The invention relates to an ultrahigh hard nano twin
diamond block material and a preparation method thereof, and specifically discloses a
nanocrystalline diamond block material containing
high density twin crystals and a synthesis method thereof. Particles of nano spherical carbon without
a diamond core (carbon with an onion structure is named as coreless onion carbon for short) are taken as the raw materials and then subjected to synthesis under a
high pressure at a high temperature to obtain nano twin
diamond blocks. The volume of obtained nano twin
diamond block is 1-2000 mm3; the Vickers
hardness is 155-350 GPa, the Knoop
hardness is 140-240 GPa, and the twin width is 1-15 nm. Compared to the prior art, the
hardness of the obtained nano twin diamond blocks is far higher than the hardness of diamond mono-
crystal and ultrahigh hard
polycrystalline diamond, wherein the Vickers hardness of diamond mono-
crystal is just around 100 GPa, the highest Knoop hardness of ultrahigh
polycrystalline diamond is 140 GPa, while the highest Vickers hardness of the nano twin diamond blocks can reach 350 GPa, and the highest Knoop hardness of the nano twin diamond blocks can reach 240 GPa. The nano twin diamond block has a wide application prospect in the machinery
processing field such as geological drilling, high speed
cutting,
ultra precision processing, and the like, the
grinding material and
grinding tool field, the wire-drawing die field, and the special optical element field.