Electrochemical and quantum chemical investigation of some cyanoacetamide derivatives as eco-friendly corrosion inhibitors for aluminum –silicon alloy in acidic solution

Cyanoacetamide derivatives (CyD) were investigated as eco-friendly corrosion inhibitors at various doses for alloy (Al/Si) in one molar HCl utilized Tafel polarization (TP), (EFM) electrochemical frequency modulation and (EIS) impedance method. The temperature influence on corrosion behavior with appending of various doses was carried out in range of temperature of 25-45ºC by EFM technique. TP plots revealed that the investigated CyD were of mixed-type. The protection efficiency (% η) was found to rise with increasing the concentration of investigated CyD but decrease with improving the medium temperature. CyD adsorption on Al/Si alloy surface was found to obey Temkin isotherm. Some adsorption and activation thermodynamic functions were measured and explained. The order of the % η of CyD is given: (1) > (2) > (3). It was noted that the data of quantum chemical calculations run parallel to the rise in % η given which support the preceding order.