PORE-SIZE DISTRIBUTION DURING COMPACTION AND EARLY STAGE SINTERING OF SILICON-NITRIDE

The effect of a number of compaction parameters on the pore size distribution in silicon nitride powder compacts has been investigated by mercury porosimetry. The powder was compacted in a uniaxial die and the parameters of interest included uniaxial load, loading rate, polymer additives and stress relaxation. The use of a low-viscosity polymer solution as a lubricant, the allowance of stress relaxation following loading and heat treatment above the glass transition temperature of the polymer lead to a more uniform pore size distribution in the green samples. The more uniform green samples, in turn, showed a more uniform pore size distribution after initial stage sintering. The potential of the present techniques for improving the microstructural uniformity in ceramic bodies is discussed. © 1990 Chapman and Hall Ltd.