The effect of tin droplet impact velocity and stainless steel substrate temperature on droplet splashing behavior

Thermal spraying technology plays a crucial role in industrial production, but the splashing phenomenon during spraying wastes raw materials, damages the cleanliness of the substrate surface, and affects the quality and adhesion strength of coatings. Therefore, controlling the splashing behavior is key to improving coating quality and reducing costs. In this study, Sn and 304 SS, representing a typical non-reactive wetting system, were selected as the research objects. A numerical model of droplet impact on a metal substrate was established based on the CLSVOF method, and the model was validated by comparing the simulation results with experimental data. The effects of droplet impact velocity and substrate temperature on splashing behavior were investigated, and the role and regulatory mechanism of solidification phenomena during spreading and wetting were explored. Additionally, the energy changes during the splashing process were analyzed. The results show that an increase in droplet impact velocity intensifies the splashing behavior, while changes in substrate temperature have a more complex effect due to the interaction of droplet phase transition effects. Specifically, the solidification at the droplet edge can become a disturbance that promotes splashing, but the change in surface tension and viscosity of the droplet driven by substrate temperature plays the dominant role. These findings provide insights into the splashing control mechanism and offer a theoretical basis for optimizing thermal spraying technology, with potential to improve coating quality, reduce material waste, and expand the application of thermal spraying in industrial production.