Deng Fuming1, 2, Lu Xuejun1, 3, Liu Ruiping1, Xu Guojun3, Chen Qiwu1, Li Wenzhu2
(1. Department of Materials Science and Engineering, China University of Mining and Technology, Beijing Campus, 100083
2. Department of Physics, Zhejiang University, 310027
3. Beijing Institute of Electro-machining, 100083)
Abstract A new type of sintered diamond reinforced by diamond-CNTs composite fibers which were randomly orientated and even distributed in the diamond matrix was synthesized by using 3(wt)% mullti-walled carbon nanotubes (MWCNTs) as starting additive under high pressure of 5.8 GPa at temperature of 1 500 ℃ for 1 min. A special polycrystalline diamond structure of direct bonding of both diamond to diamond and diamond to diamond-CNTs composite fiber was observed. The testing results show that it possesses not only high hardness (49 ~ 52 GPa) and Young's modulus (878 GPa) but also high bending strength (1 320 ~ 1 540 GPa) and fracture toughness (9.0 ~ 9.2 MPa•M1/2) as it was theoretically predicted. The high performances of the composite were contributed to the fiber strengthening effect and the special structure which can offer more extensive diamond to diamond bonding.
KeyWords Mullti-walled carbon nanotubes (MWCNTs); nano-polycrystalline diamond fiber; high pressure high temperature (HP/HT); mechanical properties