Papers by Keyword: Scanning Electron Microscopy (SEM)

Abstract: A non-Equi atomic W₂₄Ta₂₄Nb₂₄Cr₁₆Al₁₂ high entropy alloy (HEA) was designed based on thermodynamic calculations in order to obtain a single body-centered cubic (BCC) structure. The HEA was further fabricated by using the vacuum arc melting technique. The structural analysis of the HEA revealed the formation of a single BCC phase with the lattice parameter of 3.259Å. The micrograph of the HEA revealed dendritic structure with inter-dendritic segregations. The thermal analysis confirmed that the HEA is quite stable at high temperatures up to 1600°C. The thermal expansion of the HEA was also very low at 1100°C. The mechanical property such as the hardness of the HEA at room temperature, was quite high at 467 ± 20 HV₀.₅. The HEA was further heat treated at a very high temperature (1000°C) and the structural and mechanical properties were evaluated. The heat-treated HEA shows excellent structural stability as no secondary phases were formed in those samples. The mechanical property such as hardness of the HEA was increased continuously on increasing the heat treatment duration, which shows that the current alloy is highly preferable for possible high-temperature applications.

Abstract: CuO/TiO₂ nanocomposites were synthesized using an economical drop-casting method and subsequently irradiated with high-energy C⁺ ions at fluence levels of 1 × 10¹⁴, 1 × 10¹⁵, 1 × 10¹⁶, and 1 × 10¹⁷ ions cm⁻². While ion irradiation of metal oxide materials is well established, the systematic investigation of C⁺ ion effects on the structural and optical properties of CuO/TiO₂ nanocomposites under these specific fluence conditions has been limited. This study therefore contributes new insight into how controlled C⁺ irradiation can tailor the behavior of this composite. These un-irradiated and irradiated nanocomposites were characterized using various techniques such as Energy Dispersive X-Ray Spectroscopy (EDX), Raman Spectroscopy, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Photoluminescence (PL) Spectroscopy and Diffuse Reflectance Spectroscopy (DRS) to analyze structural, morphological and optical properties of these nanocomposites. The Raman and EDX analysis confirmed the formation of pure CuO/TiO₂ nanocomposites. The SEM results represent the spherical morphology of these nanocomposites in aggregated form. PL spectra’s depicted the pure and C⁺ ions irradiated nanocomposites were the same before and after C⁺ irradiation in the Photoluminescence emission. DRS results indicated that band gap energy was decreased as the fluence rate of C⁺ ions increased up to 1 × 10¹⁷ ions cm^-2.

Abstract: The effect of laser energy number of pulses on the compositional, morphological, topographic, and optical properties of selenium oxide nanoparticles SeO2 nanoparticles prepared by pulsed laser ablation of selenium in a target liquid immersed in water with Nd:YAG laser pulses with energy 400 mJ was investigated using a different number of laser pulses 250 and 300. X-ray diffraction (XRD) tests revealed that the SeO2 nanoparticles exhibited a hexagonal crystal structure. Scanning electron microscope (SEM) tests revealed that the form and size of the produced SeO2 NPs are dependent on the number of laser pulses. The dispersion of nanoparticles was proportional to the increase in laser energy generated by the number of pulses. AFM investigations revealed extremely distributed ball-shaped SeO2 particles. The optical energy gap of SeO2 nanoparticles generated was evaluated using optical characteristics and found to be 3.37 to 4.3 eV for SeO2 induced by 250 and 300 pulses, respectively. The biological effectiveness results revealed that employing laser energy with a pulse number of 300P resulted in the greatest inhibition.

Abstract: Nanoindentation, an advanced technique employed for characterizing materials, facilitates the precise determination of their hardness and Young's modulus by applying a specific, controlled force through an indenter, enabling highly localized deformation and measurement at nanometer scales. The nanoindentation gives us the view of the isotropic and anisotropic features of the materials by analyzing the zone beneath the indenter. The application of Bulk Metallic Glass (BMG) alloy, renowned for its unique combination of high strength, exceptional elasticity, and superior corrosion resistance, spans diverse industries including aerospace, biomedical, and consumer electronics. The study focuses on conducting nanoindentation analysis on the BMG alloy, aiming to characterize its deformation behavior. This involved utilizing Scanning Electron Microscopy (SEM) to discern deformation characteristics, followed by validation of the findings through simulations, ensuring robustness and reliability of the results. The modulus, determined to be 227GPa, provided insight into the material's structural rigidity, and the hardness 14.8GPa offered an indication of its resistance to localized plastic deformation. The results have been compared with the simulation results where the modulus was 242GPa and the hardness was 16.1GPa.

Abstract: Cast aluminium alloys are widely utilized in various industrial applications due to their favourable properties. A comparative analysis of fracture surfaces for EN AC 5083 cast aluminium alloy specimens processed in a single-pass by friction stir processing (FSP) and submerged friction stir processing (SFSP) has been carried out in this paper. Fracture surface evaluation involves mechanical tensile tests, microscopic investigations using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) to analyse the microstructure, fracture characteristics and elemental composition of the processed material. The findings provide valuable insights into the fracture behaviour of EN AC 5083 aluminium alloy FSP and SFSP processed, contributing to further research on optimizing friction stir processing techniques in ambient and submerged process conditions.

Abstract: Asphalt pavement performance is based on several parameters and properties of the materials’ element. surface free energy that the modifier and the asphalt binder both displays. The resistance of the modified asphalt binder to stresses and moisture damage is largely determined by the bond energies. Asphalt binder qualities may be altered by either technical or natural processes, which subsequently impact on the chemical and mechanical characteristics. In addition, a correlated investigation revealed that surface free energy values may be used to assess the compatibility of a binder in relation to moisture-induced damage. Data demonstrates that the incorporation of soft clay into the asphalt binder resulted in a favorable coating and bonding capacity, as compared to the control asphalt binder. moisture-induced damage in HMA is a combined effect of loss of cohesion of asphalt binder and loss of adhesion between asphalt binder and aggregate. It was indicated that the modified binders of BPSC ratios would delay and weaken the oxidation reaction asphalt binder which can enhance the aging process. Based on absorbance peaks of carbonyl and sulfoxide bonds, the addition of BPSC would delay the aging process of asphalt binder.

Abstract: The burning process of limestones is an important process in the modern industries, which can be described in two parts, CaCO₃ decarbonation due to the thermal stress and formation of CaO crystalline structure. It was already observed that the different composition and structure of a raw material influence the transformation process and has affect on the chemical and mechanical properties on the formed lime. This study is focused on the characterization of the raw material (porosity, chemical composition, geological age and origin) and its effect on the burning process and the formation of CaO and its properties. The microstructure of studied material burnt at different times of isothermal load was observed by SEM and the reactivity test was measured and analyzed. The limestone with a more porous inner system was burnt faster and is inclinable to overburn at longer thermal load.

Abstract: Fiber optimization is one of the key factors in fabricating fiber-reinforced composites. A higher amount of fiber loading does not correspond to improved mechanical and thermal properties of composites. Consequences such as poor fiber wetting, formation of voids, and delamination may arise due to the lower amount of matrix at higher fiber loading. In this study, the loading percentage of nito fibers were varied from 5, 10, and 15 wt%. The mechanical and thermal analysis showed that the composite with the lowest fiber loading percentage showed a better performance compared to the two composites with higher fiber loading. The tensile strength of the said composite increased by 3 MPa while the onset of degradation temperature increased by 30.91°C. The SEM micrographs confirmed that the composites with higher fiber loading percentage suffered poor wettability which resulted in poor adhesion of the fiber to the matrix. The micrographs of the composite with 5 wt% showed a superb fiber-matrix bonding which resulted in a more seamless transfer of heat and stress upon heat and load application. These results proved that optimization of fiber loading percentage is an integral step to fabricate an improved composite material.

Abstract: Scanning electron microscopy - energy dispersive X-ray spectrometry (SEM-EDS) is an elemental analysis technique widely used in various fields to identify any element in the periodic table except H, He and Li. It can be a quick way to assess the response of sensing films before deposition on sensing devices. Sensing films are usually organic thin films, but quantitative analysis of light elements and thin films is not recommended for SEM-EDS due to its limitations. In this study, SEM-EDS analysis of nitrogen in layer-by-layer polymeric thin film was optimized. The films were analyzed containing nitrogen in the form of nitrate counterions or as part of the repeat unit of the polymer. The build-up of the layer was verified by thickness measurement using atomic force microscopy. The results show that the limit for nitrogen concentration detection using nitrates was 2% by mass. Below this concentration, nitrogen content had no quantifiable response in either calculated nitrogen concentration by standardless correction methods or intensity of N Kα X-ray line. However, by adding nitrate ions to a film that already contains nitrogen in its structure the concentration was raised to 13.75%. In the range of 9.63 to 13.75%, a nonlinear response was observed using calculated nitrogen concentration while the response was linear with intensity of N Kα.

Abstract: The decomposition of limestone during the firing process is mainly based on the decarbonation of CaCO₃. In the case of crystalline limestone, it is the decomposition of calcite crystals. In this study, different limestone properties on the course of decarbonation are studied. Therefore, the samples are determined from a geological and physicochemical point of view (geological age and origin, total porosity, limestone category, chemical analyses and insoluble residue). After thorough identification of the samples, various analyses focused on limestone and lime microstructure are performed, such as SEM image analysis or lime reactivity. For these analyses, the samples are burned at different temperatures. The decrepitation amount of limestones during burning process is determined.