Studies On Preparation And Corrosion Resistance Of LDHs Films

Layered double hydroxide (LDHs), also known as anionic orhydrotalcite-like clays, are currently of intense academic and industrialresearch interests, in part, because of their properties as catalysis and catalystprecursors, adsorption, separation, biology and medicine materials. Filming orimmobilizing LDHs materials will enlarge its usability in optic, electrical,magnetical fields. In our work, LDHs films were prepared by spin-coating thenanosized LDHs sol on AZ31 Mg alloys. The structure of the LDHs films wasdiscussed. Spin-coated with LDHs as the coatings, corrosion resistanceperformance of AZ31 was remarkably improved. The corrosion mechanism ofspin-coated LDHs films were also analyzed.At first, impact and uniform MgAl-CO₃^2--LDHs films were prepared byspin-coating nanosized LDHs sol. By the measurements of XRD, SEM, TEM,the structure of this film was discussed. From the results above, We inferredthat the collaboration of revolving force and the rapid volatilization lead to theformation of this film. During the preparation of spin-coated LDHs films, firstof all, the sol become thincr as the spin-speed increase, the excrescent sol flewto edge of the substrate, then it dropped. When the spin-speed is fixed, the thickness of sol on the substrate decreased at constant velocity. As the solbecome thiner, the rapid volatilization of the solvent dominated the thinningprocess of the film. At last, the LDHs films with the plates perpendicular tothe c-axis were formed.The corrosion resistance performances of spin-coated LDHs films wascharacterized by the EIS and the non-steady state polarization curves. We canconcluded that the corrosion resistance of spin-coated AZ31 was improvedgreatly. The corrosion effects of spin-coated LDHs films could be explained asWarburg effects.