Investigation the Effect of Micro and Nano Size (SiO₂) on the Corrosion Resistance of Aluminum

This study investigated the effect of nano-SiO2 (0.125, 0.25, and 0.5 wt %) and micro-SiO2 (3, 6, and 9 wt %) additions on the corrosion resistance of aluminum (Al) fabricated by powder metallurgy (PM). The Al powder and its composite mixtures were independently ball-milled for 3.5 hrs. at 145 rpm in a 304SS vessel. Green compacts were prepared by uniaxial pressing under 650 MPa, and thereafter sintered at 528 ºC for 0.5h in an electric resistance furnace in an argon atmosphere. The potentiodynamic polarization results showed that the corrosion resistance of the Al-tested samples in a 0.1M HCl solution was improved by the addition of micro- and nano-sized SiO2 particles. Where, better improvement was detected when micro-sized SiO2 particles were added. The corrosion resistance of Al was increased by (17.07, 18.24, and 32.49) times when (3, 6, and 9) wt% micro-sized SiO2 particles were added, respectively. While the addition of nano-sized SiO2 particles improved the corrosion resistance of Al by (1.79, 2.38 and 6.62) times when (0.125, 0.25 and 0.5) wt% were added. However, the addition of micro- and nano-sized SiO2 also reduced the pitting corrosion of Al by lifting the E pit of Al to very high potential values when immersed in an acidic solution. These conclusions were obtained from the cyclic polarization results of the samples. Furthermore, XRD and FESEM were utilized to observe, and analyze the structure of the fabricated Al and its composites.