Analysis of the Dependence of the Break-Down Point on Temperature of Microwave Heating of Loaded Heterogeneous Materials (Rocks) Based on the Formation of Growth of Microcracks

Analysis of the dependence of the break-down point of granite on the temperature of microwave heating allows identification of the following characteristic areas: hardening is observed at low temperature heating up to 390 K; a decrease in strength appears in the temperature range from 390 to 460 K, which is due to generation, growth, and coalescence of smaller cracks and their redistribution to the boundaries of grains with the formation of intergranular microcracks; there is a significant decrease in the strength at the temperature range from 460 to 550 K, which is caused by the separation of grains into blocks with a small area of crack density as a result of their coalescence, and the destruction and splitting of granite samples occurs at temperatures above 593 K due to the development of all kinds of microcracks. The developed method of determining the rational parameters of the microwave energy impact on the softening of hard rocks in the field of standing electromagnetic waves allows justification of the effective parameters of the impact of microwave energy on quartz-containing hard rocks for their softening and destruction based on the study of the dynamics of induced microcracks.