Abrasive wear resistance of WC-based composites, produced with Co or Ni-rich binders

Tungsten carbide (WC) based composites are highly wear resistant, exceptionally durable and used in numerous cases as a variety of machining tools, punch and dies and drill bits. These materials are generally obtained by sintering a tungsten carbide powder and a metal binder, being cobalt the most common binder. The binder fraction and the carbide grain size of powders determine the mechanical resistance of the final product and, consequently, its tribological behaviour. However, in order to impart higher wear and corrosion resistance to the product, other binders may be used. In the present research work, several composites with different binder compositions were prepared, resulting in seven different specimens: WC-Co, WC-Ni, WC-CoNi, WC-CoCr, WC-NiCr, WC-CoNiCr and WC-NiCrMo. The mechanical properties of the different composites were evaluated and correlated with the microstructure and tribological behaviour. Concerning the abrasion characterization, from each test, the wear volume was assessed and the details of the wear surfaces were analyzed by Optical Microscopy, Scanning Electron Microscopy and profilometry. It was found that the presence of chromium in the binder increased the abrasion resistance, comparing to the other composites under study.