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US1480869A - Method of coloring magnesium and magnesium alloys by etching - Google Patents

Method of coloring magnesium and magnesium alloys by etching Download PDF

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Publication number
US1480869A
US1480869A US494948A US49494821A US1480869A US 1480869 A US1480869 A US 1480869A US 494948 A US494948 A US 494948A US 49494821 A US49494821 A US 49494821A US 1480869 A US1480869 A US 1480869A
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magnesium
metal
etching
coloring
bath
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US494948A
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Thomas Felix
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Chemische Fabrik Griesheim Elektron
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Firm Chem Fab Griesheim Elektr
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    • 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
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
    • C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
    • C23C22/24—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing hexavalent chromium compounds

Definitions

  • This invention relates to a method of coloring magnesium and magnesiumalloys by etching.
  • coloring comprises superficially etching the metal in such a way that a small amount of the magnesium metal or magnesium allo is dissolved out and is replaced by a hr of a color differing from that of the metal or metal alloy and consistin of oxides and metals of the salts cont-aine in the etching bath.
  • the colorations which as a rule are between-brass and bronze, may also be more finely graduated,'the etching bath remainingthe same, b of other acids and by modifying the duration of etching.
  • a deep black also can be obtained by adding to the bath a considerable excess of coloring metallic magnesinmnomalloysnoimacid instegl pi the additionnoil hemeavy magnesium containing small amounts of zinc or aluminium, or both these metals together,-
  • the known etching baths used for colorin metals cannot moreover be directly applied to magnesium and its alloys for the reason that they have a too powerful acid reaction, and thereby corrode the metal too strongly, and, at best, only a spongy depos1t of the metal is efiected.
  • the adhesion of the coloring to the metallic base is with most baths considerably inthe addition of small amounts creased by keeping the object for some time i in an air bath, at a temperature between 100 and 150 C., after washing oil the etching liquor, and washing thereafter with boiling water and drying in the air.
  • the object to be colored must be perfectly clean, '(especially free from fat), and su1t-' ably prepared, and is suspended in a bath which is composed as follows:
  • the temperature of the bath is 90 Cl
  • any gas bubbles'which may adhere are dislodged, and dead corners. of impbverished bath liquor are prevented.
  • the alteration of the tone of the color is observed by withdrawing the o'bj'ectfor a short time.
  • colorin'g' is generally complete in 20 seconds to 3 minutes.
  • the object is then immediately quickly rinsed in cold running Water, dipped for a few seconds in pure boiling water and dried by rubbing with a soft cloth, or placed in an air bath at a temperature in the neighbourhood of that of boiling water for a quarter of an hour.
  • a light greasing with mineral oils is advanta ous.
  • the bath is used cold.
  • the etching takes about 1 minute. After thoroughly washing the object can be dried. at once in a stove at 100'120 C., or by wiping with a soft cloth.
  • the etching takes about ha f to one minute.
  • the after treatment is the same as Example 2.
  • the bat is used eo1 .Thdebjdttserd" dipped into the bath, kept in constaiitfmove: ment, taken out after a few seconds, and when the adherent liquid of the-bath no longer reacts with'the metal ⁇ but not until thh ⁇ , are thoroughly cleaned with water.
  • the etched objects can be heated .by heat treatment at, a temperaturqnp-to to a higher temperature (300 to 400 C.) inorder to still further darken the tone.
  • a dark brown coloration for example can thereby be transformed into a brownish black.
  • Themethod of coloring magnesium and magnesium alloys by etching which comprises the simultaneous treatment of said metal with chromic acid and a solution of a salt of a heavy metal, with the addition of small amounts of another acid, and the subsequentheat treatment of the colored object.
  • magnesium alloys by etching which comprises the simultaneous treatment a:
  • the method of producing a brass yellow skin by etching magnesium and magnesium alloys which comprises treatin said metal with chromic acid, causing said skin to adhere by treatment with a salt of a heavy metal and influencing the shade of the color by1 the suitable choice of said heavy metal sa t.
  • the method of coloring magnesium alloys containing zinc by etching which comprises simultaneously treating said metal with chromic acid, a solution of a salt of a heavy metal,and a zinc salt, and adapting the zinc contents of the coloring bath to the zinc contents of the alloy.
  • the method of coloring magnesium and magnesium alloys by etching which comprises the simultaneous treatment at a temperature above the normal of said metal with chromic acid and a solution of a salt of a hea metal.
  • the method of coloring magnesium and magnesium alloys by etching which comprises simultaneously treating said metal with chromic acid and a solution of a salt of a heavy metal and modifying the duration of the treatment.
  • the method of providing an alloy of magnesium with 3% to 8% of zinc with a brown color which comprises freeing the metal from fat by cleaning, thereupon constantly moving same in a bath containing sodium bichromate, copper nitrate, nitric acid and water at a temperature of between 90 C. and as soon as the required coloration has been obtained quickly rinsing the object in cold running water, immersing it in pure boiling water, and drying the object.
  • the method of providing an alloy of magnesium with a horn color which comprises cleaning the metal and constantly moving same in a cold bath comprising sodium bichromate, manganese sulphate, nitric acid and water, thereupon washing the object in water and drying same in a stove at a temperature of C.
  • the method of providing electron metal with a black color which comprises moving the metal in a bath containing sodium bichromate, nitric acid and water for a few seconds and as soon as the bath liquor no longer reacts with the metal, but not until then, thoroughly cleaning the metal with water drying the object after dipping in boiling water and varnishing the object.

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  • Chemical & Material Sciences (AREA)
  • General Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • ing And Chemical Polishing (AREA)

Description

Patented Jan. 15, 1924.
UNITED STATES PATENT OFFICE] FELIX THOMAS, or rarmxronr-on-rnn-mam, GERMANY, assrenoa TO THE FIRM CHEMISCHE FABBIK GBIESHEIM-ELEKTBON, FRANKFORT-ON-THE-MAIN, GEE- MANY, A. COBI'OBATIONDF GERMANY. 4
mnon or cononme naennsrum AND maennsrom annoys Br n'rcnmo.
no Drawing.
To all whom it may concern:
Beit known that Fnmx THOMAS, a citizen of the German Republic, residing at 53 Paul Ehrlichstrasse, Frankfort-on-the-Main, Gerrs many, has invented certain new and useful Improvements in the Method of Coloring Magnesium and Magnesium Alloys by- Etching (for which I have'filed application in Germany Aug. 26, 1919, application No.
028,289), of which the following is a specification.
This invention relates to a method of coloring magnesium and magnesiumalloys by etching.
In the following specification and claims the term coloring comprises superficially etching the metal in such a way that a small amount of the magnesium metal or magnesium allo is dissolved out and is replaced by a hr of a color differing from that of the metal or metal alloy and consistin of oxides and metals of the salts cont-aine in the etching bath.
The only methods hitherto known for mly adherent complex deposit Application filed Augustin, 1921. Serial 1%., 494,9.
other acids, does not efi'ect a continuous liberation of hydrogen, but that after a very short time, a kmd of passive resistance takes place, the metalbecoming covered with a brass-yellow skin. When heavymetal salts are also present, this skin adheres and be comes darker in coloration. The shade of the color is influenced by the nature of the heavy metal (copper, zinc, manganese, chromium, iron, cobalt and the like) as well as by the kind of the alloy for example, the depth of the coloration in an alloy of magnesium with 3 to8% zinc changes, with increasing content of zinc and the employment of copper salts, from a light brown tone to a bronze brown.
The colorations which as a rule are between-brass and bronze, may also be more finely graduated,'the etching bath remainingthe same, b of other acids and by modifying the duration of etching. I
'Apart from the aforesaid variegated colorings, a deep black also can be obtained by adding to the bath a considerable excess of coloring metallic magnesinmnomalloysnoimacid instegl pi the additionnoil hemeavy magnesium containing small amounts of zinc or aluminium, or both these metals together,-
know-n under the name of electron metal, by means of the so-called etching agents are those based ,on the deposition of another metal such as cobalt followed by baking. The self-evident attempt to apply to magnesium the methods of metal coloring which aluminium, has not 5 are used for colorin proved very success ul. Also the method 'which is used for aluminium, that is to-first provide same with a coating of copper, silver or zinc, and then' to' color with the aid of the 40 methods known for these metals'has been recognized to.be too roundabout.
The known etching baths used for colorin metals cannot moreover be directly applied to magnesium and its alloys for the reason that they have a too powerful acid reaction, and thereby corrode the metal too strongly, and, at best, only a spongy depos1t of the metal is efiected.
Experiments have nesium and electron metal, good and durable colorations can be attained in a very Simple manner, by etching. It has been found that shown that with "magmetal salt.
According to the kind andjcomposition of the baths and thekind of the alloys to be colored, warm or cold'baths must be used.
The adhesion of the coloring to the metallic base is with most baths considerably inthe addition of small amounts creased by keeping the object for some time i in an air bath, at a temperature between 100 and 150 C., after washing oil the etching liquor, and washing thereafter with boiling water and drying in the air.
EXAMPLE 1.
3-8% of 217M. H
The object to be colored must be perfectly clean, '(especially free from fat), and su1t-' ably prepared, and is suspended in a bath which is composed as follows:
350 grammes sodium bichromate.
94 grammes copper nitrate.
' 100 cc. chemically pure nitric acid, of 1.36 specific gravity.
9,500 cc. water.
-The temperature of the bath is 90 Cl By frequently moving the object any gas bubbles'which may adhere are dislodged, and dead corners. of impbverished bath liquor are prevented. The alteration of the tone of the color is observed by withdrawing the o'bj'ectfor a short time. The
colorin'g'is generally complete in 20 seconds to 3 minutes. The object is then immediately quickly rinsed in cold running Water, dipped for a few seconds in pure boiling water and dried by rubbing with a soft cloth, or placed in an air bath at a temperature in the neighbourhood of that of boiling water for a quarter of an hour. To increase the lustre and strengthen the tone, a light greasing with mineral oils is advanta ous.
he following examples relate to the coloring of magnesium and magnesium alloys by means of bath liquors containing salts of manganese and iron.
' EXAMPLE 2.
Horn coloring.
180 grammes sodium bichromate.
133 grammes manganese sulphate crystals.
20 ccm. nitric acid, (specific gravity 1.36).
Water up to 5 litres.
The bath is used cold. The etching takes about 1 minute. After thoroughly washing the object can be dried. at once in a stove at 100'120 C., or by wiping with a soft cloth.
EXAMPLE 3.
Brass coloring.
pecially adapted for jiolishe'd articles. The etching takes about ha f to one minute. The after treatment is the same as Example 2.
Exam Block etch/mg foreleg/ran metal. 37.5 grammes; sodium bichroinate.
123 grammes nitric acid (specific gravity Water u to 1 litre.
The bat is used eo1 .Thdebjdttserd" dipped into the bath, kept in constaiitfmove: ment, taken out after a few seconds, and when the adherent liquid of the-bath no longer reacts with'the metal {but not until thh}, are thoroughly cleaned with water.
7 The reaction'fis completed when the evolution of sis no longer visible. After drying, which is'eflecterla-very quickly after a short dipping in boilingwater, the objects are lightly greased or coated"with colorless spirit varnish or a special" lacquer for electron-metal.
Finally the etched objects can be heated .by heat treatment at, a temperaturqnp-to to a higher temperature (300 to 400 C.) inorder to still further darken the tone. A dark brown coloration, for example can thereby be transformed into a brownish black.
What I claim and desire to secure by Letters Patent is 1. The method of coloring magnesium and magnesium alloys by etching, which comprises the simultaneous treatment of said chromic acid and a considerable excess or another acid. a
4. The method of coloring magnesium and magnesium alloys by etching, which comprises the simultaneous treatment of said metal with chromic acid and a solution of a salt of'heavy metal, and the subsequent heat treatment of the colored object. I
5. Themethod of coloring magnesium and magnesium alloys by etching, which comprises the simultaneous treatment of said metal with chromic acid and a solution of a salt of a heavy metal, with the addition of small amounts of another acid, and the subsequentheat treatment of the colored object.
6. The methodoLprLducing a black color on magnesium and magnesi iu'n'al'loys,. which comprlses the treatment of said metal with chromic acid and a considerable excess o'f another acid, and the subsequent heattreatment of the colored object.
7. The method of colorin magnesium and r. t
magnesium alloys by etching, which comprises the simultaneous treatment a:
metal with chromic acid, and a-solution. of
a salt of a heavy metal, and the a ent darkening of the shade of'the eoloredo est ut 400 0. r v I 8. The method of coloring magnesium and magnesium algpys by etching, which comprise'sthe simultaneous treatmentoi said metal withchromic acid. and a ,so lut ioi1 of a salt of a heavy metal, with the addition of small amounts of another acid, andt e subsequent darkening" of? the shadqof 't 'e colored object by heat treatment ate. temperature up to about 400 9."The method of producing a ,black color on ma esium and magnesium alloys,. whieh comprises the treatment of sa d metal chromic acid and' a considerable excess of another acid and the subsequent darkening metal with chromic acid, and causing said skin to adhere by treatment with a solution of a salt of a heavy metal.
11. The method of producing a brass yellow skin by etching magnesium and magnesium alloys, which comprises treatin said metal with chromic acid, causing said skin to adhere by treatment with a salt of a heavy metal and influencing the shade of the color by1 the suitable choice of said heavy metal sa t.
12. The method of coloring magnesium alloys containing zinc by etching, which comprises simultaneously treating said metal with chromic acid, a solution of a salt of a heavy metal,and a zinc salt, and adapting the zinc contents of the coloring bath to the zinc contents of the alloy.
13. The method of coloring magnesium and magnesium alloys by etching which comprises the simultaneous treatment at a temperature above the normal of said metal with chromic acid and a solution of a salt of a hea metal.
14. The method of coloring magnesium alloys containing zinc by etching which con1- prises increasing the contents of zinc in the solution with the object of altering the depth of the coloration when said alloy is subsequently simultaneously treated with chromic acid and a solution of copper salt and a zinc salt.
15. The method of coloring magnesium and magnesium alloys by etching which comprises simultaneously treating said metal with chromic acid and a solution of a salt of a heavy metal and modifying the duration of the treatment.
16. The method of providing an alloy of magnesium with 3% to 8% of zinc with a brown color which comprises freeing the metal from fat by cleaning, thereupon constantly moving same in a bath containing sodium bichromate, copper nitrate, nitric acid and water at a temperature of between 90 C. and as soon as the required coloration has been obtained quickly rinsing the object in cold running water, immersing it in pure boiling water, and drying the object.
17. The method of providing an alloy of magnesium with a horn color which comprises cleaning the metal and constantly moving same in a cold bath comprising sodium bichromate, manganese sulphate, nitric acid and water, thereupon washing the object in water and drying same in a stove at a temperature of C.
18.-The method of providing polished magnesium alloys with a brass color which comprises moving the metal in a bath 'containing sodium bichromate, ferrous nitrate, nitric acid and water and thereupon washing and drying the object.
19. The method of providing electron metal with a black color which comprises moving the metal in a bath containing sodium bichromate, nitric acid and water for a few seconds and as soon as the bath liquor no longer reacts with the metal, but not until then, thoroughly cleaning the metal with water drying the object after dipping in boiling water and varnishing the object.
In testimony whereof I afiix my signature.
DR. FELIX THOMAS.
US494948A 1921-08-24 1921-08-24 Method of coloring magnesium and magnesium alloys by etching Expired - Lifetime US1480869A (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2483510A (en) * 1945-04-14 1949-10-04 United Chromium Inc Composition for dip coating solution and dip process for coloring zinc
US2854371A (en) * 1956-02-01 1958-09-30 Shwayder Bros Inc Method and solution for treatment of magnesium articles
US3186798A (en) * 1961-12-07 1965-06-01 Francis W Juchnicki Method of and material for identifying metals

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2483510A (en) * 1945-04-14 1949-10-04 United Chromium Inc Composition for dip coating solution and dip process for coloring zinc
US2854371A (en) * 1956-02-01 1958-09-30 Shwayder Bros Inc Method and solution for treatment of magnesium articles
US3186798A (en) * 1961-12-07 1965-06-01 Francis W Juchnicki Method of and material for identifying metals

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