Fragmentation and stress response characteristics of cubic boron nitride under high pressure

Abstract

Exploring the fragmentation behavior and stress response of cubic boron nitride (cBN) particles under high pressure offers insights into preparing polycrystalline cubic boron nitride (PcBN) with excellent properties. In this study, the distribution characteristics and micro-morphology of cBN particles with different sizes (2 μm, 15 μm and 40 μm) with and without aluminum (Al) binder are investigated using scanning electron microscopy (SEM) and laser particle size distribution instrument after cold compression at pressures up to 10.0 GPa. The results demonstrate that the fragmentation of the cBN particles without Al is more evident than that with Al. Moreover, the stress distribution among cBN grains is obtained via in-situ high-pressure synchrotron radiation X-ray diffraction experiments with diamond anvil cell (DAC). The results indicate that the stress difference in the cBN grains between the high-pressure and low-pressure zones is approximately 6.0 GPa under 4.2 GPa loading, while the stress difference reached to 40.0 GPa when compressed to 62.0 GPa. The main reason for the cBN particle breakage is the stress difference caused by mutual extrusion among particles under cold compression. These findings may provide a practical guide for preparing PcBN with excellent performance using high pressure sintering methods.