The inhomogeneity of the spraying plume in thermal spraying (TS) techniques is mostly dependent on the type of feedstock used. It is more homogeneous for coating processes where a powdery feedstock is deposited (like in HVOF spraying). In contrast, if the in-flight particles are atomized from a melting bath (like in Twin Wire Arc Spraying (TWAS)) the spray jet is less homogeneous. This is due to the fact that these particles are generated by the impingement of fast continuous flowing air upon the melting tips of electrically conductive wires. This work aims to contribute to the understanding of the initiation of such particles in the TWAS process. For this purpose, cored wires filled with W-rich particles were sprayed. After interrupting the TWAS process, the tips of these cored wires were imaged by 3D μCT and scanning electron microscopy (SEM) in order to analyze how the filling powder interacts with the melted part of the velum. The analysis of the 3D tomograms shows that the resolidified melting bath of the cored wires is interspersed with both spherical and irregular-shaped W-rich particles. This irregular shape suggests a partial melting of the W-rich particles.
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