Rare earth cinnamates and their corrosion inhibition mechanisms for AS1020 steel

Speciation of the inhibitors lanthanum 2-hydroxy cinnamate and lanthanum 3-hydroxy cinnamate in solution has been evaluated and compared to the speciation of lanthanum 4-hydroxy cinnamate. The results have been correlated with corrosion inhibition efficiency for AS1020 steel in an aqueous chloride solution using a combination of analytical tools such as nuclear magnetic resonance (NMR) spectroscopy, electrospray mass spectrometry (ESMS), potentiodynamic polarisation.