Diffusion Foundations and Materials Applications Vol. 39

Abstract: The influence of low-temperature superplastic deformation on the structure and room temperature mechanical properties of ultrafine-grained titanium alloy Ti-55511 was investigated. It was shown that superplastic deformation by compression of the alloy at a strain rate of ~10^-2 s^-1 at a temperature of 823 K (0.42 T_m) leads to an insignificant growth in the elements of the UFG grain-subgrain structure with a slight decrease in the strength value compared to the initial state formed by the all-round pressing method. Additional annealing of samples at a temperature of 723 K for 5 hours after SP compression leads to an increase in mechanical properties to the level of the initial UFG alloy. It was found that preservation of high mechanical (strength) properties of the UFG Ti-55511 alloy after compression deformation can also be ensured by reducing the temperature of the superplastic deformation treatment up to 803 K.

Abstract: The superplastic deformation behavior, microstructure evolution in the volume and on the FIB-milled surface of the samples of fine-grained AA5083-type alloy with an initial grain size of ~5 µm were investigated, and the role of deformation mechanisms was discussed for two superplastic deformation regimes (1) a strain rate of 1×10^-3 s^-1 and a temperature of 0.87T_i.m. and (2) a strain rate of 5×10^-3 s^-1 and a temperature of 0.97T_i.m.. The m values were ~0.45-0.55 and elongations to failure were ~300% and ~600% for the first and second regimes, respectively. According to the shifts of the marker grid lines after straining to e=0.41, GBS contributed ~33% and ~23% to the total strain in the low-temperature and high-temperature deformation, respectively. The dislocation-induced intragranular deformation provided ~30% for the low temperature regime and ~20 % for the high temperature regime, and remaining 30-50% of strain was localized in the striated zones formed at the across grain boundaries due to both GBS and diffusion creep deformation mechanisms. Considering the strain induced by grain elongation for the low and high temperature deformation regimes, it was concluded that diffusion creep contributed 23% and 34% of the total deformation, and the recalculated GBS contribution, including both FIB grid shifts and a portion of the strain localized in the striated regions, was 43% and 38%, respectively.

Abstract: The effects of minor additions of alloying elements Fe/Ni/Co (0.5wt.%), B (0.01–0.1wt.%), and Y (0.2wt.%) on the superplastic behavior, microstructural evolution and mechanical properties of Ti-4 wt.%Al-3wt.%Mo-1wt.%V alloys are investigated. By increasing the high-angle grain boundary fraction and related facilitation of the grain boundary sliding, these elements reduce the flow stress values at the initial deformation stage and improve flow stability at a steady state. The most pronounced effect is found at low deformation temperatures when acceleration of recrystallization and globularization of the microstructure is critical. As a result, minor additions of the studied elements provide good superplasticity at relatively low temperatures of 625–775 °C (m≈0.50 and elongation to failure ≈ 500–1000%) and post-forming room-temperature strength (YS≈830 MPa and UTS≈990 MPa).

Abstract: Zinc oxide is the most widely used nanomaterial in nanotechnology due to its outstanding properties and characterizations. Enormous attention has arisen due to its unique physical properties consists of a wide energy band gap of 3.37 eV at ambient temperature and large binding energy of 60 meV, which give development to an extensive range of potential applications in many areas such as electronics, solar cells, and biological applications. The size and shape of nanoparticles are significant to ensure the process becomes faster, cheaper and more efficient compared with traditional methods. By having more active area of nanoparticles, the biological and chemical process become more effectives. The biological activity of ZnO Nanoparticles was investigated through the antibacterial activity, anti-microbial activity, as anticancer and antioxidant material. The method used to prepare the ZnO Nanoparticles also take an important part which is to reduce the by-product formation when applied in wastewater treatment. This article summarizes different preparation methods of ZnO Nanoparticles and its application uses. The ZnO nanoparticles can be used the various applications, for example for the antibacterial, anti-cancer, anti-microbial, antioxidant and for wastewater treatment applications.

Abstract: This study explores the effect of titanium dioxide (TiO₂) nanoparticles on the electrical performance of Phenosafranine (PSF) dye-based organic devices. Composite films were fabricated by blending PSF with TiO₂ nanoparticles in varying weight ratios (1:1 to 1:4), and their structural and electrical properties were systematically analyzed. Scanning Electron Microscopy (SEM) images showed that the nanoparticles were evenly spread out, which is favorable for charge movement. The I–V results, analyzed using the Cheung method and trap energy model, showed that adding a moderate amount of TiO₂ nanoparticles reduced series resistance, ideality factor, and trap energy. These changes lead to enhance carrier mobility and overall device conductivity. However, when the TiO₂ amount was too high (more than 1:3 ratio), the performance started to drop. Overall, this work shows how TiO₂ nanoparticles can help improve the overall performance of organic electronic devices by changing their structure and electrical behavior in a controlled way.

Abstract: Long chain polymers are reported to be effective in reducing drag in turbulent flow systems. However, most of the effective polymers are synthetic, which are costly, non-biodegradable, and toxic that raises environmental concerns. Natural polymers, as eco-friendly alternatives, are gaining interest as drag-reducing additives (DRA), but single natural polymers have lower drag reduction (DR) efficacy compared to synthetic ones and degrade under high shear stress. This study aims to investigate biopolymer complexes from hibiscus leaves (HL) and okra (OK) as eco-friendly DRAs, comparing their performance with individual components. Biopolymers were extracted from dried hibiscus leaves and okra and diluted to concentrations of 200–1000 ppm. Complexes were formulated by mixing 200–1000 ppm HL extract with 1000 ppm OK extract. The extracts were characterized using Fourier Transform Infrared Spectroscopy (FTIR), meanwhile all the drag reducing solutions were assessed for viscosity, viscoelasticity and DR performance using an oscillating rheometer under different shear rate (0 – 200 s^-1) and frequencies (0 – 100 Hz). All the polymer solutions showed non-Newtonian shear-thinning behavior. The biopolymers and their complexes also exhibited significant viscoelastic properties which is important for DRA stability in turbulent flow. OK solutions achieved up to 79% DR at 1000 ppm, while HL solutions reached an average of 99% DR at concentrations of 400 ppm and above. However, HL-OK complexes had lower DR efficacy, with a maximum DR of 72% at 800 ppm HL – 1000 ppm OK. This might be due to the high concentration altering the water's properties and increasing viscosity, which increases drag.In conclusion, HL and OK complexes have potential for drag reduction, but future research should optimize concentration ratios, test over a broader range of shear rates, and explore other natural polymers complexes to achieve the synergistic effect.

Abstract: Concrete deterioration is a major concern for structural engineers, as it can weaken and damage structures, posing safety risks. One of the most effective ways to protect concrete from deterioration is to modify it with pozzolanic materials. Pozzolanic can react with calcium hydroxide (Ca (OH)₂) in concrete to form strong, durable cementitious compounds. So this research aims at enhancing the durability of concrete structures against aggressive media attacks. Nanosilica (NS) was used in concrete mix design with different addition percentages of 0, 1, 1.5, 2, and 2.5 by cement weight. The durability of hardened concrete specimens was investigated as follows: measuring water absorption and contact angle; and determining chloride permeability by ion exchange chromatography. Also, the resistivity of concrete against both 3% sulfuric acid and 5% sodium chloride solutions was estimated. Finally, the electrochemical impedance spectroscopy (EIS) was used to determine corrosion resistance of the reinforced concrete. The experimental results detected that NS has a significant mechanism for improving concrete performance as follows: water absorption of concrete modified with 2% NS (M4) decreased by 41% as compared to the control sample, and contact angle increased by 66%. Meanwhile, the chloride permeability decreased by 24%. Moreover, NS is mainly responsible for enhancing concrete durability against aggressive media attacks up to 2% by cement weight. As compared to the control concrete specimen, the durability of the M4 specimen increased by 39% against sulphate attack and by 42% against chloride attack. The study provided a good solution for the problem of concrete building deterioration, especially when it is exposed to aggressive environments. Key words: Concrete durability, pozzolanic materials, nanosilica.

Abstract: This study focused on the valorization of swelling clay from Damniadio. This swelling clay is extracted during construction and dumped in the wild. The aim of this study was to valorize this clay in construction in order to produce bricks strong enough to be used in construction. The physical properties of this clay were evaluated, as well as the mechanical performance of the bricks produced. Finally, a model of a building component was produced using Autocad and Graitec OMD software. Compressive strength and tensile strength values ranged from 1.82 MPa to 30.24 MPa and from 0.14 MPa to 1.83 MPa respectively for raw earth bricks, and from 2.31 MPa to 40.6 MPa and from 0.15 MPa to 2.29 MPa respectively for kiln-dried earth bricks. The modelling of these bricks has thus shown their potential for use as load-bearing structures, making them both more environmentally friendly and more economical in a context where the purchase of concrete will be more expensive than the extraction and processing of clay.

Abstract: The high demand for solar power systems has stimulated research efforts to find better heat transfer fluids for evacuated-tube solar collectors. The present analysis aims at evaluating the thermal characteristics of an evacuated-tube solar collector which utilises engine oil as a heat transfer vehicle within a new efficient system beyond conventional flat-plate collectors. An evaluation shows that this system reacts swiftly to solar radiation changes and reaches maximum temperatures of 198 °C which makes water evaporation and superheating possible. Temperature elevation under solar radiation becomes rapid because the evacuated tube contains 20W50 engine oil which possesses a high boiling point of >350 °C and heat transfer properties including 2.5 kJ/kg K heat capacity and 88 kg/m³ density. The through-flow copper pipe is submerged in a single evacuated tube after being bent in a U-shape. Between the inner surface of the tube and the outer surface of the copper pipe, oil serves as a medium for heat transfer. Experiments are conducted for different ranges of solar radiation intensity with consequence different ranges of engine oil temperatures. According to the results, the collector, in comparison to traditional flat-plate collectors, demonstrates a high conversion efficiency and quick response to the influencing parameters. The theoretical computations and experimental findings introduce that the engine oil temperature increases to 198 °C at a solar radiation of 800 w/m². Accordingly, the temperature is high enough to cause it to heat, evaporate, and become superheated when the water passes through the copper tube inside the vacuum oil tub.