Effect of additive BaO on corrosion resistance of xNi/10NiO-NiFe 2O4 cermet inert anodes for aluminium electrolysis

Abstract

xNi/10NiO-NiFe2O4 cermet and 1BaO-xNi/ (10NiO-NiFe2O4) cermet (x=5,10,17) inert anodes were prepared and their corrosion resistance to Na3AlF6-Al 2O3 melts was studied in laboratory electrolysis. The results show that many pores are produced and electrolytes are infiltrated inside inert anodes during electrolysis based on SEM/EDS of anode. The contamination level of nickle, iron and barium in the electrolyte reach steady state after some irregular behaviour early in the tests according to XRF of electrolyte. And the wear rate of 5Ni/(10NiO-NiFe2O4), 10Ni/(10NiO-NiFe2O4), 17Ni/(10NiO-NiFe2O 4), 1BaO-5Ni/(10NiO-NiFe2O4), 1BaO-10Ni/(10NiO-NiFe2O4) and 1BaO-17Ni/ (10NiO-NiFe 2O4) is 1.23 cm year-1,1.42 cm year-1,0.96 cm year-1,3.21 cm year-1,2.37 cm year-1 and 3.94 cm year-1, respectively. Thus, sintering agent BaO can effectively promote the densification of xNi/10NiO-NiFe 2O4 cermet(x=5,10,17) inert anodes, but the addition of 1wt.% BaO(mass fraction) to xNi/10NiO-NiFe2O4 cermet(x=5,10,17) inert anodes has negative effect on corrosion resistance, perhaps because additive BaO exists in the grain boundary, which accelerates the corrosion of xNi/10NiO-NiFe2O4 cermet(x=5,10,17) inert anode. © the authors.