中文摘要：

The phosphated zinc layer was post-sealed with molybdate to obtain the composite coating without pores.The composition of the formed coating was investigated. The corrosion behavior of the coated sa^nples was studied.The coated samples w-ere first scratched and subsequently corroded in a neutral salt spray ( NSS) chamber for 2-72 h; the microstructure of the corrosion products w，as analyzed via SEM and EDS; and the self-healing performance w，as discussed. The coating obtained contains Zn3 ( PO4 ) 2 .4H20 ，Mo2O3 and MoO4 2-. The electrochemical impedance first increases and then decreases with the immersion time. How-ever, after immersion for 6 days, it remains at about 1 0 kOΩcm2, much higher than the value for the single-treated samples without corrosion. Micro structural observations show that the corrosion products in scratch increase in size and finally cover the whole scratch completely. The initial corrosion products have high P , Mo and 0 contents but almost no Cl,while in later stages the first three components decrease and Cl increases. The corrosion products form a compact mass of needle-like crystals, effectively inhibiting zinc corrosion. The composite coating exhibits good self-healing.