抄録
The present authors studied, using the transmission electron diffraction method, initial oxide films of A.I.S.I. Type 302 B (2.45% Si), 19-9 DL (0.50% Si), Durimet 20 (1.27% Si) and Nichrome (JIS No. 1, 0.5-1.5% Si) oxidized in air at 700° to 900°C. A solution of 1 cc Bromine and 50 cc Methanol was satisfactorily used for isolating the oxide films from these alloys. The electron diffraction patterns obtained from initial oxide films (700° to 900°C) of the alloys showed the existence of a rhombohedral type (mainly Cr2O3 or α-(Cr, Fe)2O3) and spinel type oxides, and no such special oxides as SiO2 could be observed in the patterns. However, α-cristobalite crystals were detected when the films were heated at 1200°C for 1 to 3 hours. Thereby the authors clarified experimentally that the special heat-resisting films consisting of amorphous SiO2 are formed on the surfaces of alloys in the earliest stages of oxidation.
