Studies on Processing and Characteristics of Iron Carbides

本研究以N_2稀释的CO气体为反应气体，对氧化铁或α-Fe进行碳化，制备出结构清晰的碳化铁颗粒和薄膜，并对其基本性能进行了研究。Fe_5C_2在300 ~ 400 ℃时形成主相。在400 ℃以上可以合成单相Fe_3C。碱金属或碱土金属的加入是合成Fe_7C_3颗粒的关键，通过对针状α-Fe颗粒与CO气体反应合成的针状Fe_3C颗粒进行处理，可以改善其磁性和矩形度。采用磁控溅射法，在Fe/C复合靶上成功地制备了Fe 3C薄膜。在350 ℃、Ar气压为5 Pa的条件下合成了单相Fe_3C薄膜，其饱和磁化强度为100 ~ 120 emu/g，矫顽力为250 Oe，具有纵向磁化方向。

In this research, the processing and the characteristics of iron carbides particles and films were investigated in detail in order to elucidate the basic properties for their application to a magnetic recording material.CO gas diluted with N_2 was found to be a very effective reactive gas for carburization of iron oxides or alpha-Fe to produce the well-defined iron carbides. Fe_5C_2 formed as a major phase at temperatures from 300 to 400^ﾟC. Fe_3C could be synthesized above 400^ﾟC as a single phase. The addition of alkali or alkaline earth to iron oxide particles was found to be a key to synthesize Fe_7C_3 particles.The improvement of the coercivity and the squareness of the magnetic characteristics could be achieved by the processing of acicular Fe_3C particles, which were synthesized from acicular alpha-Fe particles with CO gas. Their saturation magnetization, the coercivity and the squareness were 100 emu/g, 700 Oe and 0.4, respectively.Fe_3C thin films could successfully be synthesized by the controlled RF-magnetron sputtering with a composite target of Fe/C. The optimum condition to synthesize the single phase Fe_3C films found to be as follows ; temperature, 350^ﾟC, Ar pressure, 5 Pa.The saturation magnetization and the coercivity of the Fe_3C films were from 100 to 120 emu/g and 250 Oe, respectively, The films exhibits a longitudinal magnetization direction.