Preparation of porous alumina ceramics by spark plasma sintering

Porous alumina bodies were successfully prepared by spark plasma sintering of alumina powders with different amounts of graphite, and by subsequently burning out the graphite. Highly porous bodies were fabricated by spark plasma sintering at 1000 degrees C for 3 min under a pressure of 30 MPa. The heating rate was 80 degrees C/min, and the pulse pattern (on-off) was 12:2. For example, alumina bodies prepared by the addition of 10 similar to 30 vol% graphite showed high porosity of 50 similar to 57%. Porous alumina bodies prepared by the addition of 10 similar to 30 vol% graphite had a high compressive strength of 200 +/- 55 MPa, about 35 times higher than those obtained on samples prepared by pressureless sintering, and about 2.5 times higher than those in samples prepared by hot-pressing. The significant improvement in strength relative to values obtained with conventional sintering was attributed to better sintering resulting from the rapid heating between particles.