Metal Droplet Deposition: From Foundation to Engineering Manufacturing

Metal droplet deposition is of fundamental importance in many industrial and manufacturing processes. An in‐depth understanding of the fundamental issues of metal droplet deposition is particularly crucial for developing droplet deposition‐based engineering manufacturing technologies. This review systematically introduces the evolution of metal droplet deposition stages and characteristic behaviors in terms of metal droplet deposition dynamics. The characteristic morphologies of single‐metal droplets after solidification, that is, gas entrapment, ripples, bulging edges, and splashing, are reviewed. The formation mechanisms and influencing factors of different droplet morphologies are summarized. Moreover, the deposition strategy of multiple metal droplets to promote good interfacial bonding is further concluded. Based on these theoretical foundations, three typical engineering manufacturing techniques based on metal droplet deposition, that is, thermal spraying, soldering, and droplet‐based 3D printing, are presented to elucidate further the advantages and potential of metal droplet deposition applied to engineering manufacturing. Finally, some existing problems and future research perspectives are discussed.