Nanomechanics of coal:a case study of Pocahontas coal

Mechanical properties of coal are fundamental for coal mining design and safe production.Even though mechanical properties of coal coring samples were studied extensively，nanoscale mechanical properties of coal were rarely reported previously.This work reported a quantitative measurements of mechanical properties of Pocahontas coal and its topography using atomic force microscopy (AFM) in Peak-Force Tapping mode.Measurement results show that AFM PeakForce Tapping mode has the capacity to quantify the topography，Derjaguin-Muller-Toporov(DMT) modulus，adhesion，deformations and dissipation energy of coal，which can also be represented via 2D and 3D figures.The DMT modulus，adhesion，maximum deformation and dissipation energy are approximately 10～14 GPa，20 nN，12 nm and 30 keV，respectively.This study demonstrates that AFM PeakForce Tapping mode can be used to investigate nanoscale mechanical properties of coal.The applied method thus provides a new way to understand the coal failure mechanism and the mechanical coupling mechanism of coal and methane interaction at nanoscale and to investigate the nanomechanics of coal.