Magnetron Sputtering In The Mg-li Alloy Surface Preparation Of Anti-corrosion Coating

Magnesium-lithium alloy is one of the lightest metal materials, which has excellent properties such as higher specific strength,high impact toughness, casting characteristic and so on. So it should be widely used in astronavigation, automotive, electronic areas, but the poor corrosion resistance that limits its extensive applications. At the present time, studies on Mg-Li alloys were mainly focused on casting. Physical vapor deposition (PVD) as a green technique has applicable for surface modification of Mg-Li alloy.In this paper, we used magnetron sputtering to prepare several coatings on Mg-Li alloy. X-ray diffraction (XRD), Scanning electron microscope (SEM), and Atomic formic microscope (AFM) were used to characterize the phase structure and the surface morphology of the coatings. Electrochemical methods, Hydrogen evolution experiment and static agravity methods were applied to study the corrosion behavior of these coatings. The main results include:(1)The aluminium and titanium coating, which were prepared on Mg-Li alloy by DC magnetron sputtering, have some defects,they all have strongly texture and a developed columnar microstructure.(2)It is proved that aluminium film had a better corrosion resistance than titanium film. The defects which formed in the deposition process caused the failure of the film protect system.(3)The titanium nitride coating and aluminum nitride coating were prepared by reactive magnetron sputtering. Titanium nitride coating has improved the corrosion resistance of substrate, but its durability was poor, and appears abscission. Aluminum nitride coating exhibited good interface adherence but it had a loose structure.(4)Corrosion test indicate that multiple coatings have better protection effect than monolayer.