Preparation and Anticorrosion Performance of Composite Silane Films Incorporating Graphene Oxide Additives Modified with Polyethyleneimine on Sintered Ndfeb

Abstract

Polyethyleneimine modified graphene oxide (PEI-GO) was designed as the additive, which was co-deposited with silane on sintered NdFeB magnets to prepare hydrophobic and anti-corrosive PEI-GO/silane composite films via an electrochemically assisted sol-gel method. Structural and compositional characterization was carried out using FTIR, XPS, SEM and Raman spectroscopy (RS). The results confirm the successful grafting of polyethyleneimine onto graphene oxide. Silane coupling agents linked to the PEI-GO additives, as well as the sintered NdFeB through covalent bonds. The corrosion resistance of the fabricated composite films in a 3.5 wt.% NaCl solution was assessed through electrochemical impedance spectroscopy and potentiodynamic polarization tests. The corrosion current density (Icorr) of PEI-GO/silane film under the optimal deposition condition was found to be 8.365×10-8 A·cm-2, which value was two orders of magnitude smaller compared to that of the neat silane film. The enhanced anti-corrosion performance of PEI-GO/silane composite film can be primarily attributed to the grafted polyethyleneimine, which significantly enhanced the barrier effect of GO by improving its dispersion within the sol-gel system. Meanwhile, the co-deposited PEI-GO remarkably reinforced the structural integrity and compactness of the composite film's three-dimensional network.

Keywords: Sintered NdFeB, Silane film, Modified graphene oxide, Corrosion resistance