Starch consolidation of alumina: Fabrication and mechanical properties

A consolidation technique based on gelling property of starch was used to prepare alumina ceramics. Slurry containing alumina powder, dispersant and small amount of starch (2–3.5 wt.% of powder weight) was cast into a nonporous mould and heated to gelation temperature to produce a rigid green body. A defect free green body was obtained and the total linear shrinkage during drying was 2–3% and the green density observed was 64% of theoretical value. After complete drying, ceramic compacts were sintered without debinding operation. Sintered density of 99.4% was achieved after sintering at 1600 °C for 2 h. Flexural strength values of dried and sintered alumina were ∼10 and 247 MPa, respectively. The sintered ceramics showed an extremely dense microstructure.