FeAl金属间合金在熔融(Li,K)_2CO_3中的腐蚀电化学阻抗谱研究

STUDY ON ELECTRO CHEMICAL IMPEDANCE SPECTRUM OF FeAl INTERMETALLIC COMPOUND DURING CORROSION IN MOLTEN (Li,K)_2CO_3

采用电化学阻抗谱研究了ＦｅＡｌ 金属间化合物在６５０ ℃熔融（Ｌｉ，Ｋ）２ＣＯ３ 中的腐蚀行为。结果表明，在腐蚀初期，合金腐蚀电化学阻抗谱表现为典型的扩散控制的特征；随着腐蚀的进行，其电化学阻抗谱则由两个容抗弧组成。提出了相应的等效电路，解析了电化学阻抗谱，并讨论了合金腐蚀机制。

Electrochemical impedance spectrum (EIS) was employed to study the corrosion of FeAl in molten (Li,K) 2CO 3 at 650℃. It is shown that the EIS exhibited the characteristics of diffusion-controlled reaction at the initial corrosion stage, while it was composed of two capacitance loops during extended corrosion. The corrosion of FeAl at the initial stage was controlled by the diffusion of oxidants O 2 and O 2 2 formed by the chemical dissolution of oxygen in the melt. The concentration of O 2 at the scale/melt interface generated by the reduction of O 2 and O 2 2 tended to increase, which might promote the reaction of Fe 2O 3 grown on FeAl with Li 2O, forming LiFeO 2. The formation of LiFeO 2 gave rise to a larger mass gain of FeAl, but provided a better protection to the alloy. With the formation of continuous external LiFeO 2 and inner Al 2O 3 layer, the corrosion of FeAl was controlled by the transfer of the charged particles through the scale. Corresponding equivalent circuits were also proposed to fit the EIS of FeAl.