Influence of particle contact on flash sintering of ZnO and 8YSZ: Microstructure and electrical conductivity

• Published in: Ceramics international Vol. 49; no. 22; pp. 36659 - 36668
• Main Authors: Monteiro, Fábulo Ribeiro, Storion, Ana Gabriela, Ramos, Kethlinn, Jesus, Lilian Menezes, Pérez-Coll, Domingo, Mather, Glenn C., Chinelatto, Adilson Luiz, Pallone, Eliria Maria de Jesus Agnolon
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 15-11-2023
• Subjects: 8YSZ; Current ramp control; Flash sintering; Impedance spectroscopy; ZnO; Current ramp control; 8YSZ; ZnO; Impedance spectroscopy; Flash sintering
• ISSN: 0272-8842; 1873-3956
• DOI: 10.1016/j.ceramint.2023.08.349

The flash phenomenon in flash sintering of ceramic materials is closely related to electrical conductivity of the material. However, our understanding of how particle-to-particle contact of ceramic powders affects this phenomenon and, consequently, the microstructure and electrical properties of flash-sintered materials remains limited. To address this, we utilized “pseudo-in-situ” impedance spectroscopy to investigate the effect of particle-to-particle contact in nanometric powders of ZnO and 8YSZ, both before and after flash sintering. The powders were prepared using two different procedures, either grinding with a binder or employing multiple milling and calcining steps. After compacting into pellets, the samples were characterized before and after flash sintering, either with current-to-voltage control or with the application of current density ramps until the flash event occurred. Pseudo-in-situ impedance was employed to demonstrate that preparing powders using multiple milling and calcining steps improved charge-carrier mobility paths, facilitated homogeneous passage of electric current, reduced thermal gradients, and consequently resulted in better microstructural homogeneity and electrical conductivity. In addition, the use of the electric-current ramp control retained microstructural homogeneity to a greater degree.