Characterization of Ce conversion coating on Gr-f/6061Al composite surface for corrosion protection

In this study, Ce conversion coatings are investigated as corrosion inhibitors of graphite fibers reinforcement aluminum matrix (Gr-f/Al) composites. The coatings are obtained by chemical immersion in solution containing Ce(NO3)3 onto composite surface, whereas the Ce conversion coating process produces a coating with highly heterogeneous nature of the surface, but micro-cracked layer with “dry-mud” morphology. The thickness of coating is about 3 μm. The coatings were composed of Ce-rich nano-particles (∼20 nm), which were piled up for this coating. TEM observation for Ce conversion coating of the corresponding ring-like SAED patterns could not be matched to any of the previously reported structures of cerium compounds. Results of high-resolution XPS spectra of Ce 3d obtained for Ce conversion coating results show that the Ce 3d spectra have several components with binding energies characteristic of Ce3+ and Ce4+. The Ce conversion coating process produces effective corrosion protecting of Gr-f/Al composites, which is verified by electrochemical measurement results. The Rt values of coating sample is higher than those of uncoating sample, this confirms the better corrosion resistance of coating obtained after immersion treatment for Gr-f/Al composites.