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Journal of Nanomaterials
Volume 2013, Article ID 380165, 6 pages
Research Article

Nanolayered Diamond Sintered Compact Obtained by Direct Conversion from Highly Oriented Graphite under High Pressure and High Temperature

1Geodynamics Research Center, Ehime University, 2-5 Bunkyo-cho, Matsuyama Ehime 790-8577, Japan
2Electronics & Materials R&D Laboratories, Sumitomo Electric Industries, LTD., 1-1-1, Koya-kita, Itami, Hyogo 664-0016, Japan

Received 25 January 2013; Revised 19 March 2013; Accepted 19 March 2013

Academic Editor: Jun Liu

Copyright © 2013 Futoshi Isobe et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


A new type of polycrystalline sintered diamond has been successfully synthesized by direct conversion from highly oriented pyrolytic graphite at 15 GPa and 2300°C. It is optically transparent and consists entirely of layered nanocrystals (50–100 nm thick) of cubic diamond, which are tightly bound to each other and have strong [111] preferred orientation along the stacking direction. This nanolayered diamond has excellent indentation hardness (~114 GPa in Knoop scale) comparable to the highest values obtained from single crystalline diamond. Furthermore, it is expected to have significantly high wear resistance on both ends of cylindrical sintered compact, since the surfaces are terminated exclusively by the hardest planes of the layered diamond nanocrystals.