As sessile drops of aqueous colloidal suspensions dry, a close-packed particle deposit forms that grows from the edge of the drop toward the center. To compensate for evaporation over the solid’s surface, water flows radially through the deposit, generating a negative pore pressure in the deposit associated with tensile drying stresses that induce the formation of cracks. As these stresses increase during drying, existing cracks propagate and additional cracks form, until the crack density eventually saturates. We rationalize the dynamics of crack propagation and crack densification with a local energy balance between the elastic energy released by the crack, the energetic cost of fracture, and the elastic energy released by previously formed cracks. We show that the final spacing between radial cracks is proportional to the local thickness of the deposit, while the aspect ratio of the crack segments depends on the shape of the deposit.

中文翻译：

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干燥胶体悬浮液中的裂纹致密化


随着水性胶体悬浮液的无柄液滴干燥，会形成紧密堆积的颗粒沉积物，从液滴边缘向中心生长。为了补偿固体表面的蒸发，水径向流过沉积物，在沉积物中产生负孔隙压力，与拉伸干燥应力相关，从而诱发裂纹的形成。随着干燥过程中这些应力的增加，现有的裂纹会扩展并形成额外的裂纹，直到裂纹密度最终饱和。我们通过裂纹释放的弹性能、断裂的能量成本和先前形成的裂纹释放的弹性能之间的局部能量平衡，使裂纹扩展和裂纹致密化的动力学合理化。我们表明，径向裂纹之间的最终间距与沉积物的局部厚度成正比，而裂纹段的纵横比取决于沉积物的形状。