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
  • C23C22/73—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 characterised by the process
  • C23C22/74—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 characterised by the process for obtaining burned-in conversion coatings

Definitions

• the invention relates to a method for applying insulating layers to steel or iron sheet or strip by drying a bath containing nitrate and phosphate at elevated temperatures.
• the top layer can be by chemical processes, i.e. by reaction with the metal surface.
• a phosphate coating is applied by reaction with a solution containing phosphate. It is possible to carry out the reaction with the phosphating solution by immersion or spraying. You can also apply a film of such a solution to the surface and dry it or bake it at elevated temperature.
• the base material for the coating is usually silicon steel or low-carbon steel, which is then e.g. in the form of fins for the construction of electric motors, generators and the like is used.
• Other iron qualities can also be used as the base material. In the following, they are collectively referred to as steel sheet or strip.
• the generated phosphate layers should reduce the electrical conductivity between adjacent steel parts as much as possible. They are said to be hard, smooth and glassy, as well as highly moist resistance and good electrical resistance. Finally, the phosphate layers are expected to have good adhesion to the steel surface, low dust formation, compatibility with other components, high temperature resistance while maintaining the good properties of the phosphate layer and a favorable influence on the punching behavior of steel sheet or strip.
• cover layers e.g. of resins, paints, paper and the like.
• a disadvantage of the known methods is that the drying of the treatment solution is very lengthy at about 5 minutes and also requires a high amount of energy.
• the object of the invention is to provide a method for applying insulating layers to steel or iron sheet and / or strip by drying a bath containing nitrate and phosphate at elevated temperatures, which does not have and does not have the known, in particular the aforementioned disadvantages.
• Leads phosphate layers that have excellent electrical and mechanical properties and otherwise fully meet the expectations mentioned above.
• the object is achieved in that the method of the type mentioned at the outset according to the invention it is designed that a steel or iron sheet or strip with a bath, the nitrate and phosphate content of which is a total of 10 to 50% by weight, at a maximum object temperature of 93 to 204 ° C, a phosphate layer of at most 4 , 31 g / m 2 layer weight.
• a further reduction in the consumption of chemicals can be achieved if, in a preferred embodiment of the invention, phosphate layers with a layer weight of max. 3.23 g / m 2 are applied. Depending on the requirements, even lower layer weights, for example up to 2.15 g / m 2 , are possible.
• Another advantageous embodiment of the method consists in bringing steel sheet or strip into contact with a bath in which the weight ratio of phosphate to nitrate is at least 1: 1.
• the favorable properties of the phosphate layers in particular their electrical resistance, can be improved if the steel sheet or strip is brought into contact with a bath which contains an effective amount of zinc, preferably 3 to 20% by weight.
• the use of zinc is particularly recommended if layers with layer weights below 3.23 g / m 2 are to be applied.
• a further improvement in the formation of phosphate layers can be achieved if the process according to the invention is developed in such a way that the steel sheet or strip is brought into contact with a bath which is effective Amount of nickel, preferably 0.1 to 7% by weight, contains and / or its phosphate content is at least 30% by weight and its nitrate content is at least 10% by weight.
• filler material such as colloidal silica, preferably in amounts of 0.5 to 10% by weight.
• colloidal silica mica, talc and similar fillers can also be used.
• surfactants is also possible or expedient.
• the phosphate layer-forming bath can only contain nitrate and phosphate. These components are introduced in a conventional manner in the form of soluble phosphate or nitrate compounds. If the bath used is to contain other components, such as zinc and nickel, they are also introduced via water-soluble salts, e.g. Zinc nitrate or nickel nitrate .. However, it is also possible to introduce the zinc as acid zinc phosphate and the nitrate in the form of nitric acid. The use of, for example, zinc oxide in combination with acids is also possible.
• the bath is applied in the usual way. Suitable methods include roller application, immersion processes and squeezing rolls, immersion processes and air knives as well as electrostatic separation.
• the appropriate choice of application method can depend in particular on the shape depend on the part to be coated. For example, electrostatic coating methods will be used when a coil treatment is provided, while squeezing rolls are usually used when punched parts are subjected to the coating.
• the drying time is dimensioned in such a way that the phosphate layer no longer has any adhesive properties on the cooled workpiece.
• the drying times for the phosphate layers produced by the process according to the invention are usually less than 1 min, mostly in the order of 30 seconds.
• the phosphate layers produced by the process according to the invention usually contain at least 10% by weight of nitrate and at least 30% by weight of phosphate.
• the proportion of phosphate can optionally reach up to 80% by weight.
• Nitrate and phosphate should together make up at least 50% by weight. Too high nitrate levels, i.e. about 35% by weight can adversely affect the electrical resistance of the layer. You should therefore be avoided.
• the bath to be dried still contains zinc, nickel and / or filler, its contents in the layer result from the concentration in the treatment bath.
• the electrical resistance of the layers produced is such that - determined by the method according to ASTM A 344-68 - the current flow does not exceed 0.03 A / cm 2 .
• tape, sheet metal or already punched-out slats can be coated from the coil. It is also possible to coat slats again, which have been punched from coil material that has already been provided with a layer.
• a treatment bath with the following composition was used for coating:
• the solids content of the solution was about 38% by weight.
• a squeeze roll application with grooved hard rubber rolls applied a liquid film to silicon steel sheets measuring 10.16 x 25.40 cm in such a way that the amount of solids added corresponded to 3.23 g / m 2 .
• the film was then baked by placing the sheets in an oven heated to 288 ° C and heating to a maximum object temperature of 149 ° C in about 30 seconds.
• the applied phosphate layer After removing the sheets from the oven and cooling, the applied phosphate layer showed no stickiness and had excellent electrical resistance properties.
• the solids content of the bath was about 40% by weight.

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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)
• Polyesters Or Polycarbonates (AREA)
• Paints Or Removers (AREA)
• Application Of Or Painting With Fluid Materials (AREA)
• Soft Magnetic Materials (AREA)
• Magnetic Heads (AREA)
• Photoreceptors In Electrophotography (AREA)
• Insulated Conductors (AREA)
• Chemical Or Physical Treatment Of Fibers (AREA)
• Laminated Bodies (AREA)

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Publications (2)

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Citations (3)

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• 1980
  • 1980-04-14 US US06/139,902 patent/US4316751A/en not_active Expired - Lifetime
• 1981
  • 1981-04-02 DE DE8181200366T patent/DE3166407D1/de not_active Expired
  • 1981-04-02 EP EP81200366A patent/EP0038097B1/fr not_active Expired
  • 1981-04-02 AT AT81200366T patent/ATE9718T1/de not_active IP Right Cessation
  • 1981-04-10 ZA ZA00812409A patent/ZA812409B/xx unknown
  • 1981-04-13 GB GB8111700A patent/GB2074195B/en not_active Expired
  • 1981-04-13 BR BR8102267A patent/BR8102267A/pt unknown
  • 1981-04-13 CA CA000375322A patent/CA1176960A/fr not_active Expired
  • 1981-04-13 AU AU69473/81A patent/AU541727B2/en not_active Ceased
  • 1981-04-14 JP JP5620281A patent/JPS56163279A/ja active Pending
  • 1981-04-14 IT IT8121172A patent/IT1137370B/it active

Patent Citations (3)

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