Electrolytic properties and element migration in Ni–TiB2/Al2O3 composite cathode

Abstract

With alumina sol as binder and Ni metal as sintering aids, the Ni–TiB2/Al2O3 composite cathode material for aluminum electrolysis was prepared by cold-pressed sintering. The mechanical properties of the composite cathode material were measured. Its electrolytic properties were identified by a 20-A electrolysis test. Cathode samples before and after electrolysis test were measured by energy-dispersive spectroscopy (EDS). The migration behavior of various elements in the electrolysis process was studied by phase analysis. The result shows that Ni metal can effectively fill the gap between the aggregate during the sintering process, which can improve the sintering density of the composite cathode material significantly. The voltage of the 20-A electrolysis test is stable. The impurity of aluminum liquid is 0.42%. The aluminum liquid can wet the cathode surface effectively, and the Ni–TiB2/Al2O3 composite is an ideal wettable cathode material. In the process of electrolysis, the alkali elements in the electrolyte penetrate the electrode, where K goes deeper than Na. Al generated on the cathode surface will also penetrate the cathode through the gap of the composite material, while Ni in the electrode will spread into the aluminum liquid layer.