Partial discharge measurements used as a tool to assess the quality of the electrode contact in flash sintering, Milko Borisov Memorial Lecture

The measurement of phase-resolved partial discharge patterns is a well-established technique used in electrical engineering to study the degradation of electrically insulating materials placed at high voltage. The measured partial discharge (PD) signal gives information on the physics of the pre-breakdown mechanisms that may appear in this regime. In this talk, we show how this technique can also be applied to ceramics to better understand the so-called 'flash sintering' process, i.e. the sintering of ceramics under an applied electric field. We first recall the concept of phase-resolved partial discharge measurements and give details on the experimental system that was used to record simultaneously the partial discharge and the AC current. We then show results obtained on 3%mol yttria-stabilized zirconia (3YSZ) samples placed between planar electrodes and subjected to high electric fields up to 3.2 kV/cm [1]. The partial discharge signal is found to be much sensitive to quality of the contact between the platinum electrodes and the sample. The surface microstructure of the samples subjected to PD experiments exhibits various characteristics similar to those observed during dielectric breakdown.

Reference :
[1] J.-F. Fagnard et al. https://doi.org/10.1016/j.jeurceramsoc.2020.07.046 Use of partial discharge patterns to assess the quality of sample/electrode contacts in flash sintering, J Eur. Ceram. Soc. volume 41, January 2021, pp. 669-683

Acknowledgements:
This study is supported by ERDF and the Walloon Region, in the frame of IMAWA – FLASHSINT research project (program 2014-2020). The authors thank M. Vedi Dupont from BCRC for the SEM observations.