Enhanced corrosion resistance of magnesium alloy by a silane-based solution treatment after an in-situ formation of the Mg(OH)2 layer

A novel organic–inorganic Mg(OH) 2 /silane surface layer has been developed for corrosion protection of AZ31 magnesium alloy. The results of electrochemical impedance spectroscopy (EIS), the immersion tests, Fourier-transform infrared spectroscopy (FTIR) and sellotape tests showed that the Mg(OH) 2 /silane-based composite surface layer possessed excellent corrosion resistance and very good adhesion due to the formation of Si–O–Mg bond between Mg(OH) 2 layer and silane layer. Electrochemical impedance spectroscopy tests results indicated that for the long-term corrosion protection of AZ31 the increase of the curing temperature improved the impedance of the composited layer when the curing temperature was lower than 130   °С. However, the impedance of the composited layer deceased when the curing temperature was more than 130   °С due to the carbonization of the silane layer.