open access

https://hdl.handle.net/2115/76565

Effect of Water Vapor on the Oxidation Properties of Sintered Fe-3 mass%SiO<SUB>2</SUB> in air at 1273 K

日本語

dissociation

2001-02

日本金属学会

Journal of the Japan Institute of Metals

65(2)

115-121

Oxidation properties of sintered Fe-3 mass%SiO2 (Fe-3SiO2) as well as Fe-1.5 mass%Si alloy (Fe-1.5Si) and Fe, for comparison, were investigated at 1273 K for up to 7.2 ks in air and air containing 10.5 vol%H2O (air-10.5H2O). In air-10.5H2O, the Fe-3SiO2 was oxidized faster than in air and also than the Fe-1.5Si in air-10.5H2O. The scale was composed of a duplex structure, an inner FeO+Fe2SiO4 and an outer Fe-oxides layers, where many voids existed in both layers. The similar scale structure containing voids was observed for the Fe-3SiO2 in air. Marker experiment with a small Pt wire was carried out for the Fe-3SiO2 oxidized in air-10.5 vol%H2O and the Pt-marker located between the inner and outer layers, suggesting that the inner layer grows due to inward migration of oxygen and the outer layer due to outward iron diffusion. In both air and air-10.5H2O Fe showed a parabolic oxidation, forming exclusively an outer Fe-oxides scale. It was suggested that SiO2, which changed to FeO+Fe2SiO4, acts as an obstacle for the outer layer recession, leading a formation of voids in the inner layer. Oxygen used to form the inner FeO+Fe2SiO4 layer was supplied by the dissociation of outer Fe-oxides, leaving voids, probably by a perforating dissociation mechanism. Both oxygen and water molecules could be diffusing species through the void.

学術雑誌論文

Version of Record

0021-4876

1880-6880

AN00062446