Freeman Technology is pleased to announce the release of a new application note “Limitations of Simple Powder Flow Measurements and Particle Size Analysis for Bulk Powder Characterisation”.
An important point to appreciate about powders is that they are essentially three-phase systems consisting of solid particles, liquid (often relatively poorly controlled levels of water) and gas, typically air. This is why particle characterisation alone cannot reliably differentiate samples when it is bulk powder behaviour – flowability, for example – that defines value and/or performance. It also highlights the limitations of relatively simple testing techniques which often have poorly defined methodologies and attempt to capture the complexities of powders with just a single number. For example, a promptly analysed sample may exhibit different flowability from an identical sample that has deaerated upon standing if sample preparation does not eliminate such effects. Both values could also be relevant depending on the process of interest.
This work, conducted by researchers at Pennsylvania State University, involved the application of a hydrophobic surface coating to fine aluminium particles and extensive characterisation of the resulting materials. The data illustrate how powder flow properties can be substantially altered, with negligible changes in particle size, and demonstrate the limitations of simple flow measurement techniques for assessing how changes in flowability will impact process performance.
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