Relationship between compacting pressure, green density, and green strength of powder compacts used in thermal batteries

Compressibility behaviour was studied for powders used in thermal batteries, including a cathode using iron disulphide, an electrolyte made of LiCl KCl eutectic and an anode using a lithium alloy. It appeared that two models (Kawakita and Halldin et al.) are suitable in explaining the densification process. Furthermore, the use of both models is necessary to qualitatively and quantitatively characterise the compression events in the entire pressure range studied (0-800 MPa). In a second part of the study, the mechanical properties of the compacts were considered: the experimental results indicated a linear increase of green strength with compacting pressure. Green strength characterisation was carried out using three mathematical models (Duckworth, Halldin et al., and German). All of them predicted a green strength increase with increasing density. Finally, the green strength of the powders was found to be sensitive to the size of the interparticle contact area.