The effect of impact angle on the erosion rate of polycrystalline α-Al2O3

Wet erosive wear tests with SiC particle impacts at 45 degrees, 60 degrees, 75 degrees and 90 degrees were performed on polycrystalline alpha-Al2O3 specimens of mean grain size 1.2, 3.8 and 14.1 mu m. The erosion rate was found to be strongly dependent on impact angle, being three to four times greater for impacts at 90 degrees than for 45 degrees impacts. The erosion rate varied strongly with grain size, the coarse grained material had erosion rates about six times greater than those of the finest grained material. The worn areas due to impacts after short erosion times were examined by SEM to characterise the erosion mechanisms, the mechanism of erosive wear appears to be by the interaction of the cracks from adjacent impacts. The variation of erosion rates with impact angle for all grain sizes showed a power law dependence on normal impact velocity, with an exponent of similar to 3.9. (C) 1997 Elsevier Science Limited.