Comparative study of surface properties of austenitic stainless steels in sulfuric and hydrochloric acid solutions

• Published in: Electrochimica acta 1997, Vol.42 (1), p.25-35
• Main Authors: Varga, K., Baradlai, P., Barnard, W.O., Myburg, G., Halmos, P., Potgieter, J.H.
• Format: Article
• Language: English
• Subjects: accumulation of Cl − and [formula omitted] ions; Applied sciences; austenitic stainless steels; Corrosion; Corrosion environments; Exact sciences and technology; in situ radiotracer method; Metals. Metallurgy; Ru additives; specific interactions; XPS and ICP-OES studies
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/0013-4686(96)00163-6

In this work, time, concentration and potential dependence of Cl − and HSO 4 − SO 4 2− accumulations on two austenitic stainless steels (AISI 316L + 0.5%Ru and 08X18H10T (GOST 5632-61) which corresponds to AISI 304) are studied by an in situ radiotracer method and voltammetry. Several independent techniques such as XPS and ICP-OES are also used to characterize the complex features of the passivation and dissolution of steels with and without Mo and Ru as additives. From the experimental results, it is obvious that the surface excess values of bisulfate/sulfate ions on both stainless steels are much higher (up to Γ = 1.5 × 10 −9 mol cm −2) and their interaction with the passive oxide layer is substantially stronger than those of chloride ions. The surface concentration of Cl − of less than 2 × 10 −10 mol cm −2 (if any) provides evidence that only a very limited part of the real surface area of the steel samples (less than 5%) is occupied by Cl − ions, ie, pitting corrosion sites are probably formed. Some possible links between sorption phenomena and the structure and chemical composition of passive layers are also presented and discussed.