COMPARISON OF THE MECHANICAL CHARACTERISTICS OF ALUMINIUM SIC COMPOSITES CAST IN SAND AND METAL MOULDS

The consequence of sand and metal moulds on mechanical and microstructural characteristics of Aluminium Silicon Carbide (AlSiC) composite were studied. The composite material was prepared using a liquid-metallurgical technique via stir casting process. The aluminium ingot was melted in a tilting furnace of 5kg for 45 minutes at a temperature of 750ºC. Then 2.5% of silicon carbide (600 grit size) was added to the liquid metal, and to obtain homogeneous dispersion of silicon carbide, two stepwise mixing methods; mechanical and stir processes were applied. Then cast into sand and metal cast moulds respectively which were prepared earlier. The process was repeated for the other percentages of 5%, 7.5% and 10% for silicon carbide. The cast samples were allowed to be solidified and then machined into tensile, hardness and impact specimens according to their specifications. The results of the tests show that for materials which require high impact strength, metal cast process seems to be the best option to be used while for materials that require high hardness resistance, high modulus and high yield strength, the sand cast process should be used.