| 摘要 |
<p>1,242,761. Electrolytic pickling. CENTRO SPERIMENTALE METALLURGICO S.p.A. April 10, 1969 [April 12, 1968], No. 18554/69. Heading C7B. Scale is removed from a ferrous body, e.g. a hot-rolled austenitic, ferritic or martensitic steel sheet, immersed in an acid pickling solution 9 using a reference electrode 4 to control e.g. by a potentiostat 1 the P.D. between the body 5 and one or more counter-electrodes 7, 8 so that the potential of the body is maintained at a predetermined level, e.g. a value ranging from -150 to +150 mV with respect to a saturated calomel reference electrode, at which scale can be removed. For descaling a Cr-Ni stainless steel which is Cr-depleted under the scale, the P.D. between the steel body and the reference electrode is preferably maintained at a value affording a higher corrosion rate of the Cr-depleted alloy under the scale than that of the base steel. The pickling solution may contain one or more of HNO 3 , HF, HCl and H 2 SO 4 , and optionally an alkali metal or ammonium or iron salt.</p> |
