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
  • 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
  • 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
  • C23F11/00—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent
• • 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
  • C23C22/68—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 solutions with pH between 6 and 8

Definitions

• a major object of this invention is to provide sealing compositions and processes that, in combination with known primary coatings, produce improved corrosion resistance, especially in the absence of organic protective coatings.
• Other alternative or concurrent objects are to minimize adverse environmental impact compared with related previously used sealers, which often contained hexavalent chromium or other materials capable of readily damaging the environment, and to provide more economical treatments without diminishing the corrosion protection achieved.
• a process according to the invention comprises at a minimum a step of bringing a composition according to the invention as defined herein into contact with a primary coating layer for a sufficient time at a sufficient temperature that, after discontinuance o of contact and drying, optionally with intermediate rinsing or other treatment with water of the primary coating layer after its formation but before contact with the sealing composition, additional rinsing after contact with the sealing composition, and/or additional coating treatments after drying, the object treated has measurably better corrosion resistance in at least one accelerated corrosion test or at least one type of actual use than 5 does an otherwise identical object that is identically treated, except that deionized or at least equally well purified water is substituted for the sealing composition according to the invention used in a process according to the invention.
• a sealing composition according to the invention preferably contains anions including fluorine atoms, which anions may be simple fluoride anions with the chemical formula F _ , acid fluoride ions with the chemical formula HF 2 ⁇ , fluoroborate ions with the fo ⁇ nula BF 4 _ , fiuorometallate ions conforming to the general formula MF 6 -2 , where M represents Si, Ti, Zr, Sn, Sb, or Hf, or fiuorometallate ions conforming to the general formula M'F 6 ⁇ where M' represents Al or Fe.
• Simple fluoride ions are generally preferred for economy if no other reason.
• the concentration of fluorine atoms in anionic form in a working composition according to the invention preferably is at least 0.005, 0.007, 0.009, 0.012, 0.016, 0.020, 0.030, 0.040, 0.045, 0.050, or 0.054 M/kg and independently preferably is not more than, with increasing preference in the order given, 0.50, 0.40, 0.30, 0.20, 0.10, 0.080, 0.070, 0.065, 0.060, or 0.056 M/kg.
• a sealing composition according to the invention in order to avoid the cost of shipping large quantities of water, it is often preferred in practice to formulate a sealing composition according to the invention as a concentrated rather than a working composition.
• the concentrated composition preferably contains the same components as are noted above for working compositions, but in a concentration for each ingredient except water that is at least, with increasing preference in the order given, 2, 4, 6, 8, 10, 20, 30, 40, or 50 times higher than the concentration specified above for a working composition.
• the pH value of a working sealing composition according to the invention prefer- ably is at least, with increasing preference in the order given, 2.0, 3.0, 4.0, 4.5, 4.8, 5.1 ,
• a weakly ionizing acid is generally preferred, and acetic acid, which is economical and does not pose any risk of precipitating other normal ingredients of a sealing composition according to this invention, has been found highly suitable.
• the temperature of a sealing composition according to the invention, during contact with the previously primarily treated and optionally intermediately treated metal substrate as described briefly above and in more detail below preferably is, with increasing preference in the order given, at least 15, 20, 22.0, 23.0, 24.0, 25.0, 26.0 or 26.5 °C and independently, primarily for reasons of economy, preferably is, with increasing preference in the order given, not more than 90, 80, 70, 60, 50, 45, 40, 35, 30, or 28 °C.
• the sealed surfaces preferably are again rinsed with water, preferably deionized or at least equally purified water, before drying or being allowed to dry. If heat is used to accelerate drying, the temperature of the metal during drying preferably does not exceed, with increasing preference in the order given, 100, 85, 75, 66, or 60 °C, in order to avoid damage to the pro- tective quality of the coating formed by a process according to the invention
• a process according to the invention most preferably is applied to a surface on which the pre-existing primary treatment has been formed by contacting a metal surface, preferably a cleaned and deoxidized aluminum alloy surface with a primary treatment composition made by reaction in an aqueous solution comprising, preferably consisting essentially of, or more preferably consisting of, water and the following dissolved components:
• (F) a component selected from the group consisting of alkali metal and alkaline earth metal cations; and (G) fluoride and complex fluoride anions, wherein the ratio of the number of moles of component (B) to the number of moles of component (A) in the aqueous solution prior to reaction is from 0.10 to 6.8.
• the concentration of component (A) reacted preferably is such that, in a preferred primary composition used to form a primary coating before a sealing process according to the invention, the concentration of cobalt atoms is, with increasing preference in the order given, not less than 0.001, 0.002, 0.004, 0.008, 0.016, 0.032, 0.040, 0.045, 0.050, 0.055, 0.060, 0.063, 0.066, 0.069, 0.072, 0.074, or 0.076 M and independently preferably is, with increasing preference in the order given, not more than 0.8, 0.6, 0.4, 0.2, 0.17, 0.14, 0.11 , 0.090, 0.085, 0.080, or 0.078 M.
• the particular counterion(s) in the salt(s) in the form of which the cobalt(ll) cations usually are added to the aqueous solution in which they are reacted are not narrowly restricted, but any counterions that bind so stably to cobalt(ll) that they prevent it from being oxidized to cobalt(lll) during reaction with the other components should be avoided.
• the counterions for cobalt when added to the aqueous solution in which it is reacted are preferably selected from the group consisting of nitrate ions, which have relatively weak complex forming tendencies, and carboxylate ions that are part of component (B).
• Component (B) is preferably selected from the anions of unsubstituted carboxylic acids containing from 1 to 6 carbon atoms, or more preferably, with increasing prefer- ence in the order given, not more than 5, 4, 3, or 2 carbon atoms, per molecule.
• Acetate ions are most preferred, largely because they are less expensive than most other car- boxyiates.
• the ratio of the number of moles of component (B) to the number of moles of component (A) in solution before any reaction between them preferably is, with increasing preference in the order given, at least 0.1:1.0, 0.2:1.0, 0.4:1.0, 0.8:1.0, 1.2:1.0, 1.5:1.0, 1.8:1.0, 2.0:1.0, 2.2:1.0, 2.3:1.0, 2.4:1.0, 2.5:1.0, or
• 2.6:1.0 and independently preferably is, with increasing preference in the order given, not greater than 6.5:1.0, 6.0:1.0, 5.5:1.0, 5.0:1.0, 4.5:1.0, 4.0:1.0, 3.7:1.0, 3.4:1.0, 3.1 :1.0, 3.0:1.0, 2.9:1.0, 2.8:1.0, or 2.7:1.0.
• the most preferred concentrations of carboxylate ions are thus greater than can be supplied by cobalt(ll) carboxylates themselves, and for the alternative cations that serve as counterions for this "excess" carboxylate, alkaline earth metal cations, particularly magnesium and calcium, most preferably magnesium, are preferred over alkali metal cations, although the latter can also be used.
• the use of carboxylic acids to supply the needed amounts of carboxylate ions although also possible within the scope of the invention, is not preferred, because such use tends to depress the pH value of a composition according to the invention below the most preferred values as set forth below.
• the ratio of the molar concentration of peroxide moieties present in the solution before reaction to the molar concentration of cobalt atoms present in the solution preferably is, with increasing preference in the order given, at least 0.05:1.0, 0.10:1.0, 0.20:1.0, 0.30:1.0, 0.40:1.0, 0.45:1.0, 0.50:1.0, 0.55:1.0, 0.60:1.0, 0.65:1.0, 0.68:1.0, 0.71 :1.0, or 0.73:1.0 and independently preferably is, with increasing preference in the order given, not more than 10:1.0, 7:1.0, 5:1.0, 3:1.0, 2:1.0, 1.5:1.0, 1.0:1.0, 0.95:1.0, 0.90:1.0, 0.85:1.0, 0.80:1.0, 0.77:1.0, or 0.74:1.0.
• components (A) and (B) are preferably mixed together in aqueous solution at first in the absence of other constituents, except for the counterions of components (A) and (B) and optional component (E) if used, and component (C) then added to this mixture. Only after components (A), (B), and (C) have been well mixed in solution should any of component (D) (except for the air in equilibrium with the aqueous solution) be added.
• the temperature during a primary coating forming process when using one of the above noted preferred compositions preferably is, with increasing preference in the order given, not more than 90, 85, 80, 75, 72, 69, 67, 65, 63, 62, 61 , or 60 °C; and, if maximum possible corrosion resistance is desired, particularly when the metal substrates treated according to this invention are to be used without any painting or similar organic based protective coating, more preferably is, with increasing preference in the order given, not more than 55, 50, 45, 40, 39, or 38 °C.
• the contact time preferably is, with increasing preference in the order given, at least 0.2, 0.5, 0.8, 1.0, 1.5, 2.0, 2.5, 2.8, 3.2, 3.6, or 3.9 min and independently preferably is, with increasing preference in the order given, not more than 30, 25, 20, 15, 12, 9, 8, 7, 6, or 5 min.
• the contact time preferably is, with increasing preference in the order given, at least 2, 5, 8, 10, 11 ,
• the primary coating contains cobalt, oxygen, and aluminum
• the primary coating is not formed by use of a preferable composition as described above, but may be formed, for example, according to the teachings of WO94/00619, it is advantageous, in addition to or in lieu of ordinary rinsing that would normally be completed in a minute or less, to maintain contact between water and the surface treated with the primary treatment as described above for a more extended period of time.
• a single immersion for the entire time desired is satisfactory and is preferred because it is more economical, but the total period of immersion can also be achieved by two or more immersions with an interval of removal of the treated substrate from contact with water between each immersion and the immediately successive immersion if any.
• the use of an intermediate treatment is particularly preferred if it is to be followed by a sealing treatment containing vanadium along with more than preferred amounts of anionic tungsten.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Chemical Treatment Of Metals (AREA)
• Paints Or Removers (AREA)
• Application Of Or Painting With Fluid Materials (AREA)
• Preventing Corrosion Or Incrustation Of Metals (AREA)

Priority Applications (8)

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

Country Status (11)

Cited By (8)

Citations (4)

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• 1998
  • 1998-05-07 ZA ZA983867A patent/ZA983867B/xx unknown
  • 1998-05-15 TR TR1999/02799T patent/TR199902799T2/xx unknown
  • 1998-05-15 BR BR9809639-7A patent/BR9809639A/pt not_active IP Right Cessation
  • 1998-05-15 KR KR1019997010619A patent/KR20010012658A/ko not_active Application Discontinuation
  • 1998-05-15 JP JP53993498A patent/JP2002512657A/ja active Pending
  • 1998-05-15 EP EP98921044A patent/EP1009867A4/en not_active Withdrawn
  • 1998-05-15 WO PCT/US1998/009374 patent/WO1998051841A1/en not_active Application Discontinuation
  • 1998-05-15 NZ NZ501680A patent/NZ501680A/en unknown
  • 1998-05-15 AU AU73734/98A patent/AU744551B2/en not_active Ceased
  • 1998-05-15 CN CN98806298A patent/CN1260844A/zh active Pending
  • 1998-05-15 CA CA002290495A patent/CA2290495A1/en not_active Abandoned

Patent Citations (4)

Non-Patent Citations (1)

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