In this study, novel silane functionalized graphene oxide (PVSQ-GO) composite material is synthesized through the hydrolysis condensation reaction of vinyl triethoxysilane monomers occurred at the surface of graphene oxide. Results obtained from FTIR, Raman, X-ray photoelectronic spectroscopy (XPS), XRD and TGA measurements reveal that polyvinyl sesquisiloxane microspheres adhere to graphene oxide lamellae in the form of chemical bonds. Meanwhile, it is intuitive that abundant polyvinyl sesquisiloxane microspheres stick to the surface of graphene oxide and increase the thickness of the flake. Modified graphene oxide changes from hydrophilicity to hydrophobicity were owing to the existence of polyvinyl sesquisiloxane microspheres on the surface of graphene oxide (GO). PVSQ-GO composite exhibited good dispersion in eco-friendly waterborne polyurethane coating. Electrochemical impedance spectroscopy manifested that the anti-corrosion performance of waterborne polyurethane (WPU) coating embedded at 0.5 wt.% PVSQ-GO composite improved effectively. Tafel curves reveal that 0.5 wt.% PVSQ-GO/WPU coating specimen shows the lowest corrosion rate of 8.95 × 10⁻⁵ mm/year when compared with the other coating specimens. The good anti-corrosion abilities of PVSQ-GO composite coating can be interpreted as the good compatibility between PVSQ-GO composite and waterborne polyurethane, however, the intrinsic hydrophobicity of PVSQ-GO composite is beneficial to inhibit the permeation of corrosive medium and thus slows down the corrosion rate.

A novel composite of FeCO₃ nanoparticles, which are wrapped with reduced graphene oxide (RGO), is fabricated using a facile one-spot solvothermal method. The composite consists of a substrate of RGO and FeCO₃ nanoparticles that are embedded in the RGO layers. The experimental results for the FeCO₃/RGO composite reveal a minimum refection loss (−44.5 dB) at 11.9 GHz when the thickness reaches 2.4 mm. The effective bandwidth is 7.9 GHz between 10.1 and 18 GHz when the refection loss was below −10 dB. Compared to GO and RGO, this type of composite shows better microwave absorption thanks to improved impedance matching. Overall, this thin and lightweight FeCO₃/RGO composite is a promising candidate for absorbers that require both strong and broad absorption.

Cobalt ferrite is synthesized via a simple solvothermal method. Then, the effect of the degree of cobalt-ferrite growth on its morphology, structure, electromagnetic performance, and microwave absorption is studied as a function of the solvothermal reaction time. When the reaction time during synthesis is 8 h, the structure of cobalt ferrite is hollow spheres. In addition, when the reaction time is 12 h and 16 h, it becomes a submicron sphere with a diameter of 100–150 nm. With the increase of reaction time, cobalt ferrite underwent the process of cobalt ferrite formation, hollow structure formation, hollow structure disappearance, agglomeration separation and reagglomeration in 4–16 h. In general, CoFe₂O₄-8h shows better microwave absorption-the effective absorption bandwidth is 9.84 GHz (6–15.84 GHz) for a thickness of 1.72–3.72 mm. This represents a minimum return loss of −47.24 dB. A better understanding of both the synthesis parameters and the relationship between structure and electromagnetic properties can open new possibilities for applications and the development of microwave absorbing materials.

FeCl₃∙6H₂O was used as raw material to produce Fe₃O₄, using the solvothermal method with ethylene glycol as the solvent. Fe₃O₄, with different particle sizes, was obtained via mechanical ball-milling by controlling the milling time. Effect of the milling time on the structure, morphology, and electromagnetic parameters of Fe₃O₄ were studied, and the absorption properties and mechanism of Fe₃O₄, for different milling times were analyzed. The results showed that the integrity of the original small spherical structure decreased as the ball milling time increased. Fe₃O₄ showed excellent microwave absorptions as the milling time reached 2 h, the reflection loss reached the maximum of −21.19 dB at 4.64 GHz as the thickness was 6.55 mm.