Ultrasonic atomization as a novel route for the metal powder development

The widespread use of additive manufacturing and modern powder-based technologies (thermal spraying, hardfacing, sintering) encourages the search for alternative routes enhancing the development of metal/metal alloy powders. The state-of-the-art powder production processes, like gas,  water or plasma atomization, are dedicated to mass production, which limits the availability of new powder compositions.

In this study, Fe-, Co-, and Ni-based alloys were investigated. The powders were atomized by an in-house developed ultrasonic (UT) atomization set-up, called ULTRAMIZER. In this system, the atomization of melt is possible by using a high-power ultrasonic field. The atomized powders were characterized in terms of morphology, porosity, sphericity, and particle size distribution. The powder features were then correlated with operating parameters of: (i) arc melting system, mainly voltage amperage and feed rate, (ii) UT atomization system, mainly frequency and RMS power, and also (iii) the orientation of the sonotrode against the melting system, by means of distance and tilt angle.

The study shows that the ultrasonic atomization allows producing nearly spherical, defect-free particles of different types of alloys, with a very narrow and controllable size distribution. These are important advantages over other powder production methods, especially when it comes to the development of new types of powders.