In the present study, we present a novel method to sinter Cr3C2 powders under high pressure without any addittives. The sintering Cr3C2 samples were charaterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), relative density measurements, Vicker’s hardness tests and Fracture toughness tests. The reasults show that Cr3C2 powders could be sintered to be bulk under the conditions of 3-5 GPa, 800-1200 °C and the heat preservation for 15 min. Moreover, the sintering body of Cr3C2 compound with the relative density of 99.84% by simultaneously tuning the pressure-temperature conditions exhibited excellent mechanical properties: a Vickers hardness of 20.3 GPa and a fracture toughness of ~8.9 MPam1/2. These properties were much higher than that by using the previous methods. The temperature condition obtained good mechanical properties in the experiment was about 1/3 lower than that using any other methods owing to the high pressure.

PcBN–Al composites（PAC）have been synthesized by pressure infiltration(PI) and a general mixing method(GM)[1-3] with a wide grain sizes range of 4-25 um and a wide temperature range of 1200-1600°C at 5.0 GPa,respectively.Hardness ranged between 30and 40 GPa, while the flank wear (Vb) reached 0.12mm when it finished 4000m in cutting test ofPAC synthesized by PI method. Hardness ranged between 25 and 35GPa, while the flank wear (Vb) reached 0.14 mm when it finished 4000mof PAC synthesized by GM method. The homogeneity of PcBN–Al synthesized by PI have been improved compared with GM. PI is a superior method to synthesize PAC in the field of mechanical properties.

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.