Diatomite, a natural silicate-based sedimentary rock, was densified by cold sintering at room temperature and 150°C under various pressures (100, 200, and 300 MPa) and using different NaOH water solutions (0–3 M). The relative density of cold sintered diatomite can be as high as 90%, a condition that can be achieved by conventional firing only at 1200–1300°C. The cold sintered materials maintain the same mineralogical composition of the starting powder (quartz, glass, and illite) and are constituted by well-deformed and flattened grains oriented orthogonally to the applied pressure. Conversely, an evident phase evolution takes place upon conventional firing with the formation of cristobalite and mullite. The bending strength of cold sintered artifacts can exceed 40 MPa and increases to ≈80 MPa after post-annealing at 800°C, such mechanical strength is much larger than that of conventionally pressed samples sintered at 800°C, which is only ≈1 MPa.

Cold sintering of diatomaceous earth / Galotta, Anna; Giust, Enrico; Bortolotti, Mauro; Soraru, Gian Domenico; Sglavo, Vincenzo Maria; Biesuz, Mattia. - In: JOURNAL OF THE AMERICAN CERAMIC SOCIETY. - ISSN 0002-7820. - 104:9(2021), pp. 4329-4340. [10.1111/jace.17863]

Cold sintering of diatomaceous earth

Galotta, Anna
Primo
;
Bortolotti, Mauro;Soraru, Gian Domenico;Sglavo, Vincenzo Maria
Penultimo
;
Biesuz, Mattia
Ultimo
2021-01-01

Abstract

Diatomite, a natural silicate-based sedimentary rock, was densified by cold sintering at room temperature and 150°C under various pressures (100, 200, and 300 MPa) and using different NaOH water solutions (0–3 M). The relative density of cold sintered diatomite can be as high as 90%, a condition that can be achieved by conventional firing only at 1200–1300°C. The cold sintered materials maintain the same mineralogical composition of the starting powder (quartz, glass, and illite) and are constituted by well-deformed and flattened grains oriented orthogonally to the applied pressure. Conversely, an evident phase evolution takes place upon conventional firing with the formation of cristobalite and mullite. The bending strength of cold sintered artifacts can exceed 40 MPa and increases to ≈80 MPa after post-annealing at 800°C, such mechanical strength is much larger than that of conventionally pressed samples sintered at 800°C, which is only ≈1 MPa.
2021
9
Galotta, Anna; Giust, Enrico; Bortolotti, Mauro; Soraru, Gian Domenico; Sglavo, Vincenzo Maria; Biesuz, Mattia
Cold sintering of diatomaceous earth / Galotta, Anna; Giust, Enrico; Bortolotti, Mauro; Soraru, Gian Domenico; Sglavo, Vincenzo Maria; Biesuz, Mattia. - In: JOURNAL OF THE AMERICAN CERAMIC SOCIETY. - ISSN 0002-7820. - 104:9(2021), pp. 4329-4340. [10.1111/jace.17863]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11572/312294
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