Low temperature hydrothermal sintering process for the quasi -complete densification of nanometric α-quartz

Arnaud Ndayishimiye (1) , Alain Largeteau (1) , Mythili Prakasam (1) , Stanislav Pechev (1) , Marie-Anne Dourges (2) , Graziella Goglio (1)

1 ICMCB - Institut de Chimie de la Matière Condensée de Bordeaux
2 ISM - Institut des Sciences Moléculaires

We report the first successful densification of polycrystalline α-quartz. The innovative hydrothermal sintering process was used as a low temperature route on sol-gel silica nanoparticles (350 MPa, 300 °C, 90 min) in presence of water or aqueous sodium hydroxide solution (from 0.2 M up to 5 M). For the lowest NaOH concentrations, amorphous silica densification is observed, reaching a compactness of 86%. The basic physical-chemical mechanism proceeds through dissolution-precipitation. When NaOH concentration increases, the kinetics of dissolution are faster, nanoparticles totally dissolve and α-quartz is stabilized during precipitation. 98% dense α-quartz is obtained, the crystallite size increases with NaOH concentration.

Domaines: Matériaux

Arnaud Ndayishimiye, Alain Largeteau, Mythili Prakasam, Stanislav Pechev, Marie-Anne Dourges, et al.. Low temperature hydrothermal sintering process for the quasi -complete densification of nanometric α-quartz. Scripta Materialia, 2018, 145, pp.118-121. ⟨10.1016/j.scriptamat.2017.10.023⟩. ⟨hal-01737296⟩