Transparent magnesium aluminate spinel: Effect of critical temperature in two-stage spark plasma sintering

The discolouration of magnesium aluminate spinet caused by carbon contamination is a main drawback of fabricating transparent bodies by spark plasma sintering (SPS). In this study, a two-stage heating rate profile was used to produce transparent MgAl2O4 without using sintering aids by SPS at 1250 degrees C. The effect of critical temperature (Tc), at which the heating rate is decreased, on transparency and carbon contamination was investigated: higher critical temperature resulted in higher contamination. Non-uniform densification indicated that fast heating results in a hot-zone formation in the centre of sintered pellets; the higher temperature of centre favoured reaction of graphite die with spinel and formation of disordered carbon structures in residual pores.

Keywords

Magnesium aluminate spinel, Spark plasma sintering, Carbon contamination, Optical properties

Citation

Journal of the European Ceramic Society. 2020, vol. 40, issue 6, p. 2417-2425.
https://www.sciencedirect.com/science/article/pii/S0955221920300923?via%3Dihub

Document type

Peer-reviewed

Document version

Published version

Language of document

en

Document licence

Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International
http://creativecommons.org/licenses/by-nc-nd/4.0/