CHARACTERISTICS OF VACUUM DISSOCIATION OF SHOCK-SINTERED BNSPH POLYCRYSTALS

We have used mass spectrometry to investigate the characteristics of d issociation of the sphalerite modification of boron nitride sintered i n shock waves of various intensities as compared to the original BNsph powder and a specimen sintered under static conditions. We establish a correlation between the dissociation pressure and the crystallite si zes and internal distortions of the second kind. The increase in the t hermal stability of the boron nitride is a result of the strengthening of chemical bonds via changes in the degree of sp hybridization and t he difficulty of nitrogen diffusion due to the decrease in the crystal lite sizes and the increase in the level of lattice distortions. We ca lculate the energy parameters of the dissociation processes (enthalpy and Gibbs free energy).