Characteristics of vacuum dissociation of shock-sintered BNsph polycrystals

Abstract

We have used mass spectrometry to investigate the characteristics of dissociation of the sphalerite modification of boron nitride sintered in 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 sizes and internal distortions of the second kind. The increase in the thermal stability of the boron nitride is a result of the strengthening of chemical bonds via changes in the degree ofsp hybridization and the difficulty of nitrogen diffusion due to the decrease in the crystallite sizes and the increase in the level of lattice distortions. We calculate the energy parameters of the dissociation processes (enthalpy and Gibbs free energy).