Corrosion resistance of PM2000 ODS steel in high temperature supercritical carbon dioxide

Abstract

Corrosion of PM2000 ODS steel in supercritical CO 2 at 650 8C and 20 MPa for 3000 h was studied. The corrosion performance of the alloys was evaluated by weight change measurements, and the surface oxide scale was characterized by scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. PM2000 ODS steel showed significantly better corrosion resistance compared to austenitic stainless steels and nickel based alloys tested in the same conditions. The high corrosion resistance is attributed to the formation of a dense and protective aluminum-rich oxide layer on the surface. The oxide layer thickness was only about 200 nm after 3000 h exposure.

A Tracer Study on sCO2 Corrosion with Multiple Oxygen-Bearing Impurities

“…The formation of α-alumina scale is dominant over transient aluminas at temperatures above 800 °C [43,44]. In sCO 2 , a continuous alumina scale can form already at 650 °C, but it requires higher Al contents (> 3wt.%) [45,46]. Since neither XRD nor EDS could detect a subscale alumina layer, it appears that 1% Al was not sufficient to form an Al-rich layer at 750 °C in agreement with the Ni-Cr-Al map of Giggins and Pettit [43].…”

Effect of pressure on the corrosion and carburization behavior of chromia-forming heat-resistant alloys in high-temperature carbon dioxide environments

“…The corrosion and carburization behavior of several candidate materials has been studied in S-CO 2 environments at various temperatures (500-750 • C) and pressures (20)(21)(22)(23)(24)(25), conditions relevant to SFR and advanced ultra-supercritical (A-USC) fossil plant operation [12][13][14][15][16][17][18][19][20][21][22][23][24]. According to those studies, for Fe-based alloys on which Fe-and Cr-rich oxides were formed, carburization was observed at the oxide layer/matrix interface and underneath the oxide layer during S-CO 2 exposure at 550-650 • C [6,15,18].…”

Corrosion Behaviors of Heat-Resisting Alloys in High Temperature Carbon Dioxide

“…This relatively superior oxidation behavior may be related to trace elements, which are present in commercial FMs but not in FMs Fe20Cr model alloy. Moreover, compared with austenitic stainless steels (310SS, Al-6XN, 800H) and nickel-base alloys (Hay230, 625), the corrosion resistance of oxide dispersion strengthening FMs PM2000 (Fe19Cr5.5Al) was significantly improved under 650 • C/20 MPa S-CO 2 environment [57]. This may be because the oxide dispersion strengthening (ODS) FMs PM2000 possesses a very dense and protective alumina scale, which is more oxidation-resistant than chromia.…”

“…Therefore, the use of alumina-forming nickel-base alloys may be an option at higher temperatures, typically higher than 750 • C. Interestingly, carburization at the oxide/metal interface was observed in chromia-forming nickel-base alloy 600 and alloy 690 (Figure 4d) but not in alumina-forming nickel-base alloy 214 [12]. Hence, the alumina layer is a better barrier against carburization than the chromia layer [57,68]. Although the chromia-forming nickel-base alloy has superior oxidation resistance, it is also subject to carbon deposition or carburization at the oxide/metal interface [28,46].…”