Erodent particle characterization and the effect of particle size and shape on erosion

Abstract

SiC, Al2O3 and SiO2 particles in various grit sizes are characterized by image analysis in terms of their area, area diameter, width, length, width-tolength ratio W/L and perimeter squared-to-area ratio P2/A. Along with the mean, median and r.m.s. deviation of these parameters, the cumulative frequency distributions of the area and W/L are also obtained. W/L and P2/A are used as the indicators of particle shape. The particles become more elongated and less circular as the size of SiC and A12O3 particles increases and that of SiO2 particles decreases. The characterized particles are used for erosion studies on 18Ni(250) maraging steel in aged condition in a sand-blast type rest rig. The variation of erosion is studied with changes in size and shape of these particles. Erosion rate increases with increasing particle size for SiC and Al2O3 particles up to a certain value and decreases for SiO2 particles. However, it increases with increasing P2/A and decreasing W/L for all three types of particles. Erosion behavior is analyzed considering the effect of rake angle in ploughing and microcutting as observed in erosion. It is the changing contribution from ploughing and cutting with changes in shape and size of particles that accounts for erosion variation.