This paper reports solid particle erosion studies of 10-47 mu m chemical va
pour deposited (CVD) diamond coatings deposited on W and SIC substrates. Tw
o erosion test facilities were used: a water-sand slurry rig and a high-vel
ocity air-sand rig. The erodent used was silica sand with average diameters
of 135 mu m, 194 mu m and 235 mu m with the velocities in the range of 16-
268 ms(-1) and 90 degrees nominal impingement angle. The erosion rates were
plotted against particle kinetic energy and compared with those for cement
ed tungsten carbide and stainless steel. The samples were examined both pre
- and post-test by scanning electron microscopy in order to determine the m
echanisms of degradation suffered by the coating during the erosion process
; the effects of thickness and microstructure were also examined. The time
to failure of the coatings at 268 ms(-1) was found to increase from 5 to 18
5 min over the range of coating thickness tested. The erosion mechanism at
high-velocity conditions is thought to be a three-stage process consisting
of micro-chipping, development of pin-holes and interfacial debonding, foll
owed by catastrophic failure. However, it should be noted that, at particle
velocities of 268 ms(-1), 46 mu m CVD diamond coatings on tungsten display
ed approximately six times the erosion resistance of cemented tungsten carb
ide. (C) 1999 Elsevier Science S.A. All rights reserved.