Sintering of ultrafine acicular TiO2 powder

Sintering of ultrafine acicular rutile powders has been studied by a scanning mercury porosimeter, with scanning electron microscopy of powder compacts, and compared with an ordinary equiaxial powder. Acicular particles gave a relatively low green density of 50% of the theoretical value, but achieved high fired densities. This is in strong contrast to equiaxial powders, in which high fired densities were reached from a relatively high green density under the same firing conditions. Features observed with acicular particles have been interpreted as being due to the particle shape change.