Patent ID: 6565735
Filing Date: 2003-05-20
Classification: C25F

Abstract:
A process for electrolytic pickling of a material selected from the group consisting of stainless steels of the ferritic, martensitic, austenitic and duplex series, superaustenitic and superferritic steels, Ni and Ni/Cr-based super alloys, titanium and titanium alloys, the process comprising: passing the material between at least a first pair of electrodes and a second pair of electrodes in an electrolytic apparatus, in contact with an aqueous electrolyte solution, wherein a first electrode of a pair faces a first side of the material and a second electrode of a pair faces a second side of the material and wherein the first and the second electrodes of the pair have the same polarity, passing an electric current between the electrodes and the material, as the material passes between the first pair of electrodes and the second pair of electrodes, wherein the polarity of the first pair of electrodes and the second pair of electrodes in a direction in which the material is passing is opposite and a ratio of a current density in the electrolytic apparatus of a cathodic polarized area of the material to a current density of an anodic polarized area of the material is from 2:1 to 6:1, and the aqueous electrolyte solution comprises:(a) from 20 to 140 g/l H2SO4; (b) from 15 to 80 g/l of Fe+3 ions; and (c) a quantity of Fe+2 ions such that an Fe+3/Fe+2 ion ratio is >1.