The combination of powder metallurgy and ball milling method has been widely regarded as the most beneficial route for producing multi-walled carbon nanotubes (MWCNTs)-reinforced aluminum matrix composites. In this study, the effects of different milling times (1, 2, 4, and 8 h) on the structural, morphological, and crystallographic properties of MWCNTs-reinforced Al7075 composite powders were characterized by particle size analyzer, Raman spectroscopy, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), and X-ray diffraction (XRD). After the morphological and structural characterization of the milled powders, the microstructural and mechanical properties of the hot-pressed composites were evaluated using an optical microscope, SEM, density, and Brinell hardness measurements. Considering milled powder characterization, the MWCNTs were gradually distributed and embedded within the matrix as the milling time increased. Milling for 8 h resulted in a minimum level of particle size (11 µm) with shortened and uniformly dispersed CNTs. Brinell hardness of the composite increased from 91 to 237 HB -a ⁓%160 after 8 h of milling. Such a remarkable increment in hardness could be attributed to several concurrent strengthening effects related to dispersion, solution, grain refinement, and Orowan looping mechanisms. However, relative density results revealed that the composite produced by 2 h milled powders exhibited the highest density (%99.96). The observed differences between hardness and density results were ascribed to powders’ deteriorated packing and sintering behavior due to an increment in the hardness of particles and variation in particle size range and morphology, which resulted from following different milling protocols.

Nanofibers have great importance in the membrane technology used in hydrophobic surface filtration studies applied to water-oil separation products. This study improves upon the hydrophobic properties of electrospun polystyrene-based nanofibers by increasing surface contact angles. As a result, nanofibers have been produced by adding ZnO, MoO3, NiO, SiO2, and TiO2 additives to the polystyrene (PS)/dimethylformamide (DMF) polymer solution at 5% of the mass. Surface contact angle (CA), fourier-transform infrared spectroscopy (FTIR), and scanning electron microscope (SEM) images of the nanofibers were taken. The obtained results were evaluated and show the fiber diameter to range from 555 to 1553 nm. The addition process was observed to be able to affect the polystyrene fiber’s ability to retain water. Moreover, surface contact angle of polystyrene increased to 143° by TiO2 addition. Furthermore, the highest oil-carrying capacity is concluded to have been observed on the SiO2 and MoO3 doped fibers.

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