Study on the solidification behaviors of metal droplets under different temperature gradients

An experimental platform comprising droplet generation, gradient temperature substrate, and data acquisition systems was established to investigate droplet dynamic evolution from spreading to solidification under different temperature gradients. Results demonstrate that initial spreading is governed by impact inertia and surface tension, with substrate temperature having negligible influence on the first peak values of the width coefficient.

While spreading and recoil durations remain nearly constant, oscillation and solidification durations increase nonlinearly with substrate temperature, rising 89% from 275.47 ms at 100 °C to 520.87 ms at 400 °C under constant temperature substrate conditions. Under gradient temperature substrate conditions, the high-temperature side dominates solidification regulation, and the induced surface tension gradient generates marangoni flow, driving molten metal migration from low-temperature side to high-temperature side and producing asymmetric final solidification morphology.