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
  • C23C22/34—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
  • C23C22/362—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 also 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

Definitions

• the invention relates to a method for applying P hosphatüberratn to wholly or partly consisting of zinc or zinc alloys by means of acidic aqueous phosphating metal surfaces comprising zinc and / or manganese ions and phosphate ions, and fluoride ions.
• phosphate coatings to metal surfaces by bringing them into contact with phosphating solutions which contain phosphate ions, zinc and / or manganese ions and optionally additionally nickel, cobalt and / or copper ions, nitrate and / or nitrite, fluoroborate and / or Contains fluorosilicate.
• the metal surfaces treated according to the above-mentioned process are often not the desired quality.
• the sheets show considerable roughness after they have been painted.
• the gloss of the paint layer and its adhesion to the metal surface does not meet the highest demands.
• Another problem that occurs particularly on galvanized surfaces or surface areas is the so-called speck formation. These are white structures resulting from uncontrolled crystal growth in small to pinhead-sized areas, primarily from zinc phosphate of different sizes with a diameter of 50 to 150 / um and a height of 100 to 400 / um, which ultimately lead to a faulty rough surface.
• the object of the invention is to provide a process for the production of phosphate coatings on all or part of consisting of zinc or zinc alloys metal surfaces, which is the above-mentioned problems of the S tip formation with safety and regularly removed, yet simple and economical to implement.
• chloride ions When dealing with the problem, it was found that the presence of chloride ions is responsible for the formation of specks. According to the proposals cited above, it can be kept within limits as long as the chloride concentration present is low; however, with increasing concentration, it occurs back on. It should be taken into account here that the introduction of chloride ions into the phosphating solution is by no means intentional, but it is often difficult or impossible to avoid for many reasons. It is in fact practically impossible in large-scale use to remove or keep all the chloride away. For example, chloride always gets into the phosphating bath due to production-related contamination. Even when using chlorate as an accelerator, the formation of chloride cannot be avoided simply because of the chemistry.
• the weight ratio of fluoride to chloride can be adjusted with the help of simple fluoride, especially with hydrofluoric acid.
• simple fluoride especially with hydrofluoric acid.
• the effect is particularly great when the fluoride is added in the form of complex fluoride.
• a preferred embodiment of the invention provides for the metal surfaces to be brought into contact with a phosphating solution, the fluoride in the form of complex fluoride, to be precise contains in particular in the form of fluorosilicate. This is especially true when the zinc surface has been formed by F euerverzinkung.
• fluorosilicate other complex fluorides are also suitable, albeit with a reduced effect.
• the fluoride content should be increased as the proportion of the zinc surface increases.
• a concentration of 0.05 to 0.2% by weight, in particular 0.075 to 0.2% by weight should be selected.
• the fluoride concentration can be adjusted with the aid of a fluoride-sensitive electrode - if necessary after making calibration curves.
• a further preferred embodiment of the invention provides for the metal surfaces to be brought into contact with a phosphating solution which contains 0.5 to 2.5% by weight, preferably 0.5 to 2.0% by weight, of phosphate.
• the phosphating solutions usually contain one or more accelerators. It is particularly advantageous if the metal surface is brought into contact with a phosphating solution which additionally contains nitrate, preferably in amounts of 0.025 to 2.0% by weight. in particular from 0.05 to 1.0% by weight. When dosing, it must be taken into account that nitrate can form during the formation of the coating, for example if nitrite is used as an accelerator. Controlled addition of nitrate is preferred.
• a further advantageous embodiment of the invention provides that the metal surfaces with a P hosphat michsown be brought into contact, the addition of cobalt and / or nickel ions, preferably in amounts of from 0.01 to 1.0 wt .-%, contains.
• cobalt and / or nickel ions preferably in amounts of from 0.01 to 1.0 wt .-%, contains.
• These ions are expediently introduced in the form of their sulfates, phosphates, carbonates or nitrates, but in particular in the form of the carbonates.
• the phosphating solutions used in the process according to the invention can contain iron (III) ions.
• the iron ions may hosphatsammlungss in the form of salts are placed in the P; if the treated metal surface is partly made of steel, they can also get into the solution from the metal surface by pickling. If the addition is via a salt, its anion should not impair the effectiveness of the phosphating solution.
• Suitable salts are acid phosphates, nitrate, fluoride or fluoroborate. If all or part of the iron comes from the metal surface, it should be treated with suitable oxidizing agents, such as Hydrogen peroxide, permanganate or nitrite, are converted into the trivalent state.
• the concentration of iron III ions should be at least 0.0015% by weight and can reach the saturation limit.
• the preference for the content of iron III ions consists in particular in a reduction in the layer weight of the phosphate coating over a wide pH range of the phosphating solution.
• the iron III ion content is characterized by the formation of particularly adhesive phosphate coatings.
• the contact of the metal surface with the P hosphatleiterswill can be made of the part to be coated, the metal surface in the phosphating solution by conventional techniques, in particular by spraying, roller application, spraying on pre-heated surfaces or by dipping.
• the temperature of the phosphating solution can be between 43.3 ° C and the boiling point of the solution. However, temperatures in the range of 54.4 to 82.2 ° C are particularly useful, with the best results when spraying, roller application and spraying on preheated metal surfaces at 65.5 ° C and when immersing between 43.3 and 54.4 ° C lie.
• a chromic acid solution which may additionally contain chromium III ions can be used for this purpose.
• Another group of suitable rinse solutions includes poly-4-vinyl phenol, or the reaction product of P oly-4-vinyl phenol with an aldehyde or a ketone (US P Ss 3,975,214, 4,376,000, 4,457,790, 4,039,353, 4,433,015).
• another advantageous embodiment of the invention provides for the metal surfaces to be brought into contact with a phosphating solution in which the weight ratio of fluoride to chloride is at least 10 : 1, preferably at least 14: 1.
• the phosphating solution has a certain buffering effect against new and possibly unexpected chloride inputs.
• the fluoride concentration to be set does not have to be selected to be excessively high, it is advisable to ensure that an unnecessarily high chloride input is avoided either when preparing the phosphating solution itself or by carrying in solution residues from the pretreatment stage. That is, care should be taken to keep the chloride levels in the pretreatment baths as low as possible.
• the chloride content of these solutions should be below 100 ppm if possible.
• the activating agents used in the activating pre-rinse are usually also neutralized by titanyl sulfate Obtain sodium hydroxide solution and subsequent treatment with phosphoric acid.
• the activating pre-rinse solutions often contain more than 400 ppm chloride.
• Hot-dip galvanized sheets were treated according to the following procedure:

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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)
• Materials For Medical Uses (AREA)

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Publications (2)

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Citations (5)

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• 1985
  • 1985-08-26 US US06/769,433 patent/US4595424A/en not_active Ceased
• 1986
  • 1986-06-11 CA CA000511358A patent/CA1293165C/fr not_active Expired - Lifetime
  • 1986-06-13 AU AU58718/86A patent/AU594685B2/en not_active Expired
  • 1986-08-18 MX MX003465A patent/MX165325B/es unknown
  • 1986-08-21 DE DE19863628303 patent/DE3628303A1/de not_active Withdrawn
  • 1986-08-22 AT AT86111618T patent/ATE49781T1/de active
  • 1986-08-22 EP EP86111618A patent/EP0213567B1/fr not_active Expired - Lifetime
  • 1986-08-22 DE DE8686111618T patent/DE3668475D1/de not_active Expired - Fee Related
  • 1986-08-25 ES ES8601334A patent/ES2000229A6/es not_active Expired
  • 1986-08-26 JP JP61199891A patent/JPH06104906B2/ja not_active Expired - Lifetime
  • 1986-08-26 GB GB08620633A patent/GB2179680A/en not_active Withdrawn

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