| The infiu,ence of soaking time on bhe densificatrion of the compacts of thoria
ha,r, been studied at sintering temperatures of i300° to 1550° C. Same thoria.
powders used in the earlier investigation were used for this studyi1
; they were
prepared by thermal decomposition of thorium compounds. I ncr ease in the soaking
time recSuVted in significant drop, in density during a specific period for each
of the powders.
The maximum ,density attained, the extent of drop vn density anjd the period
at which it occurs are related to the optimum sintering temptera:ture of the thoria
powder. No such changes in den1sity were noticed during vacuum sintering, of the
same powders . .
This change in densification due to varying sintering conditions has been
explained to be due to entrapment of porosity during heating) to the sint.ering
temperature; the pressure exerted by the gaJes in the Pores on the vitreous matrix,
results in an enhancement of pore size and lowering of bulk density. Gradual
elimination of gases in pores by diffusion results in gmdual improvement of densification.
The microstructures of sintered compacts are in agreement with the
explanation. |
