The wear performance of ultrafine-grained tungsten carbide-cobalt (WC-Co) h
ard metals during three-body abrasion and particle erosion has been evaluat
ed and compared to that of similar conventional coarser grained hard metals
. The tungsten carbide grain size varied between 0.5 and 3 mum with cobalt
contents ranging from 6 to 15%. Silica particles were used in both forms of
testing. Erosion was carried out at 60 ms(-1) at an impact angle of 75 deg
rees and abrasion at a velocity of 0.5 ms(-1) and a load of 50 N.
The wear resistance of the ultrafine grades was found to be at least double
that of the closest conventional fine grained hard metals. These increases
in wear performance are considerably higher than any corresponding increas
e in hardness which is, at most, 25% and is not achieved at the expense of
fracture toughness which is maintained at a similar level to that of conven
tional fine grained hard metals. The increase in wear resistance coincides
with a change in the mechanism of material removal. Sub-micron materials ex
perience ductile deformation and bulk removal of material whilst coarser gr
ades display more localised response with extensive fragmentation of the WC
grains. (C) 2001 Elsevier Science B.V. All rights reserved.