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
• • 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
  • C23C22/188—Orthophosphates containing manganese cations containing also magnesium cations

Definitions

• the invention relates to a method for applying manganese phosphate layers on iron or steel surfaces with manganese, phosphate, iron (II) ions, and phosphating solutions containing nitroguanidine, and its use on workpieces which are exposed to sliding friction.
• manganese phosphate layers have proven themselves well because of their high mechanical resistance. With the initially common manganese phosphate solutions, however, relatively thick, coarsely crystalline layers were obtained, which are particularly disadvantageous when precision mechanical parts are to be treated. Numerous proposals have therefore been made with the aim of producing thin, fine-crystalline manganese phosphate layers. For example, it is known to obtain a refinement of the phosphate layer by adding condensed phosphates.
• phosphating solutions based on manganese phosphate are generally used at high temperatures, so that, owing to the considerable hydrolysis at high temperatures, the effectiveness of the condensed phosphates quickly decreases or the condensed phosphate must be replenished continuously.
• the German layout specification 1109 484 describes another way of achieving fine-grained phosphate layers. Thereafter, nitrate-containing phosphate solutions are used in which the amount of nitrate exceeds the amount of phosphate. The solutions should have a ratio of nitrate to phosphate of approximately (1.5 to 4.5): 1. However, it was found that in many cases the intended effect is not achieved. Furthermore, a method is known in which an excessive proportion of free acid in the phosphating solution is used in order to produce particularly thin layers (DE-C-1246356). However, due to their low basis weight, these layers can only be used practically for special cases.
• the object of the invention is to provide a method which leads to manganese phosphate layers with the lowest possible roughness depth, the layer thickness of which is nevertheless in the medium to high range.
• the object is achieved by designing the method of the type mentioned at the outset in accordance with the invention in such a way that the workpieces are formed with a minimum thickness of 2.5 ⁇ m and to form a manganese phosphate layer an average maximum roughness depth (R z ) of 2.5 ⁇ m - measured after drying - in contact with a phosphating solution that
• the average roughness depth is defined in accordance with DIN 4768, sheet 1 and represents the arithmetic mean of the individual roughness depths of five adjacent, equally long individual measuring sections
• R z 0.2 (Z 1 + Z 2 + Z 3 + Z 4 + Z 5 )
• the claimed maximum value of 2.5 ⁇ m relates solely to the roughness of the manganese phosphate layer and does not take into account the depth of the untreated metal surface.
• the above-mentioned total number of points is determined in a manner known per se by filtering 10 ml of the phosphating solution after dilution with water to about 50 ml using phenolphthalein as an indicator until the color changes from colorless to red.
• the number of ml 0.1 n sodium hydroxide solution used for this gives the total number of points.
• Other indicators suitable for titration are thymolphthalein and ortho-cresolphthalein.
• the free acid points are determined in a similar way, using dimethyl yellow as the indicator and titrating until the color changes from pink to yellow.
• Interfering metal ions are removed beforehand by adding hexacyanoferrate (II) or hexacyanocobaltate (III) ions.
• the S value is defined as the ratio of free P 2 O 5 to total P 2 O 5 .
• oxygen-containing gas such as compressed air
• compressed air can be blown into the phosphating solution.
• Can too Iron (II) oxidizing substances preferably potassium permanganate, are added.
• a preferred embodiment of the invention provides for the workpieces to be brought into contact with a phosphating solution which contains 0.5 to 2 g / l of nitroguanidine. Cost reasons are particularly relevant for this.
• a further advantageous embodiment of the invention provides for complexing agents to be added to the phosphating solution to complex the alloying constituents of the steel.
• Such an alloy component is especially chromium.
• tartaric acid, but especially citric acid are suitable as complexing agents.
• the addition of complexing agents intercepts the components of the steel that can have an adverse effect on the quality of the layer.
• Another advantageous development of the invention is to bring the workpieces into contact with a phosphating solution, which additionally
• magnesium ion content also reduces consumption in terms of total chemical consumption.
• the work pieces come into contact with the phosphating solution preferably at a temperature in the range from 75 to 95 ° C.
• the workpieces can be brought into contact with the phosphating solution in any way, preferably the immersion treatment.
• the treatment time is generally 1 to 15 minutes.
• Acidic, neutral or alkaline cleaners are used for this.
• water is rinsed thoroughly between the cleaning of the workpieces and the phosphating.
• the workpieces should be rinsed in an aqueous slurry of finely divided manganese phosphate in order to promote the formation of particularly uniform, fine crystalline layers in the subsequent phosphating.
• phosphate layers with a layer weight of generally 5 to 30 girr. 2 scored.
• the phosphate layers produced by the invention can be painted in a manner known per se or can be provided with plastic coatings. In conjunction with anti-corrosion oils, they serve to increase rust resistance.
• the main application of the method according to the invention is, however, in the treatment of workpieces that are exposed to sliding friction. These are, for example, axles, gear parts and pistons of internal combustion engines and compressors.
• the invention is illustrated by the following example.
• the total score of the phosphating solution was 80, the score of free acid 11 (measured with 60 g of concentrate per 1 liter of water).
• the score of free acid 11 was 60 g of concentrate per 1 liter of water.
• Finely crystalline phosphate layers with a layer weight of 7 g / m 2 , corresponding to a layer thickness of 3 to 4 ⁇ m, and an average roughness depth R z of 1.3 to 2.4 ⁇ m were obtained.
• the gas time was 2 to 3 minutes.

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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)
• Diaphragms For Electromechanical Transducers (AREA)

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• 1999
  • 1999-09-30 DE DE19947232A patent/DE19947232A1/de not_active Withdrawn
• 2000
  • 2000-09-20 ES ES00972661T patent/ES2223598T3/es not_active Expired - Lifetime
  • 2000-09-20 DE DE50007405T patent/DE50007405D1/de not_active Expired - Lifetime
  • 2000-09-20 AT AT00972661T patent/ATE273404T1/de active
  • 2000-09-20 WO PCT/EP2000/009193 patent/WO2001023638A1/fr active IP Right Grant
  • 2000-09-20 EP EP00972661A patent/EP1230423B1/fr not_active Expired - Lifetime
  • 2000-09-20 PL PL354447A patent/PL196365B1/pl unknown

Non-Patent Citations (1)

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