Development and characterisation of zinc oxalate conversion coatings on zinc

The interactions between oxalic acid and zinc substrates have been studied through the deposition of zinc oxalate coating by immersion. The corrosion behaviour of zinc was investigated by surface observation and electrochemical impedance spectroscopy (EIS). Better protective properties were observed for samples treated with 10(-1) M oxalic acid compared to other concentrations and the enrichment of corrosion product by Na was observed. The electrochemical results reveal that the oxalate coating increases corrosion protection in corrosive medium. It is proposed that the zinc oxalate coating formed act as a basis for anchoring zinc corrosion products forming simonkolleite improving corrosion resistance.