EROSION TIPPLE FORMATION MECHANISM IN ALUMINUM AND ALUMINUM-ALLOYS

The formation of ripples on pure Al and Al-12Si alloy surfaces was inv estigated. Sharp angular Al2O3 and spherical glass beads were used as erodent particles accelerated in an air-blast type system. The experim ental variables were erodent particle shape, angle of impact, and abra sive particle mixture. Scanning electron and optical microscopy used t o study the morphology of impacted surfaces showed the well-developed ripple formation on Al-12Si with beads used as abrasive. As the fracti on of Al2O3 sharp particles mixed with glass beads was increased, the ripple formation on Al-12Si diminished. An investigation of the surfac e morphology of the eroded samples provided evidence for a mechanism o f ripple formation based on material displacement instead of material removal.