Understanding the Corrosion Behavior of P92 Steel in CO₂ Using In-Situ Monitoring Technology II: Mechanism of Oxide Scale Peeling

The mechanism of oxide scale exfoliation from P92 steel during formation in CO₂ under over-temperature conditions at 650 ℃ was studied by the experiments, thermodynamics, and molecular dynamics. A duplex oxide scale with an inner FeCr₂O₄ scale and an outer Fe₃O₄ scale was formed on P92 steel, in which honeycomb pores were observed in Fe₃O₄ oxides. The honeycomb pore size and CO gas generation rate on P92 steel showed maximum values after 80 min. The exfoliation of Fe₃O₄ oxide scale was divided into two stages based on the deposition of carbon in the honeycomb pores.