Magnetic Structured Nickel Core-Shell @ Silica/PMMA Nanocomposites from Synthesis to Applications

Incorporating Ni@SiO2 nanoparticles on poly-methyl methacrylate (PMMA) can alter electrical, optical, and magnetic properties of Ni nanoparticles to be used for energy storage applications, photo electronic devices and spintronic applications. The Ni@SiO2/PMMA nanocomposite samples are prepared by casting method. The morphology of the prepared nanoparticles was examined through high resolution transition electron microscope revealed the formation of SiO2 coating on ni nanoparticles. Furthermore, the topography of nanocomposites was characterized by the field emission scanning electron microscope. We investigated the formation of crystalline phase of Ni nanoparticles through X-ray diffraction. The Complex dielectric permittivity, electrical conductivity, electric modulus and impedance spectra of the PNC films were investigated in the frequency range from 0.1 Hz to 10 MHz. The real and imaginary parts of the permittivity decrease with increasing frequency due to an increase in Ni@SiO2 content. All the nanocomposites showed relatively low conductivity values and high impedance that could be used for nano-dielectrics. UV-Vis spectrophotometer was used to measure optical properties such as transmittance, and absorbance at normal incidence in the wavelength range of 200-1100 nm. The transmittance was found to decrease while the absorbance increases with increasing Ni@SiO2 nanoparticles. The indirect optical band gap of the composite films was calculated, and it was sharply decreased. Magnetic hysteresis plots at room temperature of composites Ni@SiO2/PMMA were studied. All samples demonstrate ferromagnetic behavior with well pronounced magnetic hysteresis

Comprehensive studies for evaluating promising properties of Cu/graphene/fly ash nanocomposites

Abstract Copper (Cu)'s electrical conductivity makes it attractive for industrial usage. Due to its inferior mechanical characteristics, thermal expansion, and wear resistance, its applications are limited. This manuscript solves these issues while retaining its major feature, excellent electrical conductivity. In this regard, different quantities of graphene (Gr) and fly ash (FA) nanoparticles were combined with Cu in a planetary ball mill at 440 rpm for 20 h using powder metallurgy (PM). The microstructure of the generated powders was characterized using X-ray diffraction technique and transmission electron microscopy. The powders underwent compression and were then subjected to firing at three distinct temperature levels, reaching a maximum of 850 °C. In addition, an analysis was conducted on the microstructure, mechanical properties, wear resistance, thermal expansion behaviour, and electrical conductivity of the sintered samples. Based on the findings, the inclusion of a hybrid of Gr and FA ceramics effectively led to a reduction in particle sizes. The bulk density slightly decreases with the addition of hybrid ceramic while increasing with the rise in sintering temperature. The hybrid composited Cu/0.8 vol.% Gr/8 vol.% FA recorded an increase in the microhardness, ultimate stress, and Young’s modulus of 25, 20, and 50%, respectively, relative to the Cu matrix. Furthermore, the wear rate and coefficient of thermal expansion for the same sample decreased by 67 and 30%, respectively. Finally, increasing the sintering temperature showed a clear improvement in the mechanical, electrical, and corrosion properties. Based on the results obtained, it can be concluded that the prepared hybrid nanocomposites can be used in power generation, power transmission, electronic circuits, and other applications