Transmission electron microscopy characterization of spark plasma sintered ZrB2 ceramic

Field‐Assisted Sintering Technology/Spark Plasma Sintering: Mechanisms, Materials, and Technology Developments

“…The early stages of densification of nanopowder compacts proceed either by the plastic deformation of particles, grain rotation, and sliding, aided by softening of the particle surfaces. [37,130] These processes allow fast densification with limited grain growth. In some cases, grain coarsening may be further reduced by optimizing the temperature schedule.…”

“…However, in-depth investigations are required. Mizuguchi et al [130] compared by transmission electron microscopy ZrB 2 samples sintered by HP and FAST/ SPS. Lower impurities at grain boundaries were observed for the FAST/SPS samples, effect which was attributed to the cleaning of particle surfaces due to electrical discharges generated between particles.…”

Temperature dependence of microstructure evolution during hot pressing of ZrB2–30 vol.% SiC composites

“…It has been reported that the shape [9][10], size [11], content [12] and also the interfaces [13,14] of SiC particles in ZrB 2 TEM images of the hot pressed (HP) and spark plasma sintered (SPS) monolithic ZrB 2 ceramics showed that the amount of oxide impurities was lower in the ZrB 2 sintered by SPS, as a result of the cleaning effect of SPS cycle applied on the surfaces of ZrB 2 particles However, the dislocations were observed only in the spark plasma sintered sample due to the localized thermal stresses originated during the rapid cooling stage [15].…”

“…It is reported that due to the annihilation of dislocations at 2000 °C, no dislocation was found in the hot pressed monolithic ZrB 2 ceramics [15], but a few dislocations inside ZrB 2…”

“…However, the presence of oxygen within the ZrB 2 might be due to the inward diffusion of oxide impurities (B 2 O 3 and ZrO 2 ) presented on the surfaces of ZrB 2 powder [15,26].…”