Transparent magnesium aluminate spinel: Effect of critical temperature in two-stage spark plasma sintering |
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| Affiliation: | 1. Centre for Functional and Surface Functionalised Glass, Alexander Dubcek University of Trencin, Trencin, Slovakia;2. CEITEC BUT, Brno University of Technology, Purkynova 123, Brno, Czech Republic;3. Faculty of Mechanical Engineering, Brno University of Technology, Technicka 2, Brno, Czech Republic;4. Joint Glass Centre of the IIC SAS, TnUAD and FChPT STU, Trencin, Slovakia;5. Refractories,Ceramics, and Building Materials Department, National Research Centre, 33 El-Bohous St., 12622, Cairo, Egypt |
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| Abstract: | The discolouration of magnesium aluminate spinel 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°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. |
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| Keywords: | Magnesium aluminate spinel Spark plasma sintering Carbon contamination Optical properties |
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