Meaning
Standardized density testing using Archimedes’ principle allows manufacturers to determine the density and interconnecting porosity of powder metallurgy parts. The protocol, documented under ASTM B962, uses water immersion to calculate the volume of compacted or sintered metal components. It establishes a consistent metric for assessing the structural integrity of structural or conductive cell parts.
Test Protocol
The procedure requires weighing the dry specimen, weighing it fully saturated with water or oil in air, and then weighing it suspended in water. Saturated mass measurements prevent open pores from skewing the volume calculation because water replaces the air inside the internal voids. This method yields a highly repeatable value for both the density of the metal matrix and the percentage of remaining open porosity.
Sourcing Quality
Component specifications for current collector tabs and terminals often cite this test to ensure material density is high enough to support electrical loads. Low density in sintered connectors increases electrical resistance and can lead to localized heating under fast charging conditions. Sourcing contracts define the minimum acceptable density using these values to verify the compaction quality of the supplier.
Alternative Method
Saturated density measurements cannot be completed for water-soluble materials or highly reactive metal powders like lithium. In such cases, organic liquids or gas pycnometry must replace the water bath.
