Dry pressing boehmite gels for the fabrication of monolithic alpha-Al2O3

It is demonstrated that dense alpha alumina can be fabricated by pressing ethanol-dispersed, alpha-Al2O3 seeded boehmite. Green bodies were formed by uniaxially pressing either water or ethanol dispersed gel powder and then isostatically pressing the compacts at 280 MPa. Green microstructure and alumina densification are correlated with gel agglomerate size and dispersing medium. The ethanol-dispersed specimens showed better sinterability than the water-dispersed specimens, and sintered to more than 99% theoretical density at 1300 degrees C. It is shown that softer gel agglomerates were obtained by alcohol dispersion and resulted in better green microstructure and higher sintered density.