Relationship between nanoscale deformation of coal structure and metamorphic-deformed environments
Relationship between nanoscale deformation of coal structure and metamorphic-deformed environments
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DOI：
10.1360/04wd0205
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发表时间：
2005-08
影响因子：
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通讯作者：
Y. Ju;B. Jiang;Quanlin Hou;Guiliang Wang
中科院分区：
文献类型：
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作者：
Y. Ju;B. Jiang;Quanlin Hou;Guiliang Wang
煤构造的纳米尺度变形与变质变形环境有着更为密切的关系。在不同的变质变形环境中，煤的结构变形不仅可以发生在微米尺度上，也可以发生在纳米尺度上，甚至导致分子结构和纳米尺度孔隙（< 100 nm）结构的变化。后者是吸收煤层气的主要空间。采用X射线衍射（XRD）和液氮吸附等方法，研究了不同变质变形环境和不同变形系列煤的大分子和纳米尺度孔隙结构特征。结合高分辨透射电子显微镜（HRTEM），可以直接观察到大分子和纳米尺度的孔结构。这些结果表明，从低煤阶煤的变质变形环境到高煤阶煤的变质变形环境，构造煤中大分子BSU的堆积Lc迅速增加。对于不同构造变形煤，在相同的变质变形环境下，Lc值差异明显。这些变化主要反映了构造煤纳米尺度变形的不同温度和应力效应的差异。温度因素对大分子结构参数Lc的增加起着较大的作用，应力因素的影响也很重要。随着应力的增强，Lc呈增大趋势，LaLc呈减小趋势。因此，Lc和LaLc可以作为构造煤纳米尺度变形程度的指示指标。随着温度和压力的增加，特别是取向应力的增加，分子结构的取向性增强，C网的有序度和BSU的排列明显增强。对于纳米尺度孔隙结构的变形，在相同的变质变形环境下，沿着应力的增强，构造煤中孔占其总孔隙体积的比例大幅度降低，微孔和直径小于微孔的孔的体积比例增大，并出现亚微孔和超微孔。中孔的比表面积与其总孔的比率迅速降低，而亚微孔的量增加得更快。韧性构造煤的孔隙参数变化与弱脆性变形相似。不同变质-变形环境下形成的不同类型构造煤，其纳米尺度孔隙结构的变形和演化存在差异。总之，温度和围压对构造煤纳米尺度孔隙结构参数的变化起一定作用，而应力对构造煤纳米尺度孔隙结构特征参数的演化有重要影响。
There is a more consanguineous relation between nano-scale deformation of coal structure and metamorphic-deformed environment. In different metamorphic-deformed environments, deformation in the coal structure can occur not only at micro-scale, but also at nano-scale, and even leads to the change of molecular structure and nano-scale pore (< 100 nm) structure. The latter is the main space absorbing coalbed methane. Through X-ray diffraction (XRD) and liquid—nitrogen absorption methods, the characteristics of macromolecular and nano-scale pore structures of coals in different metamorphic-deformed environments and deformational series of coals have been studied. By combining with high-resolution transmission electron microcopy (HRTEM), the macromolecular and nano-scale pore structures are also directly observed. These results demonstrate that the stacking Lc of the macromolecular BSU in tectonic coals increases quickly from the metamorphic-deformed environment of low rank coals to that of high rank coals. For different deformed tectonic coals, in the same metamorphic-deformed environment, the difference of Lc is obvious. These changes reflect chiefly the difference of different temperature and stress effect of nano-scale deformation in tectonic coals. The factor of temperature plays a greater role in the increase of macromolecular structure parameters Lc, the influence of stress factor is also important. With the stress strengthening, Lc shows an increasing trend, and LaLc shows a decreasing trend. Therefore, Lc and LaLc can be used as the indicator of nano-scale deformation degree of tectonic coals. With increasing temperature and pressure, especially oriented stress, the orientation of molecular structure becomes stronger, and ordering degree of C-nets and the arrangement of BSU are obviously enhanced. For the deformation of nano-scale pore structure, in the same metamorphic-deformed environment, along with the strengthening of stress, the ratio of mesopores to its total pores volume of tectonic coals reduces to a large extent, the ratio of volume of micropores and the pores whose diameters are lower than micropores increases, and sub-micropores and ultra-micropores can be found. Moreover, the ratio of specific surface area of mesopores to its total pores reduces rapidly while the amount of sub-micropores increases more quickly. The ductile structure coal has a change in pore parameters similar to that of weak brittle deformation. There are differences in the deformation and evolution of nano-scale pore structure of different kinds of tectonic coals formed in different metamorphic-deformational environments. In short, temperature and confining pressure play some role in the change of nano-scale pore structure parameters, whereas stress has important influence on the evolution of characteristic parameters in nano-scale pore structure of tectonic coals.