Abstract: Process for stainless steel pickling consisting in placing the material to be treated in a bath kept at a temperature ranging from 30.degree. C. to 70.degree. C. and containing:a) HClb) Fe.sup.3+c) HFd) emulsifiers, wetting agents, polishing agents, acid attack inhibitors;the bath being fed continuously with:an air flow equal to at least 3 m.sup.3 /h per m.sup.3 bath min. and an oxidizer quantity adjusted to the bath redox potential to be kept at 250 mV min.

Abstract: Process for stainless steel pickling consisting in placing the material to be treated in a bath kept at a temperature ranging from 30.degree. C. to 70.degree. C. having the following initial composition:a) H.sub.2 SO.sub.4 150 g/l at leastb) Fe.sup.3+ 15 g/l " "c) HF 40 g/l " "d) H.sub.2 O.sub.2 (added with known stabilizers) 1-20 g/le) emulsifiers, wetting agents, polishing agents, acid attack inhibitors;in the bath being fed continuously:an air flow equal at least to 3 m.sup.3 /h per m.sup.3 bath min. and a stabilized H.sub.2 O.sub.2 quantity adjusted to the bath redox potential to be kept at .gtoreq.250 mV.

Abstract: Process for stainless steel pickling consisting in placing the material to be treated in a bath kept at a temperature ranging from 30.degree. C. to 70.degree. C. and containing:a) H.sub.2 SO.sub.4b) Fe.sup.3+c) HFd) emulsifiers, wetting agents, polishing agents, acid attack inhibitors;the bath being kept under agitation with:an air flow and continuously fed with a quantity of oxidizing agent adjusted to the bath redox potential to be kept at 250 mV min.

Abstract: An acid aqueous solution useful for phosphating metal surfaces and a phosphating process using same; said solution, which is characterized by its containing hydroxylamine phosphate as accelerator and a cationic surfactant can be applied to metal surfaces based on iron, zinc, aluminium and alloys thereof, and is specifically suitable for preventing the formation of white spots.

Abstract: An acid aqueous solution useful for phosphating metal surfaces and a phosphating process using same; said solution, which is characterized by its containing hydroxylamine phosphate as accelerator and a cationic surfactant, preferably a quaternary ammonic surfactant, can be applied to metal surfaces based on iron, zinc, aluminium and alloys thereof, and is specifically suitable for preventing the formation of white spots.

Abstract: Process for sheet titanium pickling followed by passivation. Pickling is carried out in an aqueous solution containing H.sub.2 SO.sub.4, HF and Fe.sup.3+ at .ltoreq.50.degree. C., continuously fed with an air flow, and with a stabilized H.sub.2 O.sub.2 quantity adjusted to the bath redox potential to be kept at -200 to 0 mV. Passivation is carried out in an aqueous bath containing 4 to 10 g/l HF, .ltoreq.1 g/l Fe.sup.3+, and not containing H.sub.2 SO.sub.4, with a redox potential kept at 500-600 mV by continuous feeding of stabilized H.sub.2 O.sub.2.

Abstract: A process for pickling and passivating stainless steel using a bath of the following initial composition:H.sub.2 SO.sub.4 at least 150 g/lFe.sup.3+ at least 15 g/lHF at least 40 g/lstabilized H.sub.2 O.sub.2 1-20 g/lnon-ionic surfactants and acid attack inhibitors 1 g/l,into which an air flow and an H.sub.2 O.sub.2 quantity of between 0.3 and 1 g/l per hour, controlled to maintain the bath Redox potential at .gtoreq.350 mV, are fed in continuously.