Research on the Differences in Micro-surface Mechanical Properties of Coal Samples with Different Hardness
The mechanical properties of coal itself have a significant impact on the occurrence of gas dynamic disasters.To further investigate the microscopic differences between soft and hard coal,we employed Atomic Force Microscopy(AFM)with the PF-QNM mode to scan the surfaces of two coal samples with different hardness.The results indicate substantial differences in the microscopic morphology and mechanical properties between soft and hard coal.The surface roughness of soft coal is notably greater than that of hard coal.While the microscopic surface undulations are smaller,there are more peak structures on soft coal,providing more adsorption sites for gases.The surface elastic modulus and adhesion force in different scanning areas of various coal samples both conform to a normal distribution.Influenced by structural and metamorphic factors,its microscopic structure is more closely arranged,and the overall elastic modulus is greater than that of hard coal.The microscopic mechanical properties of different coal samples manifest significant heterogeneity,with coal surfaces demonstrating a certain degree of adhesion force.The prominent soft coal shows adhesion forces concentrated mostly between 0～100 nN,while hard coal adhesion forces are concentrated mostly between 100～400 nN.The maximum attractive force distance d0 of soft coal is notably smaller than that of hard coal.Under stress perturbations or pressure gradients,gases are prone to rapid desorption,leading to potential accidents involving coal and gas outbursts.
Atomic Force MicroscopeSurface morphologyElastic modulusAdhesion forceMicrocosmic
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万方数据
