Experimental Studies of Submicron Polycrystalline Diamond without Binder under High Pressure and Temperature

This paper aims to study the sintering process and mechanical properties of submicron polycrystalline diamond (SMPD) without any secondary phases and binder materials under pressure of 7-8 GPa and 1400 °C-1800 °C, using the bi-layer assembly and the conventional assembly methods. The as prepared samples were characterized by X-ray diffraction, scanning electron microscope, and Vickers indenter hardness tests. Well sintered specimen was obtained under the condition of 8 GPa and 1600 °C using the bi-layer assembly method, and an indentation test demonstrated a Vickers hardness of 52 GPa. The graphitization of diamond was found to be an important factor determining the hardness of samples sintered using the bi-layer assembly.