ON THE PARTICLE-SIZE EFFECT IN SLURRY EROSION

The erosion rates of cylindrical steel specimens tested at a constant speed of 18.7 m s-1 in an erosion pot tester using 1.2 wt.% suspension of SiC in oil for particle diameters between 20 and 500-mu-m have been determined. The rate of particle impact on unit area of the surface at the stagnation line of erosion specimens was established as a function of particle size by short-time erosion tests, allowing a calculation of the mean mass removed for each particle impact as a function of particle size. These values were compared with the kinetic energy of particles using impact velocity values derived from a model of suspension flow. Results show that the decrease in erosion rate with decreasing particle size for suspensions of constant solids loading reflects the decrease in the proportion of particles impacting the target surface as well as the decrease in impact velocity. A value of about 24 kJ g-1 is tentatively suggested for the energy of removal of P110 steel by erosion. It is concluded that for these dilute suspensions with particle sizes greater than about 100-mu-m the erosion rate is proportional to the kinetic energy dissipated by particles during impact, but for particle sizes less than 100-mu-m other metal removal mechanisms become increasingly significant.