The present work reports on the production and characterization of acrylonitrile butadiene styrene (ABS) hybrid nanocomposite filaments incorporating graphene nanoplatelets (GNPs) and carbon nanotubes (CNTs) suitable for fused filament fabrication (FFF). At first, nanocomposites with a total nanofiller content of GNP and/or CNT of 6 wt.% and a GNP/CNT relative percentage ratio of 0, 10, 30, 50, 70, and 100 were produced by melt compounding and compression molding. Their mechanical, electrical resistivity, and electromagnetic interference shielding effectiveness (EMI SE) properties were evaluated. The hybrid nanocomposites showed a linear increase in modulus and decrease in strength as a function of GNP content; on the other hand, the addition of CNT in hybrid nanocomposites determined a positive increase in electrical conductivity, but a potentially critical decrease of melt flow index. Due to the favorable compromise between processability and enhancement of performance (i.e., mechanical and electrical properties), the hybrid composition of 50:50 GNP/CNT was selected as the most suitable for the filament production of 6 wt.% carbonaceous nanocomposites. EMI SE of ABS-filled single CNT and hybrid GNP/CNT nanofillers obtained from compression molding reached the requirement for applications (higher than −20 dB), while slightly lower EMI SE values (in the range −12/−16 dB) were obtained for FFF parts dependent on the building conditions.

Acrylonitrile–butadiene–styrene (ABS) filled with 6 wt.% of multi-walled carbon nanotubes and graphene nanoplatelets was extruded in filaments and additively manufactured via fused deposition modeling (FDM). The electrical conductivity and electromagnetic interference shielding efficiency (EMI SE) in the frequency range between 8.2 and 12.4 GHz of the resulting 3D samples were assessed. For comparison purposes, compression molded samples of the same composition were investigated. Electrical conductivity of about 10⁻⁴ S·cm⁻¹ and attenuations of the incident EM wave near 99.9% were achieved for the 3D components loaded with multi-walled carbon nanotubes, almost similar to the correspondent compression molded samples. Transmission electron microscopy (TEM) images of ABS composite filaments show that graphene nanoplatelets were oriented along the polymer flow whereas multi-walled carbon nanotubes were randomly distributed after the extrusion process. The electrical conductivity and electromagnetic interference (EMI) shielding properties of compression molded and FDM manufactured samples were compared and discussed in terms of type of fillers and processing parameters adopted in the FDM process, such as building directions and printing patterns. In view of the experimental findings, the role of the FDM processing parameters were found to play a major role in the development of components with enhanced EMI shielding efficiency.

This study investigated the potential of ceria nanoparticles to reduce the corrosion rates of AA5005 immersed in chloride-rich media at neutral pH. The colloidal ceria nanoparticle dispersion was prepared via precipitation of cerium (III) ions in presence of citric acid. Transmission electron microscopy and dynamic light scattering confirmed the fine structure of ceria; crystallites lower than 10 nm with a hydrodynamic diameter average size of about 30 nm were obtained. Potentiodynamic polarization and electrochemical impedance spectroscopy measurements were conducted on bare AA5005 panels exposed to 0.1 M NaCl with different quantities of ceria nanoparticles. Polarization curves revealed a significant reduction of cathodic current densities for AA5005 immersed in ceria containing electrolytes when compared to the background solution, i.e. a shift toward lower current densities of about one order of magnitude for those containing 5.0 and 7.5% of ceria. Impedance spectra with higher moduli at low frequencies were obtained for AA5005 immersed in ceria containing electrolytes. In general, while in contact to the ceria-containing electrolytes the rates of localized corrosion attacks at the surface of AA5005 were found to decrease and, the outputs from the electrochemical tests suggested an inhibition effect of the colloidal ceria nanoparticles prepared in this work.