Influence of Additives on Compaction Behaviour of SiC Powders

Abstract

Using ultrafine SiC powder as the model system in the present work, an attempt has been made to analyze the influence of additives (Al, C, Si₃N₄) on green density. The pressure-density plots were generated for the uniaxial mode of compaction in the range of 30-300 MPa, for both pure powders and those containing 20 wt% additives. A linear dependence was observed for the pure system which is characteristic for a soft agglomerate powder mass. In contrast, for the additive-containing powder, the density profile deviated from linearity above a critical pressure. From these plots, the effective agglomerate strength was evaluated as 196 MPa for the powder mix employed. Change in density on subsequent isostatic pressing was also studied for both types of powders. The dual compaction treatment was observed to be more effective for the multicomponent system in terms of percentage enhancement in green density.