US2348826A - Coating of objects of magnesium or the like with oxides - Google Patents

Coating of objects of magnesium or the like with oxides Download PDF

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Publication number
US2348826A
US2348826A US238976A US23897638A US2348826A US 2348826 A US2348826 A US 2348826A US 238976 A US238976 A US 238976A US 23897638 A US23897638 A US 23897638A US 2348826 A US2348826 A US 2348826A
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United States
Prior art keywords
magnesium
objects
oxides
coating
bath
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Expired - Lifetime
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US238976A
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English (en)
Inventor
Krause Ernst
Schroder Ernst
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Individual
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Individual
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Classifications

    • CCHEMISTRY; METALLURGY
    • C25ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25DPROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D11/00Electrolytic coating by surface reaction, i.e. forming conversion layers
    • C25D11/02Anodisation
    • C25D11/30Anodisation of magnesium or alloys based thereon

Definitions

  • This invention relates to the production or surface layers of oxide on objects made of magnesium or oi alloys consisting principally of magnesium by anodic treatment in alkaline solution.
  • the process according to the invention differs essentially in that the anodic treatment is carried out in aqueous solutions of alkali salts of such metal oxides as have an amphoteric character, e. g. in solutions or alkali aluminates, arsenates or zincates.
  • the protective layers obtained from such solutions are distinguished by high resistance to corrosion, great hardness and density, and good insulating power.
  • the alkalinity of the solution is maintained at a pH number oi about to 13 and the solution is kept at an elevated temperature, e. g. at a bath temperature of 30 to 70 C.
  • the 'anodic' oxidation can be assisted according to the invention, by the addition of oxygen carriers, e. g. by the addition of small amounts oi cerium sulphate, or 01' tungstates or chromates.
  • the protective layers of oxide which are obtainedby anodic treatment in baths of known composition can be considerably improved' as regards density, hardness, insulating power and resistance to corrosion by a or a preliminary or interto the invention.
  • the treatment in such baths as contain alkali arsenates has been found to be particularly advantageous while moreover solutions of alkali aluminates produce specially favourable results.
  • the solutions of these salts ofi'er also the special advantage that the metal (aluminium) is not cathodically deposited.
  • the conductivity oi. the baths is so regulated by suitable regulation or the concentration and temperature that the process is worked with currents of 1 to 3 amps. per sq. dm.
  • the bath temperature e g. to 60 to 85 C. there are obtained dark or deep black coloured protective layers.
  • the protective layers obtained according to the invention can subsequently be coloured with organic or inorganic dyestuil's. or coated with lacquers.
  • the protective layers can also be sealed and hardened by treatment with water glass'and subsequent heating to about 150 C.
  • Example 1 Water litre 1 Sodium aluminate "grams.- 200 Cerium sulphate do 3 if desired acid or alkali additions are made thereto until the desired pH value is obtained.
  • the process can be carried out using direct or alternating current. Whilst hitherto in the superficial oxidation of magnesium and magnesium containing alloys, alternating current had to be used, an advantage of the new process consists in that sufliciently strong protective layers can be obtained by the use of direct current under relatively low voltages e. g. 10 volts and with current densities which are about as high as those usual in the anodic oxidation of aluminium in aqueous solutions.
  • the protective layers obtained according to the new process produce even on profiled objects a good cormsion resistance and possess a high absorptive power for sealing agents such as water glass.
  • a process for the production of protective layers of oxide on objects made of magnesium or magnesium alloys comprising making said objects the anode in a bath containing an alkali a'rsenate, and passing an electricv current through said bath.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Preventing Corrosion Or Incrustation Of Metals (AREA)
US238976A 1937-11-18 1938-11-05 Coating of objects of magnesium or the like with oxides Expired - Lifetime US2348826A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE2348826X 1937-11-18

Publications (1)

Publication Number Publication Date
US2348826A true US2348826A (en) 1944-05-16

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ID=7995249

Family Applications (1)

Application Number Title Priority Date Filing Date
US238976A Expired - Lifetime US2348826A (en) 1937-11-18 1938-11-05 Coating of objects of magnesium or the like with oxides

Country Status (2)

Country Link
US (1) US2348826A (fr)
FR (1) FR844066A (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3293158A (en) * 1963-09-17 1966-12-20 Mcneill William Anodic spark reaction processes and articles
US3620940A (en) * 1970-05-12 1971-11-16 Us Army Method of inducing polarization of active magnesium surfaces

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3293158A (en) * 1963-09-17 1966-12-20 Mcneill William Anodic spark reaction processes and articles
US3620940A (en) * 1970-05-12 1971-11-16 Us Army Method of inducing polarization of active magnesium surfaces

Also Published As

Publication number Publication date
FR844066A (fr) 1939-07-18

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