Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
7898358 | Journal of the European Ceramic Society | 2018 | 22 Pages |
Abstract
Using a turbostratic pyrolytic boron nitride as a starting material, we synthesized a variety of ultrahard polycrystalline cubic boron nitride (PcBN) as a function of the heating duration changing from 1 to 60â¯min under a constant temperature and pressure conditions (1950â¯Â°C and 25â¯GPa) using a multi-anvil apparatus. When the heating duration was less than 13â¯min, ultrafine nano-polycrystalline cBN (U-NPcBN) with the mean grain size of <50â¯nm was produced. Among these U-NPcBNs those synthesized with 11-13â¯min were found to have a uniform texture composed purely of cBN (i.e. with no wurzite BN residue) and a Knoop hardness of >53â¯GPa, which is 20% higher than that of the hardest conventional binderless PcBN in practical use. Furthermore, the PcBNs synthesized with 18-20â¯min showed a unique nanocrystalline texture composed of relatively coarse grains dispersed in a fine grained matrix and even higher Knoop hardness (54.5-55.2â¯GPa).
Related Topics
Physical Sciences and Engineering
Materials Science
Ceramics and Composites
Authors
Yoshio Ichida, Hiroaki Ohfuji, Tetsuo Irifune, Takehiro kunimoto, Yohei Kojima, Toru Shinmei,