Iron Oxidation at Low Temperature (260–500 °C) in Air and the Effect of Water Vapor

Abstract

The oxidation of iron has been studied at low temperatures (between 260 and 500°C) in dry air or air with 2 vol% H 2 O, in the framework of research on dry corrosion of nuclear waste containers during long-term interim storage. Pure iron is regarded as a model material for low-alloyed steel. Oxidation tests were performed in a thermobalance (up to 250 h) or in a laboratory furnace (up to 1000 h). The oxide scales formed were characterized using SEM-EDX, TEM, XRD, SIMS and EBSD techniques. The parabolic rate constants deduced from microbalance experiments were found to be in good agreement with the few existing values of the literature. The presence of water vapor in air was found to strongly influence the transitory stages of the kinetics. The entire structure of the oxide scale was composed of an internal duplex magnetite scale made of columnar grains and an external hematite scale made of equiaxed grains. 18 O tracer experiments performed at 400°C allowed to propose a growth mechanism of the scale.

Influence of Hydrogen and Water Vapour on the Kinetics of Chromium Oxide Growth at High Temperature

“…1) that corresponds to alloy oxidation. The thermogravimetric curves were treated using a method after Monceau and Pierragi [16,17]. For all tested conditions, the mass gain increased reaching a quasi-stationary regime after a transitory period shorter than 125 h. This result is illustrated for the test 8 in Fig.…”

Effect of oxidation and surface roughness on the shear strength of single-lap-joint adhesively bonded metal specimens by tension loading

“…At 300 °C, a change in the oxidation rate and the dominant oxide begins [28,29]. The formation of Fe 2 O 3 with increasing temperatures, from 300 °C, has been reported to be accompanied by oxide separation from the metal surface [28,29]. These oxides were observed to occur predominately within the grinding grooves of the steel.…”

“…Fe 3 O 4 is reported as the dominant oxide at 200 °C, and has been observed to have good oxide adherence with the steel substrate [27,28]. At 300 °C, a change in the oxidation rate and the dominant oxide begins [28,29]. The formation of Fe 2 O 3 with increasing temperatures, from 300 °C, has been reported to be accompanied by oxide separation from the metal surface [28,29].…”

Corrosion of 9Cr Steel in CO2 at Intermediate Temperature I: Mechanism of Void-Induced Duplex Oxide Formation

“…23). Indeed, as hematite often crystallizes to whiskers shapes [17] and as hematite powder is known to be red-whereas thick hematite layer is black-the oxide whiskers were assumed to be hematite as well. When hematite was formed without any whiskers morphology (typically in the center of the specimen), it was observed that the colour was rather dark grey.…”