反応性イオンプレーティング法によるFe窒化物薄膜の作製とその耐食性評価

抄録

Transition metal nitrides have been used as corrosion resistant materials in recent years. To evaluate the corrosion resistance of iron nitride, iron nitride films having various compositions were produced by reactive ion plating. At a constant electron beam current the nitrogen content of the product film tended to increase as the flow rate of N₂-H₂ as the reactive gas increased. A decrease in the electron beam current used to evaporate the iron also led to an increase in the nitrogen content of the product film. X-ray diffraction showed that 7.3∼24.7 at % N nitride films had a mixed structure of α-Fe and γ′-Fe₄N, while at 26.6 at % N the films were single phase ε-Fe₃N. The amount of dissolved iron from the iron nitride film decreased with increasing nitrogen content. Corrosion of ε-Fe₃N film was apparently inhibited in 1.0kmol·m^-3 NaCl at 333K. For specimens with a mixed structure of α-Fe and γ′-Fe₄N, corrosion occurred preferentially on α-Fe. It was presumed that a portion of the α-Fe dissolved as an anode and that in this solution the reaction proceeded via a chloride as an adsorbed intermediate.