Oxidation Processes and Involved Chemical Reactions of Corrosion-Resistant Alloys in Supercritical Water

Abstract

Corrosion continues to be a major challenge in developing supercritical water-cooled reactor and supercritical water oxidation systems. Corrosion behaviors of candidate alloy materials used in these environments are significantly affected by the properties of oxides formed on alloy surfaces. This work presents a comprehensive review of the oxidation processes and involved chemical reactions of corrosion-resistant alloys in supercritical water. The oxidation process of an alloy in supercritical water is proposed to have two stages, and chemical reactions at these two stages are described in detail. The transitions of Cr/Ni/Fe oxides and the formation mechanism of oxide film are analyzed comprehensively. Moreover, the diffusion property, protection effect, and stability of oxides in supercritical water are summarized systematically.

Influence of a small velocity variation on the evolution of the corrosion products and corrosion behaviour of super 13Cr SS in a geothermal CO2 containing environment

“…The formation of FeCr2O4 may form on the surface via the following reactions [19,21,22]: The development of crystalline FeCO3 can occur not only via the one-stage process directly with carbonates [23];…”

Corrosion behavior of HR3C austenitic stainless steel in supercritical water near the critical point

“…Even though Cr 2 O 3 phase may have formed in the early corrosion stage, this oxide can be depleted to form (Fe,Cr) 3 O 4 spinel oxides by the following reaction. [ 50 ] $$${\text{2Cr}}_{2}{{\rm{O}}}_{3}{+\text{2Fe}+{\rm{O}}}_{2}\to {\text{2FeCr}}_{2}{{\rm{O}}}_{4}.$$$…”

“…Even though Cr 2 O 3 phase may have formed in the early corrosion stage, this oxide can be depleted to form (Fe,Cr) 3 O 4 spinel oxides by the following reaction. [50] → 2Cr O + 2Fe + O 2FeCr O . (2)…”

Corrosion behaviour characterisation of 316L stainless steel and Inconel 625 in supercritical water containing hydrochloric acid and high oxygen

“…Unlike stainless steel, the high content of chromium in the nickel-based alloys can continue to provide a dense oxide film. On the contrary, although stainless steel can form a dense Cr 2 O 3 layer, it cannot be continuously formed due to the low content of chromium being attacked by many impurity ions under long-term exposure [17]. It should be noted that the high corrosion resistance of nickel-based alloys in SCW is attributed to the formation of a protective chromia (Cr 2 O 3 )-based oxide rather than a spinel-based oxide [15].…”