MICROSTRUCTURE AND MECHANICAL PROPERTIES OF ULTRAFINE WC/Co CEMENTED CARBIDES WITH CUBIC BORON NITRIDE AND Cr3C2 ADDITIONS

摘要

This study investigates the microstructure and mechanical properties of ultrafine tungsten carbide and cobalt (WC/Co) cemented carbides with cubic boron nitride (CBN) and chromium carbide (Cr3C2) fabricated by a hot pressing sintering process. This study uses samples with 8 wt. % Co content and 7.5 vol. % CBN content, and with different Cr3C2 content ranging from 0 to 0.30 wt. %. Based on the experimental results, Cr3C2 content has a significant influence on inhibiting abnormal grain growth and decreasing grain size in cemented carbides. Near-full densification is possible when CBN-WC/Co with 0.25 wt. % Cr3C2 is sintered at 1350 degrees C and 20 MPa; the resulting material possesses optimal mechanical properties and density, with an acceptable Vickers hardness of 19.20 GPa, fracture toughness of 8.47 MPa.m(1/2) and flexural strength of 564 MPa.