All-Materials-Inclusive Flash Spark Plasma Sintering

Abstract

A new flash (ultra-rapid) spark plasma sintering method applicable to various materials systems, regardless of their electrical resistivity, is developed. A number of powders ranging from metals to electrically insulative ceramics have been successfully densified resulting in homogeneous microstructures within sintering times of 8–35 s. A finite element simulation reveals that the developed method, providing an extraordinary fast and homogeneous heating concentrated in the sample’s volume and punches, is applicable to all the different samples tested. The utilized uniquely controllable flash phenomenon is enabled by the combination of the electric current concentration around the sample and the confinement of the heat generated in this area by the lateral thermal contact resistance. The presented new method allows: extending flash sintering to nearly all materials, controlling sample shape by an added graphite die, and an energy efficient mass production of small and intermediate size objects. This approach represents also a potential venue for future investigations of flash sintering of complex shapes.

Spark plasma sintering and complex shapes: The deformed interfaces approach

“…A 20 K/min temperature ramp up the 100°C [11] is performed for the PMMA assembly densification. The separation step for the PMMA hemi-sphere is shown Fig.…”

“…The simultaneous sintering of many samples (multiple parts configurations) is technically possible [4,[7][8][9], but difficult to control without optimized configurations [10][11]. The main difficulty of the multiple parts configurations is the temperature homogeneity.…”

“…Finite Element Method (FEM) simulations of the Joule heating [12][13][14][15][16][17][18][19][20][21][22] and the densification [23][24][25][26][27][28][29][30] are performed by many authors, with the aim of predicting the temperature and densification field and find optimized solutions [10,[31][32][33][34][35][36]. In previous work [11], we showed that a homogenization of the temperature field can be attained for multiple parts configurations by adjusting the electric current flow with electric insulations and specific geometrical tricks.…”

Pressure‐enhanced densification of TaC ceramics during flash spark plasma sintering

“…However, although some previous literatures considered high heating rate and electric field is in favor of fine‐grained microstructure, in most cases, rapid final‐stage grain growth occurs during FSPS or FS . For example, the average grain size of Al 2 O 3 increases from 37 nm for raw powders to 16 μm for FSPSed product .…”

Spark plasma sintering of alumina/yttria‐doped silicon carbide

“…[7][8][9] Spark plasma sintering consists of a mechanical loading system such as HP, but instead of an external heating, a pulsed electric current flows through the punches, through the mold, and, depending on the electrical conductivity, also through the powder compact within the die. 10 Thanks to the good electrical conductivity of the materials used for the mold (typically, graphite), low voltages (in general, below 10 V) generate high currents (from about 1 to 10 kA), leading to efficient Joule heating. Even in the case of electrically non-conductive sintering powder, such as SiC, heat is quickly and efficiently transferred to the sample.…”