Optimization of the tape casting process for development of high performance alumina ceramics

The preparation of concentrated suspensions with high stability is crucial for tape casting . Dispersant plays an important role in the developing of high solid loading slurries with low viscosity. In this study, castor oil, phosphate ester and castor oil phosphate were selected as dispersants for alumina suspensions. The interaction between dispersant and alumina powders was characterized in terms of adsorption and viscosity measurements. Results showed that castor oil phosphate is more effective dispersant for alumina slurries. The influence of dispersant content, binder content, plasticizer/binder ratio and solid loading on the green sheet and mechanical properties of as-sintered alumina samples were also investigated. It was shown that the optimized formulation for dispersant, binder, plasticizer/binder ratio and solid loading was 2.22   wt%, 5.90   wt%, 1.0 and 31   vol%, respectively. Alumina ceramics showed improved mechanical properties, with the indentation hardness and fracture toughness as 15.91±0.15   GPa and 4.29±0.06   MPa   m 1/2 , respectively.