ε-Fe2.2C超微粒子の合成とその磁気特性(II)

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We report the preparation processes and magnetic properties of ε iron carbide ultrafine particles. Ultrafine particles of δ-FeO(OH) and CoFe2O4 were selected as starting materials for ε iron carbide ultrafine particles. δ-FeO(OH) particles and CoFe2O4 particles were coated with SiO2 for preventing agglomeration of particles during heating. δ-FeO(OH) particles were heated at 450°C for 3h in air to be transformed into a-Fe2O3. The α-Fe2O3 particles were granular and a little sintered in spite of SiO2 coating. After α-Fe2O3 and CoFe2O4 were reduced to metal, α-Fe metal and alloy particles were respectively carburized at 210°C for 4h in the mixing gas flow of CO and H2 in the volume ratio of 1/4. XRD patterns reveal that both particles are ε iron carbide single phase. Both of ε iron carbide phase particles were granular and 20-30nm in diameter. The saturation magnetizations of the ε iron carbide ultrafine particles obtained from starting materials of δ-FeO(OH) and CoFe2O4 were 65 and 69 emu/g respectively, while the coercive forces were 1200 and 1270 Oe.
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