Erosion of hardmetals: Dependence of WC grain size and distribution, and binder composition

A liquid jet erosion rig was constructed to test hardmetals of interest to the petroleum business sector. Accurate control of eroding silica particles, jet velocities (74, 56 and 37 m/s) and impact angles (90,60 and 45 degrees) were the main purposes. Hardmetals with varying binder content (5-7 wt%), binder composition (Co and CoNiCr), tungsten carbide particle size (0.6-3.5 mu m) and particle size distribution were tested. The obtained velocity exponent of 3.4 indicates a typical level for this kind of materials, and showed that the rig was performing according to the intentions. An 80% reduction in grain size reduced the erosion level to 30-50% in hardmetals with pure Co binder, at a jet angle of 90 degrees. The greatest effect was obtained at 74 m/s jet velocity. Hardmetals with the mixed binder and the same carbide size (about 0.6 mu m) showed a reduction in erosion rate of about 65% at all jet velocities. The erosion rate was reduced by 15-20% when jet angles were reduced from 90 degrees to 60 degrees, and similarly when reduced from 60 degrees to 45 degrees. The erosion classification level, E-CV, indicated that lower carbide size and lower impingement velocity change the erosion from brittle to a more ductile mode. (C) 2013 Elsevier B.V. All rights reserved.