  Microwave Pressing is a promising way to reduce microwave sintering
temperatures and stabilize microwave powder materials processing. A
multi-physics simulation was conducted of the regulated pressure-assisted
microwave cavity. This simulation took into consideration resonance phenomena
and the nonlinear temperature-dependent material parameters of zirconia. The
intrinsic behaviors of microwave systems and zirconia make the regulation of
the microwave pressing difficult. However, the same phenomena can be used to
activate flash sintering. Flash microwave sintering uses high electric fields
of the resonant microwave profile, the Negative Temperature Behavior (NTC) of
zirconia resistivity, and the mechanical pressure applied to the powder via a
die compaction configuration. The resulting flash microwave pressing still
needs improvement in terms of the processed material structure homogeneity, but
it has the capacity to become the fastest sintering treatment as it allows room
temperature activation where the total process time only takes a few seconds.
In addition, this 10-20s processing technique has shown good potential for
improving the transparency of alumina pre-sintered specimens.
