Can Die Configuration Influence Field-Assisted Sintering of Oxides in the SPS Process?

摘要

Spark plasma sintering (SPS) is a high current, low voltage process. Nevertheless, the system voltage (3-10 V) can be large enough to produce significant fields across a thin, insulating sample. A lumped circuit model is analyzed to estimate the magnitude of this field in terms of the die geometry. Normalizing the sample voltage with respect to the system voltage, and the die wall thickness to the punch radius preserves generality of the results. It is predicted that if the latter ranges from 0.15 to 0.25, then 30% of the system voltage may be expressed across the sample. Thus, a sample thickness of about 1-2 mm may experience a field of 10-30 V/cm, which would be large enough to induce field-assisted sintering in yttria-stabilized zir-conia. The results are corroborated with finite element analysis. The contact resistance is assumed to be negligible; finite values of the contact resistance would lead to fields that are higher than predicted.