Corrosion Properties Of Mg-Li Alloy And Its LDH Coating

Magnesium-lithium alloy(Mg-Li alloy)exhibits high specific strength,excellent shock absorption performance,good damping characteristics and unique electromagnetic shielding ability,so that Mg-Li alloy in aerospace,3C products,military and other fields have great application prospects,but Mg-Li alloy shows pretty poor corrosion resistance on account of its high chemical activity,especially in the environment containing corrosive media,its performance decline is more serious,which greatly limits the application of mg-Li alloy.Layered double hydroxide(LDH)have many unique properties,it can make the environment of corrosive anions and interlayer anion exchange avoids contact with the matrix,and thus improve the effect of corrosion make it has potential application prospect in the field of surface protection.In this paper,the corrosion resistance of cast Mg-Li alloy was improved by preparing protective coating on the surface,that used the traditional hydrothermal method and electrodeposition of LDH prepared by coating respectively,in which to make a study of sedimentary conditions of electrodeposition and fluoride composite coating was prepared,and the coating morphology and corrosion resistance testing,will influence the LDH coating corrosion resistance,thus can be used as a method of Mg-Li alloy surface protection.The Mg-Li alloy was analyzed by ICP,and then its composition was obtained by XRD and DSC,and its thermal properties were analyzed.The solution system used for preparing a series of basic properties of the casting Mg-Li alloy coating was Zn-Al-NO₃ system.The hydrothermal LDH coating was prepared by hydrothermal reaction under high temperature and high pressure,using XRD,SEM,EDS FT-IR XPS of phase structure surface element composition and characterization ion group analysis,EIS immersion corrosion and corrosion morphology polarization curve is used to evaluate the corrosion performance of coatings research results show that hydrothermal LDH coating with special structure,and protection for Mg-Li alloy has good performance,can greatly improve the corrosion resistance of Mg-Li alloy.The coating structure and corrosion resistance of electrodeposited LDH coating obtained under different electrodeposition conditions are different.The structure of the coating can be greatly affected by regulating the p H value of deposition.Among them,the presence of LDH can be observed and detected when the p H value is 3,and obvious LDH coating can be observed and detected when the p H value is 7 and 9,and its corrosion resistance from high to low is p H=3,p H=7 and p H=9 controlling deposition voltage mainly affects its corrosion resistance,and the order of corrosion resistance from high to low is deposition voltage-1.6V.The deposition voltage is-1.7V;Deposition voltage of 1.5V.Compared with bare Mg-Li alloy,the composite coating exhibits better corrosion resistance than the single electrodeposited LDH coating.The results show that the composite coating has better corrosion resistance than the single electrodeposited LDH coating.Although LDH coating and its composite coating improved the corrosion resistance of Mg-Li alloy,the method has not achieved the effect of long-term protection.Therefore,the preparation conditions can be further optimized and new surface protection methods can be developed to improve the corrosion resistance of Mg-Li alloy.