Role of shock waves in materials processing: Fundamentals and Applications.

In recent years, ultrasonic processing (USP) technology has led to some of the most promising scientific breakthroughs in the field of pharmaceutical, food, environmental and material sciences leading to advancements in manufacturing, process efficiency, and material performance. However, the industrial scalability of USP still remains a key challenge, largely due to the lack of awareness, standardization and predictive multiphysics models. Optimizing this technology necessitates a bottom-up approach, emphasizing fundamental understanding of the physical phenomena at play prior to scaling-up. Despite the advancements of opto-acoustic characterization tools, the underlying root-cause driving these technological innovations remains unexplored. This paper provides a comprehensive overview of our work carried out in the last 5 years to uncover the fundamental mechanism that governs the deployment of USP in areas related to metal casting, additive manufacturing, production of nanomaterials and composites by employing in-situ high-speed visualizations techniques and characterization of acoustic emissions. The results presented and discussed in this article offer a new perspective on the pivotal role of cavitation-induced shock waves, shifting the focus from being just a by-product, to a primary driver of material modification during USP.