Cubic Boron Nitride (cBN) is the second hardest known material after synthetic diamond. This advanced ceramic material is usually processed by sintering cBN with binders – resulting into ceramic/metal or ceramic/ceramic composites. The sintering process is performed under high pressure (~4,4 -7,7GPa) and high temperatures (HPHT) conditions for up to 30 min. to avoid the transformation of cBN to its hexagonal (hBN) allotropic form. cBN composites are typically used in machining processes involving high-hardness ferrous metals (e.g., alloyed and/or quenched steels) in replacement of diamond composites, which are degraded (i.e., iron promotes diamond graphitization) upon ferrous machining at temperatures higher than 700°C.

In the present study, cBN composites were prepared using a new binder, based on the Nb–Ni metallic system. The samples were sintered under HPHT conditions (7.7 GPa and 1500°C–1900°C). Microstructural observations by scanning electron and laser confocal microscopies showed a densified, well-sintered feature. Structural analyses were performed by X-ray diffraction (XRD). The machining tests were performed following the ISO 3685 standard with the alloyed carbon steel SAE 4140. The wear resistance characteristics of the samples revealed that the use of the new Ni–Nb binder enabled to improve the composite’s properties.