Distinctive mechanical properties of nano-polycrystalline diamond synthesized by direct conversion sintering under HPHT
- 作者：H. Sumiya ; sumiya@sei.co.jp ; K. Harano
- 关键词：Synthetic diamond ; Nano-polycrystalline diamond ; High pressure ; Cutting tool ; Hardness ; Wear
- 刊名：Diamond and Related Materials
- 出版年：2012
- 期刊代码：30_09259635
- 类别：ms
- 出版时间：April, 2012
- 卷：24
- 期：Complete
- 页码：44-48
- 文件大小：923 K
摘要
The mechanical properties of nano-polycrystalline diamond (NPD) synthesized by the direct conversion of graphite under high pressure and high temperature have been investigated. Indentation hardness and bending strength tests revealed that NPD has considerably high hardness and high transverse rupture strength (TRS) at high temperature, far surpassing those of conventional polycrystalline diamond (PCD) and single-crystal diamond (SCD). The hardness remained higher than 100 GPa even at 800 掳C, while the hardness of SCD sharply decreased to 60 GPa above 300 掳C. The TRS remained at about 3 GPa up to 1000 掳C, above which it showed a positive temperature dependence, while the TRS of PCD decreased rapidly at about 500 掳C. Wear tests using a diamond wheel indicated that the abrasive wear resistance of NPD is equivalent to those of the high wear-resistance directions on SCD, and from 10 to 50 times higher than those of PCD. These results suggest that NPD has outstanding potential for cutting tools.