Laboratory‐scale simulation of industrial neutral electrolytic pickling as a bipolar system—Parameters affecting indirect polarization pickling of annealed stainless steel

• Main Authors: Teemu Tuovinen, Tuomas Vielma, Ulla Lassi
• Format: Article
• Language: English
• Published: Wiley 2020-10-01
• Series: Engineering Reports
• Subjects: bipolar electrode; current efficiency; factorial analysis; neutral electrochemical pickling; stainless steel
• Online Access: https://doi.org/10.1002/eng2.12245

Abstract As the production of stainless steel increases, environmental concerns due to an increasing demand of production capacity, require an efficient use of energy and materials. Efficient removal of otherwise slow‐to‐dissolve chromium oxide layer can be achieved with electrochemical pre‐pickling before final mixed acid pickling. Neutral electrolytic pickling can be used to rapidly dissolve chromium oxides but suffers from low current efficiency of both the reaction and the system. In order to study the effect of critical parameters for the current efficiency of the system, a pickling device was assembled. A system current efficiency factorial analysis of bipolar neutral electrolytic pickling was conducted for temperature, electrolyte concentration, cell potential, and electrode‐to‐sample distance. Lowering the concentration of electrolytes shows potential to increase current efficiency significantly as conductivity can be used to reduce electrode‐to‐electrode short‐circuiting, which is the biggest cause of decreased efficiency in neutral electrolytic pickling. Increasing the temperature has a positive effect on efficiency, despite increased conductivity, possibly from increasing reaction kinetics.