科研之友
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摘要
Marble, one of the most precious construction materials, is often used for building decorations and statues. Acid rain falls caused by industrial pollution may harm marble ornaments in a very destructive manner. By X-ray diffraction and optical mineralogical microscopy, calcium sulphate and calcium nitrate are found to be the most important reaction products. Atomic force microscopy approach was used to reveal the erosion structure of the marble samples exposed to a moderate acid rain of pH 4 for about several weeks. Two stages of nano erosion are evidenced. The first stage affects the inside structure of calcite grain, inducing a nano erosion promotion at an exposure from 0 to 6 days. The transition to the second stage is substantially related to the propagation of nano erosion to the grain borders, which is very pronounced on day 6. At this stage the marble ornaments are seriously damaged. The second stage corresponds to the massive erosion of the surface at day 24, with irremediable damage to the marble ornaments. The surface roughness was found to progressively increase during the 24 days of exposure to acid rain.
- 出版日期2013-11
