Reactive flash sintering (RFS) in oxide systems: kinetics and thermodynamics

Flash Sintering Research Perspective: A Bibliometric Analysis

“…As shown in the inset of Figure 5c, the documents come from six different countries: The USA, China, Brazil, Spain, India, and Israel. All authors internationally collaborate, besides authors from Israel with two single-country publications [124,125]. More details about author clusters and institutions are shown in Figure 5c.…”

Reactive Flash Sintering of Ceramics: A Review

“…They suggested that capillarity and osmotic effects would be responsible for the ultrafast reactions. [ 98 ] The rapid formation of equilibrium phases reported in RFS would be related to immediate and full mixing of the oxides constituents melt, this would be possible due to the high electric field applied. [ 97,98 ]…”

“…The open question is whether the RFS mechanism of accelerating reactions would always involve liquid phase formation. Chaim pointed out that “the ‘nonequilibrium’ condition, stated in the solid‐state reaction assumption, cannot lead to equilibrium phase reactants.” [ 98 ] However, recent in situ characterization studies have revealed that indeed solid‐state reactions often evolve through nonequilibrium intermediates before the formation of the equilibrium phase. [ 112,113 ] Understanding the role of thermodynamics versus kinetics during materials formation is thus a fundamental question in materials processing, even in the conventional heating regime, where the materials would be continually heated under “near‐equilibrium” conditions.…”

“…[20,95] Despite the consensus on flash ignition, there is still a lot of discussion on whether the phenomena developing in the flash state can be entirely described by the thermal effects originating from Joule heating, such as high temperature, rapid heating, local heating, and melting. [96][97][98] Additionally, contributions from nonthermal effects, such as field-induced defect generation, [99][100][101] electric field enhancement/inhibition of crystallization, [46,51,52] and electrochemical reactions [91,101,102] have also been proposed.…”

“…They suggested that capillarity and osmotic effects would be responsible for the ultrafast reactions. [98] The rapid formation of equilibrium phases reported in RFS would be related to immediate and full mixing of the oxides constituents melt, this would be possible due to the high electric field applied. [97,98] Using in situ synchrotron XRD, Jha et al [48] demonstrated that starting with mixed powders of alumina-titania (80/20 vol% TiO 2 -Al 2 O 3 ) sintering occurred in Stage II of flash.…”