Sintering of mixtures of seeded boehmite and ultrafine alpha-alumina

alpha-Alumina was fabricated by dry pressing mixtures of seeded boehmite an d fine alpha-alumina (i.e., 0.2 and 0.3 mu m diameter) to reduce the large shrinkage of boehmite-derived alpha-alumina. The maximum green density was obtained with mixtures containing similar to 70% alpha-alumina for both alu mina powders. The similar to 15% linear shrinkage and microstructures of th ese samples were comparable to 100% alumina powder samples. Samples with 0. 2 mu m alumina sintered to densities >95% at 1300 degrees C whereas 1400 de grees C was needed for samples with 0.3 mu m alumina. These results indicat e that boehmite can be used as a substitute for relatively expensive ultraf ine alpha-alumina powders.