Instrumentation for automated and quantitative low temperature compaction and sintering

Abstract

This report describes the design, operation, and capabilities of a semiautomated uniaxial press with in situ measurement of platen displacements designed to facilitate, understand, and improve compaction and densification of particulate materials contained in conventional metal dies under modest temperatures. While not exclusive to one implementation, the instrumentation is particularly well-suited to study cold sintering. The instrumentation shares similarities to dilatometry, given the ability to monitor pellet compaction, and calorimetry, given the ability to monitor phase transitions by their molar volume signatures. Pursuant to these similarities, we refer to this device as a sinterometer. A critical benefit to this automation is a new ability to conduct experiments unattended for indefinite amounts of time under constant pressure while collecting quantitative data. We demonstrate densification profile computation (i.e., sintegram) using this instrument, including methods to account for the thermal expansion background of the metal die. A set of examples are provided where this stable and long-term data collection allows one to identify densification mechanisms and phase transformations that occur during cold sintering, which would be extremely time consuming, or impossible, to extract using a conventional, manual press.