Erosive–corrosive wear of aluminum alloy composites: Influence of slurry composition and speed

Abstract

The Erosion–corrosion behavior of a SiC particle reinforced Al–Si alloy has been studied in two different environments, namely saline and acidic, to simulate sea water and mining atmospheres, respectively. These studies were performed at different sand concentrations (20–40 wt%) and varying rotational speeds (700–900 rpm). It is noted from the present study that the composite exhibited better wear resistance than the alloy in marine and acidic atmospheres irrespective of sand content and speed. It is also noted that the wear rates increased with increasing sand content and speed irrespective of material due to increase in the severity of erosive/abrasive attacks. However, the wear rates decreased at higher speeds (e.g., 1100 rpm) due to increased intercollisions and rebounding and also the decrease in the mobility of the erodant particles. It is observed that erosion is the dominant mode of material removal in these two media. Corrosive attack was more predominant in the acidic media than in the NaCl media at lower sand concentrations (0–20 wt%). However, at higher sand concentrations (30–40 wt%) corrosive attack was more severe in the NaCl medium. Scanning electron microscopic (SEM) observation shows that Al/Si interfaces act as predominant sites for corrosion attack rather than the Al/SiC interfaces. Formation and removal of the passive layer, preferential attack at the Al/Si interfaces, fragmentation and wear of SiC particles were observed as mechanisms of material removal in marine and acidic media. SEM studies of the eroded–corroded surfaces indicated that an increase in the sand content of the slurry and in the rotational speed of the slurry increased resulted in greater damage to the SiC particles and matrix, resulting in an increase in wear rates.