Morphological instability of a non-equilibrium ice–colloid interface

Abstract

We assess the morphological stability of a non-equilibrium ice-colloidal suspension interface, and apply the theory to bentonite clay. An experimentally convenient scaling is employed that takes advantage of the vanishing segregation coefficient at low freezing velocities, and when anisotropic kinetic effects are included, the interface is shown to be unstable to travelling waves. The potential for travelling-wave modes reveals a possible mechanism for the polygonal and spiral ice lenses observed in frozen clays. A weakly nonlinear analysis yields a long-wave evolution equation for the interface shape containing a new parameter related to the highly nonlinear liquidus curve in colloidal systems. We discuss the implications of these results for the frost susceptibility of soils and the fabrication of microtailored porous materials.

Fabrication and characterization of biomimetic collagen–apatite scaffolds with tunable structures for bone tissue engineering

“…As a result, ice front velocity $\left(\frac{dZ}{dt}\right)$ and ice front movement distance (Delta; Z ) are larger in panel a. The inter-lamellae spacing of scaffold (λ) is determined by the magnitude of constitutional supercooling, which is the degree of temperature difference of the suspension ahead of the freezing front below its equilibrium freezing temperature [53–55]. The cooling rate could be monitored to control the freezing rate $\left(\frac{dZ}{dt}\right)$ and thereby adjust the inter-lamellae spacing [40–44].…”

“…It has been found that the velocity of ice front movement is proportional to the cooling rate. The rate of ice crystal growth depends on the heat extraction rate, which in turn determines the inter-lamellae spacing of the lamellar scaffold [28, 54, 55]. …”

In situ observation the interface undercooling of freezing colloidal suspensions with differential visualization method

“…[16][17][18][19] For example, particulate constitutional supercooling caused by concentration gradients in colloidal system can trigger a thermodynamic instability that leads to morphological transitions in the pattern of segregated ice. 17 Moreover, these thermodynamic models were extended to cohesive particle systems, giving conditions for the formation of ice lenses.…”

Frost Heave in Colloidal Soils

“…where T m is the freezing temperature of pure water, Π(φ) is the osmotic pressure of the particles, ρ l the density of water and L f is the latent heat of fusion [25], [32]. Figure 2.1a shows measurements of Π(φ) for silica spheres of radius R = 0.5 µm [16].…”

“…This expression, plotted as the dashed line in figure 2.2b, captures the essential limiting behaviours that D approaches a constant in the dilute limit and diverges in the fully consolidated (close-packing) limit [40,33]. In [32] we worked in the low-concentration regime where the diffusivity is approximately a constant. In this paper, we are interested in the close-packing limit and as can be seen from figure 2.2b, (2.6) shows good agreement with the exact expression (2.4) in the close-packing regime φ → φ p .…”