Effect of Electrical Field/Current on Sintering of Fully Stabilized Zirconia

Abstract

To highlight the peculiarities of sintering under electric field, 8 mol% yttria‐stabilized zirconia (8YSZ) specimens were tested in a sinter‐forging apparatus equipped with laser scanners and power supply. This enables to monitor axial and radial shrinkage under controlled ac field with current limitation. Current flow results in expansion related to an increase of several hundreds of °C. This proves that the whole specimen experiences, due to Joule heating, significantly higher temperatures than its environment.

Consolidation of Partially StabilizedZrO2in the Presence of a Noncontacting Electric Field

“…Francis and co-workers postulated that the applied electric field creates a high concentration of defects within the material that can increase both mass transport and electrical conductivity. [19] This description is consistent with dielectric breakdown phenomena that ultimately lead to local leakage currents [20] and thus, current assisted densification [11,30,31].…”

Flash sintering of ceramic materials

“…The second approach uses an adapted dilatometer [24] or mechanical loading frame [25], or similar home-built devices [26]. In this case some degree of loading is required to keep the sample in place, though generally in these setups the applied uniaxial force has been kept very low.…”

“…Both dogbone shaped samples [4] and pellets [25] have been successfully flash sintered, using both Pt wire electrodes to suspend the dogbones [4,21] and the Pt discs/grids or paint electrodes for pellets [24,25,38,47,78,79].…”

“…A variety of experimental apparatus setups have been used, including the vertical tube furnace with suspended dogbone construction [4,21], an adapted dilatometer [38,47,78], a standard tube furnace [24], a split vertical furnace mounted in a mechanical testing machine [25], and a custom-built vertical arrangement with pellet shaped samples, with the ability to add load [79]. Both DC [21] and AC [38] conditions have been used for densification.…”

“…Spikes can also be applied consecutively ("double-flash") to obtain further degrees of densification [79], indicating that processes causing the flash sintering are not depleted by flash sintering occurring. Baraki et al [25] held the temperature at 1200 o C for 120 minutes to obtain a 10% increase in the bulk density compared to that immediately after sintering in the FAST regime.…”