Method for coating metallic surfaces and use of the substrates coated in this manner

Coating process according to one of the preceding claims, characterised in that the phosphating solution has a content of sodium in the range from 0.01 to 10 g/l and/or a content of potassium in the range from 0.01 to 10 g/l.

Coating process according to one of the preceding claims, characterised in that the zinc:phosphate weight ratio of the phosphating solution is maintained in the range from 0.016:1 to 1.33:1, phosphate being calculated as PO4.

Coating process according to one of the preceding claims, characterised in that the phosphating solution has a content of phosphate in the range from 3 to 75 g/l, phosphate being calculated as PO4.

Coating process according to one of the preceding claims, characterised in that the phosphating solution has a chloride content in the range from 0.01 to 6 g/l and/or a chlorate content in the range from 0.01 to 5 g/l.

Coating process according to one of the preceding claims, characterised in that the phosphating solution has a content of silicon hexafluoride in the range from 0.1 to 5 g/l.

Coating process according to one of the preceding claims, characterised in that the phosphating solution has a content of free fluoride in the range from 0.001 to 0.8 g/l.

Coating process according to one of the preceding claims, characterised in that the phosphating solution has a total content of fluoride in the range from 0.01 to 5 g/l.

Coating process according to one of the preceding claims, characterised in that the phosphating solution has a content of at least one accelerator in the range from 0 to 40 g/l.

Coating process according to one of the preceding claims, characterised in that the phosphating solution has a content of nitrite in the range from 0.01 to 0.3 g/l, a content of nitrate in the range from 1 to 30 g/l, a content of compounds based on peroxide in the range from 0.001 to 3 g/l calculated as H2O2, a total content of nitrobenzenesulfonate (NBS), nitropropane, nitroethane and/or other nitro-organic compounds—with the exception of compounds based on nitroguanidine—with oxidising properties in the range from 0.1 to 3 g/l calculated as NO2, a content of compounds based on nitroguanidine in the range from 0.1 to 5 g/l, a chlorate content in the range from 0.05 to 4 g/l, a content of reducing sugar compounds in the range from 0.1 to 10 g/l and/or a content of compounds based on hydroxylamine (HA) in the range from 0.1 to 6 g/l, calculated as HA.

Coating process according to one of the preceding claims, characterised in that the metallic substrates are coated for a time of up to 20 minutes, wherein strip material is preferably coated for a time of 0.1 to 120 seconds and particularly preferably for a time of 0.3 to 60 seconds, and wherein parts are preferably coated for a time from 1 to 12 minutes and particularly preferably for a time from 2 to 8 minutes.

Coating process according to one of the preceding claims, characterised in that the temperature of the phosphating solution in the coating procedure is in the range from 10° to 72° C., wherein strip material is preferably coated in the range from 40° to 70° C. and wherein parts are preferably coated in the range from 20° to 60° C. and particularly preferably in the range from 32° to 58° C.

Coating process according to one of the preceding claims, characterised in that the free acid has a value of 0.1 to 10 points, the total acid according to Fischer has a value of 5 to 50 points, and the ratio of the total acid according to Fischer to free acid is in the range from 0.01 to 0.7.

Coating process according to one of the preceding claims, characterised in that the pH of the phosphating solution is in the range from 1 to 4.

Coating process according to one of the preceding claims, characterised in that the phosphating solution is applied to the surface of the substrates by knife coating, flow coating, spraying, sprinkling, brushing, dipping, nebulising or rolling, wherein individual process steps may be combined with one another, the application optionally being followed by squeezing off.

Coating process according to one of the preceding claims, characterised in that substrates with a metallic surface predominantly containing aluminium, iron, copper, magnesium, tin or zinc are coated with the phosphating solution, in particular surfaces of at least one of the materials based on aluminium, iron, steel, zinc and/or alloys with a content of aluminium, iron, copper, magnesium, tin or zinc.

Coating process according to one of the preceding claims, characterised in that a phosphate coating that has a layer weight in the range from 0.2 to 6 g/m2 is deposited from the phosphating solution.

Coating process according to one of the preceding claims, characterised in that the metallic surfaces are cleaned, pickled, rinsed and/or activated before the phosphating.

Coating process according to one of the preceding claims, characterised in that the metallic surfaces are galvanised directly before the phosphating.

Coating process according to one of the preceding claims, characterised in that the metallic surfaces are prephosphated.

Coating process according to one of the preceding claims, characterised in that the phosphated substrates are rinsed at least once and are optionally treated between two rinse procedures with a post-rinse solution to provide additional passivation.

Coating process according to one of the preceding claims, characterised in that after the phosphating the metallic surfaces are welded, bonded and/or formed/shaped, and are then optionally rephosphated.

Coating process according to one of the preceding claims, characterised in that the metal parts provided with a first and/or second phosphate layer are coated with a paint, with another type of organic coating, with a film and/or with an adhesive layer and are optionally formed/shaped, wherein the metal parts coated in this way may in addition be bonded or welded to other parts and/or joined together in some other way.