Freezing of Impacted Drops: Contact Line Dynamics

We experimentally explore the mechanisms of a water drop freezing while impacting a cold surface. The liquid drop spreads and partially freezes during the impact and then retracts upon ice. In the meantime the contact line is pinned thoughout a certain time of residence, unlike the case without solidification. Experimental measurements reveal non-trivial variations of this duration with the substrate thermal properties and drop impact velocity. A scaling law model enables us to interpret this phenomenon as the dynamic of the contact angle, which is affected by the solidification.