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

Abstract

The invention relates to a method for coating metallic surfaces by a manganese-zinc phosphatizing process, using an aqueous phosphatizing solution, in which nickel is deliberately not added. Said method is characterized in that the zinc:manganese weight ratio of the phosphatizing solution is maintained in the region of between 0.05:1 and 0.99:1 and that the phosphatizing solution has the following contents: between 0.05 and 5 g/l zinc, between 0.075 and 5.2 g/l manganese and between 0.008 and 0.050 g/l copper and/or hexafluoride complexes of titanium, hafnium and/or zirconium totalling between 0.002 and 0.5 g/l, calculated as F 6 . The invention also relates to the use of the metal parts coated in this manner.

1 . Process for the coating of metallic surfaces by manganese-zinc phosphating with an aqueous phosphating solution, in which no nickel is intentionally added to the phosphating solution, characterised in that 
 the zinc:manganese weight ratio of the phosphating solution is maintained.in the range from 0.05:1 to 0.99:1,    and that the phosphating solution has the following contents: 
 zinc in the range from 0.05 to 5 g/l,  
 manganese in the range from 0.075 to 5.2 g/l, as well as  
 copper in the range from 0.008 to 0.050 g/l, and/or  
 a total amount of 0.002 to 0.5 g/l of hexafluoride complexes of boron, aluminium, titanium, hafnium and/or zirconium, calculated as F 6 .  
   
     
     
         2 . Coating process according to  claim 1 , characterised in that the phosphating solution has a content of silver in the range from 0.0001 to 0.05 g/l.  
     
     
         3 . 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.  
     
     
         4 . 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 PO 4 .  
     
     
         5 . 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 PO 4 .  
     
     
         6 . 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.  
     
     
         7 . 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.  
     
     
         8 . 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.  
     
     
         9 . 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.  
     
     
         10 . 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.  
     
     
         11 . 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 H 2 O 2 , 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 NO 2 , 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.  
     
     
         12 . Coating process according to one of the preceding claims, characterised in that the phosphating solution has the following contents, in particular for parts: 
 zinc in the range from 0.6 to 1.4 g/l,    manganese in the range from 0.7 to 2.0 g/l,    zinc:manganese weight ratio in the range from 0.6:1 to 0.95:1,    phosphate calculated as PO 4  in the range from 12 to 25 g/l,    zinc:phosphate weight ratio in the range from 0.02 to 0.12,    copper in the range from 0.008 to 0.025 g/l,    total content of fluoride as free fluoride, as bound fluoride and/or as at least one complex fluoride, in the range from 0 to 6 g/l, calculated as F,    wherein the complex fluoride SiF 6  is contained in an amount in the range from 0 to 4.5 g/l calculated as SiF 6 , and    nitrate in the range from 0 to 22 g/l and/or at least one other accelerator selected from the group comprising nitrite or compounds based on hydroxylamine, nitroguanidine and/or peroxide, in each case in the range from 0.01 to 2 g/l.    
     
     
         13 . Coating process according to one of the preceding claims, characterised in that the phosphating solution has the following contents in particular for strip material, particularly preferably for galvanised strip surfaces: 
 zinc in the range from 0.1 to 4 g/l,    manganese in the range from 0.5 to 5 g/l,    zinc:manganese weight ratio in the range from 0.02:1 to 0.9:1,    phosphate calculated as PO 4  in the range from 10 to 40 g/l,    zinc:phosphate weight ratio in the range from 0.0025 to 0.4,    copper in the range from 0.008 to 0.032 g/l,    total content of fluoride as free fluoride, as bound fluoride and/or as at least one complex fluoride in the range from 0 to 6 g/l calculated as F,    wherein the complex fluoride SiF 6  is contained in an amount in the range from 0 to 4.5 g/l, calculated as SiF 6 , and    nitrate in the range from 0 to 22 g/l and/or at least one further accelerator selected from the group comprising nitrite or compounds based on hydroxylamine, nitroguanidine and/or peroxide, in each case in the range from 0.01 to 2 g/l.    
     
     
         14 . Coating process according to one of the preceding claims, characterised in that the phosphating solution for the prephosphating has the following contents: 
 zinc in the range from 1.3 to 2.3 g/l,    manganese in the range from 1.7 to 2.6 g/l,    zinc:manganese weight ratio in the range from 0.5:1 to 0.95:1,    phosphate calculated as PO 4  in the range from 10 to 20 g/l,    zinc:phosphate weight ratio in the range from 0.06 to 0.23,    copper in the range from 0.008 to 0.048 g/l,    total content of fluoride as free fluoride, as bound fluoride and/or as at least one complex fluoride in the range from 0 to 6 g/l calculated as F,    wherein the complex fluoride SiF 6  is contained in an amount in the range from 0 to 4.5 g/l, calculated as SiF 6 , and    nitrate in the range from 0 to 22 g/l and/or at least one further accelerator selected from the group comprising nitrite or compounds based on hydroxylamine and/or nitroguanidine, in each case in the range from 0.01 to 2 g/l, or peroxide in the range from 0.01 to 3 g/l.    
     
     
         15 . Coating process according to one of the preceding claims, characterised in that the phosphating solution has the following contents: 
 zinc in the range from 0.6 to 1.4 g/l,    manganese in the range from 0.7 to 2.0 g/l,    zinc:manganese weight ratio in the range from 0.6:1 to 0.95:1,    phosphate calculated as PO 4  in the range from 12 to 25 g/l,    zinc:phosphate weight ratio in the range from 0.02 to 0.12,    total content of fluoride as free fluoride, as bound fluoride and/or as at least one complex fluoride, in the range from 0.012 to 6 g/l, calculated as F,    wherein the total content of complex fluorides of titanium, hafnium and/or zirconium is in the range from 0.002 to 0.5 g/l, calculated as F 6 , and wherein the complex fluoride SiF 6  is contained in an amount in the range from 0 to 4.5 g/l, calculated as SiF 6 , and    nitrate in the range from 0 to 22 g l and/or at least one further accelerator selected from the group comprising nitrite or compounds based on hydroxylamine, nitroguanidine and/or peroxide, in each case in the range from 0.01 to 2 g/l.    
     
     
         16 . 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.  
     
     
         17 . 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.  
     
     
         18 . 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.  
     
     
         19 . 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.  
     
     
         20 . 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.  
     
     
         21 . 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.  
     
     
         22 . 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/m 2  is deposited from the phosphating solution.  
     
     
         23 . 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.  
     
     
         24 . Coating process according to one of the preceding claims, characterised in that the metallic surfaces are galvanised directly before the phosphating.  
     
     
         25 . Coating process according to one of the preceding claims, characterised in that the metallic surfaces are prephosphated.  
     
     
         26 . Coating process according to  claim 25 , characterised in that the phosphating solution for the prephosphating has the following contents: 
 zinc in the range from 0.4 to 5 g/l,    manganese in the range from 0.5 to 5.2 g/l,    copper in the range from 0.008 to 0.050 g/l.    
     
     
         27 . Coating process according to  claim 25  or  26 , characterised in that at least partially prephosphated, optionally at least partially formed/shaped, optionally at least partially welded metallic substrates are phosphated by coating with an aqueous phosphating solution, in which no nickel is intentionally added to the phosphating solution or the coating is carried out only with a nickel content of the phosphating solution of up to 0.3 g/l, wherein the phosphating solution has the following contents: 
 zinc in the range from 0.05 to 5 g/l, and  
 manganese in the range from 0.075 to 5.2 g/l.  
 
     
     
         28 . 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.  
     
     
         29 . 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.  
     
     
         30 . 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.  
     
     
         31 . Coating process according to one of  claims 1  to  30 , characterised in that the metal parts provided with a first and/or second applied phosphate layer are coated either before or after the forming and/or assembly with a coating corresponding to  claim 29 .  
     
     
         32 . Use of the metal parts coated by the process according to at least one of  claims 1  to  31  as prephosphated metal parts for a renewed conversion treatment or for a renewed conversion pretreatment, in particular before painting, or as pretreated metal parts in particular for the automobile industry, especially before painting, or an end-phosphated metal parts, which may optionally also subsequently be painted, organically coated in another way and/or coated with a film, with an adhesive layer, formed/shaped, assembled and/or welded together.  
     
     
         33 . Use of the substrates coated by the process according to at least one of  claims 1  to  31  in the production of strip material, for the production of components or car body parts or preassembled elements in the automobile or aerospace industry, in the building and construction industry, in the furniture industry, for the production of instruments and units, in particular domestic appliances, measuring instruments, control devices, testing devices, structural components, claddings/linings as well as small parts; as wire, wire coiling, wire mesh, metal sheeting, cladding/lining, screening, car bodies or parts of car bodies, parts of vehicles, trailers, mobile homes or missiles, as electronic or microelectronic components, as coverings, housings, lamps, lights, hanging light units, items of furniture or furniture parts, components of domestic appliances, frames, profiled sections, moulded parts of complicated geometry, beam barrier, radiator or sauna parts, automobile bumpers, parts of or with at least one pipe and/or a profiled section, window, door or bicycle frames, or as small parts such as for example screws, nuts, flanges, springs or spectacle frames.