Analysis of Mechanical and Physical Properties of Al-Si (Al-Si) Casting Alloys Reinforced with Various Eggshell Nanopowders

Al-Si alloy was synthesized of combining aluminum and silicon (Al-Si). The addition of 15% silicon was aimed to improve the ductility and hardness of aluminum up to 525 MPa. It was also intended for reducing defects from gas porosity. However, the use of more than 15% silicon would make the alloy more brittle drastically which microscopically representing by the formation of crystalline silica granules. This study involved eggshell nanopowders as reinforcing material in enhancing hardness and ductility of Al-Si alloy. The casting process began with synthesizing eggshells into nanopowders. We added a certain amount of eggshell nanopowders (ESNPs) (0.05%, 0.1%, or 0.2%) into the Al-Si molten and subsequently mixed using a stirrer for 1 minute. The resulting mixture was poured into a permanent mold. It was shown that the Al-Si casting reinforced with 0.1% ESNPs had the highest tensile strength of 20.38 kg/mm² and the highest hardness of 137.9 HV. Further analysis revealed that the microstructure homogeneity of the samples is strongly affected its hardness.