Plasma in spark plasma sintering of ceramic particle compacts

Abstract

Cuboidal LiF microcrystal powder was densified by spark plasma sintering at different pressures up to 500°C. Densification at pressures above the yield stress occurred by plastic deformation and strain hardening. Densification at 2 MPa, below the yield stress, occurred by particle rearrangement assisted by viscous flow at the particle surfaces. Scanning electron microscopy examination of the fracture surfaces of the partially dense specimens revealed partial melting of the particle surfaces due to the plasma. The onset temperature for plasma formation was 180°C.

Implementation of a spark plasma sintering facility in a hermetic glovebox for compaction of toxic, radiotoxic, and air sensitive materials

“…Graphite punches generate pressures (up to ∼100 MPa) and also serve as electrodes providing a pulsing direct current (up to 10 V and 10 kA) through the powder and dies. 5,6 Apart from the ongoing scientific discussion concerning the actual mechanisms (presence 7 or absence 8 of plasma during processing by SPS) and the actual effect of the electric field and current, it presents a very efficient technique for powder consolidation compared to classical sintering of green pellets.…”

On thermal runaway and local endothermic/exothermic reactions during flash sintering of ceramic nanoparticles

“…Local melting on the surfaces of cuboidal-shape LiF microcrystals was clearly observed during the spark plasma sintering as shown in Fig. 4 [54]. Several reasons can be accounted for why such a catastrophic melting was not observed in flash sintered specimens.…”

“…The main heat loss is by radiation from the nanoparticles at the external surfaces of the specimen, where the nanoparticles within the specimen volume inter-radiate to each other, hence their heat is preserved. The Knudsen layer formed at the Figure 4 Local melting observed during interrupted spark plasma sintering experiments using LiF microcrystals heated to 500°C under 2 MPa applied pressure [54].…”

Enhanced ferromagnetic properties of low temperature sintering LiZnTi ferrites with Li2O–B2O3–SiO2–CaO–Al2O3 glass addition

“…Inside the LBSCA glass, Al 2 O 3 increases the viscosity of the LBSCA glass, while CaO and Li 2 O which are modifier oxides lower the softening point of the glass and increase fluidity [4]. Sintering occurs through the viscous flow mechanism in which liquidation of the glass has a dominant role [21][22][23][24][25][26][27][28][29][30]. In this study, we use LBSCA glass with the optimum addition to prepare microwave LiZnTi ferrites, which so far has been rarely reported.…”