Ice Sintering by Sublimation and Condensation.

The sintering behavior of ice has been the subject of controversy for more than 160 years. Various factors have led to confusion about the mechanisms behind mass transport during sintering; erroneously derived growth rate exponents, experimental challenges in achieving equilibrium conditions, and incorrect comparisons between ice sintering and snow densification have all played a role. Here we demonstrate that sintering of ice under equilibrium conditions proceeds primarily through sublimation and condensation. Mass transfer occurs through the vapor phase, driven by increased volatility at the formed neck due to its high curvature. Our findings on the sintering of ice spheres are consistent with the healing of micrometer-sized scratches in ice under similar conditions.