We analysed with different methods the densification of UO2 nanopowders in SPS under constant heating rate (CHR) and isothermal sintering conditions. The apparent activation energy of densification in SPS (75 kJ/mol with CHR method) is significantly smaller than in conventional sintering. It is shown that this is likely not an effect of the applied current. We also observed a threshold stress at 64 MPa for the transition from pressure-insensitive sintering (stress exponent n approximate to 0) to pressure-assisted sintering, suggesting that the contribution of the capillary stresses in such nanopowders is comparable with the typical stress applied in SPS.
Spark plasma sintering of UO2 nanopowders: Pressure, heating rate and current effects / Margueret, A.; Balice, L.; Popa, K.; Holzhäuser, M.; De Bona, E.; Bonani, W.; Bulgheroni, A.; Audubert, F.; Cologna, M.. - In: JOURNAL OF THE EUROPEAN CERAMIC SOCIETY. - ISSN 0955-2219. - 42:13(2022), pp. 6056-6066. [10.1016/j.jeurceramsoc.2022.05.070]
Spark plasma sintering of UO2 nanopowders: Pressure, heating rate and current effects
De Bona E.;Bonani W.;Cologna M.
2022-01-01
Abstract
We analysed with different methods the densification of UO2 nanopowders in SPS under constant heating rate (CHR) and isothermal sintering conditions. The apparent activation energy of densification in SPS (75 kJ/mol with CHR method) is significantly smaller than in conventional sintering. It is shown that this is likely not an effect of the applied current. We also observed a threshold stress at 64 MPa for the transition from pressure-insensitive sintering (stress exponent n approximate to 0) to pressure-assisted sintering, suggesting that the contribution of the capillary stresses in such nanopowders is comparable with the typical stress applied in SPS.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione