JultikaUniversity of Oulu repository

Abstract

Dimensionally stable anodes (DSAs) are a type of anode materials in which the degradation process during electrolysis is significantly slower when compared to other traditionally used anodes. DSAs consist of substrate material (such as titanium) and an electro-active top layer. The electro-active layer consists of one or multiple metal oxides of the noble- or platinum group metals: ruthenium dioxide (RuO2), rhodium dioxide (RhO2), palladium dioxide (PdO2), osmium dioxide (OsO2), iridium dioxide (IrO2), and platinum dioxide (PtO2). In neutral electrolytic pickling stainless steel strips are pickled from the scale that has formed during the manufacturing process. Lead is typically used in neutral electrolytic pickling, however, during pickling lead-based anodes suffer from high overpotential towards oxygen evolution reaction (OER), corrosion and formation of impurities. It has been estimated that only around 10 % of the applied current during pickling goes to the pickling of the scale, and the other 90 % to the OER. DSAs with electro-active metal oxide coatings RuO2 and IrO2 are measured to have significantly lower overpotentials towards OER, allowing higher current efficiencies during pickling. So, it is important to study the possibilities that DSAs could bring to the industry of neutral electrolytic pickling and whether they could increase the current efficiency of the pickling process and by then reduce the overall operation costs in this era of increasing energy prices.