Use of partial discharge patterns to assess the quality of sample/electrode contacts in flash sintering

Abstract

In a flash sintering process, a straightforward way to control the current uniformity through the sample is contacting the sample to the electrodes with platinum paste. This method is however costly for large-scale applications. We show that the in-situ phase resolved partial discharge technique is suitable to assess the quality of the contact between Pt electrodes and uncoated 3YSZ samples. In the temperature range 250−500 °C and for 50 Hz electric fields ramped up to 3.2 kV/cm, a sudden increase of the partial discharge current well before any curvature change of the 50 Hz current is found to be a signature of a defective electrical contact. Changes in the partial discharge amplitude are observed around the current rush. The surface microstructure of the samples subjected to partial discharges shows characteristics similar to those observed during dielectric breakdown, although the applied electric field is well below their typical dielectric strength.