Formation of stable aggregates by fluid-assembled solid bridges
Formation of stable aggregates by fluid-assembled solid bridges
复制标题
DOI：
10.1073/pnas.1913855117
复制
发表时间：
2020-02-18
影响因子：
11.1
通讯作者：
Jerolmack, Douglas J.
中科院分区：
文献类型：
--
作者：
Seiphoori, Ali;Ma, Xiao-guang;Jerolmack, Douglas J.
当胶体悬浮液干燥时，毛细压力可能压倒排斥的静电力，使聚集体脱离热平衡。这个鲜为人知的过程赋予了许多地质和工业材料内聚强度。在这里，我们观察了蒸发驱动的天然和合成颗粒的聚集，探测了它们在再润湿下的稳定性，并使用原子力显微镜测量了键合强度。内聚力产生于共同的长度尺度（类似于5 μ m），粒子间的吸引力超过粒子的重量。在多分散混合物中，较小的颗粒在收缩的毛细管桥内凝聚，在较大的颗粒之间建立稳定的“固体桥”。这种动态在不同尺度上重复，形成了非常强大的分层簇，其内聚力来自粒度而不是矿物学。这些结果可能有助于理解自然土壤的强度和可蚀性，以及其他多分散颗粒在瞬态水动力作用下的可蚀性。
When a colloidal suspension is dried, capillary pressure may overwhelm repulsive electrostatic forces, assembling aggregates that are out of thermal equilibrium. This poorly understood process confers cohesive strength to many geological and industrial materials. Here we observe evaporation-driven aggregation of natural and synthesized particulates, probe their stability under rewetting, and measure bonding strength using an atomic force microscope. Cohesion arises at a common length scale (similar to 5 mu m), where interparticle attractive forces exceed particle weight. In poly-disperse mixtures, smaller particles condense within shrinking capillary bridges to build stabilizing "solid bridges" among larger grains. This dynamic repeats across scales, forming remarkably strong, hierarchical clusters, whose cohesion derives from grain size rather than mineralogy. These results may help toward understanding the strength and erodibility of natural soils, and other polydisperse particulates that experience transient hydrodynamic forces.