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
  • C23C22/34—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 fluorides or complex fluorides
  • C23C22/36—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 fluorides or complex fluorides containing also phosphates
  • C23C22/368—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 fluorides or complex fluorides containing also phosphates containing magnesium cations

Definitions

• the invention relates to a method for phosphating galvanized steel, optionally together with additionally present aluminum, before painting with phosphating solutions based on zinc magnesium phosphate.
• the object of the invention is to provide a process for the phosphating of galvanized steel, optionally together with additionally present aluminum, as a pretreatment for the coating, which does not have the aforementioned disadvantages, but rather makes it possible to produce uniform phosphate layers on the metals which are outstanding as Are suitable for painting.
• galvanized steel is understood to mean steel which, for example, on the hot-dip path or in the electrolytic process with zinc or zinc alloy coatings e.g. Pure zinc, zinc nickel, zinc iron, zinc aluminum was coated.
• zinc or zinc alloy coatings e.g. Pure zinc, zinc nickel, zinc iron, zinc aluminum was coated.
• aluminum in the sense of the invention includes Pure aluminum and alloys of aluminum with magnesium, zinc, copper, silicon, manganese etc.
• the concentration of fluoride detected with the fluoride-sensitive electrode corresponds approximately to that in the Phosphating solution present proportion of dissociated fluoride (F ⁇ ).
• F (el) value 80 to 400 mg / l at the usual phosphating bath pH values of the baths, about 0.4 to 0.9 g / l NH4HF2 or equivalent amounts of other single fluoride-containing compounds must be added will.
• the bath is preferably supplemented by adding enough fluoride-containing compound to the phosphating bath until the desired measured value of F (el) is reached.
• the metal surfaces to be treated must be free from disruptive deposits of oils, lubricants, oxides and the like, which can impair proper layer formation.
• the surfaces are cleaned in a suitable manner.
• the surface is preferably coated with an activating agent known per se, e.g. an aqueous suspension containing titanium phosphate, activated.
• the activating agent can be used in the cleaning bath or as a separate process step.
• the phosphating solutions according to the invention are used in spraying, spray-immersion or immersion at temperatures between 40 and 60 ° C.
• the times during which the metal surfaces are brought into contact with the phosphating solution to form a covering phosphate layer are in the case of galvanized steel, e.g. between 20 sec and 10 min, for aluminum e.g. between 1 and 10 min.
• the cations zinc, magnesium and nickel are in the Phosphating solution introduced, for example, as metal, oxide, carbonate, phosphate, nitrate, chloride and / or complex fluoride.
• the phosphate portion is fed to the solution via phosphates and / or phosphoric acid.
• additional cations for example Na, K, NH4 or anions, for example nitrate, chloride, sulfate, are used.
• the value of the free acid (total acid) is identical to the consumption of ml 0.1 n NaOH for neutralizing a 10 ml bath sample against the first turning point (second turning point) of the phosphoric acid.
• the phosphating bath also contains at least one oxidizing agent from the group consisting of nitrate, nitrite, chlorate, bromate, peroxide and nitrobene sulfonate, e.g. the following quantities can be used: 2 to 20 g / l nitrate; 0.05 to 0.5 g / l nitrite; 0.5 to 5 g / l chlorate; 0.2 to 3 g / l bromate; 0.02 to 0.1 g / l peroxide; 0.1 to 1 g / l nitrobenzenesulfonate.
• the oxidizing agents can also be combined with one another, e.g. Nitrate nitrite, (nitrate) chlorate nitrite, nitrate bromate, (nitrate) chlorate nitrobenzenesulfonate, nitrate nitrobenzenesulfonate.
• the three components chloride and / or Bromide), (nitrate) and (nickel) only two each in a concentration of more than 0.1 g / l, while the third may only be present in a maximum concentration of 0.1 g / l.
• Chloride and bromide are counted as one component and their individual concentrations are added. Chloride can, for example, get into the phosphating bath from the preparation water for the phosphating solution and / or as a reduction product of chlorate.
• the bromate accelerator in particular should be regarded as the source.
• the phosphating bath preferably contains simple and / or complex fluoride.
• the group of suitable complex fluorides includes e.g. Fluoroborates and fluorosilicates.
• the phosphating solutions used in the process according to the invention can also contain further additives, but mostly in minor amounts. These include Copper, manganese, calcium, iron, cobalt, polyphosphates, polyhydroxycarboxylic acids, surfactants and agents for influencing the sludge separation.
• the phosphate layers produced according to the invention are used as preparation for a subsequent painting. They are preferably used for workpieces which are subsequently electrocoated, in particular cathodically electrocoated. In this way you get layers of paint, which are characterized by a high resistance to infiltration when exposed to corrosion, e.g. due to normal outdoor weathering, outdoor weathering accelerated with salt, moisture, salt spray and wash liquor, and have very good adhesion to scratching and impact stress before and after corrosion.
• the method according to the invention is particularly suitable for the pretreatment of housings for household appliances and technical apparatus, of metal furniture, of vehicle bodies and of vehicle accessories before painting.
• Sheets made of steel, electrolytically galvanized steel, hot-dip galvanized steel and AlMgSi were treated after alkaline cleaning, water rinsing and activation in an aqueous titanium phosphate suspension with the phosphating solutions listed in the table at 50 ° C for 2 minutes by spraying or 3 minutes by immersion. This was followed by rinsing with water, an aqueous passivating solution containing chromium (VI), demineralized water and a drying stage.
• VI chromium
• the table shows that flawless layers could be obtained on galvanized steel throughout the work area, with the exception of the cases in which nitrate, chloride and nickel were present in a concentration of more than 0.1 g / l each (Examples 6 and 11), insofar as the ranges essential to the invention were taken into account for the Zn, Mg and Ni concentration. Crystalline, uniform layer formation was always achieved on AlMgSi when the fluoride concentration F (el) measured electrometrically with a fluorine-sensitive electrode was in the range between 80 to 400 mg / l (Examples 4 to 6 and 13 to 20).
• the layers were provided with a cathodic electrodeposition paint and an automotive paint structure and subjected to the usual technical tests. In all cases where crystalline layers were present on the metal substrate, excellent test results were achieved.

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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)

Applications Claiming Priority (2)

Publications (2)

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• 1988
  • 1988-07-26 ES ES198888201613T patent/ES2036666T3/es not_active Expired - Lifetime
  • 1988-07-26 DE DE8888201613T patent/DE3871031D1/de not_active Expired - Lifetime
  • 1988-07-26 EP EP88201613A patent/EP0304108B1/de not_active Expired - Lifetime
  • 1988-08-09 CA CA000574254A patent/CA1333147C/en not_active Expired - Fee Related
  • 1988-08-12 JP JP63200322A patent/JP2680618B2/ja not_active Expired - Lifetime
  • 1988-08-19 GB GB8819791A patent/GB2208876B/en not_active Expired - Lifetime
  • 1988-08-19 ZA ZA886167A patent/ZA886167B/xx unknown

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