The effect of methane decomposition on the formation and magnetic properties of iron carbide prepared from oolitic hematite

Abstract

A chemical metallurgical method was used to prepare iron carbide from high phosphorus oolitic hematite in an atmosphere of H₂/CH₄. The relationship between the rate of methane decomposition and the iron carbide formation was discussed by using the Mossbauer spectrum to accurately determine the content change of iron carbide with time in the carburized product. Moreover, the carburized samples were characterized by transmission electron microscopy (TEM), Raman spectroscopy and X-ray diffraction (XRD), and the magnetic properties were examined by a vibrating sample magnetometer (VSM). The results show that 1023 K is the optimum temperature for iron carbide preparation from high phosphorus oolitic hematite. After deep reduction in the initial period of contact with CH₄, the conversion of deposited carbon to the iron carbide rises rapidly, and then declines quickly. A polycrystalline electron diffraction analysis reveals that iron carbide, graphite and quartz are in the carburized sample. The iron carbide prepared from high phosphorus oolitic hematite in an H₂/CH₄ atmosphere is a soft magnetic material with relatively high magnetic properties.