Fabrication Of Super-hydrophobic Layer On The Surface Of Pure Magnesium And Corrosion Behavior

Magnesium and magnesium alloy have a series of advantages such as lowdensity, high strength-to-weight ratios, high conductivity, therefore the corrosionprotection of Magnesium and magnesium alloy is widely concerned. A goodprotection method is meaningful to magnesium’s future application. In this paper, afacile one-step process was developed to fabricate superhydrophobic surfaces on thesurface of pure Magnesium by cathodic deposition successfully. The electrolytecontains nitrate, myristic acid and ethanol.The process parameters of electrodeposition affect the surface morphology andcorrosion resistance significantly. The results of this part experiments were obtained.In the process of electrodeposition, with the time increasing, the layer’s thicknessand compactness increased. The improvement of voltage, which leads to highercurrent density, was helpful to obtain smaller grain size and better compactness. Alayer with better corrosion resistance can be obtained by using pulse voltage whenother conditions were kept unchanged, comparing to direct voltage. Because pulsevoltage can accelerate the transport of charged particles, enhance activationpolarization and decrease the concentration polarization, so the nucleation rate canbe improved and the defections reduced. The main composition of the layer includecalcium myristate and cerium myristate.What’s more, cerium myristate deposits preferentially on the cathodecomparing to calcium myristate, because of its smaller radius and higher Chargedensity. The increasement of Ce content could destroy the layer’s compactness.While, a new method called Dropping process was adopted based on the conclusionabove, which effectively combine the high compactness of calcium myristate andthe corrosion inhibition of cerium. The experiment results showed that thisDropping Layer had excellent corrosion resistance and a high contact angle morethan150°. The main composition of this kind layer include calcium myristate andcerium myristate. The immersion corrosion test show that pitting holes appeared atthe9thday.Comparing to NO3-, the existence of Cl-in ethanol electrolyte can lead to alayer with smaller grain size and fewer defections, which show better property ofcorrosion resistance. Because Cl-has a better conductive ability than NO3-andadsorbs to the surface of cathode more easily. In that way a layer with bettercorrosion resistance could be abtained. The highest contact angle could be160°. Themain composition of this kind layer was calcium myristate. The immersion corrosion test show that pitting holes appeared at the96thhours, twice as long as0.05Ca(NO3)2layer.