Comparative Evaluation of Characterization Methods for Powders Used in Additive Manufacturing

In recent years, the interest in additive manufacturing technologies has increased significantly, most of them using powders as feedstock material. It is therefore essential to check the quality of the powder before processing in order to ensure the same quality of the printed components at all times. This kind of quality assurance of a powder should be carried out independently of the additive manufacturing technology used. Since there is a lack of standards in this field, various powder analysis methods are available, with which, in principle, the same characteristics can often be measured, at least nominally. To verify the validity of these methods, three different nickel-based powders used for additive manufacturing were examined in the present study using standard methods (apparent density, tap density, Hall flow rate, optical microscopy, scanning electron microscopy) and advanced characterization methods (dynamic image analysis, x-ray microcomputed tomography, adsorption measurement by Brunauer–Emmett–Teller method). A special focus has been given on particle size distribution, particle shape, specific surface area, and internal porosity. The results of these measurements were statistically compared. This study therefore provides an insight into the advantages and disadvantages of various optical characterization techniques.