Effect of Natrium Carbonate (Na2CO3) on porosity and hardness in the melting of aluminium canned

The smelting process is a process to form a product that resembles the original, one way to recycle products or household waste include melting aluminium cans of refreshing drinks to reduce waste, melting the cans into ingot specimens as raw material for making fishing boat propellers in order to reduce high production costs and to find out good quality, the method of melting aluminium cans mixed with Sodium Carbonate as much as 2.5%, 5%, and 7,5% into aluminium ingots which results are tested by hardness testing and digital microscope to see porosity and find out the hardness of each specimen, from experimental smelting mixed with 2,5% Sodium Carbonate has a hardness value of 56.44 and a mixing of Sodium Carbonate of 5% has a hardness value of 52.66 and a mixing of Sodium Carbonate of 7,5% has a hardness value of 55, 32. As for the porosity itself, the result of mixing 2,5% Sodium Carbonate has a porosity of 0.70 mm and a mixing of Sodium Carbonate of 5% has a large Porosity of 0.45 mm and a mixing of Sodium Carbonate of 7,5% has a large porosity of 0.21 mm.