In situ formation of LDH-based nanocontainers on the surface of AZ91 magnesium alloy and detailed investigation of their crystal structure

Abstract

In the presented work, the possibility of direct synthesis of LDH (layered double hydroxide) on the AZ91 surface in the presence of a chelating agent (diethylenetriaminepentaacetic acid - DTPA) is reported. Conversion layer of LDH nanocontainers were formed under ambient pressure conditions without carbonate addition in the electrolyte. The obtained LDH was characterized using experimental (SEM, XRD, TGA, XPS, Raman, etc.) and computational methods (thermodynamic calculation, modeling of possible LDH crystal structures). A comparison of three possible LDHs (LDH-OH, -NO3 and -CO3) was performed. Based on the experimental results and crystal simulation approach, it was confirmed, that the mixed LDH-OH/CO3 is grown on the surface in the presence of DTPA pentasodium salt.