Effect of Re addition on the microstructure and mechanical properties of WC-10Co cemented carbides fabricated by chemical coating method

Abstract

WC-Co composite powder with nano‑cobalt coatings doped with rhenium (Re) varying from 0 to 3 wt% were prepared by a novel sol-gel method. The effects of Re on the microstructure and mechanical properties of WC-10(Co, xRe) cemented carbides fabricated by composite powder were studied by XRD, SEM and TEM. The results indicated that C4H6CoO4·4H2O with or without NH4ReO4 was homogenously distributed on WC powder particles. After reduction in H2 atmosphere, nano‑cobalt with Re was coated on WC particles with a uniform distribution in composite powder. WC-10(Co, xRe) cemented carbide containing Re exhibited homogeneous grain distribution. Moreover, no stabilization effect for hexagonal close-packed (hcp) cobalt by Re addition was found mainly due to the minor additive amount and the unique preparation method. WC grains were refined and binder phases were strengthened due to the dissolved Re in binder phases. With increasing the content of Re from 0 to 3 wt%, an improved microstructure led to better mechanical properties, the hardness increased from 87.8 ± 0.1 HRA to 89.4 ± 0.2 HRA, transverse rupture strength (TRS) increased from 2810 ± 89 MPa to 3410 ± 113 MPa.