Influence of natural beach mineral corundum on the wear characteristics of LM30 aluminium alloy composites

Abstract

Abstract The work investigates the effect of corundum (Al2O3) reinforcement on the dry sliding wear of LM30 aluminium alloy composites. Composites with the different size range of corundum particles (fine; 1–20 μm, medium; 32–50 μm and coarse; 75–106 μm) and weight percentages varying from 5–20 wt.% were prepared. The stir casting process was used for the fabrication of composites. LM30 billets were melted at 850 and stirred with the graphite stirrer for 3–4 min. Corundum particles were added to the melt and the molten mass was stirred for another 3–4 min. Finally, the mixture was poured into a cast iron mould. Pins of 8 mm diameter were prepared for wear test and tested against the hardened die steel disc. Optical microscopy of the composites revealed a uniform distribution of corundum particles in the matrix. The microstructure of the composite also got refined. The acicular morphology of eutectic silicon in base alloy got refined to globular for the composites leading to improvement in the hardness of the composites. Dry sliding wear analysis of the composites revealed the decrement in the wear rate of the composites over the base alloy. Similar to the wear rate, the coefficient of friction of the composites also decreased with the increase in the corundum weight percentage. Finally, the wear tracks and debris analysis of the composites revealed the underlying wear mechanisms during the dry sliding wear behavior at a low contact pressure of 0.2 MPa and high contact pressure of 1.8 MPa. The wear mechanism of the composite is dependent on contact pressure. At low contact pressure of 0.2 MPa, the abrasive type wear transformed to adhesive type at a high contact pressure of 1.8 MPa.