An investigation of new barium phosphate chemical conversion coating on AZ31 magnesium alloy

► Chemical conversion coating on Mg AZ31 alloy with Ba(NO3)2 and NH4H2PO4 as the precursors. ► Investigations of pH, temperature, concentrations of Ba(NO3)2 and NH4H2PO4, and deposition time. ► A two-layer coating featuring an amorphous under layer and a crystalline top layer. ► Enhanced corrosion resistance.