High-speed micro-droplet impact on a super-heated surface

In this study, we experimentally show that the condition for micro-droplets to splash depends on the temperature of the surface on which the droplets impact. We vary droplet diameter (30$\sim$120 $\mu$m) and surface temperature (20$\sim$500$^{\circ}$C). For an impacting droplet, splashing becomes possible for high surface temperature $T>$160$^{\circ}$C and Weber number $We>$100. In contrast, at low surface temperature $T<$140$^{\circ}$C, no splash was observed up to the maximum Weber number in our experiments, i.e. $We\sim$7,000. Our results show that the criteria for splashing of micro-droplets may be different from those of milli-sized droplets, in particular when the impacted surface is heated.