The role of CuO-TiO2 additives in the preparation of high-strength porous alumina scaffolds using directional freeze casting

Lamellar porous Al2O3 scaffolds with initial solid loading of 30 vol% were prepared by freeze casting using micron-sized Al2O3 powders as raw material and CuO-TiO2 additives as sintering aid. The effects of the composition of CuO-TiO2 on the microstructure, porosity and compressive property of the Al2O3 scaffolds were investigated and the mechanisms for sintering promotion addressed. The sintering aid effect was prominent when CuO:TiO2 was 1:2 in mass and their amount reached 3 wt% of the total ceramic powders. The corresponding compressive strength reached 176 +/- A 20 MPa with the porosity being 45 +/- A 1 % after sintering at 1450 A degrees C for 2 h. Activation of the Al2O3 lattice due to partial substitution of Ti4+ for Al3+ and formation of a low-melting eutectic liquid were presumed to play a significant role in the sintering and strengthening of the Al2O3 scaffolds.