Synthesis of high functional Fe compound thin films NAME

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Recently, application ofcementite (Fe_3C) to supersteel materials and to steel materials with low environmental load are considered. While steel is one of the oldest used materials fundamental properties of iron oxides, nitrides, and carbides are not fully understood. Our group was the first to succeed in producing single-phase Fe_3C film. Electron shower method was used, and hardness of Fe_3C (Hv1180O) and temperature dependency of hardness were obtained.Fe_3C was also found out to be a metastable phase, and the surface became a amorphous oxide film even when kept at room temperature. Corrosion resistance of Fe_3C is two times greater than iron which is not so high, but this amorphous oxide film stopped corrosion of iron. As a result, Fe_3C became a protection film of iron in room temperature. Also, not only thin filmsbut surface of Fe_3C in pearlite oxidized in room temperature. Thus, thorough care is required in appreciating properties of Fe_3C. We were also the first to produce (Fe, Ni)_3C films. Compared to pure Fe_3C, films with Ni/Fe ratio 0.05-0.1 had 1.4 times saturation magnetic flux density, 20-30K higher Curie temperature, and 1.3 times hardness. Thus, an addition of a third elementimproved properties of Fe_3C. Further increase of Ni content resulted in deterioration of properties since Ni cannot completely dissolve. (Fe, Ni)_3C films had almost same corrosion resistance withiron but corrosion resistance fell remarkably in presence of Ni metal. α-Fe_2O_3 films produced by vacuum evaporation method andactivated reactive evaporation had low adhesion and is not a protective film. On the other hand, α-Fe_2O_3 films produced by electron-shower PVD method did not peel off at all and could be used as protective film. In addition, iron irradiated with electron shower did notrust. Existence of FeO on surface of iron substrate is suggested to be the reason. Electron shower irradiation is expected to be a new method to resist corrosion of iron.