Surface Treatment of Gray Cast Iron and Copper for Corrosion Resistance by Alumina Coating Using an In-Mold Sand Treatment Method
摘要
This article examines the impact of surface treatment of gray cast iron and copper with aluminum on corrosion resistance. We conducted a treatment study in a silica sand clay mold whose imprint was covered with a thin layer of aluminum. Two materials were used: lamellar gray cast iron and copper. The samples, cylindrical in shape, had two different diameters: 15 mm and 50 mm. Observation under an optical microscope revealed the formation of a continuous layer on the surface of the two materials, X-ray diffraction analysis showed that these layers are constituted by the FeAl, Al2FeO4 phases with an average Vickers microhardness of 726 Hv for gray cast iron, and Cu2O, CuO, Al2Cu with an average microhardness of 95 Hv for copper. The electrochemical study carried out in a NaCl solution (3.5%) revealed, through Tafel curves, an improvement in the corrosion resistance of cast iron and copper. Treated cast iron with a diameter of 15 mm shows a slight improvement in corrosion resistance compared to treated cast iron with a diameter of 50 mm. For the 15 mm diameter, the corrosion rate improved from 28.44 mm/year to 16.54 mm/year. While the copper showed a remarkable improvement in corrosion resistance, with a potential shift of 263 mV. For the 15 mm diameter samples, the corrosion rate decreased significantly from 11.646 mm/year to 7.623 mm/year. In addition, the 15 mm diameter samples showed better corrosion resistance compared to the 50 mm diameter samples.