摘要:
Disclosed is a process of producing a phosphate coating on a metal having a surface which consists at least in part of iron or steel. The metal is contacted at a temperature in the range from 30.degree. to 50.degree. C. with a phosphatizing solution which contains 5 to 25 g/l zinc, 1 to 10 g/l manganese, 0.1 to 13 g/l iron(II), 5 to 40 g/l phosphate (calculated as P.sub.2 O.sub.5), 5 to 50 g/l nitrate, and which also contains 0.5 to 5 g/l fluoroborate (calculated as BF.sub.4), and 0.05 to 3 g/l tartaric acid and/or citric acid. The solution has been adjusted to weight ratios of Zn:P.sub.2 O.sub.5 =(0.5 to 3):1 and of Mn:Zn=(0.04 to 0.5):1 and to a ratio of free acid to total acid of (0.04 to 0.2):1.It is preferred to add nickel, copper and/or calcium to the phosphatizing solution and to adjust it to a content of Fe(II) not in excess of 10 g/l. The process is particularly suitable for preparing metals for cold working.
摘要:
During a method of phosphating a metal surface which includes at least in part iron or steel and is dipped into or flooded with a phosphating solution which contains layer-forming cations and nitrate or equivalent accelerators, the iron content is limited by a precipitation of iron phosphate. A partial volume of the phosphating solution is intermittently withdrawn from the bath tank and in a separate aerator is contacted with oxygen or an oxygen-containing gas. The iron phosphate sludge is removed from the resulting solution, which is then returned to the bath tank. The partial volume of the phosphating solution is supplied from below into and is aerated in an aerator, which is provided with an aspirating aerating agitator and which is tapered at least in its lower portion. When the aerator has been terminated, the phosphating solution which has been depleted of iron(II) is sucked off upwardly and is returned to the bath tank.
摘要:
The application of an aqueous soap to a phosphatized metal surface is improved by including in the soap composition a complex former stable to hydrolysis and capable of forming a water-soluble complex with the metal of the phosphate coating.
摘要:
An aqueous acidic zinc phosphate solution which contains at least 6 g/l of Zn, at least 5 g/l P.sub.2 O.sub.5, at least 1.0 g/l of an accelerator, calculated as ClO.sub.3, from about 1 to about 50 g/l of sulfate ion, which solution has a total acid number of at least 20, a weight ratio of free P.sub.2 O.sub.5 of 0.2-0.6:1 and a weight ratio of P.sub.2 O.sub.5 : Zn: ClO.sub.3 of 1:0.5-4.0: 0.01-1.0. The phosphatizing bath preferably contains from about 1 to 5 g/l chlorate in combination with at least 8 g/l nitrate, with a weight ratio of P.sub.2 O.sub.5 : NO.sub.3 of 1:0.2-6.0. The baths may be used to form phosphate coatings on ferrous metal surfaces using immersing or flow coating techniques and the phosphate coatings formed are found to have increased thickness and adhesion or coalescence to the metal surface.