Beschreibung:
<jats:p>Binder-less nanopolycrystalline cBN (BL-PcBN) synthesized by direct conversion under high pressure and high temperature has a fine texture consisting of small cBN grains (<100nm), high hardness (40–50 GPa) and high transverse rupture strength (1.3–1.6 GPa). Their mechanical properties strongly depend on their starting materials and synthetic conditions. In this study, Ball-end mill tools prepared from several kinds of BL-PcBN synthesized under various conditions (8–20 GPa, 1500–2300oC) were examined for precision cutting of high-strength hardened steel comparing with conventional sintered cBN. A fine mirror-finish surface with Ra of 20 nm could be produced by precision BL-PcBN tools, while not by conventional sintered cBN tools. The tool wear of BL-PcBN synthesized from hBN at 10 GPa and 2200°C was four to five times less than that of conventional cBN. These results revealed that the BL-PcBN tools have excellent potential for precision cutting on ferrous materials.</jats:p>