Abstract
The process by which spark plasma sintering produces high densification of powder specimens is examined to determine the role of sparks and plasma. Measurements are reported of the electromagnetic emission during the pulsing current using the state-of-the-art Tektronix MDO4104B-6 to obtain voltage vs time and simultaneously radio frequency (rf) emission in selected power vs frequency regions. The results show strong rf emission over the selected frequency region 0–160 kHz during pulsing and nearly an order of magnitude decrease of power during pulsing but in the gap (no pulse). These measurements showed no rf emission dependence on the electrical conductivity of the specimen or with current levels between 0–500 A and support the conclusion that no sparking or plasma production takes place in the specimen. The steep slope of the current vs time profile is demonstrated to produce the rf emission in a manner described by Hertz and is suggested to provide forces on the sintering material that encourage densification.
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