Die Inhibition der Chloridkorrosion (Lochfraß) auf chemisch beständigen Stählen durch Nitrat‐, Sulfat‐ und Chromationen und die Bestimmungsmethoden des Lochfraßpotentials

Abstract

Inhibition der Chloridkorrosion auf einem 18–10‐Chrom‐Nickel‐Stahl durch Nitrat‐, Sulfat‐ und Chromationen. — Einengung des Lochfraßpotentialbereiches durch Nitratzusätze. — Verschiebung des Lochfraßpotentials zu positiveren Potentialen durch Sulfationen. — Bestimmung des Lochfraßpotentials durch potentiostatische und galvanostatische Halteversuche, potentiokinetische Messungen und sog. Selbstpassivierungsversuche — Diskussion der erhaltenen unterschiedlichen Ergebnisse. — Inhibition der kathodischen Teilreaktion des Korrosionsvorganges bei Zugabe von Chromationen zum Elektrolyten.

Environmental Factors Affecting the Critical Potential for Pitting in 18–8 Stainless Steel

“…At faster rates of potential change, as in our measurements, NO3-does not have time to reduce, and Vc therefore moves toward more noble values with increasing NOz-concentrations, similar to the shift which occurs with SO4--or OH-additions. In agreement, Herbsleb (7) showed through potentiokinetic measurements of 18-8 that a critical potential Vc in 1M NaC1 q-0.5M NaNO3 solution, which we find according to Fig. 8 to be in the inhibiting range, is observed only at slow (0.2 v/hr) but not at fast (2 v/hr) rates of potential change.…”

“…Early measurements also showed a so-called "break through" or "critical" potential at which pitting initiates. Recent measurements of such critical potentials for stainless steels are reported by Rosenfeld and Maximtschuk (2), Rocha (3), Brauns and Schwenk (4), Defranoux (5), Pourbaix et al (6), Herbsleb (7), Tomashov et al (8). and by Fokin et al (9).…”

A Contribution to the Applicability of Critical Pitting Potentials

“…Very little follow up to this work took place, save for the work of Mahla and Neilson (3) in 1947, until the last five or six years during which a considerable amount has appeared in the literature (4)(5)(6)(7)(8)(9).…”

A Method for determining safe concentrations of chloride ions in pitting corrosion of steels in nitrate media

“…Pitting corrosion in acid, neutral, and alkaline nitrate solutions differs from analogous damage in media with different anion compositions in a single, but very important, aspect: it is manifested in the passive region as an additional peak preceding the overpassivation process [5][6][7][8][9][10][11][12]. The boundaries of this peak are determined by the ratio of concentrations of and NO 3 -Cl -ions, the temperature and pH of the solution, the composition of the steel, and certain other factors [10][11][12].…”