Study on Corrosion Resistance and Surface Structure of RE Conversion Coating with HF
The influence of HF-on the corrosion resistance was investigated by 5% NaCl solution at 30 ℃ and potentiodynamic polarization curves.Coating microstructure was analysed by SEM and EDX.The results show that the anticorrosive properties of the coatings enhance by adding accelerant A,and the coating is mainly formed by Ce oxides/hydroxides,but addition of intermetallic compounds (such as AlFeSiMn,β-AlFeSi) and the irregular particles on the surface of the coatings derived from alkali corrosion stage have different opposite effect.The existent particles contribute to the improvement of cathode properties of out phase interface and offer underlay for the depositon of Ce.The electric doublet and tip stress are formed,which can decrease the properties of conversion coating.