Corrosion Protection Of Magnesium Alloy AZ80 By Thermal Sprayed Al Coating

As the lightest metallic structural material, magnesium alloys have low density, high specific strength and specific stiffness, rich in raw materials and so on. With these salient features, magnesium alloys have good application prospect. However, because of active chemical properties, corrosion resistance of magnesium alloys is poor and its application has been greatly hampered. Therefore, improving the corrosion resistance of magnesium alloys become the main task.The object of study was AZ80 magnesium alloy with thermal spray aluminum coating. Al coating was sprayed using the arc spraying and HVOF spraying. After spraying, AZ80 magnesium alloy deformed in varying degrees. Then, studed its corrosion resistance with different deformation ratio. The bonding strength has a major impact on corrosion resistance. Thus the study used different spraying methods, different coating thickness and different extrusion ratio to observe the change of bonding strength. Experiment which used electrochemical test, immersion test, mechanical property testing, metallographic observation, measurement elements and other methods studied corrosion resistance of magnesium alloys and bond strength under different conditions. The result was as follows:As the deformation increased, corrosion resistance and bond strength decrease initially and then increase. Deformation degree of 60%, the magnesium alloy had the best corrosion resistance in comparison. When the deformation degree was 45%, it had the smallest bonding strength. And it found that the thicker the coating thickness, the lower the bonding strength. Comparing the bonding strength, HVOF spray was superior to arc spray. Because the Al coating formed by HVOF had a higher density, and there was more sawtooth in the cross-section of transition zone of coating and the substrate.