US3850701A - Anode coated with magnetite and the manufacture thereof - Google Patents

Anode coated with magnetite and the manufacture thereof Download PDF

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Publication number
US3850701A
US3850701A US00409682A US40968273A US3850701A US 3850701 A US3850701 A US 3850701A US 00409682 A US00409682 A US 00409682A US 40968273 A US40968273 A US 40968273A US 3850701 A US3850701 A US 3850701A
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United States
Prior art keywords
magnetite
hydrogen
anode
percent
iron
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Expired - Lifetime
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US00409682A
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English (en)
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R Itai
H Kanai
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Japan Carlit Co Ltd
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Japan Carlit Co Ltd
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Classifications

    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
    • C23F13/00—Inhibiting corrosion of metals by anodic or cathodic protection
    • C23F13/02—Inhibiting corrosion of metals by anodic or cathodic protection cathodic; Selection of conditions, parameters or procedures for cathodic protection, e.g. of electrical conditions
    • 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
    • C25B11/075—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material consisting of a single catalytic element or catalytic compound
    • C25B11/077—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material consisting of a single catalytic element or catalytic compound the compound being a non-noble metal oxide
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
    • C25C7/00—Constructional parts, or assemblies thereof, of cells; Servicing or operating of cells
    • C25C7/02—Electrodes; Connections thereof

Definitions

  • the anode manufactured in this way is quite suitable for the production of chlorine, chlorates, and bromates, and, furthermore, it is also usable for electrolytic oxidation processes in general and as an anode for electro-winning of copper, for electrolysis of sodium sulphate, for cathodic protection, and for electrodialysis.
  • a magnetite anode has hitherto been manufactured by casting as a hollow cylinder or a hollow plate, but disadvantages of the product were inferior workability, limited shapes available and inferior electric conductivity.
  • An improved anode coated with magnetite was proposed in order to eliminate these disadvantages by allowing iron containing iron oxide to deposit electritically on a substrate consisting of iron or titanium, or by coating a solution containing iron compound which generates iron oxide on heating, followed by subjecting the treated substrate to heat treatment in a gaseous atmosphere consisting of a mixture of hydrogen and steam.
  • An essential object of this invention is to provide a process for manufacturing an anode coated with magnetite with industrially advantageous performance.
  • Another object of this invention is to provide a process for forming a fine-grained and durable magnetite coating on a metallic substrate.
  • Still another object of this invention is to provide a process for manufacturing an anode coated with magnetite having an industrially advantageous life.
  • This invention relates to a process for manufacturing an anode coated with magnetite which comprises electrodepositing iron on a metallic substrate of an electrically conductive, corrosion-resistant metal such as titanium, zirconium, tantalum, or niobium by using an electrolyte containing ferrous sulfate, then dipping said iron deposited substrate in a solution containing about 30 g/l of ammonium ferric oxalate under a reduced pressure of 10 30 mm Hg abs., further heating said treated substrate at a temperature of between 550 and 700C in an atmosphere of a gaseous mixture of hydrogen and steam wherein the hydrogen content is 10 25 percent by volume and the steam content is 75 90 percent by volume.
  • Any commercially available materials in the forms ofa plate, wire, screen or rod of titanium, zirconium, tantalum, or niobium may be used as an electrically conductive, corrosionresistant metallic substrate.
  • a sulfate bath As an electrolyte for electrodepositing iron, a sulfate bath is preferable.
  • a chloride bath is used, although it is commonly used now in industry, close control of the temperature, pH, and the composition of the bath is necessary in order to obtain a fine-grained and firmly deposited metal bonded to the metallic substrate.
  • a sulfate bath in accordance with this invention is used, on the other hand, satisfactory results of the electrodeposition can always be obtained under a wider range of the conditions of electrodeposition.
  • the sulfate bath is less readily oxidized by the air than the chloride bath, and therefore said electro-deposition can be carried out in the absence of the ferric salt.
  • the presence of a ferric salt accelerates, the generation of hydrogen on the electrodepositing surface, causing undesirable formation of pinholes, lowering the cathodic current efficiency and resulting in less adherent deposits, as is described in Japanese Pat. No. 219,829.
  • the sulfate bath in accordance with this invention contains no ferric salt and gives an essentially high cathodic current efficiency, thus assuring a satisfactory deposit with few pinholes and a good adherence.
  • the composition of the electrolyte for electrodepositing iron consists of, for instance, g/l of ferrous sulfate (heptahydrate), 100 g/l of ammonium sulphate and about 3 10 g/l of additives such as an ammonium salt of an organic acid, phenol, formalin, or hexamethylene tetramine, etc. Electrodeposition is carried out at a temperature of 10 40C and at a cathodic current density of 1.0 2.5 A/dm for about 7 20 min. Under these conditions the atmospheric oxidation of the ferrous salt in said electrolyte is retarded, and almost no hydrogen is generated at the electrodepositing surface, thus, a uniform and fine-grained deposit is obtained.
  • the iron deposited substrate is dipped into a solution of ammonium ferric oxalate (NH Fe(C- 0
  • NH Fe(C- 0) ammonium ferric oxalate
  • Said treatment is performed by dipping the iron deposited substrate in a sealing solution containing about 10 30 g/l of ammonium ferric oxalate, at about 10 25C, then by allowing said iron deposited substrate-to stand for about 20 min under a reduced pressure of H0 30 mm Hg abs.
  • a concentration of ammonium ferric oxalate below 10 g/l is too dilute to be effective, and above 30 g/l, an undesirable deposition of crystals will occur. Further, if the pressure is higher than 30 mm Hg abs., the replacement of the air within pinholes with said solution is only imperfectly accomplished and only unsatisfactory results are obtained. The minimum pressure is limited by the saturated vapor pressure of the sealing solution.
  • Ammonium ferric oxalate permeated iron deposit is decomposed by a heat treatment as hereunder described, and generates gaseous ammonia and carbon dioxide, leaving only iron oxides. There are no particular difficulties in the subsequent operations.
  • a desired composition of magnetite and the best electric conductivity and the corrosion-resistant property of the product can be obtained by carrying out said heat treatment while maintaining conditions strictly within the range prescribed in the foregoing.
  • Said heat treatment is preferably carried out at a temperature ranging from 550 and 700C.
  • the reaction is very slow at a temperature below 550C, requiring longer time for the operation.
  • a temperature higher than 700C more ferrous oxide forms and the desirable magnetite composition may not be obtained.
  • the preferable range of composition of the gaseous mixture in which said heat treatment is to be carried out is from 10 to 25 percent by volume of hydrogen and from 75 to 90 percent by volume of steam.
  • an atmosphere of a gaseous mixture containing less than 10 percent by volume of hydrogen and more than 90 percent by volume of steam more ferric oxide will form, on the other hand, when the hydrogen content is higher than 25 percent by volume and the steam content lower than 75 percent by volume in said gaseous mixture, more ferrous oxide will form.
  • the desirable magnetite composition may not be or is difficult to be obtained.
  • the hydrogen content is higher than 25 percent by volume, difficulties due to the hydrogen embrittlement of the metallic substrate may arise.
  • the gaseous hydrogen-steam mixture of this invention is prepared by saturating hydrogen with steam by passing hydrogen in water maintained at an appropriate temperature decided by taking the vapor pressure. Said gaseous mixture is introduced into a tube furnace to perform said heat treatment. The time required for said heat treatment is about 2 hr. Finally, a magnetitecoated layer of 3 20 u in thickness is obtained.
  • a fine-grained magnetitecoated layer having desirable durability may be formed on the surface of a metallic substrate having high electric conductivity and sufficient corrosion-resistance.
  • said sealing treatment of the iron deposit in an ammonium ferric oxalate solution produces a final product as anode having a life of one year, more than twice as that whereby no such treatment has been applied, thus offering a practical advantage.
  • the anode coated with magnetite manufactured in accordance with this invention is quite suitable for the manufacture of chlorine, chlorates, and bromates.
  • said anode can be used for any electrolytic oxidation processes in general, and as an anode for electro-winning of copper, as an insoluble anode for electrolyzing sodium sulphate, for cathodic protection, and for electro-dialysis.
  • EXAMPLE 1 A previously polished titanium plate 200 mm X 50 mm and 1 mm thick was defatted in a boiling percent NaOH solution, and was dipped into a 5 percent hydrofluoric acid solution at room temperature for l min, and then washed with water. Electro-deposition was carried out for 19 min in an electrolyte at 25C consisting of l30 g/l of ferrous sulfate (heptahydrate), 100 g/l of ammonium sulfate and 6 g/l of formalin by using said titanium plate as a cathode (a cathodic current density 2.5 A/dm) and a low carbon steel as an anode.
  • a cathode a cathodic current density 2.5 A/dm
  • said iron deposited titanium plate was washed well with water, and then dipped into a solution of 20 g/l of ammonium ferric oxalate at 13C, and was allowed to stand for 20 min under a reduced pressure of 15 mm Hg abs. produced by a vacuum pump and dried under the reduced pressure and was then subjected to heat treatment at 650C for 2.5 hrs. in an atmosphere of a hydrogen/steam gaseous mixture consisting of percent by volume of hydrogen and 80 percent by volume of steam prepared by passing hydrogen into hot water at 94C.
  • a hydrogen/steam gaseous mixture consisting of percent by volume of hydrogen and 80 percent by volume of steam prepared by passing hydrogen into hot water at 94C.
  • the thickness of said layer was confirmed to be 20 p. by weighing said product. The appearance of said product was uniformly black and fine-grained and no crack was observed therein.
  • EXAMPLE 2 A tantalum plate of 200 X 50 mm and 2 mm in thickness was defatted in a boiling 10 percent NaOH solution and was dipped in an aqueous solution of 5 percent hydrofluoric acid for l min. It was then washed with water, and was electrodeposited for 10 min in an electrolyte at 20C consisting of 100 g/l of ferrous sulfate (heptahydrate), 100 g/l of ammonium sulfate, 3 g/l of phenol, and 5 g/l of ammonium phthalate by using said tantalum plate as a cathode (cathodic current density 1.0 A/dm with the use of a low carbon steel as an anode.
  • cathodic current density 1.0 A/dm with the use of a low carbon steel as an anode.
  • said iron deposited tantalum plate was washed well with water, and was then dipped into a solution containing 30 g/l of ammonium ferric oxalate at 23C, and was then allowed to stand for 25 min under a reduced pressure of 28 mm Hg abs. After said treatment was finished, it was dried in vacuum and was heat-treated at 580C for 4 hrs. in an atmosphere of a hydrogen/steam gaseous mixture consisting of 15 percent by volume of hydrogen and percent by volume of steam prepared by passing hydrogen into hot water maintained at 95 96C. By this treatment a uniform and fine-grained magnetite-coated layer of 4.6 u in thickness was obtained.
  • EXAMPLE 3 A 200 X 50 mm titanium net having a wire diameter of 1 mm and mesh of 1 mm was defatted in a boiling 10 percent solution of NaOH, and was dipped into an aqueous solution of 5 percent hydrofluoric acid at room temperature for l min, and then washed. Electrodeposition was carried out for 15 min in an electrolyte maintained at 35C consisting of I50 g/l of ferrous sulfate (heptahydrate), 100 g/l of ammonium sulfate and 10 g/l of ammonium citrate by using said titanium net as a cathode (cathodic current density 2 A/dm and a low carbon steel as an anode.
  • EXAMPLE 4 An electrolyte consisting of 250 g/l sodium chloride, 70 g/l of sodium chlorate, and 2 g/l of sodium bichromate was electrolyzed at 60C for l 1 months with an anodic current density of 10 A/dm by using an anode coated with magnetite prepared as described in Example l as an anode with the use of a mild steel plate as a cathode. The current efficiency was 85 percent and the average cell voltage was 3.38 V. The required en- 2.
  • An anode prepared by Almost no change was the process of this I 1 months observed.
  • invention (Example 1).
  • An anode prepared by A stripping off of the the process of this magnetite-coated layer was invention except that 4.5 months distinctly observed. and dipping in an aqueous the substrate was laid solution of ammonium bare. ferric oxalate was omitted.
  • EXAMPLE 5 Sea water having a sodium chloride concentration of 27 g/l, pH 8, and 25C in temperature, was electrolyzed by an anodic current density of 3 A/dm", using an anode coated with magnetite prepared by the process described in Example 3 with the use of a mild steel as a cathode. A solution containing 0.5 g/l of sodium hypochlorite was continuously obtained. Even after 6 months no abnormalities were observed on said coated anode.
  • a process for manufacturing an anode coated with magnetite comprising electrodepositing iron onto an electric conductive corrosion-resistant metallic substrate, such as titanium, zirconium, tantalum, niobium, and the like in an electrolyte containing ferrous sulfate, dipping said iron deposited substrate into a solution containing about 10 30 g/l ammonium ferric oxalate for about min under a reduced pressure of 10 mm Hg abs, and then heating said treated substrate at 550 700C for about 2 5 hrs. in an atmosphere of a hydrogen/steam gaseous mixture consisting of hydrogen of a content in a range of 10 25 percent by volume and steam of a content in a range of 75 90 percent by volume.
  • ammonium sulfate 100 g/l of ammonium sulfate, and about 3 10 g/l of an additive selected from a group consisting of ammonium salts of an organic acid, phenol, formalin and hexamethylene tetramine, and mixtures thereof.
  • An anode coated with magnetite manufactured by a process which comprises electrodepositing iron onto an electric conductive corrosion-resistant metallic substrate, such as titanium, zirconium, tantalum, niobium, and the like in an electrolyte containing ferrous sulfate, dipping said iron deposited substrate into a solution containing about l0 30 g/l ammonium ferric oxalate for about 20 min. under a reduced pressure of 10 30 mm Hg abs., and then heating the treated substrate at 550 700C for about 2 5 hrs. in an atmosphere of a hydrogen/steam gaseous mixture consisting of hydrogen of a content in a range of 10 25 percent by volume and steam of a content in a range of percent by volume.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Mechanical Engineering (AREA)
  • Electrodes For Compound Or Non-Metal Manufacture (AREA)
  • Chemical Treatment Of Metals (AREA)
  • Other Surface Treatments For Metallic Materials (AREA)
  • Electrolytic Production Of Metals (AREA)
US00409682A 1973-04-06 1973-10-25 Anode coated with magnetite and the manufacture thereof Expired - Lifetime US3850701A (en)

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JP3874973A JPS5339029B2 (enrdf_load_stackoverflow) 1973-04-06 1973-04-06

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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4445989A (en) * 1982-08-11 1984-05-01 The United States Of America As Represented By The Secretary Of The Army Ceramic anodes for corrosion protection
US4946570A (en) * 1989-02-28 1990-08-07 The United States Of America As Represented By The Secretary Of The Army Ceramic coated strip anode for cathodic protection
US6051326A (en) * 1997-04-26 2000-04-18 Cabot Corporation Valve metal compositions and method
US20090308144A1 (en) * 2006-12-22 2009-12-17 Areva Np Gmbh Method and device for pretreating a fuel rod cladding tube for material tests, test body and method for testing corrosion characteristics
US20120021010A1 (en) * 2010-04-29 2012-01-26 University Of Calcutta Antiplatelet agent and methods of using the same
CN103088329A (zh) * 2013-02-27 2013-05-08 郑家园 一种铝合金涂装前处理剂
CN103088331A (zh) * 2013-02-27 2013-05-08 郑家园 一种冷轧板涂装前处理剂

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS53103980A (en) * 1977-02-23 1978-09-09 Japan Carlit Co Ltd Manufacture of magnetite coating electrode
JPS53123385A (en) * 1977-04-04 1978-10-27 Nat Res Inst Metals Electrolytic ferrite coated electrode and manufacture
JP6222121B2 (ja) * 2015-01-21 2017-11-01 株式会社豊田中央研究所 不溶性電極の製造方法

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3236756A (en) * 1957-04-09 1966-02-22 Amalgamated Curacao Patents Co Electrolysis with precious metalcoated titanium anode

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3236756A (en) * 1957-04-09 1966-02-22 Amalgamated Curacao Patents Co Electrolysis with precious metalcoated titanium anode

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4445989A (en) * 1982-08-11 1984-05-01 The United States Of America As Represented By The Secretary Of The Army Ceramic anodes for corrosion protection
US4946570A (en) * 1989-02-28 1990-08-07 The United States Of America As Represented By The Secretary Of The Army Ceramic coated strip anode for cathodic protection
US6051326A (en) * 1997-04-26 2000-04-18 Cabot Corporation Valve metal compositions and method
US6231689B1 (en) 1997-04-26 2001-05-15 Cabot Corporation Valve metal compositions and method
US6517645B2 (en) 1997-04-26 2003-02-11 Cabot Corporation Valve metal compositions and method
US20090308144A1 (en) * 2006-12-22 2009-12-17 Areva Np Gmbh Method and device for pretreating a fuel rod cladding tube for material tests, test body and method for testing corrosion characteristics
US8191406B2 (en) * 2006-12-22 2012-06-05 Areva Np Gmbh Method and device for pretreating a fuel rod cladding tube for material tests, test body and method for testing corrosion characteristics
US20120021010A1 (en) * 2010-04-29 2012-01-26 University Of Calcutta Antiplatelet agent and methods of using the same
CN103088329A (zh) * 2013-02-27 2013-05-08 郑家园 一种铝合金涂装前处理剂
CN103088331A (zh) * 2013-02-27 2013-05-08 郑家园 一种冷轧板涂装前处理剂
CN103088331B (zh) * 2013-02-27 2014-11-19 海安县科技成果转化服务中心 一种冷轧板涂装前处理剂
CN103088329B (zh) * 2013-02-27 2014-11-19 海安县科技成果转化服务中心 一种铝合金涂装前处理剂

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Publication number Publication date
JPS5339029B2 (enrdf_load_stackoverflow) 1978-10-19
JPS49125235A (enrdf_load_stackoverflow) 1974-11-30

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