DE2035929A1 - Process for the production of a multilayer electrode for electrochemical processes - Google Patents

Description

VEB CHEMIEKOMBIHAT BITTEEB ¹ ELD Bitterfeld, 7 Jan * 1970

4.04.20 / 1498

Inventor: Prof. Br. Hans Hofmann, Halle Dr, Joachim Barthel, Freiberg Dr. Hermann Kögel, Kirchberg

Process for the production of a multiple face «- electrode for electrochemical processes

The invention relates to a method of manufacture a mono- »or bipolar multi-layer electrode for electrochemical processes, especially for electrolytic processes Procedure.

It is known that the graphite previously used as anode material in chlor-alkali electrolysis is replaced by metallic anode materials in the form that a metal that carries the electrical current conducts well and can be passivated under electrolysis conditions, with a thin coating of precious metals or their alloys is provided »As a result, compared to compact noble metal electrodes, the specific use of precious metals significantly reduced. The application of the precious metals or their alloys takes place either by purely ohemical or by electrochemical Absoheideverfahren »It would be im Principle possible through explosive plating of precious metal »

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Welding foils or foils made of precious metal alloys onto the passivatable base metals. The explosive plating process is not used for this purpose, however, because the smallest diameter of the metal coating ₉ that can be obtained with this process is a multiple of the strength that can be obtained with other processes too hooh. A disadvantage of the platinum-plated anodes is the loss of precious metal through chemical or electrochemical attack «

Duroh use of electrodes that fit on a v.ier « metal coatings made of noble metal oxides or mixtures of noble metal oxides and oxides that can be absorbed Containing metals or corresponding misohoxides, the specific precious metal losses are to be reduced The coating of passivatable metals with noble metal oxides or solids containing them oxides is also done duroh chemical or dwell electro-chemical processes «Je & ooh will auoii bei this type of electrode is required for dar .metall · also occur auoli Precious metal losses on

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It has recently become known for chlorate electrolysis has become to use materials containing lead oxide as anodes «Bas lead oxide becomes almost exclusively electrochemically deposited on the base material Hatred prevailed, because their lifespan was not can satisfy

In the electrochemical production of peroxy Compounds, especially of peroxydisulfates, are mainly anodes made of platinum coated Tantalum used · Here, too, the disadvantages mentioned sohon occur, such as those associated with the use of precious metal anodes have been described on «

The application of any other material that turns out to be Surface resistances are suitable for electrodes, on metals, for example, causes extraordinary difficulties When magnetite is applied to titanium using a thermal process, the metallic substrate reacts with the magnetite «This ensures the good resistance of the magnetite to the electrolyte and the electrolysis products eliminated. On the other hand, electrolytic deposition of magnetite is eliminated not possible on metals.

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The purpose of the invention is the production of Electrodes for electrochemical processes enabled ** liohen that have high chemical and electrochemical resistance, good electrical conductivity and for the separation of the desired electrolysis » products have a low overvoltage · Furthermore, by using less cost « playful material a lowering of the investment " costs are achieved "

The task of the invention is OTgrunäe, mono · »© d®r bipolar multi-tube electrodes for elektro @ heaii © fe @ Processes to produce ^ iaiem 'pae © ivi @ pbiTO © cto aioki passivatable® metals or

Graphite as the main body ver

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Base body pressed in, so that a good bond is created between the two «The result is expressed in the good conductivity or in the low electrical contact resistance * depending on the amount of the powder used, the particles are either only pressed into the base body or, if more, Powder is applied, it forms an electrically conductive, firmly adhering Sohioht, which has a strength of can be several millimeters

For example, titanium or aluminum can be used as passivatable metals · The passivatable Alloy can consist of zirconium and hafnium »As non-passivatable metals, for example Use copper or nickel and non-passivatable alloy brass. As a solution powder only substances used that conduct the electric current and from the electrolyte and from the electrical lysis products are not or only slightly attacked. They offer metals, alloys, graphite and inorganic and organic substances that conduct or semi-conduct electricity, such as carbides, Nitrides, borides, sulfides, oxides and miso oxides and methylene blue and crystal violet «

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To improve the chemical, electro-chemical and chemical resistance of the electrodes, it has proven to be advantageous to reinforce the surface layer or to give it special protection brings in, in larger quantities and thus receives, as sohon besohrleben, a stronger solution, or another suitable substance is applied to the surface that conducts the electric current in a suitable manner in addition, nooh need to electrolytically deposit another substance. One can also manufacture them using the explosive method. Surface · sohloht muster thermlBoh or mechanically pulverförraige substances "Also, on the surface layer ginw more Sohioht duroh a shock wave method aufgebraoht · In some cases AUOH good effects can be erreioht daduroh that one ψ using the Explosiwerfahrens mixing, η the electric current highly conductive materials and other inorganic or organic substances applied as a powder on the surface of the carrier material "the last-mentioned substances can fluoräthen glasses, Polvtetra", polyvinyl chloride or epoxy resins, which conduct electricity elektrischeη nloht and at a higher temperature sohmelzen or _t soften or Soloh "

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Substances that conduct an electric current. In the first case, the proportion of the added substance must be be dimensioned so that the conductivity of the surface is low because it is only slightly influenced "

For many electro-chemical processes it is advantageous to use bipolar electrodes Electrodes can also be carried out according to the method according to the invention. The following exist three ways to manufacture!

1 «The powdery substance is on one side and a metal bleoh on the other side of the Carrying material through the Sxplo β i throw on «You can do both of the process steps can be carried out in one operation "

2 “A metal or an alloy becomes electrochemical

«If one side of the substrate is deposited® the other side is by means of the. Srpiosiwer-

the powdery substance

For each powder, JLa becomes a lae-itsgaag © ter la. GiQbrerett operations »on fixed Saltea tea Sr% ® «aaierials applied · -.

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Furthermore, a simultaneous coating of several carrier materials can be carried out in one operation in such a way that the carrier materials to be coated are arranged one on top of the other, the powder to be applied is placed on each and the powdery particles are pressed in with a detonation powder sweeteners that a separation of the leiohte besohiohte- ™ th materials ensures Ie istenj to give as the intermediate layer and applies this then a second layer ά®Β bring the powder "such a substance tarn graphite or a thin Kunststoffplai '» s to be "Hey 1be An aqueous emulsion of graphite has been shown to be beneficial for the separation of the base.

A bipolar electrode is used

a core of an electrical current good! © itea » the metals i) EW · one

Copper or brass

will be in the middle

! Powder applied « On he © satire Since © ier ÄcfloßiTplatijlersmg © & ® ^ q & wbb

no

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layer applied · The bipolar electrode can expediently also consist of a highly conductive, non-conductive Passivatable metal core consist, the duroh explosive plating or naoh another known process with a passivatable metal, for example titanium, is plated. Then on the passivatable metal according to the invention a powder applied · to the side of the highly conductive, non-passivable metal according to known chemical, electroohemlsohen, mechanical or shock wave processes another metal, for example Nickel, can be applied · The plating of the metal and the application of the powder can be carried out in the Manufacture of the bipolar electrode in one operation take place close to the shock wave method »

The invention is intended to be based on the following illustrative B-examples to be explained in more detail

Example 1:

A copper sheet to be coated is placed on a steel plate, which is degreased according to the known method, placed. It is provided with a layer of tungsten powder, which has a grain size of 0.25 mm

2
Required amount of 6 ml per dm area to be coated. is evenly distributed on the sheet »At a distance of 10 mm, a steel sheet on which 100 g

Gelatinedonarlt are located per dm, arranged »Naoh der

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Detonation of the explosive is the copper bleoh ^ ' covered with a firmly adhering Wolframsohloht.

The electrode produced can be used as a cathode in chlor-alkali electrolysis because it is a has a very low overvoltage for hydrogen »

Example 2:

20 ml of powdered chromium-nickel-boron alloy are placed on a steel plate, which serves as a base

ρ
Form applied per dm area to be coated.

The grain size of the particles of the powder is smaller than 2 mm. The application takes place in such a way that a uniform Schioht arises. The degreased and pickled titanium bleoh is arranged at a distance of 10 mm.

A portion of 100 g of gelatin donarite is placed on top of this

each given the sheet metal, after the detonation of the explosive is the surface of the sheet metal with a feat «- adhesive sohioht covered. The Bleoh coated in this way is used as a cathode in the chlor-alkali electrolysis Use·

Example 3t

A 1 to 2 'mm thick aluminum sheet, which in usual Way was degreased and etched, is provided with a Sohioht graphite powder grain size 0.1 to 0.5 mm «The Amount of 10 ml per dm is applied evenly on the bleoh

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distributed «At a distance of 5 mm from the surface of the Powder layer is a steel plate on which

80 g gelatine donarit per dm to be ignited «The ent · * standing graphite surface conducts the electrical current Well.

Example 4:

A 1.5 to 2 mm thick titanium sheet, which is soft-annealed, is degreased using known methods and pickled · On a steel plate, which serves as an anvil, 6 ml of ground fused magnetite are placed with a

p Grain size from 0.5 to 0.75 mm y ± c dm in a uniform layer. At a distance of 1 to 2 mm from the surface of the powder layer, the titanium bleoh

Attached 2, added to the 95 g Donarit per dm are "intermediate Titanbleoh and explosives, a plastic ·· is plate-added" NaOH _(detonation of the explosive layer is the downwardly facing side of the Titanbleohes covered with a diohten Sohioht magnetite to protect the TitanblechrUokseite "

Example 5t

Sin Titenbleoh is, as described in Example 4 with magnetite, the one with 4 percent by weight of polytetrafluoroethylene powder is mixed, coated «Ifaoh the Detonation is pressed into the underside of the Titanium Bleohes magnetite and is on this layer

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In addition, an approximately 1 mm thick magnetite layer pressed on, which with polytetrafluoroethene. is sintered.

Example 6:

The magnetite which has not been pressed into the metal is removed again from a titanium sheet coated according to Example 4 by mechanical means, such as brushing or scraping. The titanium-Magnetitblech is directed at lotwendig «« · ness by known means "Then a uniform Schioht is applied a Misohung of magnetite with 4 percent by weight PolytetrafluoräthenpiilTer" the loosely applied pulper is aufschließend by heating to 300 to .400 ⁰ G while * 20 minutes sintered

The coating according to Examples 4 to 6 can such. take place on both sides ,, wherein each page oäer both sides are coated together © The prepared according to Examples © in "or both sides beschichteten.litanbleche as pcm © polar® -Slek can» trodes' for the chlor-alkali electrolysis ₈ Ohloratelektro- "analysis or other elektrocheiiisolie Process ^ fo®. ^J nioht vulnerable anodes required will be _g eläget "

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Example 7:

9 ml of silicon carbide powder are placed on a steel base

with a grain size of 0.3 to 1.0 mm per dm to be coated Area given in an even layer. A titanium sheet, which according to Example 4 is prepared, put that with 100 g gelatin donarite per dm is imposed. After the explosive is detonated, the sheet metal has a firmly adhering surface covered by silicon carbide. The contact resistance between metal and carbide and the resistance of the Karbideohioht are very low, so that the coated sheet is good as an electrode for electrochemical processes can be used,

Example 8r

A steel base is made with 5 ml of zirconium nitride per dm with a grain size of 0.1. sprinkled up to 0.3 mm »A 1.5 Up to 2 mm thick titanium sheet, which is degreased and

is pickled, is covered with 95 g Donarit per dm · That duroh the detonation of the explosive with a firmly adhering and dense nitridesohiohfc Sheet metal can be used as an electrode in electrochemical processes with good success.

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Example 9J

A copper sheet with a thickness of 4 μm is clad with a sheet of titanium by means of the known explosive plating, the latter having a thickness of the above. 2 mm has · Bas produced copper «Titanium» Bleoh is rolled out to a thickness of approx »1.5 mm · Then the titanium side is coated with magnetite according to Examples 4 to 6« The copper side is then coated according to a known electrolytic! Nickel-plated process · The electrode obtained is used as a bipolar electrode in chlor-alkali electrolysis with an ion exchange membrane «

Example 10:

A layer of

6 ml magnetite per dm with a grain size of 0.5 to 0,? 5 mm is added, graphite powder is sprinkled on top and covered with a second layer of magnetite A titanium sheet is attached at a distance of 1 to 2 mm from the surface of the powder layer, and

on this 100 g of Donarit per dm are ignited. After the detonation of the explosive, both are Titanium sheet with a dense layer of the "" pressed magnetite and can be easily separated from each other »

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Example 11:

10 ml

2
Melt magnetite given per di «The magnetite powder coated plate is filled with 100 g Donarit pro

dm on a base made of titanium sheet shot «This gives the titanium sheet a

thick, adherent coating of pressed-in magnetite.

Example 12:

A niokelbleoh is placed at a distance of 1 mm

ο placed titanium sheet with 10 ml magnetite per dm

is sprinkled with a grain size of 0.2 to 0.6 mm « After the detonation of the applied 120 g of Donarit

ρ
per dm a moving steel plate, which is arranged at a distance of 1 to 2 mm from the magnetite powder layer, hits the magnetite powder into the titanium surface in one operation and connects the titanium sheet with the nickel sheet, thus creating a bipolar electrode «

Example 13s

A titanium sheet is made according to known electrolytic insulation Method coated with nickel on one side. On the other side, according to Example 4, magnetite powder is used applied to the surface,

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Example 14:

On the after. Example 3 produced graphite surface lead dioxide is deposited electrolytically · Such an electrode can be used for various oxidation processes.

Example 15:

On an aluminum plate provided with a graphite surface according to Example 3, the inventive method is applied would be a mixture of graphite powder and polytetrafluoroethylene (2 percent by weight) applied.

The body produced in ^{this way is heated to 300 to 400 °} C. for half an hour, which means that the coating adheres particularly firmly. "

Example 16:

Was coated on a copper sheet after the ^ Explosiwerfähren with magnetite ₉ is a mixture of lead dioxide ~ Polyvinylehlopid "Pulirep aufgehämmerte

Example 17s

On the other hand near the Esploslwerfstaeii the beginning fair magnetite layer is © iae liüQtaing τοη magnetite «powder © it ipolytondeasigsteren. fitoffen ΐ4 # ά ia of hits © die S © mä @ asat emerging FolykondeaeEt Iwsm. for example Sposläliars sein _e

Ί Π ß) S ^ R / 1 Ä? ?

I ti t? ö ti y ί \ ^ & * c>

Claims (1)

4.04.20 / 1498 Patent claims: 1 \ Process for the production of monopolar and bipolar electrodes for carrying out electroohemic processes, characterized in that on one or on both sides of a base material which conducts the electrical current according to a shock wave process, preferably the explosive process, one conducts the electrical current from the electrolyte and the electrolysis products non-vulnerable, powdery substance is applied and, if necessary, treated in accordance with known methods or in accordance with the method according to the invention, 2, method according to claim 1, characterized in that a metal or alloy that can be passivated during the electrolysis process is used as the base material, which conducts the electrical current well, 3, method according to claim 1, characterized in that a metal that conducts the electrical current well or a well-conductive alloy, which is or which is not suitable for the electrolysis process, is used as the base material. 10983 5/1422 4.04 * 20/1498 4. Procedure naoh. Claim 1, characterized by that graphite is used as the base material « 5 · Method according to Claim 1, characterized by that the powdery substance is a metal, an alloy, Graphite or an inorganic or organic one that conducts or semiconductors the electric current Connection is. 6. The method NaOH Anspruoh 1 and 5 _S daduroh in that the powdery material, inorganic or organic high polymeric substances dia at höherar temperature sohmelzen or soften _e ^ such as certain types of glass or Polytetrafluoräthen added
will. 7 method according to claim 6, characterized in that that the coating is sintered after application " 8 · The method according to claim 1, because it is possible that on the basis of the shock wave processing
set surface a substance that is not vulnerable under electrolysis conditions meohanieoh, thermal,
ohemisoh or electrochemically deposited " 10 9 8 35 / U22 4.04.20 / 1498 A3 9. The method naoh claim 1 and 5 * daduroh characterized, that several powdery substances on top of each other by shock wave method on one Base material can be applied simultaneously or one after the other. 10. Method according to claims 1 to 6, characterized by that both sides of the base material at the same time or one after the other with powdery Fabrics are coated 11. The method according to claims 1 to 6, characterized by that several base materials are treated with powdery substances at the same time, between which the powder to be applied is located. 12. The method according to Anspruoh 11, characterized by that for better separation of the coated materials the powder layer between the surfaces is separated into two layers by a fabric will. 13. The method according to claim 12 “characterized in ₃ that the substance is graphite powder. Λ. 109835/1422 4. O *. 20/1498 14. Method according to claim 12, characterized in that the fabric leans on a thin sheet of lunatoff 15 «Method according to Anipruch 11, characterized in that the surface which is not to be finished is coated with a graphite egg. 16 · Process for the manufacture of bipolar electrodes according to claim 1, characterized in that on a metal that conducts electricity well, preferably copper, by means of the explosive plating or chemical or electrochemical processes a metal or electrical current conducting Alloy layer applied on one side and the other side with a powdery substance the shock wave process is coated. 17. The method according to claim 16, characterized in that that the application of the metal to be plated and the powder carried out in one operation will. 18 · Method according to claim 16, characterized in that the material applied by explosive plating is a passivatable metal, in some cases titanium, and on this a powdery? Fabric according to claims 1 to 6 is applied® 1 0 9 8 3 5/1 U 2 2 A.04.20 / 1498 19 · method naoti claim 18, characterized ^ on the non-coated side of the non-ivable, highly conductive metal according to known ones Ischen, electrochemical, mechanical processes another metal, preferably nickel, is applied using a shock wave process Po / Fl 1Q9835 / U22