Abstract
Elastic deformation, plastic deformation and deformation in theirtransitional region of coal at room temperature have been discussed from the relationbetween Vickers hardness or micro-Vickers hardness and load.
From the above relations, a parameter of the distribution of flow units in coal has been deduced.The relation between this parameter and rank of coal is related to that between thermal decomposition range and rank of coal .
A parameter corresponding to the mechanical relaxation time has been deduced from the relation between micro-, Vickers hardness and loading time.The relation between this time parameter and rank of coal is similar to that between hardness member or Young's modulus and rank of coal.Therefore it is supposed that the relation between internal viscosity and rank of coal is similar to the above one.
