Grain growth during spark plasma and flash sintering of ceramic nanoparticles: a review

Abstract

Spark plasma and flash sintering process characteristics together with their corresponding sintering and densification mechanisms and field effects were briefly reviewed. The enhanced and inhibited grain growth obtained using these field-assisted densification techniques were reported for different ceramic nanoparticle systems and related to their respective densification mechanisms. When the densification is aided by plastic deformation, the kinetics of grain growth depends on the particles' rotation/sliding rate and is controlled by lattice and pipe diffusion. When the densification is aided by spark, plasma, and the particles' surface softening, grain growth kinetics is controlled by viscous diffusion and interface reactions. Grain growth in both cases is hierarchical by grain rotation, grain cluster formation and sliding, as long as the plastic deformation proceeds or as long as plasma exists. Densification by diffusion in a solid state via defects leads to normal grain growth, which takes over at the final stage of sintering. Various field effects, as well as the effect of external pressure on the grain growth behaviour were also addressed.

Influence of processing parameters on the densification and the microstructure of pure zinc oxide ceramics prepared by spark plasma sintering

“…5). The improved densification is due to the re arrangement of the particles by rotation [21]. Dargatz et al [9,26] previously reported on the sintering of pure ZnO at 400°C and 50 MPa in a dry and wet state.…”

Review of thermo‐kinetic correlation during grain growth in nanocrystalline materials

“…Table 1 summarizes the representative review articles and their foci. [31][32][33][34][35] It is shown that these articles focus mainly on strategies and methods for improving the thermal stability of NC materials. Unfortunately, among these papers the thermodynamics and the kinetics are mostly reviewed independently; only single effect (one of the thermodynamic and the kinetic effects) is generally considered to account for the stabilization mechanism of NC materials.…”

Rapid Sintering of Li2O-Nb2O5-TiO2 Solid Solution by Air Pressure Control and Clarification of Its Mechanism

“…There are small pores in the SEM images, and the density of the material does not seem to be so high. Here, we focus on the effect of grain growth, where the densification mechanism should be distinguished from the grain growth mechanism [17]. …”