Superhard pcBN materials with chromium compounds as a binder

摘要

Superhard cBN-based materials with Cr 3 C 2 , Cr 2 N and CrB 2 binders were sintered in a high-pressure high-temperature (HPHT) toroidal apparatus under a pressure of 7.7 GPa and in the temperature range of 1600-2450°С. Initial mixtures of three compositions were chosen with 60 vol.% of cBN, 35 vol.% of binder phase and 5 vol.% of Al. Phase composition and microstructure of sintered samples were investigated by X-ray analysis and scanning electron microscopy, respectively. Elastic properties were measured using the ultrasonic pulse-echo technique. Composites with Cr 3 C 2 and CrB 2 binders sintered at 2000°C have the highest values of hardness.