Consolidation of Cr3C2 doping WC–1TiN–5MgO micro–nano composites by two-step sintering

Abstract

ABSTRACTThe effect of Cr3C2 additions on WC–1TiN–5MgO composites by two-step hot-pressing sintering (heated to 1750°C and then immediately cooled to 1575°C with a soaking time of 60 min under a sintering pressure of 50 MPa) was comprehensively investigated. The microstructure was characterized by means of scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), and X-ray diffractometry (XRD). Mechanical properties, such as hardness, transverse rupture strength, and fracture toughness, were measured. The experimental results show that no η-phase or brittle phases such as W2C were formed, and excellent mechanical properties were achieved for 0.6 wt.% Cr3C2 additions with a hardness of 24.76 GPa, a flexural strength of 1257.1 MPa, and a fracture toughness of 10.08 MPa · mm1/2. Cr3C2 addition brought about an improvement in the sinterability and contributed to the homogeneous distribution of second phase nanosized MgO. Crack deflection and crack bridging are the major mechanisms contributing to the drastically enhanced flexural strength and fracture toughness.