Pa. Smith et al., MICROSTRUCTURAL CHARACTERIZATION OF ALUMINA AND SILICON-CARBIDE SLIP-CAST CAKES, Journal of the American Ceramic Society, 79(10), 1996, pp. 2515-2526
The effect of solids loading, particle-size distribution, and suspensi
on viscosity on the resultant microstructure of slip-cast monolithic c
eramics prepared from aqueous suspensions of alumina and silicon carbi
de was studied, Unimodal alumina suspensions (average particle size =
0.6 mu m) were prepared at 35, 37, and 42 vol%. Silicon cal bide suspe
nsions (average particle size = 0.7 mu m) were produced with different
quantities of dispersant at 37 vol%. Similarly, aqueous alumina suspe
nsions of 42 and 50 vol% were produced with a bimodal particle-size di
stribution. The slip-cast microstructures were characterized by mercur
y porosimetry and small-angle neutron scattering, which provided pore
size (distribution), pore fraction, and pore morphology, Essentially,
the combination of these techniques deciphered packing differences obt
ained in the cake microstructures, For the alumina cakes produced from
the 35, 37, and 42 vol% suspensions, the individual characterization
techniques? mercury intrusion, and the neutron scattering measurements
showed that the cake microstructures mere similar in pore size and qu
antity, However, comparison of the techniques and their assumptions sh
owed differences in the pore shape, Mercury porosimetry and neutron sc
attering showed bimodal porosity for the cake produced from a mixture
of 85% 6-mu m particles and 15% 0.6-mu m particles, Pore volume fracti
on and pore size increasers mere correlated with increased viscosity i
n the silicon carbide suspensions, In addition, the silicon carbide ca
ke microstructures were measured, and homogeneity was evaluated as a f
unction of position in the cast.