Fe-低Si合金の高温初期酸化に対する温度とSi濃度の影響

概要

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Effect of Si and temperature on an initial stage of oxidation of Fe-Si (0∿1.5 mass%) alloys in air was investigated for up to 150s at temperatures between 1323 and 1473K. Iron and the Fe-0.1Si alloy formed a triplex oxide layer structure of FeO (Fe_3O_4 included)/Fe_3O_4/Fe_2O_3, obeying a parabolic rate law and the temperature dependence of the parabolic rate constants yield activation energies of 101 and 156kJ/mol for Fe and an Fe-0.1%Si alloy, respectively. The alloys containing 1.0 and 1.5 Si showed very slow oxidation below 1373K due to a formation of duplex Fe_2O_3 and SiO_2 layers. These alloys oxidized faster, obeying a linear rate law owing to liquid Fe_2SiO_4 formation in the triplexlayer structure of FeO (Fe_3O_4 included)/Fe_3O_4/Fe_2O_3 at 1473K. At temperatures of 1373 and 1423K the alloys containing 0.4, 0.5, and 1.0Si oxidized slowly during initial periods and then the oxidation rate increased rapidly due to liquid Fe_2SiO_4 formation. Measurements of sample temperatures showed that this is due to over-heating of the sample by the rapid oxidation. The composite FeO and Fe_3O_4 layer between the FeO and Fe_3O_4 layers was suppressed in the Fe and Fe-low Si alloys, when oxidized at temperatures below 1173K, while it appeared even in rapidly quenched samples oxidized above 1273K.
社団法人日本鉄鋼協会の論文