Incorporation of SiC ceramic nanoparticles into the aluminum matrix by a novel method: production of a metal matrix composite

SiC ceramic nanoparticles were incorporated into the A356 aluminum matrix with different compositions using a combination of stir casting and semisolid extrusion. The microstructure and mechanical properties of the produced nanocomposites were evaluated. The results showed that the presence of Nickel acts as an appropriate metallic carrier for SiC nanoparticles, which causes uniform dispersion and spherical grains. Consequently, the coexistence of SiC nanoparticles and Nickel resulted in UTS of above 304 MPa and elongation of 5.8%. However, the addition of Titanium caused the formation of flake-like intermetallics, which decreased the elongation of the nanocomposites. The method introduced in this study for the incorporation of SiC ceramic nanoparticles can be used as a promising process instead of conventional methods, which are expensive and time-consuming

Strength-ductility trade-off via SiC nanoparticle dispersion in A356 aluminium matrix

A process was developed to disperse β-SiC nanoparticles (NPs), with a high propensity to agglomerate, within a matrix of A356 aluminum alloy. A suitable dispersion of 1 wt% SiC NPs in the A356 matrix was obtained through a hybrid process including a solid-state modification on the surface of the NPs, a two-step stirring process in the semi-solid and then the liquid-state, and a final hot-rolling process for fragmentation of the brittle eutectic silicon phase and porosity elimination. Titanium and nickel where used as the nanoparticle SiC surface modifiers. Both modifiers were found to improve the mechanical properties of the resulting material, however, the highest improvement was found from the nickel surface modification. For the nickel modification, compared to the non- reinforced rolled alloy, more than a 77%, 85%, and 70% increase in ultimate tensile strength (UTS), yield strength (YS), and strain % at the break, respectively were found with respect to the unreinforced rolled A356. For the rolled nanocomposite containing 1 wt % SiCnp and nickel modification, an average YS, UTS, and strain % at the break of 277 MPa, 380 MPa, and 16.4% were obtained, respectively, which are unique and considerable property improvements for A356 alloy

Synthesis of graphene oxide/magnesium oxide nanocomposites with high-rate adsorption of methylene blue

A series of graphene oxide/magnesium oxide nanocomposites (GO/MgO NCs) were and applied for the removal of Methylene Blue (MB) from aqueous solutions. The prepared NCs were characterized using scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectrum, X-ray photoelectron spectroscopy, and thermogravimetric analysis. The results showed that MgO particles was successfully decorated on GO. The impacts of different experimental variables on the removal of MB including GO/MgO NCs dosage, pH, contact time, and initial MB concentration were investigated. The experimental analysis of adsorption isotherms indicated that adsorption data was best fit with the Langmuir isotherm model. Among the three different synthesized weight ratios of GO/MgO (5:1, 1:1, and 1:5), 5:1 ratio showed the maximum adsorption capacity as 833 mg/g, which is higher than any previously reported GO-based composites. The synthesized GO/MgO NC is also observed to have higher adsorption capacity for MB removal, in comparison with pure GO and MgO. The kinetic adsorption data was best described by pseudo-second-order kinetic model. The pH of point of zero charge (pH(pzc)) of GO/MgO NCs was determined to be 9.7, 10.5, and 10.5 for ratios 5:1, 1:1, and 1:5, respectively. The results revealed that electrostatic attraction can be the dominant mechanism of adsorption between GO/MgO NCs and MB for pH above pH(pzc); whereas for pH below pH(pzc), other adsorption mechanisms such as hydrogen bonding and pi-pi interaction may attribute to adsorption. The high adsorption capacity of GO/MgO composites, thus makes it a promising adsorbent for water and wastewater treatment. (C) 2016 Elsevier B.V. All rights reserved