In situ synthesis of polycrystalline cubic boron nitride with high mechanical properties using rod-shaped TiB₂ crystals as the binder

Abstract

Polycrystalline cubic boron nitride (PcBN) was sintered in the temperature range of 1050-1650°C under an ultra-high pressure of 5.0 GPa for 20 min using an in situ synthesis method. X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy and energydispersive spectrometry were used to study the compositional and morphological changes during the synthetic process. The results showed that rod-shaped TiB 2 crystals could be detected at 1150°C, and their quantity increased with sintering temperatures. The TiB 2 crystals distributed homogeneously and grew randomly among the cBN grain boundaries and interstitial spaces, ultimately forming an interlocking structure. The PcBN prepared at 1650°C exhibited optimal comprehensive mechanical properties, with a micro-hardness of 44.42 GPa and a flexural strength of 862.5 MPa. Moreover, based on the experimental results, the chemical reaction mechanism and the strengthening mechanisms occurred during the sintering process were also proposed to properly interpret the synthesis of PcBN.

The Influence of Molasses Concentration on the Physical and Mechanical Properties of Evaporation Boat Waste-Based Crucibles

“…In this study, the change in weight percentage within the BN and TiB2 phases was caused by the firing treatment during specimen formation [45]. The growth of the TiB2 phase can be observed at a firing temperature of 1150˚C and will increase when given a higher firing temperature [50]. However, a study conducted by Tong, et al, (2008) showed that the presence of the BN phase could inhibit the growth of other compound phases [51].…”