Super-hard diamond indenter prepared from high-purity synthetic diamond crystal

Abstract

The Knoop hardness in (001)⟨110⟩ of high-purity synthetic type IIa diamond crystal synthesized under high pressure and high temperature is known to be extremely high. Knoop indenters were prepared from the synthetic type IIa diamonds by taking the tip orientation to the hard crystal orientation of the diamonds, i.e., the z axis and the longitudinal direction of the indenter tip are parallel to the ⟨001⟩ and ⟨110⟩ direction of the crystal, respectively. Numerous indentation tests on diamond crystals revealed that the indenter is substantially rigid and has very high performance. The lifetime of the indenter was more than ten times longer than that of the conventional natural diamond indenter.