A two-step process was applied to synthesize the cobalt ferrite-graphene composite materials in a one-pot hydrothermal reaction process. Graphene Oxide (GO) was synthesized by a modified Hummer’s method. The synthesized composite materials were characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and Fourier-transform infrared spectroscopy (FTIR). The XRD and FTIR results were in good agreement with the TGA/DTG observations. SEM and TEM disclosed the spherical shape of the nanoparticles in 4–10 nm. The optimized CoFe₂O₄-G (1–5 wt.%) composite materials samples were tried for their conductivity, supercapacity, and corrosion properties. The CV results demonstrated a distinctive behavior of the supercapacitor, while the modified CoFe₂O₄-G (5 wt.%) electrode demonstrated a strong reduction in the R_ct value (~94 Ω). The highest corrosion current density valves and corrosion rates were attained in the CoFe₂O₄-G (5 wt.%) composite materials as 5.53 and 0.20, respectively. The high conductivity of graphene that initiated the poor corrosion rate of the CoFe₂O₄-graphene composite materials could be accredited to the high conductivity and reactivity.

The carbonation rate of reinforced concrete is influenced by three parameters, namely temperature, relative humidity, and concentration of carbon dioxide (CO₂) in the surroundings. As knowledge of the service lifespan of reinforced concrete is crucial in terms of corrosion, the carbonation process is important to study, and high-performance durable reinforced concretes can be produced to prolong the effects of corrosion. To examine carbonation resistance, accelerated carbonation testing was conducted in accordance with the standards of BS 1881-210:2013. In this study, 10–30% of micro palm oil fuel ash (mPOFA) and 0.5–1.5% of nano-POFA (nPOFA) were incorporated into concrete mixtures to determine the optimum amount for achieving the highest carbonation resistance after 28 days water curing and accelerated CO₂ conditions up to 70 days of exposure. The effect of carbonation on concrete specimens with the inclusion of mPOFA and nPOFA was investigated. The carbonation depth was identified by phenolphthalein solution. The highest carbonation resistance of concrete was found after the inclusion of 10% mPOFA and 0.5% nPOFA, while the lowest carbonation resistance was found after the inclusion of 30% mPOFA and 1.5% nPOFA.

The beneficial effects of V addition on the corrosion of a newly manufactured Ti6AlxV (x = 2 wt %, 4 wt %, 6 wt %, and 8 wt %) alloys after various exposure periods in 3.5% NaCl solutions were reported. The Ti6AlxV were produced from their raw powders using mechanical alloying. Several electrochemical techniques such as electrochemical impedance spectroscopy, cyclic potentiodynamic polarization, and potentiodynamic current versus time at 300 mV experiments were conducted. The surface morphology and the elemental analysis were performed using scanning electron microscopy and energy dispersive X-ray analyses. All results were consistent with each other revealing that the increase of V content increases the resistance of the alloys against corrosion. The increase of corrosion resistance was achieved by the role of V in decreasing the rate of corrosion as a result of the formation of oxide films on the surface of the alloys. This effect was found to increase with prolonging the immersion time of the Ti6AlxV alloys in the test medium from 1 h to 24 h and further to 48 h.

Al-x wt.% Fe bulk alloys were fabricated from a powder mixture of pure Al and x wt.% of Fe, where x = 2 wt.%, 5 wt.% and 10 wt.%. Initially, as-mixed mixtures were processed using a mechanical-alloying (MA) technique in an attritor for 4 h. The milling was performed in an argon atmosphere at room temperature followed by the sintering of the milled powders in a high-frequency induction furnace to produce bulk samples. Scanning electron microscopy (SEM) was used to study the morphology of the produced alloys, and X-ray diffraction (XRD) to determine the phases formed after the sintering process and their crystallite size. The corrosion behavior of the fabricated samples was studied by immerging them in a 3.5% sodium chloride (NaCl) solution at room temperature using cyclic-polarization (CP) and electrochemical-impedance-spectroscopy (EIS) techniques. The SEM results showed that Fe was uniformly distributed in the Al matrix, and XRD revealed the formation of Al and intermetallic, i.e., Al₆Fe and Al₁₃Fe₄, phases in the Al-Fe alloys after sintering. The hardness of the Al-Fe alloys was increased with the addition of Fe due to the formation of intermetallic compounds. Electrochemical results showed that there was a proportional relationship between the percentage of Fe additives and corrosion potential (E_corr) where it shifted toward a nobler direction, while corrosion current density (i_corr) and corrosion rate decreased with an increasing Fe%. This observation indicates that the addition of Fe into an Al matrix leads to an improvement in the corrosion resistance of the alloys.

Advanced materials with high strength are in great demand for structural applications, such as in aerospace. It has been proved that fabrication strategy plays a vital role in producing composites to satisfy these needs. This study explores new strategies for flake powder metallurgy, with the aim of designing an effective strategy to achieve the highest possible mechanical strength for a metal matrix nanocomposite without changing the reinforcement fraction. Different strategies were used to regulate the mechanical properties for similar composites based on shift speed ball milling. Ultra-ductile composites on one hand, and ultra-strong composites on the other hand, were fabricated using similar composites. The results demonstrate that shifting the ball milling speed can be used to manipulate the mechanical properties of the composite to achieve the desired properties for any specific application.

The aim of this investigation was to assess the corrosion behavior of gray cast iron (GCI) alloyed with copper. Alloyed GCI specimens were austempered isothermally at varying temperatures. After austenitizing at 927 °C, the samples were austempered at different temperatures ranging from 260 to 385 °C with an interval of 25 °C for 60 minutes. As a result, these samples developed an ausferrite matrix with different percentages of austenite. The resulting microstructures were evaluated and characterized by optical microscope (OM), scanning electron microscope (SEM), and X-ray diffraction (XRD). The corrosion characteristics were determined using potentiodynamic polarization tests and electrochemical impedance spectroscopy (EIS) of these samples. These tests were carried out in a medium of 0.5 M H₂SO₄ and 3.5% NaCl solution. It was observed from the potentiodynamic polarization results that with increasing austempering temperature, the corrosion rate decreased. All results of the EIS were in accordance with a constant phase element (CPE) model. It was found that with an increase in austempering temperature, the polarization resistance (R_p) increased. The austenite content was also found to influence the corrosion behavior of the austempered gray cast iron (AGCI).