Fig. 2: Mechanical properties of the high-density stacking-fault diamond (HSD) and its comparison with other diamonds.
a Hardness of HSD as a function of applied load. Beyond 9.8 N, the hardness HV decreases to the asymptotic values of ~208.3 GPa. The inset shows the typical indentation morphology of HSD-1 and the diagonal lengths of the indentation and crack. b, c, Vickers hardness (HV) (b) and fracture toughness (KIc) (c) for HSD-1 to HSD-4, (100) single crystalline diamond (SCD) and polycrystalline diamond (PCD). d Statistical plot of diamond hardness as a function of sample diameter (The square shape of the samples according to its longest side as the diameter). e Demonstration of HSD growth on the surface of a tungsten carbide end mill. A very uniform superhard diamond coating (bottom left) was grown using this method on a standard tungsten steel mill (top left), with enlarged surface images of tungsten steel and diamond coatings in red boxes on the right; representative result from three independent experiments showing similar morphology. f Chemical vapor deposition (CVD) SCD without scratches (top left). The diagram of using HSD-1 to scratch a single crystal diamond (bottom left). The clear scratch morphology of the surface of the single crystal diamond is scratched by a cutting tool made of HSD-1 (right). g The scratch depth morphology (left) was obtained by laser confocal scanning microscope of the red box in figure f. Depth profile (right) of the transverse surface of the scratch of the red line in the left figure. h Comparison of abrasive ratio across polycrystalline cubic boron nitride (c-BN), sintering-PCD, PCD film, SCD and HSD samples. The error bars in (a–c) represent the standard deviations from seven parallel measurements. Source data are provided as a Source Data file.
