Synthesis of high functional Fe compound thin films NAME

近年来，人们开始考虑将Fe_3C应用于超级钢材料和低环境负荷的钢铁材料。虽然钢是最古老的使用材料之一，但铁的氧化物、氮化物和碳化物的基本性质尚未完全了解。本课题组在国内首次成功地制备了单相Fe_3C薄膜。采用电子束轰击法，测定了Fe_3C（Hv1180O）的硬度和硬度随温度的变化关系，发现Fe_3C是一种亚稳相，在室温下表面仍为非晶态氧化膜。Fe_3C的耐腐蚀性是普通铁的2倍，但这种非晶态氧化膜阻止了铁的腐蚀。结果表明，Fe_3C在室温下形成了铁的保护膜。珠光体中Fe_3C不仅薄膜被氧化，而且其表面也被氧化。因此，在评价Fe_3C的性能时，必须十分小心。我们还首次制备了（Fe，Ni）_3C薄膜。Ni/Fe比为0.05-0.1时，薄膜的饱和磁通密度为纯Fe_3C的1.4倍，居里温度提高20-30K，硬度提高1.3倍。因此，第三种元素的加入改善了Fe_3C的性能。Ni含量的进一步增加导致性能劣化，因为Ni不能完全溶解。(Fe（Ni）_3C膜的耐蚀性与铁相当，但金属Ni的存在使膜的耐蚀性显著下降。真空蒸镀法和活化反应蒸镀法制备的α-Fe_2O_3薄膜附着力差，不能作为保护膜。而电子束溅射法制备的α-Fe_2O_3薄膜没有剥落现象，可以作为保护膜使用。此外，铁离子经电子簇射后，其抗氧化能力下降。铁基体表面存在的FeO是其原因。电子束辐照有望成为一种新的抗铁腐蚀方法。

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.