Isothermal field-assisted sintering of two-phase, 50vol% 3YSZ-alumina composites exhibit an incubation time for the onset of the flash event. Weaker applied fields and lower temperatures lengthen the incubation period. The effect is highly non-linear. For example at 1300°C and 150Vcm-1 the flash occurs nearly instantaneously (in 10s), but extends to 2h at 1275°C and 65Vcm-1. This behavior is reminiscent of nucleation and growth phenomena in chemically driven experiments involving phase transformations in the solid state. Here, a model for nucleation under electrical driving forces, based upon the growth of embryos of colossal permittivity is presented. Nucleation is the precursor to the onset of a flash. Therefore it occurs at the furnace temperature. Joule heating is a consequence of nucleation not the cause of it. © 2014 Elsevier Ltd.
Flash sintering as a nucleation phenomenon and a model thereof
Sglavo, Vincenzo Maria;
2014-01-01
Abstract
Isothermal field-assisted sintering of two-phase, 50vol% 3YSZ-alumina composites exhibit an incubation time for the onset of the flash event. Weaker applied fields and lower temperatures lengthen the incubation period. The effect is highly non-linear. For example at 1300°C and 150Vcm-1 the flash occurs nearly instantaneously (in 10s), but extends to 2h at 1275°C and 65Vcm-1. This behavior is reminiscent of nucleation and growth phenomena in chemically driven experiments involving phase transformations in the solid state. Here, a model for nucleation under electrical driving forces, based upon the growth of embryos of colossal permittivity is presented. Nucleation is the precursor to the onset of a flash. Therefore it occurs at the furnace temperature. Joule heating is a consequence of nucleation not the cause of it. © 2014 Elsevier Ltd.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione
