Synthesis of Thermoelectric Mg₂Si by Reactive Sintering Utilizing Directly Applied Current Sintering

Abstract

Synthesis of the thermoelectric Mg 2 Si sintered body was tried by reactive pulsed current sintering (PCS) using graphite punches and a nonconductive quartz glass die (directly applied current sintering). The mechanically milled powder mixture of Mg and Si was heated by directly applied current sintering, the densification behavior, Mg 2 Si phase formation and the power consumption during sintering, and the relative density and the microstructure of the sample were compared to those of a sample sintered by the conventional PCS (using graphite punches and a graphite die). When the mechanically milled powders were heated by directly applied current sintering, the densification of a powder compact became larger during heating and the density of a sintered body was also significantly higher as compared to those of the sample sintered by the conventional PCS. The relative density of a compound sintered in a quartz die at 973 K for 10 min was 99.3%, which is almost the same as that of the sample sintered by the conventional PCS at 1073 K for 60 min, 99.6%. Furthermore, directly applied current sintering is found to accelerate the reaction between Mg and Si to form Mg 2 Si phase.

Flash‐induced defects in single‐crystal 8YSZ characterized by TEM, XRD, and Raman spectroscopy

“…Flash sintering has been shown to apply widely 11 to oxide ceramics, [12][13][14][15][16][17][18][19][20][21] non-oxide ceramics, [22][23][24][25][26][27] and, most recently, to metals. 28 The flash effect is seen in single crystals as well, which suggests that it is a bulk and not a grain boundary phenomenon.…”

Flash spark plasma sintering of magnesium silicide stannide with improved thermoelectric properties

“…Due to the nature of the indirect heating, the ramp rate is limited and the holding time is in minutes to hours, which is helpful to achieve uniform bulk materials, but makes it difficult to maintain precise control of the volatile components and avoid grain coarsening. 15 In the last ten years, electric current assisted sintering technology (ECAS, also known as FAST), [16][17][18] especially spark plasma sintering (SPS) and pulse activated sintering, are the most popular routes to achieve high performance materials from nanopowders. SPS inherited the same graphite die/punch assembly as used in hot-pressing.…”