Study On Corrosion And Protection Of Aluminium Alloy In Coolant Soulution Of Automobile Engine

Aluminium alloys is one of the most important metal which has beenextensively employed in various essential industries, especially in automotive.It has many superior properties, such as low-density, high specific strength,excellent transmission of the heat and the electricity. But it can suffer severecorrosion in moist environment. Currently, the main composition of aconventional coolant is30-70vol%ethylene glycols. But the oxide of ethyleneglycols will influence the corrosion resistance of the aluminium alloysautomotive engine. In this paper, the corrosion and protection of aluminiumalloys in ethylene glycol-water solution was investigated by fluorescentspectrometry, weight loss method, electrochemical measurements, and surfaceanalysis techniques. The primary results are as follows:(1)The fluorescent probe of o-phenolsalicylimene (PSI) was synthetizedwith2-hydroxyaniline and2-hydrolyl-benzaldehyde by the Schiff base reaction.The corrosion of5052alloys in ethylene glycols-water solution whichcontained Cl-was monitored by fluorescence probe technology. The resultsshowed that the change of Al3+concentration in the solution detected byfluorescence technology can monitor the corrosion of the alloy, and thefluorescence image can indicate the pit corrosion of the alloy.(2)The effects of ethylene glycol–water solution contaminants of chloride(Cl-)、cupric (Cu2+) and ferric (Fe3+) ions, in four different mixture combinationof Fe3++Cu2+、Cl-+Fe3+、Cl-+Cu2+and Cl-+Fe3++Cu2+, were examined onthe corrosion behaviour of5052alloys, using mass loss technique. Thecorrosivity of the solution in the presence of the combination of ions was in theorder: Fe3++Cu2+> Fe3++Cu2++Cl-> Fe3++Cl-> Cu2++Cl-. The resultsgave first-order kinetics with respect to aluminium in ethylene glycolsolution-ion systems.(3)The inhibition behavior of cinnamic acid and Ce3+(cerous nitrate) forA356alloys corrosion in ethylene glycols-water solution was investigated.Cinnamic acid and Ce3+have a limited inhibition effects for aluminium alloys,respectively. It showed that combination of cinnamic acid with Ce3+can improve the inhibition effect. It reachs96.76%with1mM Ce3+and cinnamicacid whose molar ratio is2:1at48h. The combination of cinnamic acid andCe3+has a strong synergistic inhibition effect.