Inhibitive Action of Potassium Iodide on the Corrosion of Stir-Cast Al–Si/SiC in NaCl-KI Interface

The inhibitive action of potassium iodide (KI) on the corrosion of Al–Si/SiC particulate composite in 3.65% NaCl solution was investigated using gravimetric and potentiodynamic polarization techniques at 298 K. The results showed that KI in NaCl-aluminum alloy/SiC composite environment decreased the corrosion rate at all the concentrations considered. Inhibitor efficiencies (IEs) of 97.17, 97.34, and 97.57% with 0.5 g/v addition using gravimetric method were achieved after 92, 196, and 288 h of exposure times, respectively. The IEs from the potentiodynamic polarization method under both conditions (uninhibited/inhibited) were significantly enhanced. The high-resolution scanning electron microscopy for surface morphology of the as-corroded, uninhibited specimens showed the formation of pits and cracks compared with the as-corroded inhibited specimens. The addition of KI as corrosion inhibitor indicates increased potential value, % IE, and polarization resistance value with the decreasing current density. The two methods employed for the corrosion assessment of the composite were in agreement, and mixed-type corrosion has been demonstrated to occur which followed Langmuir adsorption isotherms.