Back
 MSA  Vol.10 No.9 , September 2019
Electrochemical Degradation Mechanism of a Cermet Anode for Aluminum Production
Abstract: Tests on (NixFeyO4 - Ni1?xFexO)/(CuxNiyFez) cermets, considered as promising anode for the aluminium production, were performed under electrolysis at 0.8 A·cm-2 in molten mixture of cryolite at 960°C. In order to predict phase compositions, a thermodynamic study was performed and experimentally verified by SEM-EDS analysis. The metallic phase oxidation leads to the formation of different phases such as FeF2, Ni0.90Fe0.10O, NiF2 and Cu2O phases, while NixFe3-xO4 spinel is continuously enriched up to x = 0.90, the thermodynamically stable nickel composition. When the cermet material is fully oxidized, metallic and oxide phases are converted into soluble or non-conductive phases, leading to the end of anode service life.
Cite this paper: Meyer, P. , Massot, L. , Gibilaro, M. , Bouvet, S. , Laurent, V. , Marmottant, A. and Chamelot, P. (2019) Electrochemical Degradation Mechanism of a Cermet Anode for Aluminum Production. Materials Sciences and Applications, 10, 614-629. doi: 10.4236/msa.2019.109044.
References

[1]   Charles-M. (1889) Hall. US Patent No. 400766.

[2]   Pawlek, R.P. (2002) Inert Anodes: An Update. In: Grandfield, J., Ed., Light Metals, Springer, Cham, 449-456.

[3]   Oudot, M., Cassayre, L., Chamelot, P., Gibilaro, M., Massot, L., Pijolat, M. and Bouvet, S. (2014) Layer Growth Mechanisms on Metallic Electrodes under Anodic Polarization in Cryolite-Alumina Melt. Corrosion Science, 79, 159-168.

[4]   Helle, S., Pedron, M., Assouli, B., Davis, B., Guay, D. and Roué, L. (2010) Structure and High-Temperature Oxidation Behaviour of Cu-Ni-Fe Based Alloys Prepared by High-Energy Ball Milling for Application as Inert Anodes Fort Aluminum Electrolysis. Corrosion Science, 52, 3348-3355.
https://doi.org/10.1016/j.corsci.2010.06.011

[5]   Gallino, I., Kassner, M.E. and Busch, R. (2012) Oxidation and Corrosion of Highly Alloyed Cu–Fe–Ni as Inert Anode Material for Aluminum Electrowinning in as-Cast and Homogenized Conditions. Corrosion Science, 63, 293-303.
https://doi.org/10.1016/j.corsci.2012.06.013

[6]   Olsen, E. and Thonstad, J. (1999) Nickel Ferrite as Inert Anode in Aluminium Electrolysis: Part II-Material Performance and Long-Term Testing and Preliminary Testing. Journal of Applied Electrochemistry, 29, 301-311.
https://doi.org/10.1023/A:1003464304488

[7]   Zarrabian, P., Kalantar, M. and Ghasemi, S.S. (2014) Fabrication and Characterization of Nickel Ferrite Based Inert Anodes for Aluminum Electrolysis. Journal of Material Engineering Performance, 23, 1656-1664.
https://doi.org/10.1007/s11665-014-0914-y

[8]   Pawlek, R.P. (2014) Inert Anodes: An Update. In: Grandfield, J., Ed., Light Metals, Springer, Cham, 1309-1313.
https://doi.org/10.1007/978-3-319-48144-9_219

[9]   Tian, Z.L., Lai, Y.Q., Li, J., Li, Z.Y., Zhou, K.C. and Liu, Y.X. (2008) Effect of Cu-Ni content on the Corrosion Resistance of (Cu-Ni)/(10NiO-90NiFe2O4) Cermet Inert Anode for Aluminum Electrolysis. Acta Metallurgica Sinica, 21, 72-78.
https://doi.org/10.1016/S1006-7191(08)60022-8

[10]   Ray, S.P. (1980) Composition for Inert Electrodes, Aluminum Company of America. US Patent No. 4399008.

[11]   Ray, S.P. (1980) Inert Electrode Formulation, Aluminum Company of America. US Patent No. 4374761.

[12]   Tarcy, G.P. (1986) Corrosion and Passivation of Cermet Inert Anodes in Cryolite-Type Electrolytes. In: Grandfield, J., Ed., Light Metals, Springer, Cham, 309-320.

[13]   Weyand, J.D., Deyoung, D.H., Ray, S.P., Tarcy, G.P. and Baker, F.W. (1985) Inert Anodes for Aluminium Smelting. Aluminium Company of America, Final Report.

[14]   Lai, Y.Q., Tian, Z.L., Li, J., Ye, S.L. and Liu, Y.X. (2006) Preliminary Testing of NiFe2O4-NiO-Ni Cermet as Inert Anode in Na3AlF6-AlF3 Melts. Transactions of Nonferrous Metals Society of China, 16, 654-658.
https://doi.org/10.1016/S1003-6326(06)60116-7

[15]   Tian, Z.L., Lai, Y.Q., Li, J. and Liu, Y.X. (2008) Effect of Ni Content on Corrosion Behaviour of Ni/10NiO-90NiFe2O4) Cermet Inert Anode. Transactions of Nonferrous Metals Society of China, 18, 361-365.
https://doi.org/10.1016/S1003-6326(08)60063-1

[16]   Liu, J.Y., Li, Z.Y., Tao, Y.Q., Zhang, D. and Zhou, K.C. (2011) Phase Evolution of 17(Cu-10Ni)-(NiFe2O4-10NiO) Cermet Inert Anode during Aluminum Electrolysis. Transactions of Nonferrous Metals Society of China, 21, 566-572.
https://doi.org/10.1016/S1003-6326(11)60752-8

[17]   He, H.B., Wang, Y., Long, J.J. and Chen, Z.H. (2013) Corrosion of NiFe2O4-10NiO-Based Cermet Inert Anodes for Aluminium Electrolysis. Transactions of Nonferrous Metals Society of China, 23, 3816-3821.
https://doi.org/10.1016/S1003-6326(13)62934-9

[18]   Tian, Z., Lai, Y., Yang, S., Li, J., Hwang, J.Y. and Liu, Y. (2015) Anodic Corrosion Behavior of NiFe2O4-Based Cermet in Na3AlF6-K3AlF6-AlF3 for Aluminum Production. Metallurgical and Materials Transactions B, 46, 1257-1261.
https://doi.org/10.1007/s11663-015-0328-8

[19]   Meyer, P., Gibilaro, M., Massot, L., Pasquet, I., Tailhades, P., Bouvet, S., Chamelot, P. (2018) Influence of Ni Content on NixFe3-xO4 Spinel Chemical Stability in Molten Fluorides. Materials Science and Engineering B, 228, 117-122.
https://doi.org/10.1016/j.mseb.2017.11.025

[20]   Chamelot, P., Lafage, B. and Taxil, P. (1996) Studies of Niobium Electrocrystallization Phenomena in Molten Fluorides. Journal of Electrochemical Society, 143, 1570-1576.
https://doi.org/10.1149/1.1836681

[21]   Sterten, A. (1980) Structural Entities in NaF-AlF3 Melts Containing Alumina. Electrochimica Acta, 25, 1673-1677.
https://doi.org/10.1016/0013-4686(80)80021-1

[22]   Gilbert, E., Robert, E., Tixhon, J.E. and Ostvold, O.T. (1995) Acid-Base Properties of Cryolite Based Melts with CaF2, MgF2 and Al2O3 Additions. In: Grandfield, J., Ed., Light Metals, Springer, Cham, 181-194.

[23]   Kelly, M., Zanghi, D., Salanne, M., Stabrowski, V. and Bessada, C. (2018) Anionic Structure in Molten Cryolite-Alumina Systems. Journal of Physical Chemistry, 122, 21807-21816.
https://doi.org/10.1021/acs.jpcc.8b06905

[24]   M. Oudot, L. Cassayre, P. Chamelot, M. Gibilaro, L. Massot, M. Pijolat, S. Bouvet (2014) Layer Growth Mechanisms on Metallic Electrodes under Anodic Polarization in Cryolite-Alumina Melt. Corrosion Science, 79, 159-168.
https://doi.org/10.1016/j.corsci.2013.10.040

[25]   Massot, L., Cassayre, L., Chamelot, P. and Taxil, P. (2007) On the Use of Electrochemical Techniques to Monitor Free Oxide Content in Molten Fluoride Media. Journal of Electroanalytical Chemistry, 606, 17-23.
https://doi.org/10.1016/j.jelechem.2007.04.005

[26]   Cassayre, L., Chamelot, P., Arurault, L., Massot, L. and Taxil, P. (2008) Oxidation of Stoichiometric Nickel Ferrites Used as Inert Anodes for Aluminium Electrolysis in Molten Cryolite Mixtures. Materials Science Forum, 595-598, 593-600.
https://doi.org/10.4028/www.scientific.net/MSF.595-598.593

[27]   Corso, S. (2004) Elaboration et caractérisation de céramiques à base de ferrites de nickel. Etude de leurs propriétés en vue de la conception d’anodes inertes de type oxydes ou cermets destinées à l’électrolyse de l’aluminium, PhD Thesis, Université Paul Sabatier Toulouse.

[28]   Morin, F.J. (1954) Electrical Properties of NiO. Physical Review Journals Archive, 93, 1199-1204.
https://doi.org/10.1103/PhysRev.93.1199

[29]   Lorentsen, O. (2000) Behaviour of Nickel, Iron and Copper by Application of Inert Anodes in Aluminum Production. Norwegian University of Science and Technology, Trondheim.

 
 
Top