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
  • C23C22/18—Orthophosphates containing manganese cations
  • C23C22/182—Orthophosphates containing manganese cations 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
• • 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
  • C23C22/13—Orthophosphates containing zinc cations containing also nitrate or nitrite 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

• This invention relates to an improved process for producing zinc phosphate containing protective layers on the surface of iron, steel, and other metal articles. Such layers, when sufficiently uniform and dense, provide effec­tive substrates for lubrication prior to subsequent drawing or similar metal forming operations. More particularly, this invention relates to treatment solution compositions and processes that reduce the amount of sludge formed during the phosphating operation.
• Metal phosphating solutions have been widely used to form coatings on the surfaces of metal articles, particu­larly those made of iron or carbon steels.
• Metal phosphat­ing solutions are generally dilute aqueous solutions of phosphoric acid and other chemicals, often including zinc, calcium, and other metal ions, which are contacted with the surfaces of metal by immersion, spraying, or similar means.
• the surface of the metal reacts with the solution and, under suitable conditions, such reaction forms over the surface an integral layer of substantially insoluble crystalline phosphates of various metals, usually including some iron, if that is a part of the metal being phosphated, and some of any metal present as cations in the solution.
• the coatings thus formed serve as effective bases for subsequent application of paints, lubricants, and other materials. Such coatings also often resist corrosion, and inhibit corrosion of the underlying metal, in various environments to which metal articles are often exposed in use. Such coatings have achieved widespread commercial use.
• hydroxylamine in phosphating solutions has been known in the art to accelerate the phosphating reac­tion, thereby increasing the amount of phosphate coating formed under given conditions of treatment from a phosphat­ing solution containing hydroxylamine, compared with an otherwise similar solution not containing hydroxylamine.
• sludge undesirable material generally known in the art as "sludge", an insoluble mixture of metal phosphates and sometimes other substances that precipitate from phosphating solutions during their use and that must eventually be removed to permit continued satisfactory operation. If the sludge accumulates beyond a certain level, some of it will usually adhere to some of the metal articles being phosphated, thereby making unacceptable surface blemishes on these articles. Disposal of the sludge is costly, because its high concentration of toxic metal ions requires environ­mental protection measures under current laws. Thus, reduction in the amount of sludge formed during operations is a highly desirable object of improvement in phosphating processes.
• phosphate coatings for pre-drawing lubricity can be formed in the range of coating weights between 3 and 15 grams per square meter (hereinafter "g/m2") of surface and that lower coating weights within this range are sometimes preferred, provided that a dense continuous phosphate film is formed. It has also been found that the presence of controlled amounts of hydroxylamine in a zinc phosphating solution, including such solutions that also contain calcium and/or some other metal ions, significantly reduces the formation of sludge during operations, without having any adverse effect on the phosphating process.
• One preferred embodiment of the invention is a phosphating solution having a pH in the range of 1 to 3.7, more preferably in the range of 2.5 to 3.5 and comprising, or more preferably consisting essentially of, the following components: (A) from 1 to 4 % by weight of zinc ions; (B) up to 3 % by weight of calcium ions; (C) from 1 to 7.5 % by weight of phosphate ions; (D) at least 0.02 % by weight of hydroxylamine; (E) an accelerator other than hydroxylamine, as known in the art, which may include more than one chemical species, in an accelerating-effective amount; (F) up to 0.1 % by weight of nickel and/or copper cations; (G) up to 0.2 % by weight of manganese cations; and (H) water.
• A from 1 to 4 % by weight of zinc ions
• B up to 3 % by weight of calcium ions
• C from 1 to 7.5 % by weight of phosphate ions
• D at
• any statements of the amount of "phosphate ions” are to be understood as the stoichiometric equivalent as PO4 ⁇ 3 of the sum of all stages of ionization of phosphoric acid and of undissociated acid that may be present in the solutions. Also, it is to be understood that necessarily implied counter-ions, chemically harmless during phosphating, for any constituents stated to be present in ionic form, are also present in the solutions according to the invention.
• the preferred accelerator is nitrate ion in an amount between 1 and 7.5 % by weight of the phosphating solution.
• Other suitable accelerators include, but are not limited to, sulfite ions, picrate ions, vanadates, and/or molyb­dates.
• the amount of the sum of nickel and copper cations within the range of 0.001 to 0.01 % by weight, with the most preferred value being 0.006 % by weight. If calcium ion is present in the solutions, it is more preferred that it be present in a concentration of at least 0.5 % by weight.
• an amount of hydroxylamine such that an otherwise identical zinc phosphating solution in which all the hydroxylamine has been replaced by an amount of nitrite ion equal to 3 % the weight of the hydroxylamine replaced generates at least 50 % more sludge than the hy­droxylamine containing solution for the same amount of metal surface phosphated. It is generally preferred to use not more than 0.4 % by weight of hydroxylamine in the solutions, and the most preferred value for the concentra­ tion of hydroxylamine is 0.05 % by weight.
• Treatment of metal surfaces with hydroxylamine con­taining phosphating solutions according to this invention may be by immersion, spray, a combination, or any other method that establishes effective contact, and the temper­atures, times, and other conditions of treatment are generally the same as those already known in the art for phosphating with solutions containing the same concentra­tions of the same metal ions and other accelerator(s).
• the phosphating treatment according to this invention may be advantageously combined with other known process steps, such as pre-phosphating cleaning, pickling, and conditioning procedures and post-phosphating rinses, chromate or other coating passivation treatments, application of lubricants, painting, and the like, all in the general manner well known to those skilled in the art.
• hydroxylamine is preferably sourced from a shelf-stable salt or complex, several of which are commercially available. Most preferred is hydroxylamine sulfate, sometimes also called hydroxylammonium sulfate and generally represented chemically as (NH2OH)2 ⁇ (H2SO4) or (NH3OH)2SO4. Hydroxylamine sulfate is briefly denoted hereinafter as "HAS”.
• the volume of sludge generated during use of a phosphating solution may be measured by means known to those skilled in the art. Normally, an aliquot sample of the solution is removed from the container in which the process is being performed, with care to assure a repre­sentative sample. The aliquot of solution, with its suspended solids, is transferred to a transparent graduated conical vessel and allowed to settle under the influence of ambient gravity for about 24 hours. Such settling produces a readily visible demarcation between the sludge in the bottom of the vessel and the overlying liquid. The volume of sludge is then read from the graduations on the vessel.
• Typical phosphating solutions according to this inven­tion generate 7 to 11 milliliters (hereinafter “ml”) of sludge per square meter (hereinafter “m2”) of metal phosphated, while conventional zinc phosphate coating solutions generate 14 to 25 ml of sludge per square meter of metal phosphated.
• ml milliliters
• m2 sludge per square meter
• zinc phosphate coating solutions generate 14 to 25 ml of sludge per square meter of metal phosphated.
• compositions of solutions for these examples is shown in Table 3.
• the same sources of the components as in Examples 1 - 5 were used, and sodium nitrite was used as the source of nitrite ions.
• Table 2 Coating Weights and Sludge Volumes for Examples 1-5 Example No.
• Comparative Example 1C is a traditional zinc solution for high coating weight phosphating and 2C is a conventional solution for low coating weight phosphating, both of these having no calcium. Comparative Example 3C contains calcium but is otherwise fairly close to 1C. All these comparative examples contain nitrite as an accelerat strictlyor, along with nitrate.
• Example 7 used a solution that is identical with that for Comparative Example 3C, except that the hydroxylamine in the solution of Example 7 has been replaced in the solution of Comparative Example 3C by nitrite ion; the amount of nitrite ion used is 3 % by weight of the amount of hydroxylamine substituted.
• the phosphating coating weight and quality produced by the two solutions is substantially identical, but the amount of Table 4 Coating Weights and Sludge Volumes, Examples 6-7 and 1-3C Example No.
• Coating Weight Range g/m2 Sludge Volume, ml/m2 6 8 - 10 8.4 1C 9 - 14 14 2C 6 - 9 25 3C 4 - 8 14 7 4 - 8 7.9 sludge is over 40 % less for Example 7.
• Comparison of Example 6 with Comparative Example 1C shows the same general effect for solutions with a higher zinc:calcium ratio.
• This example describes an integrated process, including use of a phosphating solution according to the present invention, that is very effective in preparing steel tubing or wire for subsequent drawing or cold heading processes.
• the steel should be cleaned to assure removal of all grease and oil, generally with the aid of a surfactant as known in the art. After use of a surfactant, the steel is rinsed thoroughly with hot water. If any scale or rust is still detectable on the surface, it should be removed by conventional pickling, preferably in hot inhibited sulfuric or hydrochloric acid. After pickling, the metal must be thoroughly rinsed to prevent too much acidic material from contaminating the phosphating solution. It is advisable to use two water rinses, with the first rinse cold and the second either hot or cold as desired.
• the metal in immersed in a phosphat­ing solution according to this invention, maintained at a temperature of about 71 to 93° C, and kept in the solution for about 30 seconds to about 5 minutes in order to produce the desired coating.
• the optimum coating weight depends on the exact composition of the metal being treated, the pretreatment steps, and the type of subsequent processing to be performed on the treated metal, in a manner generally known to those skilled in the art.
• the phosphating solution is made by combining separate make-up and additive solutions in a stainless steel processing tank.
• 100 gallons of working solution is made by filling the tank about three-quarters full with water and then adding 12.2 gallons of a make-up solution with a composition as specified below. Then about 3.7 gallons of additive solution, with composition specified below, is added to complete preparation of the phosphating mixture.
• the make-up solution for this highly preferred embodiment consists of 87.5 parts of zinc oxide, 2.3 parts of nickel nitrate aqueous solution containing 13.7 % by weight of nickel ions, 211.0 parts of 75 % aqueous phosphoric acid, 6.0 parts of HAS, and 113 parts of nitric acid of 42° Baume, all dissolved in sufficient water to make 1000 parts total.
• the additive solution is made by mixing 261.7 parts of calcium hydroxide and 665.4 parts of nitric acid of 42°. Baume, with sufficient water to make 1000 parts total. (All parts noted in this paragraph are by weight.)
• the treated article is rinsed well to remove, and prevent any carryover of, the phosphating solution.
• a suitable lubricant is then applied from an aqueous soap solution. The article is then ready for drawing or other forming operations that substantially stress the metal.

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• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
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• Chemical Treatment Of Metals (AREA)

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Citations (4)

• 1990
  • 1990-05-08 ZA ZA903498A patent/ZA903498B/xx unknown
  • 1990-05-12 EP EP90108989A patent/EP0398202A1/fr not_active Withdrawn
  • 1990-05-17 CA CA002017012A patent/CA2017012A1/fr not_active Abandoned
  • 1990-05-17 JP JP2128101A patent/JP2994428B2/ja not_active Expired - Fee Related
  • 1990-05-17 BR BR909002318A patent/BR9002318A/pt unknown
  • 1990-05-19 CN CN90103728A patent/CN1047537A/zh active Pending
  • 1990-05-23 AU AU55778/90A patent/AU5577890A/en not_active Abandoned

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