TY - JOUR
T1 - Improved transparency and hardness in α-alumina ceramics fabricated by high-pressure SPS of nanopowders
AU - Ghanizadeh, Shaghayegh
AU - Grasso, Salvatore
AU - Ramanujam, Prabhu
AU - Vaidhyanathan, Bala
AU - Binner, Jon
AU - Brown, Peter
AU - Goldwasser, Judah
PY - 2017/1
Y1 - 2017/1
N2 - Nanocrystalline alumina powder with an average crystallite size of ≤50 nm has been consolidated by spark plasma sintering (SPS) and hot pressing (HP) with a view to achieving dense, fine grained alumina bodies that display transparency. When as-synthesised powder was densified directly, excessive grain growth resulted from both the SPS and HP techniques and hence a large final grain size was observed. Attempts to improve the uniformity of the green microstructure prior to densification were unsuccessful when spray freeze dried granules were used, whether pre-pressed into a compact or not. The use of 53% dense slip cast green compacts, however, enabled final density of ~99.96% and a mean grain size of ~0.32 µm to be achieved when SPS conditions of 1200 °C and 500 MPa were applied for 20 min. These samples offered in-line transmittance values of up to ~80% and microhardness values of 22 GPa.
AB - Nanocrystalline alumina powder with an average crystallite size of ≤50 nm has been consolidated by spark plasma sintering (SPS) and hot pressing (HP) with a view to achieving dense, fine grained alumina bodies that display transparency. When as-synthesised powder was densified directly, excessive grain growth resulted from both the SPS and HP techniques and hence a large final grain size was observed. Attempts to improve the uniformity of the green microstructure prior to densification were unsuccessful when spray freeze dried granules were used, whether pre-pressed into a compact or not. The use of 53% dense slip cast green compacts, however, enabled final density of ~99.96% and a mean grain size of ~0.32 µm to be achieved when SPS conditions of 1200 °C and 500 MPa were applied for 20 min. These samples offered in-line transmittance values of up to ~80% and microhardness values of 22 GPa.
U2 - 10.1016/j.ceramint.2016.09.150
DO - 10.1016/j.ceramint.2016.09.150
M3 - Article
SN - 02728842
VL - 43
SP - 275
EP - 281
JO - Ceramics International
JF - Ceramics International
IS - 1
ER -