Sintered microstructure and mechanical properties of high purity alumina ceramics made by high-speed centrifugal compaction process

An alumina powder with a purity of 99.99 % and an average particle size of 0.22 μ m, which is dispersed into a slip, and compacted under a centrifugal force of 10-20 kG. The compact can sinter at a rather low temperature of 1503 K in 5.4 ks to give superior mechanical properties with no additive, and retains a homogeneous microstructure in a wide range of sintering conditions up to 1773 K for 5.4 ks. The highest value of the four-point bending strength of this newly developed alumina is 975 MPa, which is about 1.3 times higher than that of the alumina made of the same starting material and sintered to the same porosity and to the same grain size.