Cerium-cysteine complex inhibitor for aluminium alloy AA7075-T6

Abstract

Aluminium AA7075 alloy with its low density and good mechanical properties, widely responds to the requirements of aerospace, navy, and defense industries. However, corrosion is the most common problem that affects the reliability and service life of components and constructions based on this alloy. One of the most practical methods for protecting metals from corrosion is the use of inhibitors. Chromates are known as excellent inhibitors but chromate compounds are highly toxic, carcinogenic, and thus hazardous to humans and the environment. The aim of this study was to synthesize an organic eco-friendly compound (cerium-cysteine) and to investigate its inhibitory property on aluminum alloy AA7075-T6. Rare-earth metals are effective and environmentally friendly substances for aluminium protection as well as cysteine that can be found in many proteins and enzymes such as the keratin in hair. The synthesized inhibitor was confirmed and analyzed by FTIR. The survey of samples corrosion resistance was conducted by three electrochemical methods: linear polarization resistance (LPR), electrochemical impedance spectroscopy (EIS), and polarization measurements (Epit) in a 0.1M NaCl solution at room temperature. Different concentrations of ceriumcysteine were used to find the best efficiency. The best results were then tested for time dependence (up to 72 h). The inhibitory effectiveness of the cerium complex is shown to depend on a variety of factors such as concentration and time dependence.