The Pressure induced by salt crystallization in confinement.
The Pressure induced by salt crystallization in confinement.
复制标题
DOI：
10.1038/srep30856
复制
发表时间：
2016-08-05
影响因子：
4.6
通讯作者：
Shahidzadeh N
中科院分区：
文献类型：
--
作者：
Desarnaud J;Bonn D;Shahidzadeh N
盐结晶是岩石、艺术品和纪念碑风化的主要原因。只有当晶体在限制条件下（即在这些材料的孔隙空间内）继续生长时，才会发生损伤，从而产生机械应力。我们报告了在微观尺度上对碱卤化物盐晶体生长所施加的力的直接测量，同时观察了它们的自发成核和生长。实验揭示了生长晶体与围壁之间的润湿膜对压力的发展起着至关重要的作用。我们的研究结果表明，测得的力来自于由约1.5 nm的液膜隔开的类似电荷的围壁和盐晶体之间的斥力。事实上，如果壁是疏水性的，就不会观察到膜，也不会检测到排斥力。我们还表明，诱导压力的大小是系统特异性的，这解释了为什么不同的盐对多孔材料的破坏程度不同。
Salt crystallization is a major cause of weathering of rocks, artworks and monuments. Damage can only occur if crystals continue to grow in confinement, i.e. within the pore space of these materials, thus generating mechanical stress. We report the direct measurement, at the microscale, of the force exerted by growing alkali halide salt crystals while visualizing their spontaneous nucleation and growth. The experiments reveal the crucial role of the wetting films between the growing crystal and the confining walls for the development of the pressure. Our results suggest that the measured force originates from repulsion between the similarly charged confining wall and the salt crystal separated by a ~1.5 nm liquid film. Indeed, if the walls are made hydrophobic, no film is observed and no repulsive forces are detected. We also show that the magnitude of the induced pressure is system specific explaining why different salts lead to different amounts of damage to porous materials.