Interface instability modes in freezing colloidal suspensions - revealed from onset of planar instability

TL;DR

This study identifies three distinct interface instability modes in directional freezing colloidal suspensions through in-situ imaging, revealing their origins in the competition between solute and particle boundary layers during initial instability onset.

Contribution

It introduces a direct in-situ imaging method to observe the initial transient stage of interface instability and classifies three new instability modes in freezing colloidal suspensions.

Findings

Identified three interface instability modes: Mullins-Sekerka, global split, local split.

Revealed the origin of instability modes from boundary layer competition.

Provided insights into pattern formation during freezing processes.

Abstract

Freezing colloidal suspensions widely exists in nature and industry. Interface instability has attracted much attention for the understandings of the pattern formation in freezing colloidal suspensions. However, the interface instability modes, the origin of the ice banding or ice lamellae, are still unclear. In-situ experimental observation of the onset of interface instability is still absent up to now. Here, by directly imaging the initial transient stage of planar interface instability in directional freezing colloidal suspensions, we proposed three interface instability modes, Mullins-Sekerka instability, global split instability and local split instability. All the three instability modes come from the competition of the solute boundary layer and the particle boundary layer, which only can be revealed from the initial transient stage of planar instability in directional freezing.