Deng Fuming1,2;Lu Xuejun1,3;Liu Ruiping1;Xu Guojun3;Chen Quwu1;Li Wenzhu2
(1.Department of Materials Science and Engineering, China University of Mining
and Technology, Beijing Campus, Beijing, 100083, China)
(2.Department of Physics, Zhejiang University, Hangzhou, 310027, China)
(3.Beijing Institute of Electro-machining, Beijing, 100083, China)
Abstract A new type of sintered diamond reinforced by diamond MWCNTs composite fibers which were randomly orientated and even distributed in the diamond matrix was synthesized by using 3wt% mullti-walled carbon nanotubes(MWCNTs) as starting additive under high pressure of 5.8 GPa at temperature of 1500 ℃ for 1 min. A special polycrystalline diamond structure of direct bonding of both diamond to diamond and diamond to diamond-MWCNTs 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 (1320~1540 GPa) and fracture toughness (9.0~9.2 MPa.m1/2) as it was theoretically predicted. The high performances of the composite were contributed by the fiber strengthening effect and the special structure which can offer more extensive diamond to diamond bonding.