INFLUENCE OF CRACKS AND PORES IN COAL O N ITS IMPEDANCE SPECTRA

A model of coal containing coincidentally distributed closed pores and randomly oriented cracks was considered for theoretical substantiation of the experimental curves for the electrochemical impedance of a dry coal with a middle-stage metamorphism. Analytical expressions for the frequency dependences of the real and imaginary parts of the impedance of this coal have been obtained. Hodographs of the impedances of coals with different degrees of cracking have been constructed in the form of two overlapping semicircles in the upper half-plane of the system of axes. It was established that the high-frequency semicircle represents the closed porosity in a coal and the lowfrequency semicircle is due to its cracking. A method of determining the coeffi cients of cracking and closed porosity of coal by its experimental impedance spectra is proposed.
   
Author:  L. I. Stefanovich, É. P. Fel′dman, and A. K. Kirillov
Keywords:  coal, metamorphism, electrochemical impedance, impedance spectroscopy, impedance hodograph, cracking, closed porosity
Page:  886