Pressure slip casting of bimodal silicon carbide powder suspensions

Two silicon carbide powders with different particle size distributions were blended in various proportions and then dispersed in aqueous media with a deflocculant. Bodies were consolidated from these suspensions via pressure slip casting. The relative density and the water content of the green bodies were measured and the optimum body in terms of packing ability was then chosen to evaluate the effects of: (i) the amount of deflocculant, (ii) the casting time on deposition rate, (iii) the microstructure of the consolidated layers. The results showed that the proportion between coarse and fine powders that produced a maximum packing density is independent of applied casting pressure but that the packing degree is normally lower than that obtained by normal slip casting. The amount of deflocculant required to maximise the green density within pressure casting was found to be higher in comparison with slip casting. Further, as the casting time increased the packing density continuously improved. These results may be interpreted in terms of deposition rate and time allowed for particle rearrangements. (C) 1999 Elsevier Science Ltd and Techna S.r.l. All rights reserved.