Dm. Liu et al., Interdependence between green compact property and powder agglomeration and their relation to the sintering behaviour of zirconia powder, CERAM INT, 25(6), 1999, pp. 551-559
Interdependence of green density and corresponding powder agglomeration and
their influence on the sintering behaviour of commercial fine zirconia pow
ders under a constant rate of heating (non-isothermal sintering) were inves
tigated. Agglomeration of the powder was controlled by different time perio
ds of ball-milled processing and was defined as the size ratio of sedimenta
tionally measured particle size to the size of primary particles which were
microscopically-determined (hereinafter termed agglomeration parameter or
AP). Green compact density shows to be approximately linearly related to po
wder agglomeration under identical consolidation technique, which is decrea
sed with increasing degree of agglomeration. Both the green density and pow
der agglomeration affect sintering behaviour over entire sintering schedule
. For a given AP the shrinkage rate reduces with increasing green compact d
ensity and vice versa, which is consistent with the literatured reports. Th
e experimental results also showed that compacts with identical starting de
nsity showed a lower shrinkage rate when the compacts contained less agglom
eration (i.e. low AP) than does for high-AP compacts. However, a higher end
-point density can be obtained for low-AP compacts, suggesting a better pac
king structure of the powders. The use of agglomeration parameter defined c
urrently, which is taken as an indication of the level of powder agglomerat
ion in commercial fine ceramic powders, is likely to provide some useful un
derstanding in characterising the sintering behaviour and possibly potentia
l evolution of sintered microstructure on sintering. (C) 1999 Elsevier Scie
nce Ltd and Techna S.r.l. All rights reserved.