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.
Deng Fuming~(1,2) Lu Xuejun~(1,3) Liu Ruiping~1 Xu Guojun~3 Chen Quwu~1 Li Wenzhu~2 (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)
A regrown composite fiber was synthesized during the sintering of diamond under high pressure 5.8 GPa and high temperature 1500℃for 1 min,using 3wt%MWCNTs as additive.SEM observation of the fiber after alkali and acid treatment revealed that the outer layer of the fiber is composed of nano-polycrystalline diamond.EDS,XPS,XRD and Raman spectrum analysis further identified that the fiber is composed of MWCNTs in the inner part and nano-polycrystalline diamond in the out layer.It is proposed that the untransformed MWCNTs may act as a template for the regrown outer layer of nano diamond fiber under high pressure and high temperature.
Deng Fuming~(1,2) Lu Xuejun~(1,3) Liu Ruiping~1 Xu Guojun~3 Chen Quwu~1 Li Wenzhu~2 (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)
