Influence of Metal Wall Materials and Process Parameters on the Adhesion Behavior of Airborne Powder Particles

Caking and powder adhesion are widespread challenges in dry powder processes. The influence of process parameters such as humidity and temperature on the adhesion behavior of dry powders has been extensively studied in numerous studies. Besides that, the impact of other process characteristics, such as additional process parameters or wall materials, has received little attention so far. In addition, existing methods to characterize caking behavior do not account for powders in a fluidized state. To address phenomena based on process and material behavior, a test rig was specifically designed to investigate the adhesion of dry particles to different metal walls at varying speeds at a 90° angle, representing the main novelty of this study. The deposition area, deposition mass, and maximum deposition thickness were evaluated, and the correlations were discussed. The investigations revealed that at low velocities (<12 m/s) and for smooth surfaces (Sq < 0.3–0.4 µm), wall materials with a high ratio of dispersive to polar surface energy components (D/P: 13–15.8) exhibit minimal powder adhesion. The test rig has demonstrated its effectiveness as a straightforward method for measuring adhesion across various powder–wall material pairs and could serve as a valuable preliminary test for industrial applications.