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
  • C23C22/05—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
  • C23C22/07—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 phosphates
  • C23C22/08—Orthophosphates
  • C23C22/12—Orthophosphates containing zinc cations
• • 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
  • C23C22/07—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 phosphates
  • C23C22/08—Orthophosphates
  • C23C22/10—Orthophosphates containing oxidants

Definitions

• the subject of the invention is a bath and a method for phosphating of metallic substrates as well as metallic substrates treated using these baths and process.
• the metallic substrates concerned are those based steel possibly coated with zinc or zinc alloys with other metals like iron, nickel, aluminum, manganese, as well as those based on aluminum possibly ally.
• Phosphating baths are generally applied by immersion, sprinkling or by combinations of these methods which may include the implementation of applicator rollers.
• baths consist of aqueous solutions acids containing phosphate ions, fluorides (simple and / or complexed with one or more elements chosen from silicon, boron, zirconium and titanium), nitrates, bivalent cations such as zinc, as well that possibly those of the group comprising Mn, Mg, Ni, Cu, Ca, Fe and monovalent cations such as Na.
• They may also contain polyoses, derived from sugar, heteropolysaccharides and glucose.
• the accelerators conventionally used are those from the group comprising nitrites, metal chlorates alkaline, m-nitrobenzene sulfonate, hydrogen peroxide, more recently hydroxylamine and different combinations of these compounds.
• the nitrites ions have the disadvantage major not to be stable in an acid medium and to decompose into nitrogen oxides; permanent food baths in nitrite ions is therefore necessary even in the absence of consumption linked to the processing of parts; a another disadvantage of nitrite ions lies precisely in the fact that they break down into nitrogen oxides which are known for their dangerous nature, which poses worker safety issues.
• chlorate ions leads, after reaction to the formation of chloride ions known to be detrimental to the corrosion resistance of layers produced; they also promote the appearance of white dots in these layers when processing certain galvanized substrates, forcing the operator to sand manually treated substrates.
• Oxygenated water is not stable in a acid conversion containing the metals mentioned above, and its optimal concentration range is very narrow, which makes the bath difficult to control industrially; of more, this bath tends to form large amounts of sludge during use, sludge which should be removed by left at the dump.
• M-nitrobenzene sulfonate is not easily dosable on the treatment line (this dosage indeed requires the use of chromatographic techniques whose cost and technicality are not compatible with a price of returns acceptable); moreover, its use leads to the generation of significant sludge.
• Hydroxylamine to work well, must be used at levels leading to relatively low costs high, and especially its degradation can be significant in the presence of metal ions at phosphating temperature high.
• the object of the invention is, above all, to propose to the user an accelerator for baths and processes phosphating without the disadvantages of those of the prior art.
• the above-mentioned trivalent cobalt complexes are stable at acidic pH from 1 to 5.5, preferably from 2.5 to 3.5, unlike the simple salts of Cobalt III such as CoF 3 which decomposes into a black oxide insoluble in the phosphating.
• complexes are most often described in ionic form; in the case of cationic complexes, the associated anion is for example one of the anions of the group comprising Cl, Br, F, I, NO 3 , CN, SCN, PO 4 , SO 4 and acetate; when anionic complexes are involved, the associated cation is for example one of the cations of the group comprising Na, K, Li, Mg, Ca and NH 4 .
• the phosphating bath according to the invention can contain a conventional accelerator in addition to the accelerator consisting of a trivalent cobalt complex.
• the metal substrate according to the invention which is obtained by implementing the phosphating process according to the invention, is characterized by the presence of cobalt in the phosphate coating.
• the invention also relates to a concentrate specific to provide, by a dilution of about 1% to about 10% with water, the phosphating bath according to the invention.
• the phosphate coatings obtained through the invention have finesse and homogeneity in less equivalent to those of coatings obtained with placing using accelerators of the prior art.
• the free acidity of the phosphating bath is measured by the quantity (in ml) of NaOH N / 10 necessary to bring the pH of 10 ml of this bath at the value of 3.6.
• Scoring involves measuring the width of the paint peeling perpendicular to the scratch.
• the acceptance criterion is a separation less than or equal to 8 mm.
• the adhesion of the paint is evaluated by the test of squaring carried out according to standard ISO 2409.
• the acceptance limit corresponds to a quote maximum grip of 2.
• Scoring involves measuring the width of the paint peeling perpendicular to the scratch.
• the acceptance criterion is less than or equal detachment at 3.5 mm.

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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)
• Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
• Manufacture And Refinement Of Metals (AREA)

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Publications (2)

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Citations (7)

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• 1996
  • 1996-09-02 FR FR9610684A patent/FR2752851B1/fr not_active Expired - Fee Related
• 1997
  • 1997-09-01 ES ES97402032T patent/ES2146069T3/es not_active Expired - Lifetime
  • 1997-09-01 EP EP97402032A patent/EP0826792B1/de not_active Expired - Lifetime
  • 1997-09-01 PT PT97402032T patent/PT826792E/pt unknown
  • 1997-09-01 DE DE69701659T patent/DE69701659T2/de not_active Expired - Fee Related
  • 1997-09-01 AT AT97402032T patent/ATE191754T1/de not_active IP Right Cessation
  • 1997-09-02 US US08/921,877 patent/US6068709A/en not_active Expired - Fee Related
  • 1997-09-02 JP JP23686097A patent/JP3993280B2/ja not_active Expired - Fee Related
  • 1997-09-02 CA CA002214398A patent/CA2214398A1/en not_active Abandoned

Patent Citations (7)

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