Study On Preparation Technique Of TiB₂/Al₂O₃ Composite Cathode

The new technology for aluminum smelting based on inert anode, is expected to greatly reduce energy consumption and eliminating green-house gas release. The inert cathode is the key and prerequisite for successfully empoldering the new aluminum electrolysis technology.Funded by the National High Technology Research and Development Program (863 project), with the aim of developing satisfactory inert wettable cathode material for aluminum electrolysis, TiB2/Al2O3 composite cathode is taken as the research object. In order to improve the properties of composite cathode, the effects of preparation and compose on the bulk density, porosity, compressive strength, bending strength, thermal shock resistance of composite cathode were investigated. The grain composition of composite cathode was obtained. The main work and achievements are as follows:(1) The mixing process of the carbon fiber pre-dispersion combination with ball mill was determined. Compare with direst blending, the bulk density of composite cathode prepared by optimized mix process improved 9.5%, porosity decrease 16.18%, compressive strength and bending strength improved 49.28%,162.18%, respectively.(2) The composition of composite cathode was obtained. With the increase of TiB2 mass fraction, the bulk density, porosity, compressive strength, bending strength of composite cathode were optimized; With the increase of colloidal mass fraction and carbon fiber mass fraction increased; the bulk density, compressive strength, bending strength, thermal shock resistance of composite cathode first increase then reduce, the porosity of composite cathode first reduces then increases。The composite cathode prepared by the best composition (colloidal alumina 50wt%, TiB210wt%, corundum 40wt%, match outside carbon fiber 1.5wt%), has a bulk density of 2.72g/cm3, a porosity of 29.88%, a compressive strength of 38.75MPa, a blend strength of 21.39MPa, a residual anti-flexural strength of 5.11MPa, a strength retention rate of 23.89%.(3) The optimum grain composition of composite cathode was obtained:large corundum particle (0.6-0.7mm) 42wt%, secondary corundum particle (R=5) 18wt%, corundum powder 20wt%, TiB2 powder 20wt%。The composite cathode prepared has a bulk density of 2.92g/cm3, a porosity of 24.16%, a compressive strength of 42.33MPa, a blend strength of 24.78MPa.