US3202551A - Method for producing adherent coatings on iron and steel parts - Google Patents

Method for producing adherent coatings on iron and steel parts Download PDF

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Publication number
US3202551A
US3202551A US222195A US22219562A US3202551A US 3202551 A US3202551 A US 3202551A US 222195 A US222195 A US 222195A US 22219562 A US22219562 A US 22219562A US 3202551 A US3202551 A US 3202551A
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United States
Prior art keywords
acid
solution
treated
weight
chromic acid
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Expired - Lifetime
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US222195A
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English (en)
Inventor
Gerischer Heinz
Herbst Willy
Ludwig Heinz
Schaefer Helmut
Wagner Ernst
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Hoechst AG
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Hoechst AG
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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
    • C23C22/82—After-treatment
    • C23C22/83—Chemical after-treatment
    • 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
    • C23C22/78—Pretreatment of the material to be coated

Definitions

  • the present invention relates to a method for producing adherent uniform coating on iron and steel parts, which serve in particular to prevent corrosion and to improve the adhesion of lacquers and varnishes.
  • the invention is in particular concerned with the coating of iron and steel parts which is brouhgt about by contacting these parts in a first step with an aqueous solution containing at least one aliphatic hydroxycarboxylic acid as an essential component and in a second step with an aqueous solution containing chromic acid as an essential component, and by rinsing the metal parts thus treated in a subsequent step.
  • the metals, freed from water deposits are treated with a solution containing a chromate or chromic acid, an organic reducing agent for the chromate, phosphoric acid and a hydrogen phosphate of a bivalent metal ion.
  • a solution containing a chromate or chromic acid, an organic reducing agent for the chromate, phosphoric acid and a hydrogen phosphate of a bivalent metal ion In the film of solution adhering to the surface the oxidizing and reducing substances are destroyed by heating, so that finally a coating is formed that is composed of approximately equal parts of chromium hydroxide and phosphate.
  • the metal parts are treated in a pickling bath comprising a solution, almost heated to boiling, of chromic acid or a salt thereof, to which is added a colloidal sulfur compound splitting oil sulfur and/ or an oxidizing agent.
  • a colloidal sulfur compound splitting oil sulfur and/ or an oxidizing agent for example, as sugar, to solutions of chromic acid of 0.5 to strength, has also already been proposed, the metal parts being previously treated with nitric acid of 1 to 20% strength.
  • the metal surface is treated with the co-operation of heat with a chromic acid solution that is free from activator ions in a manner such that a chemical reaction takes place with the formation of a coating.
  • the metal parts may be treated at least at 105 C. with a concentrated chromic acid solution having a boiling point of at least 105 C. until a visible coating has been formed on the retail parts, or the solution is applied to the metal parts in the form of a film which is burned in at elevated temperature so that a chemical reaction takes place.
  • the above described process according to the invention is illustrated in the single figure of the drawing.
  • the flow diagram there set forth shows the three step process according to one embodiment of the invention wherein the metal surface is first contacted with a hydroxycarboxylic acid, secondly contacted with a s-olu tion of chromic acid and lastly rinsed with either water or a very dilute solution of chromic acid.
  • aliphatic hydroxycarboxylic acids there may be used according to the invention mono, biand tribasic hydroxycarboxylic acids, i.e., hydroxycarboxylic acids containing 1, Z or 3 COOH groups, which contain not more than 6 carbon atoms in the molecule, for example, glycolic acid, lactic acid, tartaric acid and citric acid.
  • lactic acid, tartaric acid and citric acid can be used with advantage in the process of the present invention.
  • a pretreatment bath (1) that has a total acid concentration within the range of about 0.5 to about 20% by weight, preferably 1.5 to 8% by weight.
  • the solutions (I) may contain phosphoric acid and/or oxalic acid and, if desired, inhibitors. Further, it is of advantage when the proportion of phosphoric acid and/ or oxalic acid to hydroxycarboxylic acid does not exceed 1.
  • the addition of appropriate acid inhibitors is especially suitable when concentrated solutions are employed, in the case of operationally conditioned prolonged periods of treatment or when higher bath tem peratures are applied for the treatment of largely rustfree metal parts.
  • Suitable inhibitors are substances which even at temperatures within the range of about 60 C. to about C. satisfactory reduce the pickling action exerted by the hydroxycarboxylic acids, the oxalic acid and the phosphoric acid on the surfaces of iron and steel and which, during the regeneration of the exhausted solutions in the cation exchanger, are not absorbed.
  • a suitable inhibitor diet e.g.,yl thiourea may be mentioned which is used in a concentration within the range of about 0.06% to about 0.25%, calculated on the total acid.
  • the metal parts which have been pretreated with solution (1) containing hydroxycarboxylic acid are treated with a chroniatization solution (ii) containing chromic acid.
  • concentration of chromic acid in solution (II) is advantageously within the range of about 0.1 to 10% by Weight, preferably 0.25 to 3.5% by weight.
  • a good protection can also be attained by treating the metal parts with solutions containing, for example, 25% by Weight of chromic acid and a small portion of alkali metal phosphate and by subsequently rinsing them thoroughly with water that is free from chromic acid.
  • chromic acid solutions that are free from-any additives.
  • phosphates there may be used in particular alkali metal ortho phosphates and alkali metal polyphosphates, for'example, Na PO K PO and Na l O
  • concentration of the phosphate added depends in the first line on the chromic acid concentration of the solution and, if possible, it should not exceed by weight of the content of chromic acid.
  • the treatment of the metal parts with solutions (I) and (II) and the subsequent rinsing step can be carried out according to the invention at temperatures within the range of about 3 C. to about 80 C., advantageously at temperatures Within the range of about 5 f C. to about C. Bath temperatures above 30 C. are in particular suitable When very rusty parts are treated for a short time.
  • a special advantage of the process of the invention resides inthe fact that the exhausted treatment solutions, that is to say both pretreatment solution (I) and chromatization solution (H), can be regenerated by cation exchangers, whereby the iron ions which got into solution ,(I) when the metal parts were being treated with solution (I) are removed from that solution and the iron ions and the Cr ions originating from the reduction of chromic acid are removed from solution (H), whereupon the regenerated solutions can be used again in the process of .the invention.
  • the treated metal parts are provided with insufiicient protective coatings only when the treated metals, after hawng been degreased and then rinsed with water, are directly treated with solutions containing compounds of hexavalent chromium such, for example, as chromic acid. Even if high concentrations of chromium (VI) compounds are applied,
  • the method according to the present invention is suitably oarried out in the following way:
  • the iron or steel parts are treated according to the oxydic nature of their surfaces for up to about 10 minutes with pretreatment solution (I) defined above and then, after a short intermediate rinsing with desalted water, which rinsing may be dispensed with, introduced into chromatization bath (II), which contains chromic acid and in addition thereto may contain phosphoric acid and/ or alkali metal phosphate.
  • chromic acid which should contain no more than 0.08% byweight of CrO or, if desired, with desalted water (when a chromic acid bath (ll) of higher ing the corresponding concentrates in the same measure as they are consumed.
  • the iron ions enriched in the operating pretreatment baths can be determined in known manner and removed by ion exchangers.
  • EXAMPLE 1 Degreased steel plates for bodies of motor cars were dipped for 8 minutes at a temperature of 20 C. into a solution (1) containing 2.1% by weight of lactic acid. After another 6 minutes during which time the plates hung in the air they wererinsed for 1 minute with desalted water and after having stayed for another 6 minutes in the air they were dipped at a bath temperature of 20 C. into a bath (II) containing 3.52 grams per liter of chromic acid and 0.48 gram per liter of N21 PO The sheets were then again hung for 6 minutes in the air, then aftertreated in a bath 'containing'0.21 gram per liter of chromic acid and 0.029 gram per liter of Na PO and .dried with hot air.
  • a solution (1) containing 2.1% by weight of lactic acid.
  • steel plates for bodies of motor cars were sand-blasted and part of the sand-blasted plates was dipped for 60 minutes into a bath containing 240 grams per liter of chromic acid and having'a temperature of 25 C.
  • the other part of the sand-blasted steel plates "was treated for 15 minutes with a solution containing 3.52
  • the specimens thus treated had an excellent lacquer adherence and a very good protection against correction.
  • Example 2 The samples thus treated were lacquered in the manner described in Example 1 and tested. They had an excellent lacquer adherence and a very good protection against corrosion.
  • EXAMPLE 4 Degreased steel plates for bodies of motor cars were dipped for 10 minutes at 20 C. into a solution (1) containing 2.4%-of lactic acid and after 3 minutes, during which period the plates hung in the air, they were rinsed :for 30 seconds at 13 C. with desalted water. After being exposed to the action of air for another 3 minutes they were treated'with a chromic acid bath (II) having the a composition indicated in Table 2, into which they were 'The test plates treated as indicated under ([2) and were exposed for another 3 minutes to the action of air 'and'then treated for a minute at about C. with desalted water. The test plates treated as indicated under ,(a), (d) and (e) were rinsed for 1 minute at about 20 C.
  • the method of producing'adherent uniform' coatings on iron :and steel parts, particularly for preventing corrosion and providing adherence of lacquers and varnishes which method consists essentially of contacting the surfaceof saidmetal parts in a first step at a temperature between about 3 C. and about 80 C. with .an aqueous solution (I) containing about 0.5% by weight to about 20% by weight of at least one aliphatic hydroxycarboxylic.
  • said solution (I) additionally contains at least one acid selected from the group consisting of phosphoric acid and oxalic acid, the total amount of the acids contained in said soluo ticn not exceeding 20% by weight and the ratios of phosphoric acid:hydroxycarboxylic acid and oxalic acidzhydroxycarboxylic acid being not more than 1.
  • said solution (II) additionally contains at least one substance selected from the group consisting of phosphoric acid and alkali metal phosphate in a quantity not exceeding 25% by weight of the amount of the chromic acid present.

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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)
  • Chemical Treatment Of Metals (AREA)
US222195A 1961-09-13 1962-09-07 Method for producing adherent coatings on iron and steel parts Expired - Lifetime US3202551A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DEF34918A DE1238742B (de) 1961-09-13 1961-09-13 Verfahren und Loesungen zur Chromatierung von Eisen- und Stahloberflaechen

Publications (1)

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US3202551A true US3202551A (en) 1965-08-24

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US222195A Expired - Lifetime US3202551A (en) 1961-09-13 1962-09-07 Method for producing adherent coatings on iron and steel parts

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US (1) US3202551A (ja)
AT (1) AT248817B (ja)
CH (1) CH420781A (ja)
DE (1) DE1238742B (ja)
GB (1) GB1018184A (ja)
NL (1) NL282799A (ja)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3466207A (en) * 1967-07-19 1969-09-09 Dow Chemical Co Treatment of metals for promoting adhesion of polyolefins
US3630789A (en) * 1970-04-02 1971-12-28 Du Pont Hexavalent chromium/fumarate solutions and the treatment of metal substrates therewith

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102007021364A1 (de) 2007-05-04 2008-11-06 Henkel Ag & Co. Kgaa Metallisierende Vorbehandlung von Zinkoberflächen

Citations (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1911537A (en) * 1930-08-08 1933-05-30 Eobebt r
US2067214A (en) * 1933-06-24 1937-01-12 Patents Corp Method of coating metal
GB483551A (en) * 1935-10-19 1938-04-14 Patents Corp Improvements in and relating to the formation of chemical coatings on metals
US2250508A (en) * 1936-06-15 1941-07-29 John S Thompson Treating zinc with organic acids
US2331196A (en) * 1941-08-22 1943-10-05 Westinghouse Electric & Mfg Co Protective phosphate coating
US2493934A (en) * 1946-12-27 1950-01-10 Reynolds Metals Co Production of protective coatings on aluminum and alloys thereof
US2505785A (en) * 1945-09-17 1950-05-02 Howard R Moore Method of producing a corrosion inhibitive coating on ferrous metals
US2853406A (en) * 1956-04-17 1958-09-23 Kelsey Hayes Co Metal coating
CA606022A (en) * 1957-11-28 1960-09-27 Rausch Werner Process for continuously operating chromatic solutions
US3015594A (en) * 1959-10-23 1962-01-02 Parker Rust Proof Co Phosphate coating process
US3079288A (en) * 1960-09-07 1963-02-26 Amchem Prod Method and composition for increasing the corrosion resistance of phosphatetype chemical conversion coatings on metal surfaces
US3118793A (en) * 1960-12-06 1964-01-21 Detrex Chem Ind Method of pretreating and phosphatizing a metal surface for siccative coatings
US3132975A (en) * 1959-06-04 1964-05-12 Framalite Soc Process for pickling and passivating enclosed structures

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2768103A (en) * 1952-03-18 1956-10-23 Heintz Mfg Co Method for coating metals
US2768104A (en) * 1952-03-25 1956-10-23 Heintz Mfg Co Method for coating iron
US2875110A (en) * 1953-06-29 1959-02-24 Sandvikens Jerwerks Aktiebolag Corrosion resistant treatment for hollow drill rods
CA581081A (en) * 1953-07-30 1959-08-11 K. Schuster Ludwig Corrosion resistant coated steel members and method of making
BE542208A (ja) * 1954-10-20

Patent Citations (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1911537A (en) * 1930-08-08 1933-05-30 Eobebt r
US2067214A (en) * 1933-06-24 1937-01-12 Patents Corp Method of coating metal
GB483551A (en) * 1935-10-19 1938-04-14 Patents Corp Improvements in and relating to the formation of chemical coatings on metals
US2250508A (en) * 1936-06-15 1941-07-29 John S Thompson Treating zinc with organic acids
US2331196A (en) * 1941-08-22 1943-10-05 Westinghouse Electric & Mfg Co Protective phosphate coating
US2505785A (en) * 1945-09-17 1950-05-02 Howard R Moore Method of producing a corrosion inhibitive coating on ferrous metals
US2493934A (en) * 1946-12-27 1950-01-10 Reynolds Metals Co Production of protective coatings on aluminum and alloys thereof
US2853406A (en) * 1956-04-17 1958-09-23 Kelsey Hayes Co Metal coating
CA606022A (en) * 1957-11-28 1960-09-27 Rausch Werner Process for continuously operating chromatic solutions
US3132975A (en) * 1959-06-04 1964-05-12 Framalite Soc Process for pickling and passivating enclosed structures
US3015594A (en) * 1959-10-23 1962-01-02 Parker Rust Proof Co Phosphate coating process
US3079288A (en) * 1960-09-07 1963-02-26 Amchem Prod Method and composition for increasing the corrosion resistance of phosphatetype chemical conversion coatings on metal surfaces
US3118793A (en) * 1960-12-06 1964-01-21 Detrex Chem Ind Method of pretreating and phosphatizing a metal surface for siccative coatings

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3466207A (en) * 1967-07-19 1969-09-09 Dow Chemical Co Treatment of metals for promoting adhesion of polyolefins
US3630789A (en) * 1970-04-02 1971-12-28 Du Pont Hexavalent chromium/fumarate solutions and the treatment of metal substrates therewith

Also Published As

Publication number Publication date
AT248817B (de) 1966-08-25
GB1018184A (en) 1966-01-26
NL282799A (ja)
DE1238742B (de) 1967-04-13
CH420781A (de) 1966-09-15

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