CORROSION RESISTANT MANGANESE PHOSPHATE COATINGS FOR MG AM-LITE ALLOY

摘要

A facile chromate-free method to deposit manganese phosphate conversion coatings upon magnesium alloy AM-lite for corrosion protection was developed. Surface treatment to remove the intermetallic particles from surface was applied prior to coating process. Coating nature, including morphology, phase composition, and corrosion resistance in NaCl solution was characterised by using scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), potentiodynamic polarisation and salt spray. The results indicate that the conversion coating is an amorphous structure, containing Mg, O, Mn, and P in a complex surface chemistry. Such surface coating was able to significantly improve the corrosion susceptibility of AM-lite alloy.