Ultrafast Sintering

TL;DR

This paper reviews recent advances in ultrafast sintering techniques, their mechanisms, and potential for high-throughput materials discovery, especially in complex ceramics.

Contribution

It critically assesses mechanistic understanding and technological developments in ultrafast sintering, highlighting new methods and scientific questions.

Findings

Ultrafast sintering enables rapid densification without passing electric currents.

Multiple approaches like laser, plasma, and induction methods have been developed.

Reactive ultrafast synthesis offers new opportunities for complex ceramics.

Abstract

This Perspective critically assesses recent advances in ultrafast sintering and highlights open scientific questions and emerging technological opportunities. Mechanistic studies of flash sintering indicate that the flash event initiates as a coupled thermal and electrical runaway, while rapid densification is enabled by ultrahigh heating rates and elevated sintering temperatures. Building on this understanding, ultrafast sintering has been realized without passing electric currents through the specimens via multiple approaches, including rapid thermal annealing (using intense infrared heating), ultrafast high-temperature sintering (in which specimens are sandwiched between graphite felt heaters), blacklight sintering (employing blue laser or intense ultraviolet irradiation), atmospheric-pressure plasma sintering, and induction ultrafast sintering (utilizing skin currents in direct induction heating or no current in the specimens in susceptor-heating mode). Reactive ultrafast synthesis and sintering have also been demonstrated. Although several hypotheses have been proposed, the mechanisms governing ultrafast sintering and its kinetics warrant further investigation. In particular, reactive ultrafast synthesis and sintering of compositionally complex ceramics are scientifically intriguing to understand while also presenting technological opportunities. The expanding range of ultrafast sintering methods provides a versatile platform for high-throughput materials discovery, especially in the rapidly growing field of high-entropy and compositionally complex ceramics, which feature vast compositional spaces to explore.