Nanopolycrystalline Diamond Sintered from Onion-Like Carbon

Abstract EN

The onion-like carbons (OLCs) annealed at 900–1400°C were used as raw materials to synthesize additive-free D-D type nanopolycrystalline diamond (nPCD) compacts in the industrial sintering conditions of 5.5 GPa, 1200°C, and 15 min.

The results showed that the OLCs were transformed into additive-free D-D type nPCD compacts in industrial sintering conditions.

The nPCD compacts contained a large number of nanotwins.

The purities and performances of nPCD compacts were homogeneous in three dimensions.

The purity and physical and mechanical performances of the nPCD compact (denoted as nPCD11) sintered from the OLCs annealed at 1100°C were the highest.

The average Vickers hardness, density, and nanodiamond grain size of nPCD11 were 32 GPa, 2.7 g/cm3, and 12 nm.

During sintering process, the graphite layers of OLCs ruptured from inside toward outside forming larger nanodiamond particles.

At the same time, the OLCs bonded adjacent to OLCs forming additive-free D-D type nPCD compacts.