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采用真空感应熔炼法制备铝电解用Fe-40Cr-2Ce合金阳极。研究了合金阳极900℃下的氧化和电解腐蚀行为。电解测试采用900℃的NaF-AlF3低温电解质体系,阳极电流密度为0.5 A/cm2,电解时间10 h。结果表明:合金的氧化动力学曲线遵循抛物线规律;合金中高浓度的Ce形成晶界沉淀,造成Ce的“活性元素效应”失效。电解后的阳极表面生成连续的FeCr2O4尖晶石相氧化膜。根据热腐蚀酸-碱溶解机理,氧化物在氧化物/电解质界面上的溶解度负梯度造成了阳极表面氧化物的持续的溶解。电解质中高浓度的氧化铝有利于减缓氧化膜的酸性溶解,降低合金阳极的电解腐蚀速率。
Preparation of Fe-40Cr-2Ce Alloy Anode for Aluminum Electrolysis by Vacuum Induction Melting. The oxidation and electrolytic corrosion behaviors of the alloy anode at 900 ℃ were investigated. Electrolysis test using 900 ℃ NaF-AlF3 cryogenic electrolyte system, the anode current density of 0.5 A / cm2, electrolysis time 10 h. The results show that the oxidation kinetics curve of the alloy obeys the parabolic law. The high concentration of Ce in the alloy forms grain boundary precipitation, resulting in the failure of the “active element effect” of Ce. After the electrolysis anode surface to generate a continuous FeCr2O4 spinel phase oxide film. According to the hot-corrosive acid-base dissolution mechanism, the negative gradient of the solubility of the oxide at the oxide / electrolyte interface causes continued dissolution of the oxide on the surface of the anode. The high concentration of alumina in the electrolyte helps to slow down the acidic dissolution of the oxide film and reduce the electrolytic corrosion rate of the alloy anode.