Synthesis and characterization of organically modified silicate/NiZn ferrite hybrid coatings

Hybrid coatings based on organically modified silicate (Ormosil)/Ni0.5Zn0.5Fe2O4 (10–30 wt.%) were synthesized through a sol–gel technique. Tetraethylenepentamine, 3-glycidoxypropyltrimethoxysilane, tetraethoxysilane and Ni0.5Zn0.5Fe2O4 were used as precursors for the hybrid coatings. These hybrid films were deposited via spin coating onto an aluminum alloy in order to improve the corrosion protection and to act as infrared stealth coatings. The effects induced by the NiZn ferrite content on the chain dynamic, ferromagnetic behavior, infrared stealth and corrosion performances of the coated samples were investigated. The rotating-frame spin–lattice relaxation times and scale of the spin-diffusion path length indicated that the configuration of the hybrid films was highly cross-linked, dense and adhered to the aluminum alloy substrates. The magnetic properties of the resulting hybrids showed super-paramagnetic behavior, such as zero coercive force (coercivity = 0 G) and a low blocking temperature (∼75 K). The thermal extinction of the hybrid coatings increased with the increase in the NiZn ferrite content. Potentio-dynamic and salt-spray analysis revealed that the hybrid films provided an exceptional barrier and corrosion protection in comparison with untreated aluminum alloy substrates.