming base and having rhodium and/or iridium incorporated in the surface oxide film during formation thereof in an amount of up to 1 g/m 2 (as metal) per projected surface area of the substrate.
  • the surface oxide film of the barrier layer is rendered non-passivating by the incorporation of the rhodium and/or iridium as metal or as a compound, usually the oxide or a partially oxidized compound.
  • Another aspect of the invention is a method of manufacturing such an electrode in which the formation of the barrier layer involves the application of a very dilute acidic paint, i.e. one which contains a small quantity of a thermodecomposable iridium and/or rhodium compound that during decomposition and simultaneous formation of the surface film of film-forming metal oxide will be fully absorbed by this surface film, this dilute paint containing generally about 1-15 g/I of iridium and/or rhodium (as metal).
  • a very dilute acidic paint i.e. one which contains a small quantity of a thermodecomposable iridium and/or rhodium compound that during decomposition and simultaneous formation of the surface film of film-forming metal oxide will be fully absorbed by this surface film, this dilute paint containing generally about 1-15 g/I of iridium and/or rhodium (as metal).
  • the paint used will typically include an organic solvent such as isopropyl alcohol, an acid (notably HCI, HBr or HI) or another agent (e.g. NaF) which attacks the film-forming metal and encourages the formation of film-forming metal oxide during the subsequent heat treatment, and one or more thermo-decomposable salts of iridium and/or rhodium.
  • an organic solvent such as isopropyl alcohol
  • an acid notably HCI, HBr or HI
  • NaF another agent which attacks the film-forming metal and encourages the formation of film-forming metal oxide during the subsequent heat treatment
  • thermo-decomposable salts of iridium and/or rhodium e
  • Ions of the film-forming metal are thus provided by the base for conversion to oxide during the subsequent heating, this oxide being partly formed within the pores of the first layer.
  • the porosity of the resulting oxide film is thus reduced after each coating cycle until no more film-forming metal from the base can be converted to oxide.
  • An extremely stable, relatively compact and impermeable film of film-forming metal oxide can thus be formed by the application of a limited number of coats of acid paint followed by drying and heating.
  • each applied coat of paint includes such a small quantity of the iridium and'/or rhodium compound that the electrocatalyst formed by thermocomposition becomes fully incorporated in the integral surface film of film-forming metal oxide that is formed each time.
  • each applied coat of the paint will contain at most about 0.2 g/m 2 or iridium and/or rhodium per projected surface area of the base, usually far less. Additionally, application of further layers of the dilute paint is stopped after the number of coats beyond which growth of the surface oxide film on the film-forming metal ceases or is inhibited.
  • the optimum quantity of electrocatalytic agent in the dilute paint and the optimum number of coats to be applied to produce a satisfactory compact, impermeable barrier layer can be determined quite easily for any particular substrate, solvent/acid and electrocatalytic material.
  • two to ten layers of the very dilute paint will be applied, each followed by drying and heating from about 400 to 600°C for about 5 to 15 minutes, with the possible exception of the final layer which may be heated for a longer period - possibly several hours or days at 450-600°C in air or in a reducing atmosphere (e.g. ammonia/hydrogen).
  • barrier layers produced in this manner on an etched or non-etched titanium base usually retain the same range of distinctive appearances as titanium oxide films prepared in the same manner which do not contain the iridium and/or rhodium electrocatalyst, typically a bright blue, yellow and/or red "interference" film colour.
  • the dilute acidic point solution used. to prepare the barrier layer according to the invention preferably only includes a thermo- decomposable iridium and/or rhodium compound, since the film-forming metal oxide component is provided by the base.
  • the dilute paint may include small amounts of other components such as other platinum-group metals (ruthenium, palladium, platinum, osmium, in particular ruthenium), gold, silver, tin, chromium, cobalt, antimony, molybdenum, iron, nickel, manganese, tungsten, vanadium, titanium, tantalum, zirconium, niobium, bismuth, lanthanum, tellurium, phosphorous, boron, beryllium, sodium, lithium, calcium, strontium, lead and copper compounds and mixtures thereof.
  • platinum-group metals ruthenium, palladium, platinum, osmium, in particular ruthenium
  • any small quantity of a film-forming metal compound it will be a different metal to the film-forming metal substrate so as to contribute to doping of the surface film.
  • Excellent results have been obtained with iridium/ruthenium compounds in a weight ratio of about 2:1, as metal.
  • additives When such additives are included in the dilute paint composition, they will of course be in an amount compatible with the small amount of the main electrocatalyst, i.e. an iridium and/or rhodium compound, so that substantially all of the main electrocatalyst and additive is incorporated in the surface film of film-forming metal oxide.
  • the total amount of iridium and/or rhodium and other metals is below 1 g/m 2 , and usually below 0.5 g/m 2 and the extra metal will be present in a lesser amount than the rhodium and/or iridium.
  • These iridium/rhodium compounds and other metal compounds may be thermodecomposable to form the metal or the oxide, but in neither case is it necessary to proceed to full decomposition.
  • barrier layers containing partially decomposed iridium chloride containing up to about 5% by weight of the original chlorine have shown excellent properties.
  • Barrier layers containing as little as 0.1 to 0.3 g/m 2 (as metal) of iridium and/or rhodium oxide/chloride in their surface films give excellent results. Tests have shown that a barrier layer containing 0.5 to 0.6 g/m 2 (as metal) or iridium produces an optimum affect in terms of the increased lifetime of the coated electrodes. Increasing the quantity of iridium above these values does not further increase the lifetime.
  • the surface oxide film is found to be predominantly rutile titanium dioxide; presumably, the formation of rutile e.g. at about 400-500°C is catalysed by the rhodium and/or iridium in the dilute coating solution.
  • the porous outer electro- catalytic coating is applied using standard techniques, for example by applying over the preformed barrier layer a plurality of coats of a relatively concentrated solution containing a thermodecomposable platinum-group metal compound and heating.
  • Each applied outer coat will contain at least 0.4 g/m 2 of the platinum-group metal per projected area of the substrate, and the coating procedure is repeated to build up an effective outer coating containing at least about 2 g/m 2 of the platinum-group metal(s), usually in oxide form.
  • the coating components may be chosen to provide a coating consisting predominantly of a solid-solution of at least one film-forming metal oxide and at least one platinum-group metal oxide, as described in US Patent No.
  • the coating is a solid solution of ruthenium and titanium oxide having a ruthenium :titanium atomic ratio of from 1:1 to 1:4.
  • the coating consists of several superimposed layers typically having a micro-cracked appearance and is quite porous.
  • Employing an improved barrier layer according to the invention with such a coating greatly improves the performance of the electrode in standard accelerated life-time tests in oxygen- evolution conditions.
  • the improved electrode will have a substantially longer lifetime since it is known that one of the reasons for failure of these electrodes after extended use in chlorine production is due to the action of oxygen on the substrate.
  • the outer coating may also be formed of one or more platinum-group metals, for example a platinum-iridium alloy, useful for chlorate production and to a limited extent in diaphragm or membrane cells for chlorine production.
  • platinum-group metals for example a platinum-iridium alloy
  • the coatings must be relatively thick (at least about 5 g/m 2 ) to avoid passivation problems.
  • thinner and more porous layers of the platinum metals can be used without problems arising due to oxidation of the substrate, or the drawbacks associated with the previously known passive barrier layers of titanium oxide.
  • the outer coating by plasma-spraying a solid solution of a film-forming metal oxide and a platinum-group metal oxide.
  • a solid solution powder can be prepared by flame-spraying as described in US Patent No. 3 677 075 and this powder is then plasma-sprayed onto the base.
  • the coating is applied by plasma-spraying at least one film-forming metal oxide over the preformed barrier layer and subsequently incorporating the platinum-group metal(s) and/or oxides thereof in the plasma-sprayed film-forming metal oxide, for example according to the procedure of US Patent No. 4 140 813.
  • the improved barrier layer increases lifetime and enables a reduction of the precious metal content of the coating.
  • a set of electrode sub-strates are subjected together to a series of pre-treatments including etching and formation of the barrier layer by dip-coating the set of substrates in said dilute solution and heating the set of sub- strates, and thereafter the outer electro- catalytic coating is applied to the substrates one at a time.
  • This procedure obviates the drawback in commercial electrode coating plants associated with a "bottleneck" between the etching bath and the coating line.
  • a set of substrates is pretreated by sandblasting followed by etching, rinsing and drying and these sub- strates are then individually coated at a coating/baking line.
  • the electrode base may be a sheet of any film-forming metal, titanium being preferred for cost reasons.
  • Rods, tubes and expanded meshes of titanium or other film-forming metals may likewise be surface treated by the method of the invention. Titanium or other film-forming metal clad on a conducting core can also be used.
  • the base will be etched prior to the surface treatment to provide a rough surface giving good anchorage for the subsequently applied electrocatalytic coating. It is also possible to surface-treat porous sintered or plasma-sprayed titanium with the dilute paint solutions in the same manner, but preferably the porous titanium will be only a surface layer on a non-porous base.
  • the electrodes with an improved barrier layer according to the invention are excellently suited as anodes for chlor-alkali electrolysis. These electrodes have also shown outstanding performance when used for electrowinning in a mixed chloride-sulphate electrolyte giving mixed chlorine and oxygen evolution.
  • Coupons measuring 7.5 x 2 cm of titanium available under the trade name "Contimet 30" were degreased, rinsed in water, dried and etched for 1/2 hour in oxalic acid.
  • a paint solution consisting of 6 ml n-propanol, 0.4 ml HCI (concentrated) and 0.1 g of iridium and/or rhodium chloride was then applied by brush to both sides of the coupons in four thin coats.
  • the coupons were dried to evaporate the solvent and then heated in air to 500°C for 10 minutes after each of the first three coats and for 30 mins. after the final coat. This gives a content of about 0.2 to 0.3 g/m 2 of rhodium and/or iridium (calculated as metal) in the barrier layer depending on the amount of solution in each applied coat, as determined by weight measurement.
  • a titanium oxide-ruthenium oxide solid solution having a titanium: ruthenium atomic ratio of approximately 2:1 was then applied by brushing on a solution consisting of 6 ml n-propanol, 0.4 ml HCI (concentrated), 3 ml butyl titanate and 1 g RuCI 3 and heating in air at 400°C for 5 mins. (Note: this solution is 10 times more concentrated in terms of precious metal:propanol solvent than is the dilute solution used for producing the barrier layer). This procedure was repeated until the coating was present in thickness of approximately 10 g/m 2 (i.e. approx. 4 g/m 2 of Ru metal).
  • Electrodes so produced as being subjected to comparative electrochemical tests with similar electrodes (a) having a Ti0 2 barrier layer produced by the same procedure but with a paint consisting solely of 6 ml n-propanol and 0.4 ml HCI (concentrated) and (b) having no barrier layer.
  • the initial results indicate that the electrode according to the invention has a greatly superior lifetime in accelerated lifetime tests as anodes in oxygen evolving conditions and, in chlor-alkali electrolysis, should have a lifetime many times-longer than comparative anode (a) and considerably longer than comparative anode (b).
  • a titanium coupon was degreased, rinsed in water, dried, etched and then surface-treated as in Example I with a paint solution containing iridium and ruthenium chlorides in the weight ratio of 2:1 (as metal). The treatment was repeated four times until the titanium dioxide film formed contained an amount of 0.2 g/m 2 Ir and 0.1 g/m 2 Ru, both calculated as metal. The heat treatment was carried out at 400°C for 10 minutes after each applied coat. An outer coating of TiO 2 ⁇ Ru0 2 was then applied as in Example I. The same comparative electrochemical tests have given the same initial promising results as for Example I.
  • Titanium coupons were degreased, rinsed in water, dried and etched as in Example I and treated with an iridium chloride solution similar to that of Example I. The solution was applied in four thin coats and the coupons were dried to evaporate the solvent and then heated to 480°C for 7 minutes at the end of each coat. The iridium concentration was varied to give a content of 0.3, 0.6 and 0.8 g/m 2 of iridium (calculated as metal) in the barrier layer.
  • a titanium dioxide - ruthenium dioxide solution coating was then applied as in Example I, except that the coating thickness corresponded to 20 g/m 2 (approx. 8 g/m 2 of Ru metal). These electrodes were subjected to accelerated lifetime tests in oxygen evolving conditions. The maximum lifetimes was observed with the coupon having a barrier layer containing 0.6 g/m 2 Ir. This represented an increase by a factor of 10.3 of the lifetime of a similar electrode without a barrier layer (or with a barrier layer of Ti0 2 containing no iridium). In comparison, a similar coated electrode with no barrier layer but with the addition of 0.6 g of iridium dispersed in the coating shows only a marginal increase of lifetime.
  • Electrodes were prepared in a similar manner to Example I, but using a dilute paint containing chlorides of various platinum-group metals, including palladium, platinum and ruthenium alone, as well as rhodium and iridium as previously described, for production of the barrier layer. These electrodes were subjected to comparative lifetime tests as oxygen- evolution anodes. Only the electrodes having a barrier layer containing Rh and/or Ir showed a marked increase in lifetime in this test; combinations of Rh and/or Ir with smaller quantities of the other platinum-group metals or their compounds, in particular Ru and Pd also produced substantial improvements.
  • Titanium coupons were provided with barrier layers containing approx. 0.2 g/m 2 of iridium and/or rhodium following the procedure of Example I. They were then painted with a solution containing 0.5 g of iridium chloride and 1 g of platinum chloride in 10 ml of isopropyl alcohol and 10 ml of linalool, and heated in an oven to 350°C. An ammonia/hydrogen mixture was then passed for approximately 30 seconds to produce a coating containing 70% Pt and 30% lr. The coating procedure was repeated to build up a coating containing 4 g/m 2 of the Pt/lr alloy.
  • Titanium coupons were provided with barrier layers containing approx. 0.2 g/m 2 of iridium and/or rhodium following the procedure of Example I: A layer of approximately 400 g/m 2 of titanium oxide was then plasma-sprayed onto the barrier layer, using standard techniques. The plasma-sprayed titanium oxide layer was then coated with coatings containing 2 g/m 2 (as metal) of ruthenium oxide and/or iridium oxide in various ratios, by painting with a solution of 6 ml propanol and 1 g of RuCI 3 and/or IrCI 3 and heating in air to 500°C for 10 minutes after each coating.
  • a layer of approximately 400 g/m 2 of titanium oxide was then plasma-sprayed onto the barrier layer, using standard techniques.
  • the plasma-sprayed titanium oxide layer was then coated with coatings containing 2 g/m 2 (as metal) of ruthenium oxide and/or iridium oxide in various ratios, by painting with a solution of 6 ml propanol and 1
  • Titanium coupons were provided with barrier layers containing approx. 0.3 g/m 2 of iridium, rhodium and iridium/ruthenium in a 2:1 weight ratio, following the procedure of Example I (except that in some instances the final heating was prolonged for several hours).
  • aqueous solution containing iridium chloride and tantalum chloride (with Ir and Ta metals in an equal weight ratio) was applied by brush over both sides of the coupons in 5, 10 and 15 coats. Each applied coat contained about 0.5 g/m 2 of iridium. After each coat, the coupons were dried and heated in air for 10 minutes at 450°C, and for 1 hour after the final coat. The resulting coating was a solid solution of iridium and tantalum oxides containing approx. 2.5, 5 and 7.5 g/m 2 of iridium.
  • the electrodes were tested as anodes in 10% sulfuric acid at 60°C at a current density of 1.2 kA/m 2 , the current being stopped for 15 minutes in each 24-hour period without the electrodes being removed from the acid bath.
  • the initial results indicate a superior performance over similar electrodes on a plain titanium substrate and on a substrate of a titanium-palladium alloy containing 0.15% palladium.
  • the titanium substrate with a barrier layer according to the invention is of course far less expensive than this titanium-palladium alloy and provides a greatly improved resistance to cell shutdown and the passivating action of oxygen evolution. From the preliminary indications, the electrodes according to the invention with a low iridium loading (2.5 g/m 2 + 0.3 g/m 2 in the barrier layer) should have an outstanding lifetime compared to similar electrodes without the barrier layer.

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Claims (22)

1. Elektrode zum Gebrauch in einem elektrolytischen Prozess mit einem Substrat aus einem filmformenden Metall und mit einer porösen elektrokatalytischen Schicht aus mindestens einem Platingruppenmetall und/oder einem Oxid hiervon welches möglicherweise mit anderen Metalloxiden gemischt ist, wobei die Menge des Platingruppenmetalls mindestens 2g/m2 der projektierten Oberfläche des Substrats beträgt, und wobei das Substrat unter dieser Schicht eine vorgeformte Schutzschicht aus einem Oberflächenoxidfilm aufweist welcher auf dem Substrat gewachsen ist, dadurch gekennzeichnet dass die vorgeformte Schutzschicht Rhodium und/oder Iridium aufweist, welche in den Oberflächenoxidfilm während seiner Entstehung in einer Menge von bis zu einem Gramm (als Metall) pro M 2 der projektierten Oberfläche des Substrats eingebettet wurden.
2. Elektrode nach Anspruch 1 wobei die poröse elektrokatalytische Schicht aus einer Mehrzahl von übereinanderliegenden Schichten mikroskopisch rissiger Struktur besteht.
3. Elektrode nach Anspruch 2 wobei die poröse elektrokatalytische Schicht hauptsächlich aus einer festen Lösung zumindest eines filmformenden Metalloxids und mindestens eines Platingruppenmetalloxids besteht.
4. Elektrode nach Anspruch 3 worin die poröse elektrokatalytische Schicht eine feste Lösung von Ruthenium und Titanoxid besteht, welche ein Atomverhältnis von Ruthenium zu Titan von 1:1 bis 1:4 aufweisen.
5. Elektrode nach Anspruch 1 worin die poröse elektrokatalytische Schicht hauptsächlich aus einem oder mehreren Platingruppenmetallen besteht.
6. Elektrode nach Anspruch 5 worin die poröse elektrokatalytische Schicht eine Platin-Iridium-Legierung ist.
7. Elektrode nach Anspruch 1 worin die poröse elektrokatalytische Schicht aus einer plasmagespritzten Schicht aus mindestens einem filmformenden Metalloxid besteht, welche Platingruppenmetalle und/oder Oxide hiervon aufweist.
8. Elektrode nach einem der vorhergehenden Ansprüche worin der Oberflächenoxidfilm der Schutzschicht zusätzlich zu Rhodium und/oder Iridium ein weiteres Metall aufweist, welches in einer geringeren Menge als des Rhodium und/oder das Iridium vorliegt, wobei der gesamte Metallinhalt der Schutzschicht bis zu einer Gramm pro m2 beträgt.
9. Elektrode nach Anspruch 8 worin der Film bis zu 0.5 Gramm pro m2 Iridium und Ruthenium in einem Gewichtsverhältnis von etwa 2:1 aufweist.
10. Elektrode nach einem der vorhergehenden Ansprüche worin das Substrat aus Titan besteht und der Oberflächenfilm vorwiegend aus rutilem Titandioxid besteht.
11. Verfahren zur Herstellung einer Elektrode zum Gebrauch in elektrolytischen Prozessen wobei eine Schutzschicht auf einem Substrat aus einem filmformenden Metall und über der Schutzschicht eine poröse äussere elektrotatalytische Schicht aus mindesten einem Platingruppenmetall und/oder Oxiden hiervon, welche möglicherweise mit anderen Oxiden vermischt sind, gebildet wird, wobei das Substrat mindestens etwa 2 Gramm des Platingruppenmetalls pro m2 der projektierten Oberfläche des Substrats enthält, dadurch gekennzeichnet dass die Schutzschicht durch Aufbringen von einer oder mehreren Schichten eines stark verdünnten (wie weiter unten definiert) Säurelösung aufgebracht wird, welche eine thermisch zersetzbare Verbindung von Rhodium und/ oder Iridium aufweist, Trocknen und Aufheizen der Schicht(en) um auf dem Substrat einen Oberflächenfilm des filmformenden Metalloxids zu formen, und gleichzeitig die genannte Verbindung zumindest teilweise zu zersetzen, wobei die bzw. jede der aufgebrachten Schichten dieser stark verdünnten Lösung eine Menge der genannten Verbindung enthält, welche im wesentlichen vollständig im Oberflächenfilm während des Heizens absorbiert wird, wobei die Anzahl der aufgebrachten Schichten derart ist, dass die derart geformte Schutzschicht bis zu einem Gramm Rhodium und/oder Iridium pro m2 der projektierten Oberfläche des Substrats enthält.
12. Verfahren nach Anspruch 11 worin die oder jede aufgebrachte Schicht der Lösung bis zu 0.2 g Rhodium oder Iridium Metall pro m2 der projektierten Oberfläche des Substrats enthält.
13. Verfahren zur Herstellung einer Elektrode für den Gebrauch in elektrolytischen Prozessen wobei eine Schutzschicht auf einem Substrat eines filmformenden Metalls und über dieser Schutzschicht eine poröse äussere elektrokatalytische Schicht aufgebracht wird, welche zumindest ein Platingruppenmetall und/oder Oxide hiervon aufweist, welche möglicherweise mit anderen Oxiden gemischt sind, wobei das Substrat mindestens etwa 2g Platingruppenmetall(e) pro m2 der projektierten Oberfläche aufweist, dadurch gekennzeichnet dass die Schutzschicht durch Aufbringen verschiedener Schichten auf des Substrat hergestellt ist, von denen jede bis zu 0.2g (als Metall pro m2 der projektierten Oberfläche des Substrats) einer thermisch zersetzbaren Verbindung von Rhodium und/oder Iridium in einer Lösung aufweist, welche das filmformende Metallsubstrat angreift, und aufheizen jeder Schicht nach Trocknung un eine Schutzschicht eines Oxids des filmformenden Materials zu erzeugen, welche bis zu 1 g Iridium und/oder Rhodium pro m2 aufweist.
14. Verfahren nach einem der Ansprüche 11 1 bis 13 wobei zwischen 2 und 5 Schichten der verdünnten Lösung aufgebracht werden, wovon jede hernach auf zwischen 300 und 600°C während 5 bis 15 Minuten aufgeheizt wird, wobei die letzte Schicht möglicherweise für eine längere Zeitspanne aufgeheizt wird.
15. Verfahren nach einem der Ansprüche 11 1 bis 14 wobei das Heizen derart ausgeführt wird, dass die genannte Verbindung unvollständig zersetzt wird.
16. Verfahren nach einem der Ansprüche 11 1 bis 15 worin die poröse äussere elektrokatalytische Schicht durch Aufbringen einer Mehrzahl von Schichten einer relativ konzentrierten Lösung mit einer themisch zersetzbaren Platingruppenmetallverbindung auf das Substrat und Aufheizen hergestellt wird.
17. Verfahren nach Anspruch 16 wobei jede aufgebrachte äussere Schicht mindestens 0.4g des Platingruppenmetalls pro m2 der projektierten Oberfläche der Substratunterlage enthält.
18. Verfahren nach einem der Ansprüche 11 1 bis 15 wobei die poröse äussere elektrokatalytische Schicht durch Plasmaspritzen aufgebracht wird.
19. Verfahren nach einem der Ansprüche 11 bis 15 worin die poröse äussere elektrokatalytische Schicht durch Plasmaspritzen mindestens eines filmformenden Metalloxids auf die vorgeforme Schutzschicht und nachfolgendes Einbringen des Platingruppenmetalls und/oder Oxiden hiervon in das plasmagespritzte filmformende Metalloxid hergestellt wird.
20. Verfahren nach einem der Ansprüche 11 1 bis 19 wobei ein Satz von Elektrodensubstraten zusammen einer Reihe von Vorbehandlungen unterzogen wird, welche Ätzen und die Formation einer Schutzschicht durch Eintauchen des Satzes von Substraten in die genannte verdünnte Lösung und Aufheizen des Satzes von Substraten umfassen, wobei die äusseren elektrokatalytischen Schicht einzeln auf jedes Substrat aufgebracht werden.
21. Elektrode dadurch gekennzeichnet, dass sie durch das Verfahren nach einem der Ansprüche 11 bis 20 hergestellt ist.
22. Gebrauch einer Elektrode nach einem der Ansprüche 1 bis 10 oder 21 als Anode für die Chlor-Alkali Elektrolyse.
EP80303526A 1979-10-08 1980-10-07 Beschichtete Metallelektrode mit Sperrschicht und Verfahren zu deren Herstellung und Verwendung Expired EP0027051B1 (de)

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CA1190186A (en) * 1980-08-18 1985-07-09 Henri B. Beer Electrode with mixed oxide interface on valve metal base and stable outer coating
EP0063540B1 (de) * 1981-04-06 1986-04-02 Eltech Systems Corporation Wiederanlegung eines Elektrodenüberzugs
EP0103014A1 (de) * 1982-03-11 1984-03-21 Engelhard Corporation Verbesserung von katalytischen platina-iridium elektroden mit blei, tantalum, ruthenium und sauerstoff
JPS58171589A (ja) * 1982-03-31 1983-10-08 Ishifuku Kinzoku Kogyo Kk 電解用電極及びその製造方法
CH649315A5 (en) * 1982-09-22 1985-05-15 Bbc Brown Boveri & Cie Method of producing an electrode, and electrode for an electrochemical cell
JPS6022075B2 (ja) * 1983-01-31 1985-05-30 ペルメレック電極株式会社 耐久性を有する電解用電極及びその製造方法
JPH0726240B2 (ja) * 1989-10-27 1995-03-22 ペルメレック電極株式会社 鋼板の電解酸洗又は電解脱脂方法
LU88516A1 (de) * 1993-07-21 1996-02-01 Furukawa Electric Co Ltd Sauerstoff erzeugende Elektrode und Verfahren dieselbe herzustellen
JP3810043B2 (ja) * 1998-09-30 2006-08-16 ペルメレック電極株式会社 クロムめっき用電極
EP1620582B1 (de) * 2003-05-07 2016-12-21 De Nora Tech, Inc. Glatte oberflächenbeschichtungen für eine anode
ZA200601219B (en) * 2003-10-08 2007-05-30 Akzo Nobel Nv Electrode
DE102010043085A1 (de) * 2010-10-28 2012-05-03 Bayer Materialscience Aktiengesellschaft Elektrode für die elektrolytische Chlorherstellung
CN212729805U (zh) * 2017-10-16 2021-03-19 株式会社村田制作所 生物体信号传感器

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NL122179C (de) * 1959-02-06 1966-12-15
GB1206863A (en) * 1968-04-02 1970-09-30 Ici Ltd Electrodes for electrochemical process
US3775284A (en) * 1970-03-23 1973-11-27 J Bennett Non-passivating barrier layer electrodes
GB1351741A (en) * 1970-03-25 1974-05-01 Marston Excelsior Ltd Electrodes
US3926773A (en) * 1970-07-16 1975-12-16 Conradty Fa C Metal anode for electrochemical processes and method of making same
US3711385A (en) * 1970-09-25 1973-01-16 Chemnor Corp Electrode having platinum metal oxide coating thereon,and method of use thereof
DE2255690C3 (de) * 1972-11-14 1985-01-31 Conradty GmbH & Co Metallelektroden KG, 8505 Röthenbach Anode für elektrochemische Prozesse
NL7502841A (nl) * 1975-03-11 1976-09-14 Stamicarbon Werkwijze voor het vervaardigen van een metaal- elektrode.
US4112140A (en) * 1977-04-14 1978-09-05 The Dow Chemical Company Electrode coating process

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NO802985L (no) 1981-04-09
ES8205882A1 (es) 1982-06-16
JPS5658984A (en) 1981-05-22
BR8006373A (pt) 1981-04-14
ATE8414T1 (de) 1984-07-15
ZA806185B (en) 1981-09-30
KR860001050B1 (ko) 1986-08-01
MX159655A (es) 1989-07-25
IS2586A7 (is) 1981-04-09
NO155702B (no) 1987-02-02
JPS6160147B2 (de) 1986-12-19
KR830004461A (ko) 1983-07-13
AU540213B2 (en) 1984-11-08
DE3068540D1 (en) 1984-08-16
FI68090B (fi) 1985-03-29
EP0027051A1 (de) 1981-04-15
GR70316B (de) 1982-09-10
DK153166B (da) 1988-06-20
SU1292670A3 (ru) 1987-02-23
ES504762A0 (es) 1982-06-16
AU6298480A (en) 1981-04-16
ES8205887A1 (es) 1982-06-16
IS1141B6 (is) 1983-12-05
NO155702C (no) 1987-05-13
ES495705A0 (es) 1982-06-16
DK153166C (da) 1988-12-19
DD153397A5 (de) 1982-01-06
FI803173L (fi) 1981-04-09
FI68090C (fi) 1985-07-10

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