Pattern Formation in Silicate Glass Corrosion Zones
Pattern Formation in Silicate Glass Corrosion Zones
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DOI：
10.1111/ijag.12046
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发表时间：
2013-12-01
影响因子：
2.1
通讯作者：
Denkler, Rene
中科院分区：
文献类型：
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作者：
Dohmen, Lars;Lenting, Christoph;Denkler, Rene
考古玻璃的蚀变带在背散射电子图像中经常显示出耐人寻味的片层图案。在这里，我们报告了两种不同硅酸盐玻璃的静态玻璃腐蚀实验结果，它们揭示了硅基腐蚀区内的层状孔隙率和次级化学图案，类似于自然蚀变的古代玻璃中看到的那些。除了常见的层流模式外，在沿着裂缝网络发展的腐蚀区中观察到了更复杂的模式。这种图案的形成不能用任何现有的玻璃腐蚀模型来解释。我们认为，硅基腐蚀区的形成过程涉及玻璃网络的一致溶解，这一过程在空间和时间上与向内移动的反应界面上无定形二氧化硅的沉积相耦合。这些图案可能是由于界面溶液中pH和盐度的波动而形成的，界面溶液中的pH和盐度控制着二氧化硅的溶解度、沉积和溶解速度，因此，它的微观结构和孔隙率也受到玻璃的溶解速度和二氧化硅反应层的传输特性的控制。然而，造成界面溶液中pH波动的确切反馈机制尚未确定，这是一个有待于进一步研究的问题。
Alteration zones of archeological glasses often show intriguing lamellar patterns in backscattered electron images. Here, we report results of static glass corrosion experiments with two different silicate glasses that revealed laminar porosity and subordinately chemical patterns inside silica-based corrosion zones that resemble those seen in naturally altered, ancient glasses. Aside from common laminar patterns, more complex patterns were observed in corrosion zones that developed along a fracture network. The formation of such patterns cannot be explained by any of the existing glass corrosion models. We suggest that silica-based corrosion zones form by a process that involves the congruent dissolution of the glass network, which is spatially and temporally coupled to the deposition of amorphous silica at an inwardly moving reaction interface. The patterns likely form in response to fluctuations of the pH and salinity in the interfacial solution, which govern the silica solubility, deposition, and dissolution rate, and thus, its microstructure and porosity, and, in turn, are controlled by the dissolution rate of the glass and the transport properties of the silica reaction layers. However, the exact feedback mechanism producing pH fluctuations in the interfacial solution has not yet been identified and is an open question for future research.