Electrical conductivity of Cu/(10NiO-NiFe₂O₄) cermet inert anode for aluminum electrolysis

Abstract

Cu/(10NiO-NiFe₂O₄) cermets containing mass fractions of Cu of 5%, 10%, 15% and 20% were prepared, and their electrical conductivities were measured at different temperatures. The effects of temperature and content of metal Cu on the electrical conductivity were investigated especially. The results indicate that the metallic phase Cu distributes evenly in 10NiO-NiFe₂O₄ ceramic matrix. The mechanism of electrical conductivity of Cu/(10NiO-NiFe₂O₄) cermets obeys the rule of electrical mechanism of semiconductor, the electrical conductivity for cermet containing 5% Cu increases from 2.70 to 20.41 S/cm with temperature increasing from 200 to 900 °C. The change trend of electrical conductivity with temperature is similar with each other and it increases with increasing temperature and content of metal Cu. At 960 °C, the electrical conductivity of cermet increases from 2.88 to 82.65 S/cm with the content of metal Cu increasing from 0 to 20%.

Keywords

NiFe₂O₄ / NiO / cermet / inert anode / aluminum electrolysis / electrical conductivity

References

[1] PawlekR. P.. Inert anodes: An update[C]. Schneider W. Light Metals 2002, 2002, Warrendale, PA, TMS: 449-456

[2] SadowyD. R.. Inert anode for the Hall-Héroult cell: The ultimate materials challenge[J]. JOM, 2001, 53(5): 34-35

[3] OlsenE., ThonstadJ.. The behaviour of nickel ferrite cermet materials as inert anodes[C]. HALE W. Light Metals 1996, 1996, Warrendale, PA, TMS: 249-257

[4] OlsenE., ThonstadJ.. Nickel ferrite as inert anodes in aluminium electrolysis: Part I. Material fabrication and preliminary testing[J]. Journal of Applied Electrochemistry, 1999, 29(3): 293-299

[5] MarkG., MargaretH.. Laboratory-scale performance of a binary Cu-Al alloy as an anode for aluminium electrowinning[J]. Corrosion Science, 2006, 48: 2457-2469

[6] JentoftsenT. E., LorentsenO. A., DewingE. W., et al.. Solubility of iron and nickel oxides in cryolite-alumina metals[C]. ANJIER J L. Light Metls 2001, 2001, Warrendale, PA, TMS: 455-460

[7] LaiY.-q., TianZ.-l., QinQ.-w., et al.. Solubility of composite oxide ceramics in the melt of Na₃AlF₆-Al₂O₃[J]. Journal of Central South University of Technology: Natural Science, 2003, 34(3): 245-248

[8] McleodA. D., LihrmanJ. M., HaggertyJ. S., et al.. Selection and testing of inert anode materials for Hall cells[C]. ZABREZNIK R D. Light Metals 1987, 1987, Warrendale, PA, TMS: 357-365

[9] WangC.-f., LiG.-xun.. Influence of metal additives on the electrical conductivities of the oxide ceramics as an electrode material[J]. Rare Metals, 1993, 12(2): 126-130

[10] YuY.-x., YangB.-g., YuX.-j., et al.. Electrical conductivities of zinc ferrite and nickel ferrite spinels material at high temperature[J]. The Chinese Journal of Nonferrous Metals, 1998, 8(S2): 336-337

[11] ElshoraA. I., ElhitiM. A., ElnimrM. K., et al.. Semiconductivity in Ni_1+xMn_xFe_2−2xO₄ ferrites[J]. Journal of Magnetism and Magnetic Materials, 1999, 204(1): 20-28

[12] LaiY.-q., DuanH.-n., LiJ., et al.. On the corrosion behaviour of Ni-NiO-NiFe₂O₄ cermets as inert anodes in aluminium electrolysis[C]. KVANDE H. Light Metals 2005, 2005, Warrendale, PA, TMS: 529-534

[13] WeyandJ. D., DeyoungD. H., RayS. P., et al.. Inert anodes for aluminium smelting[R]. PA 15069, 1986, Washington D C, Aluminum Company of America

[14] ZhangG., LaiY.-q., TianZ.-l., et al.. Preparation of nickel ferrite based cermets for aluminum electrolysis[J]. Journal of Material Science and Engineering, 2003, 21(4): 44-47

[15] QinQ.-w., LaiY.-q., XiaoJ., et al.. Preliminary testing of NiFe₂O₄-NiO as ceramic matrix of cermet inert anode in aluminum electrolysis[J]. Transactions of Nonferrous Metals Society of China, 2003, 13(5): 1208-1212

[16] SuM.-zeng.Solid State Chemistry[M], 1987, Beijing, Peking University Press: 92-97