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Improved transparency and hardness in α-alumina ceramics fabricated by high-pressure SPS of nanopowders
journal contributionposted on 2016-10-14, 10:46 authored by Shaghayegh Ghanizadeh, Salvatore Grasso, Prabhu Ramanujam, Vaidhy VaidhyanathanVaidhy Vaidhyanathan, J.G.P. Binner, Peter M. Brown, Judah Goldwasser
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 minutes. These samples offered in-line transmittance values of up to ~80% and microhardness values of 22 GPa.
- Mechanical, Electrical and Manufacturing Engineering
Published inCeramics International
CitationGHANIZADEH, S. ...et al., 2017. Improved transparency and hardness in α-alumina ceramics fabricated by high-pressure SPS of nanopowders. Ceramics International, 43 (1), Part A, pp. 275-281.
- AM (Accepted Manuscript)
Publisher statementThis work is made available according to the conditions of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) licence. Full details of this licence are available at: https://creativecommons.org/licenses/by-nc-nd/4.0/
NotesThis paper was accepted for publication in the journal Ceramics International and the definitive published version is available at http://dx.doi.org/10.1016/j.ceramint.2016.09.150.