Performance evaluation of phosphite NaCo(H2PO3)3·H2O as a corrosion inhibitor for aluminum in engine coolant solutions

Abstract

The inhibiting action of a novel inorganic compound (NaCo(H₂PO₃)₃·H₂O) (NaCoPh) synthesized in our laboratory on the corrosion of aluminum in engine coolant solutions has been studied. In this study, potentiodynamic polarization measurements with SEM/EDX investigations were employed. Polarization curves reveal that NaCoPh is a mixed type (cathodic/anodic) inhibitor for aluminum corrosion in the engine coolant solution. The inhibition efficiency increases with increasing concentration of NaCoPh but decreases with increasing temperature and flow rate. SEM/EDX investigations reveal the adsorption of NaCoPh on the aluminum surface. A mixed adsorption (physisorption and chemisorption) for NaCoPh was proposed.