TY - JOUR
T1 - Comparison of different alumina powders for the aqueous processing and pressureless sintering of Al2O3-SiC nanocomposites
AU - Baron, B.
AU - Kumar, C. S.
AU - Le Gonidec, G.
AU - Hampshire, S.
PY - 2002/9
Y1 - 2002/9
N2 - Four different alumina powders, from European and Japanese sources having similar particle size (350-700 nm) were used for the fabrication of nanocomposites. They were compared in terms of green properties, sintering behaviour, microstructure and mechanical properties. The processing route used (attrition milling and freeze-drying) leads to a reduction in green density of the processed aluminas and composites compared to the as-received alumina. All powders had similar green properties except one, which contained a binder from the manufacturer. The presence of this binder led to the formation of hard agglomerates. In this case the pressing did not eliminate, totally, the inter-agglomerate pores, leading to an incomplete sintering. Calcining the powder to remove the binder resulted in similar pressing and sintering behaviour to the other powders and densities > 99% were achieved at 1750 °C by pressureless sintering. All the composites exhibited similar microstructures (matrix grain size 3 μm) and elastic properties, hardness and fracture toughness. A finer matrix microstructure could be obtained with one of the European powders which achieved 99% density at 1700 °C. The presence of 5 vol.% SiC resulted in a mean grain size of 2 μm for the alumina matrix compared with 13.9 μm for a monolithic alumina prepared under identical conditions.
AB - Four different alumina powders, from European and Japanese sources having similar particle size (350-700 nm) were used for the fabrication of nanocomposites. They were compared in terms of green properties, sintering behaviour, microstructure and mechanical properties. The processing route used (attrition milling and freeze-drying) leads to a reduction in green density of the processed aluminas and composites compared to the as-received alumina. All powders had similar green properties except one, which contained a binder from the manufacturer. The presence of this binder led to the formation of hard agglomerates. In this case the pressing did not eliminate, totally, the inter-agglomerate pores, leading to an incomplete sintering. Calcining the powder to remove the binder resulted in similar pressing and sintering behaviour to the other powders and densities > 99% were achieved at 1750 °C by pressureless sintering. All the composites exhibited similar microstructures (matrix grain size 3 μm) and elastic properties, hardness and fracture toughness. A finer matrix microstructure could be obtained with one of the European powders which achieved 99% density at 1700 °C. The presence of 5 vol.% SiC resulted in a mean grain size of 2 μm for the alumina matrix compared with 13.9 μm for a monolithic alumina prepared under identical conditions.
KW - AlO-SiC
KW - Green properties
KW - Mercury porosimetry
KW - Microstructure-prefiring
KW - Nanocomposites
KW - Sintering
UR - http://www.scopus.com/inward/record.url?scp=0036722311&partnerID=8YFLogxK
U2 - 10.1016/S0955-2219(01)00467-8
DO - 10.1016/S0955-2219(01)00467-8
M3 - Article
AN - SCOPUS:0036722311
SN - 0955-2219
VL - 22
SP - 1543
EP - 1552
JO - Journal of the European Ceramic Society
JF - Journal of the European Ceramic Society
IS - 9-10
ER -