Erosion and erosion-corrosion of Al-brass alloy: Effects of jet velocity, sand concentration and impingement angle on surface roughness

Effects of jet velocity, sand concentration and impingement angle on the surface roughness of Al-brass alloy were investigated after erosion and erosion-corrosion tests. The tests were performed using a jet impingement rig. The eroded surfaces were characterized using 2-D and 3-D surface profilometery and scanning electron microscopy (SEM). The results showed that there was an increase in the surface roughness of the erosion-corrosion samples as sand concentration was increased to 1, 5 and 10 g/L at jet velocities of 9, 6 and 3 m/s, respectively. However, the surface roughness decreased with a further increase in sand concentration. This decrease in the surface roughness was attributed to the higher work hardening of the surface, rebounding or blanketing effect and very high frequency of the impacts at the higher sand concentrations. The surface roughness increased as the jet velocity increased. The results also showed that the change in the surface roughness with impingement angle was not significant at two jet velocities of 3 and 6 m/s. However, at a higher jet velocity of 9 m/s, formation of ripples on the erosion surfaces at oblique angles resulted in a higher surface roughness as compared with the normal impingement angle.