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
  • C23C22/07—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
  • C23C22/14—Orthophosphates containing zinc cations containing also chlorate anions
• • 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
  • C23C22/22—Orthophosphates containing alkaline earth metal cations

Definitions

• the invention relates to a process for the production of phosphate coatings on iron or steel surfaces by immersion or flooding with an aqueous acidic zinc phosphate solution and its application to the preparation of metal surfaces for cold forming.
• phosphate coatings on metal surfaces in particular from iron and steel, by treatment with a zinc phosphate solution is generally common.
• one or more oxidizing agents are added to the phosphating solution.
• phosphating processes uses phosphating solutions which contain oxidizing agents which convert iron (II) to iron (III), so that insoluble iron phosphate is formed. With increasing throughput on the surface, considerable amounts of sludge then arise, which are physically removed. In some processes, however, the physical removal of sludge is difficult or difficult to carry out, so that it is more advantageous to conduct the phosphating process in such a way that practically no or only a little sludge is formed.
• the phosphating solution is formulated from chemicals that do not convert the iron that is in solution into the trivalent state. This can be achieved, for example, by using nitrate or similarly weak oxidizing agents as accelerators.
• urea is to be added to the phosphating bath, as a result of which the temperature during the phosphating can be increased without risking significantly increased sludge formation. Accelerated phosphate layer formation is also associated with this.
• the other disadvantages mentioned above also remain here.
• heating of the phosphating solution which is not per se energy-wasting, is required.
• attempts have been made to solve the sludge problem by increasing its solids content and consequently reducing the amount of sludge (GB-PS 1 555 529).
• the metal surfaces are treated with a solution which contains at least 6 g / 1 Zn, 5 g / IP 2 O 5 , 1 g / l C10 3 and 8 g / l NO 3 .
• the ratio P 2 O 5 : Zn should be in the range of 1: (0.8--4).
• the object of the invention is to provide a process for producing phosphate coatings on iron or steel surfaces which does not have the known, in particular the aforementioned disadvantages, and is simple to carry out without additional chemicals and without sacrificing layer quality.
• the object is achieved by carrying out the method of the type mentioned at the outset in accordance with the invention in such a way that the surfaces are brought into contact with a solution which contains at least 0.3% by weight of Zn and at least 0.3% by weight of PO 4 and contains at least 0.75% by weight of NO 3 or a similarly acting iron (II) non-oxidizing accelerator, in which the weight ratio Zn: P0 4 is greater than 0.8, the ratio of total acid to free acid is at least 5 and in which an iron (II) content of 0.05 to 1% by weight is set by suitable dimensioning of ClO 3 or an accelerator which oxidizes iron (II) to iron (III).
• a solution which contains at least 0.3% by weight of Zn and at least 0.3% by weight of PO 4 and contains at least 0.75% by weight of NO 3 or a similarly acting iron (II) non-oxidizing accelerator, in which the weight ratio Zn: P0 4 is greater than 0.8, the ratio of total acid to free acid is at least 5 and in which an iron (II
• An advantageous embodiment of the invention consists in bringing the surface into contact with a solution which contains a maximum of 2.2% by weight of Zn, max. 2.2% by weight PO 4 and max. Contains 5.5% by weight of NO 3 or an accelerator with the same effect, in which the weight ratio Zn: PO 4 is less than 4 and the ratio of total acid to free acid is max. 30.
• a treatment solution should preferably be used which contains 0.3 to 1% by weight of Zn, 0.3 to 1% by weight of PO 4 and 1 to 3% by weight of NO 3 or an accelerator with the same effect, in which the Weight ratio Zn: P0 4 0.8 to 2, in particular 0.8 to 1.4 and which is a ratio of total acid to free acid of max. 15, in particular 7 to 12, and in which one by suitable dimensioning of chlorate or an equivalent accelerator sets an iron (II) content of 0.08 to 0.5, in particular up to 0.2,% by weight.
• nitroguanidine is also suitable, for example.
• the expenditure of chlorate or an iron (II) which has the same effect as iron (III) oxidizing accelerator is such that its concentration in the treatment solution is generally less than 0.1% by weight (calc ClO 3 ). Higher doses cause the iron (II) content to be too low and considerable sludge formation occurs.
• chlorate content or an equivalent accelerator is set to concentrations below 0.05% by weight, preferably below 0.035% by weight (calculated as CI0 3 ).
• CI0 3 concentrations below 0.05% by weight
• Optimal results are obtained at concentrations in the range of 0.001 to 0.035% by weight (calculated as ClO 3 ).
• the phosphating bath e.g. does not contain any iron (II) ions in the starting phase. It is therefore not necessary to add the iron (II) oxidizing accelerator at this point. It is also not necessary to meter this accelerator continuously. It can also be introduced with the chemicals that are usually added to the bath supplement.
• a further development of the method provides for the surfaces to be brought into contact with a solution which additionally contains calcium in quantities of 0.01 to 0.88% by weight, preferably 0.15 to 0.5% by weight.
• the weight ratio Zn: Ca should be 1.5 to 4. Best results are achieved with a ratio of 2.5.
• the phosphating solution can also contain other additives which are customary for zinc phosphating solutions, such as copper, cobalt, nickel, simple or complex fluoride. When dosing with fluoride, make sure that no calcium fluoride fails. Magnesium can partially or completely replace calcium.
• urea can be added to the phosphating solution.
• the surfaces to be brought into contact with the method according to the invention must be free of rust and scale and should therefore first be pickled with mineral acid, such as hydrochloric or sulfuric acid, and then rinsed with water. Depending on the level of contamination, degreasing or other treatment can also be carried out to clean the surfaces, for example with an organic solvent or an alkaline cleaner, followed by a water rinse.
• mineral acid such as hydrochloric or sulfuric acid
• the cleaned surfaces can be subjected to an activation treatment, e.g. B. by hot water rinsing or with a titanium orthophosphate dispersion.
• an activation treatment e.g. B. by hot water rinsing or with a titanium orthophosphate dispersion.
• the dipping or flooding of the surfaces which, in contrast to spraying, largely avoids sludge formation due to oxidation by atmospheric oxygen, is carried out according to a preferred embodiment of the process according to the invention at a temperature of 35 to 98 ° C., preferably 55 to 85 ° C.
• the duration of the Contact between the surface and the phosphating solution is preferably in the range from 5 to 15 minutes.
• the phosphate coating After the phosphate coating has been formed, it can be rinsed with cold water and treated with a passivating rinse solution. There can also be a lubricant coating on the Phosphate layer can be applied.
• the method according to the invention has proven particularly useful as a preparation for non-cutting cold forming. However, it is also advantageous in the other fields of application of phosphating, e.g. for corrosion protection, to facilitate sliding friction and for electrical insulation.
• a phosphating solution was prepared from a batch concentrate which contained and had a ratio of total acid to free acid of 7. The dilution was carried out in the ratio of one part of concentrate to 20 parts of water.
• Wire was immersed in the phosphating bath kept at a temperature of 70 ° C. After a contact time of 10 minutes, the wire was removed, rinsed with water, provided with a lubricant coating and pulled in the usual way.
• the phosphating bath could be kept practically constant at concentrations of being held.
• the ratio of total acid to free acid was 8.7.
• the process could be operated for a long time with only a small amount of sludge.

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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)
• Glass Compositions (AREA)
• Treatment Of Sludge (AREA)
• Paints Or Removers (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (2)

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ID=10515046

Family Applications (1)

Country Status (8)

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• 1981
  • 1981-06-18 GB GB8118780A patent/GB2080835B/en not_active Expired
  • 1981-07-15 JP JP56111535A patent/JPS5751266A/ja active Pending
  • 1981-07-21 EP EP81200830A patent/EP0045110B1/de not_active Expired
  • 1981-07-21 AT AT81200830T patent/ATE9823T1/de not_active IP Right Cessation
  • 1981-07-21 DE DE8181200830T patent/DE3166602D1/de not_active Expired
  • 1981-07-24 ES ES504609A patent/ES504609A0/es active Granted
  • 1981-07-24 IT IT23121/81A patent/IT1167480B/it active
  • 1981-07-24 PT PT73426A patent/PT73426B/pt unknown

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