US2395694A - Processes for removing oxide from the surface of metals - Google Patents

Processes for removing oxide from the surface of metals Download PDF

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Publication number
US2395694A
US2395694A US538538A US53853844A US2395694A US 2395694 A US2395694 A US 2395694A US 538538 A US538538 A US 538538A US 53853844 A US53853844 A US 53853844A US 2395694 A US2395694 A US 2395694A
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United States
Prior art keywords
oxide
bath
metal
fused
acid
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Expired - Lifetime
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US538538A
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English (en)
Inventor
Harry R Spence
Horace W Hooker
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Occidental Chemical Corp
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Hooker Electrochemical Co
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Publication date
Priority to BE476664D priority Critical patent/BE476664A/xx
Priority to US22887D priority patent/USRE22887E/en
Application filed by Hooker Electrochemical Co filed Critical Hooker Electrochemical Co
Priority to US538538A priority patent/US2395694A/en
Priority to GB13705/45A priority patent/GB612419A/en
Application granted granted Critical
Publication of US2395694A publication Critical patent/US2395694A/en
Priority to FR945530D priority patent/FR945530A/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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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
    • C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
    • C23G1/00—Cleaning or pickling metallic material with solutions or molten salts
    • C23G1/28—Cleaning or pickling metallic material with solutions or molten salts with molten salts

Definitions

  • Our invention relates more particularly to processes for removing oxide from the surface of metals, and especially the ferrous metals, also copper, and their alloys, which have been or are in the process of being rolled out into sheets or drawn into tubes, wires or other shapes, at more or less elevated temperature.
  • This work generally involves heating the metal and passing it several times through the rolls, at temperatures sufliciently elevated to soften the metal. At these temperatures metal picks up oxygen from the air and forms the dark oxide. Ordinarily, this oxide readily scales off; but in the course of the working above described, the metal becomes toughened and hardened and the oxide film rolled into it until, in the case of the ferrous metals and their alloys, it may form a dense coal black glaze.
  • finishing passes through dies at lower temperatures such as result from the work of friction and deformation.
  • the oxide may be reduced to the metallic state. This is done by cathodic electrolysis, generally in an electrolyte of fused alkali, in which the metal serves as cathode.
  • the reduced oxide may form a sponge layer on the surface of the metal, or it may fall off into the electrolyte, where it accumulates as sludge.
  • the metal to a brief anodic treatment prior to the cathodic treatment.
  • the effect of this treatment may be increased by the addition of a substantial proportion of a chloride such as sodium chloride to the fused bath.
  • a typical treatment of this nature would be an anodic oxidation of 30 seconds followed by a cathodic reduction of 2 minutes, in a bath of fused caustic soda containing 20 per cent sodium chloride, at 500 to 550C. and a current density of 100 to 150 amperes per square foot of surface of the metal under treatment.
  • this treatment leaves the surface in a.
  • an effect equal or superior to that of the anodic treatment may be secured by subjecting the metal to the action of an anhydrous oxidizing agent that is effective without electrolytic decomposition, such as an alkali metal or alkaline earth nitrate, chlorate, peroxide, dichromate, manganate, permanganate or persulphate, without any electrolysis.
  • an anhydrous oxidizing agent that is effective without electrolytic decomposition, such as an alkali metal or alkaline earth nitrate, chlorate, peroxide, dichromate, manganate, permanganate or persulphate, without any electrolysis.
  • the oxidizing agent may be added to the fused bath.
  • our process consists in soaking the article in a bath of fused caustic alkali containing 1 to 20 per cent, and preferably 5 to per cent, of an active oxidizing agent, at a temperature between 300 and 600 C., and preferably at about 500 0., depending upon the oxidizing agent, for 1 to 20 minutes, the time depending on caustic alkali and oxidizing agent used and upon the proportion of oxidizing agent in the bath, and then dipping it briefly, e. g. for to 60 seconds, in a di- 39 lute nonoxidizing acid, such as 1 to per cent hydrochloric acid, preferably at 65 to 85 C. It is desirable to wash off excess caustic alkali before the acid dip.
  • resulting powder is ofthe fineness of paint pigment.
  • the extreme fineness of this oxide probably accounts for the readiness: with which it is attacked by the dilute acid.
  • the removal of this oxide by the acid dip leaves a frosted or mat surface, of the kind that is preferred for further drawing, and of a color from steel grey to silvery white, depending on the nature of the steel.
  • the bath contains sodium chromate in solution. This might be thought to indicate that the chromium is oxidized, the oxide forming with the caustic soda the sodium salt of chromium. which then dissolves oil in the bath.
  • Our fused alkali bath may consist of caustic soda, caustic potash or a mixture of these alkalies with each other or with their carbonates or calls-- tic lime.
  • the presence of the oxidizing agent lowers the melting point of the bath.
  • 10 per cent of sodium nitrate lowers the melting point of caustic potash from 360 to 315 C.
  • by proper proportioning of a mixture of alkalies it is possible to produce a bath of substantially lowor melting point than that of any one of its individual components.
  • a mixture of commercial caustic soda and caustic potash in equal proportions by weight melts at 205 0., whereas these alkalies, in commercial grades, melt at 325 and 360 C. respectively.
  • the coating produced by our process need not be removed until after the final drawing. In that case, it serves as a very effective base for the lubricant for the dies during the next four or five successive operations, perhaps because the particles of oxide are so fine that they roll. This makes it possible to dispense with the lead coating generally applied for lubrication purposes. After the final working the metal is given the quick acid dip, which leaves it with the frosted surface above described.
  • the oxidizing agent may, if preferred, be used by itself in a separate step preliminary to the treatment in the fused caustic alkali bath. In this case the choice of oxidizing agents is increased.
  • Example I A drawn rodof "18-8 stainless steel having a dark glazed surface was immersed for 4 min- 40 utes in a bath of fused caustic soda containing 10 per cent sodium nitrate by weight at 575 C. When removed the surface coating had been converted to a condition resembling lamp black. A water wash and dip of 30 seconds in dilute hydrochloric acid removed the oxide completely, leaving a clean frosted silvery grey surface.
  • Example 11 A piece of the same rod as that of Example I was treated in the same way except that the temperature was 500 C. and the time 5 minutes. The result was substantially the same. This at present represents preferred practice.
  • Example III A piece of the same rod as that of Example I was treated in the same way except that the temperature was 420 C. and the time 15 minutes. The result was substantially the same. A comparison of this example with the two preceding shows that the time of treatment in our process is a function of the temperature of the bath.
  • Example IV 1 aromas- Examplc V Another piece of the same rod was immersed verted to a coating resembling reddish brown paint pigment. A water 'wash and acid dip of one minute removed the brown coating. leaving a clean frosted surface.
  • Example VI Another piece of the same rod as that treated in Example I was immersed in a bath of fused caustic potash containing per cent sodium nitrate by weight for 4 minutes at 420 C. It
  • Example V came out with the oxide converted to a brown coating resembling that of Example V.
  • the water wash and acid dip removed this, leaving a clean frosted surface, though not quite so bright as that of Example I; probably due to the time not having been quite long enough.
  • Example VII Another piece of the same rod was immersed for 6 minutes in a bath of fused caustic potash containing 10 per cent of potassium chlorate by weight at 420 C. It came out with the oxide converted to a condition resembling that of Example V. The water wash and acid dip left the surface frosted and silvery white, brighter than in any of the preceding examples, showing that the chlorates are very effective oxidizing agents for the purpose of our process.
  • Example VIII Another piece of the same rod was immersed in a fused bath of caustic soda and caustic potash in equal proportions by weight, without any oxidizing agent, at 400 C., for 10 minutes. It came out a very dark brown in color. The wash and acid dip removed a part but not all of the oxide, showing that in the absence of the oxidizing agent the effect is less positive.
  • Example IX Another piece of the same rod was immersed in a bath of fused sodium nitrate alone for 6 minutes and given a water wash and acid dip. It was little aifected. This is believed to show that the caustic alkali is essential.
  • Example X Another piece of the same rod was immersed for 5 minutes. in fused sodium nitrate, then for 5 minutes in a bath of fused caustic soda at 415 0., followed by a water wash and dip in dilute acid. The result was similar to that of Example 111, showing that the treatments with oxidizing agent and caustic soda may be simultaneous or successive.
  • Example XII A badly rusted cast-iron pipe elbow was treated as in Example XI. It came out with the lamp black like coating. After the wash and acid dip it was the grey color of clean cast iron.
  • Example XIII A piece of old badly rusted steel pipe was treated as in Example XI with the same result.
  • Example XIV A strip of Nichrome containing per cent nickel and 20 per cent chromium and no iron, heavily coated with dark oxide, was immersed in the same bath as in Example III for the same time and at the same temperature. It came out with a reddish brown irridescent coating which was completely removed by the water wash and acid dip, leaving a beautiful shiny surface.
  • Example XV A sheet of "MoneP coated with dark oxide was immersed in a fused bath of caustic soda containing 6 y per cent sodium nitrate at 500 C. for 5 minutes. It came out with the oxide converted to a coating resembling lamp black. It was quenched in water and immersed in warm 10 per cent hydrochloric acid for one minute. The surface was left a beautiful silvery white.
  • Example XVI Pieces of cast and stamped copper heavily coated with a mottled reddish brown oxide were treated as in Example III. They came out quite black. After the wash and acid dip their surfaces were immaculately clean, that of the casting appearing frosted.
  • the acid should be non-oxidizing and have used only dilute hydrochloric acid as an illustration of such an acid, we do not-wish to be limited thereto.
  • Other acids including nitric and sulphuric acid, which are ordinarily considered as oxidizing acids, may be used if in such dilution and at such a temperature that they do not have an oxidizing effect or otherwise attack the metal.
  • caustic alkali containing a substantial but minor proportion of an oxidizing agent stable therewith, said bath being at substantially the same electrical potential as the metal, at a temperature of 300 to 600 C., for not less than 1 minute, and then subjecting the modified oxide to the action of a weak aqueous inorganic acid.
  • the method of removing from the surface of metals that have been treated by the process or claim 2 oxide that has formed thereon through subsequent exposure to air at annealing temperture which comprises subjecting the oxide to the action of a fused substantially anhydrous bath comprising caustic alkali containing a substantial but minor proportion of an oxidizing agent stable therewith, at a temperature of 300 to 600 C'., and then subjecting the a weak inorganic acid.
  • the method of removing from the surface of metals resistant to fused caustic alkalies dense firmly adherent oxide that has formed thereon through exposure to air under oxidizing conditions which comprises subjecting the oxide to the action or a fused substantially anhydrous bath, comprising at least one caustic alkali of the group consisting of sodium, potassium and calcium hydroxides and a substantial but minor proportion of at least one oxidizing agent of the group consisting of the alkali metal and alkaline earth chlorates, peroxides, nitrates, dichromates,
  • said bath being at substantially the same electrical potential as the metal, at a temperature of 300 to 600 C fo r not less than 1 minute, and
  • the method of removing from the surface of metals of the group consisting of iron, nickel and cobalt and their alloys with each other and with chromium, manganese, molybdenum, tungsten, vanadium and copper, dense firmly adher ent oxide that has formed thereon through exposure to air under oxidizing conditions which comprises subjecting the oxide to the action of a fused substantially anhydrous bath, comprising caustic alkali containing a, substantial but minor proportion of an oxidizing agent stable therewith, said bath being at substantially the same electrical potential as the metal at a temperature of 300 to 600 6., for not less than 1 minute, and then subjecting the modified oxide to the action of a weak aqueous inorganic acid.
  • the method of removing from the surface of chrome-nickel stainless steel dense firmly adherent oxide that has formed thereon through exposure to air under oxidizing conditions which comprises subjecting the oxide to the action of a fused substantially anhydrous bath, comprising caustic soda containing 5 to 15 per cent of potassium chlorate, said bath being at substantially-the same electrical potential as the metal, at 400 to 600 C., for not less than lminute, and subjecting the modified oxide to the action of 5 to 15 per cent aqueous hydrochloric acid.
  • the method of removing from the surface of chrome-nickel "stainless steel" dense firmly adherent oxide thathas formed thereon through exposure to air under oxidizing conditions which comprises subjecting the oxide to the action of a fused substantially anhydrous bath, comprising caustic soda containing 5 to 15 per cent of sodium chlorate, said bath being at substantially the same electrical potential as the metal, at 400 to 600 C., for not less than 1 minute, and subjecting the modified oxide to the action of 5 to 15 per cent aqueous hydrochloric acid.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Chemical Treatment Of Metals (AREA)
  • Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)
  • ing And Chemical Polishing (AREA)
US538538A 1944-06-02 1944-06-02 Processes for removing oxide from the surface of metals Expired - Lifetime US2395694A (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
BE476664D BE476664A (enrdf_load_html_response) 1944-06-02
US22887D USRE22887E (en) 1944-06-02 Process for removing oxide from
US538538A US2395694A (en) 1944-06-02 1944-06-02 Processes for removing oxide from the surface of metals
GB13705/45A GB612419A (en) 1944-06-02 1945-05-31 Processes for removing oxide from the surfaces of metals and alloys
FR945530D FR945530A (fr) 1944-06-02 1947-04-21 Procédé pour enlever l'oxyde de la surface des métaux

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Cited By (25)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2442195A (en) * 1945-07-31 1948-05-25 Gen Electric Cleaning and electroplating process
US2458661A (en) * 1944-01-29 1949-01-11 J H Shoemaker Process of cleaning metal surfaces and compositions therefor
US2488108A (en) * 1946-08-02 1949-11-15 Pennsylvania Salt Mfg Co Stainless steel pickling
US2538702A (en) * 1944-06-02 1951-01-16 Freeport Sulphur Co Metal surface cleaning
US2567456A (en) * 1947-04-07 1951-09-11 J H Shoemaker Metal cleaning composition and process
US2567835A (en) * 1949-08-29 1951-09-11 Dow Chemical Co Removing copper-containing incrustations from steam generators
US2569158A (en) * 1946-02-21 1951-09-25 United States Steel Corp Method of removing scale from ferrous articles
US2630393A (en) * 1948-06-25 1953-03-03 Charles B Francis Method of cleaning and descaling ferrous bodies
US2641559A (en) * 1948-09-08 1953-06-09 United States Steel Corp Method of cleaning and descaling ferrous articles and a bath therefor
US2671717A (en) * 1950-08-29 1954-03-09 Gen Electric Chemical brightening of aluminum
US2676900A (en) * 1947-07-08 1954-04-27 Hooker Electrochemical Co Processes for removal of oxides from the surface of metals
US2678289A (en) * 1944-06-02 1954-05-11 Pottberg Rolfe Metal surface treatment
US2678290A (en) * 1946-09-05 1954-05-11 Pottberg Rolfe Process of removing surface oxide films on metal
US2726970A (en) * 1954-06-01 1955-12-13 Ford Motor Co Deoxidizing copper base metal parts
US2738294A (en) * 1951-09-13 1956-03-13 Diamond Alkali Co Salt bath system and method for treating metals
US2809103A (en) * 1953-11-10 1957-10-08 Sylvania Electric Prod Fabrication of semiconductor elements
US2931778A (en) * 1954-09-28 1960-04-05 Diamond Alkali Co Alkaline composition
US3025189A (en) * 1958-12-10 1962-03-13 Purex Corp Ltd Composition and process for removing heat scale from metal parts
US3030239A (en) * 1957-10-24 1962-04-17 Hooker Chemical Corp Process and salt for descaling of metals
US3096261A (en) * 1959-05-25 1963-07-02 Hooker Chemical Corp Salt bath for electrolytic cleaning of metals
US3457107A (en) * 1965-07-20 1969-07-22 Diversey Corp Method and composition for chemically polishing metals
US3646946A (en) * 1969-01-06 1972-03-07 Olin Mathieson Copper alloy cleaning process
US3728155A (en) * 1969-01-06 1973-04-17 Olin Corp Copper alloy cleaning process
US3923540A (en) * 1973-03-01 1975-12-02 Kansai Paint Co Ltd Method for treatment of metallic surface
US6203691B1 (en) 1998-09-18 2001-03-20 Hoffman Industries International, Ltd. Electrolytic cleaning of conductive bodies

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2738293A (en) * 1952-07-25 1956-03-13 Diamond Alkali Co Salt bath system and method for treating metals
US3020175A (en) * 1958-06-12 1962-02-06 Gen Dynamics Corp Chemical cleaning of printed circuits
US3043712A (en) * 1959-05-27 1962-07-10 Gil Mfg Company Method of porcelain enameling ferrous metal and product
US3011923A (en) * 1960-02-19 1961-12-05 Charles O Coffer Surface treatment of molybdenum metal
FR2525637B1 (fr) * 1982-04-23 1986-05-09 Stephanois Rech Mec Procede de traitement de pieces en metal ferreux en bain de sels oxydant, pour ameliorer leur resistance a la corrosion, les pieces contenant du soufre

Cited By (25)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2458661A (en) * 1944-01-29 1949-01-11 J H Shoemaker Process of cleaning metal surfaces and compositions therefor
US2538702A (en) * 1944-06-02 1951-01-16 Freeport Sulphur Co Metal surface cleaning
US2678289A (en) * 1944-06-02 1954-05-11 Pottberg Rolfe Metal surface treatment
US2442195A (en) * 1945-07-31 1948-05-25 Gen Electric Cleaning and electroplating process
US2569158A (en) * 1946-02-21 1951-09-25 United States Steel Corp Method of removing scale from ferrous articles
US2488108A (en) * 1946-08-02 1949-11-15 Pennsylvania Salt Mfg Co Stainless steel pickling
US2678290A (en) * 1946-09-05 1954-05-11 Pottberg Rolfe Process of removing surface oxide films on metal
US2567456A (en) * 1947-04-07 1951-09-11 J H Shoemaker Metal cleaning composition and process
US2676900A (en) * 1947-07-08 1954-04-27 Hooker Electrochemical Co Processes for removal of oxides from the surface of metals
US2630393A (en) * 1948-06-25 1953-03-03 Charles B Francis Method of cleaning and descaling ferrous bodies
US2641559A (en) * 1948-09-08 1953-06-09 United States Steel Corp Method of cleaning and descaling ferrous articles and a bath therefor
US2567835A (en) * 1949-08-29 1951-09-11 Dow Chemical Co Removing copper-containing incrustations from steam generators
US2671717A (en) * 1950-08-29 1954-03-09 Gen Electric Chemical brightening of aluminum
US2738294A (en) * 1951-09-13 1956-03-13 Diamond Alkali Co Salt bath system and method for treating metals
US2809103A (en) * 1953-11-10 1957-10-08 Sylvania Electric Prod Fabrication of semiconductor elements
US2726970A (en) * 1954-06-01 1955-12-13 Ford Motor Co Deoxidizing copper base metal parts
US2931778A (en) * 1954-09-28 1960-04-05 Diamond Alkali Co Alkaline composition
US3030239A (en) * 1957-10-24 1962-04-17 Hooker Chemical Corp Process and salt for descaling of metals
US3025189A (en) * 1958-12-10 1962-03-13 Purex Corp Ltd Composition and process for removing heat scale from metal parts
US3096261A (en) * 1959-05-25 1963-07-02 Hooker Chemical Corp Salt bath for electrolytic cleaning of metals
US3457107A (en) * 1965-07-20 1969-07-22 Diversey Corp Method and composition for chemically polishing metals
US3646946A (en) * 1969-01-06 1972-03-07 Olin Mathieson Copper alloy cleaning process
US3728155A (en) * 1969-01-06 1973-04-17 Olin Corp Copper alloy cleaning process
US3923540A (en) * 1973-03-01 1975-12-02 Kansai Paint Co Ltd Method for treatment of metallic surface
US6203691B1 (en) 1998-09-18 2001-03-20 Hoffman Industries International, Ltd. Electrolytic cleaning of conductive bodies

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Publication number Publication date
USRE22887E (en) 1947-06-03
BE476664A (enrdf_load_html_response)
GB612419A (en) 1948-11-12
FR945530A (fr) 1949-05-06

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