Corrosion inhibition of pre-formed mussel adhesive protein (Mefp-1) film to magnesium alloy

•A protective film was formed on Mg alloy surface by the self-absorption of Mefp-1.•Mefp-1 films can effectively inhibit the localized corrosion of Mg alloy.•Mefp-1 film pre-formed at low pH imparts an increasing impedance resistance to Mg alloy. A range of ex situ and in situ analytical techniques were applied to gain insights into the formation and properties of the pre-formed Mefp-1 film on magnesium-1.0 wt.% calcium (Mg-1.0Ca) alloy. The results revealed that the Mefp-1 film pre-formed at pH 4.6 shows a net-like structure, whereas it is more packed at pH 8.5. in situ scanning micro-reference electrode technique results demonstrated the Mefp-1 films formed at both pH can effectively inhibit the localised corrosion of Mg-1.0Ca alloy. Moreover, the film pre-formed at pH 4.6 provides an increasing corrosion inhibition to Mg-1.0Ca alloy during 7 days of exposure.