http://yetl.yabesh.ir/yetl1/handle/yetl/19062 Tue, 25 Aug 2026 00:37:17 GMT 2026-08-25T00:37:17Z https://localhost:443/yetl1/bitstream/id/184274/ http://yetl.yabesh.ir/yetl1/handle/yetl/19062 http://yetl.yabesh.ir/yetl1/handle/yetl/4316939 Investigation of Zinc-Doped Titanium Nanocomposites and Their Photocatalysis Effectiveness Fadhali, Mohammed M.; Dhameri, Mariam A.; Sharma, Mukul; Masmali, Nada A. Abstract. TiO2 nanocomposites doped with Zn have been prepared via the sol-gel method. These nanocomposites with various doping percentages exhibited multi-phase structures with promising photocatalytic efficiency for the removal of pollutants, manifested by methylene blue degradation. Common characterization techniques, including X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy (SEM), and UV–Vis spectroscopy, were employed to characterize the prepared samples. The identified phases are the rutile tetragonal and wurtzite hexagonal crystal structures of TiO2 and ZnO, respectively, while the doped samples tend to exhibit multi-phase structures of rutile, anatase, zincite, spinal, and inverse spinel cubic phases. Doping significantly influenced the energy gaps, which ranged from 2.9 eV to 3.45 eV. SEM morphological studies confirmed that the average size of the nanoparticles was around 150 nm, while the size of the crystallites varied with doping, ranging from 18 nm to a maximum of approximately 42 nm at a 5 wt% of Zn doping, which is manifested as the optimal doping amount that enhanced the properties of the nanocomposite. However, further increases in doping concentration resulted in the creation of additional scattering centers, which negatively impacted photocatalytic efficiency. The optimal doping ratio resulted in a photocatalytic efficiency of about 98%. Thu, 01 Jan 2026 00:00:00 GMT http://yetl.yabesh.ir/yetl1/handle/yetl/4316939 2026-01-01T00:00:00Z http://yetl.yabesh.ir/yetl1/handle/yetl/4316873 Effect of 100 Days of Hot-Wet Conditioning on Mechanical Properties of PU-Coated Polymer Composites Adusumalli, Ramesh; Mallineni, Chandra Babu; Gulipalli, Pallavi; Mushtaq, Mohammed; Bonavath, Padma; Abraham, Anu Anna Abstract. Bidirectional silica fabric-based polymer composite laminates were fabricated using resin transfer molding followed by oven curing. To evaluate the effects of environmental exposure, samples were cut as per testing requirements, and a substrate was surface-coated with a 300-µm-thick polyurethane (PU) layer. Both PU-coated and uncoated samples were subjected to hot-wet conditioning in a climatic chamber for 100 days under critical conditions of 65 °C and 85% relative humidity (RH). In this study, density, thermal conductivity, pull-off adhesion, scratch resistance, and various mechanical strengths at room temperature and 100 °C were measured before and after conditioning. For uncoated composites, a significant effect of hot-wet conditioning on mechanical strengths, with reductions ranging between 15 and 30%, was observed. When compared between uncoated and coated composites, coated composites exhibited an additional reduction in tensile strength, flexural strength by 14–25%, and interlaminar shear strength decreased from 53 MPa (uncoated, after conditioning) to 46 MPa (after coating & conditioning), although compression and in-plane shear strengths were relatively unaffected. Furthermore, coated samples experienced over a 35% reduction in scratch resistance and pull-off adhesion strength (declined significantly from 8.1 MPa to 5.1 MPa), while density and thermal conductivity remained unchanged. These degradations were attributed to the formation of micro-crevices between the composite substrate and the PU coating, resulting in cavitation damage and matrix degradation. Based on these findings, PU coatings are not recommended for outdoor applications wherein environmental conditions are 65 °C and 85% RH. Thu, 01 Jan 2026 00:00:00 GMT http://yetl.yabesh.ir/yetl1/handle/yetl/4316873 2026-01-01T00:00:00Z http://yetl.yabesh.ir/yetl1/handle/yetl/4316784 Corrosion Behavior of Additively Manufactured H13 Tool Steel in Salt Solution (3.5 wt% NaCl) Byiringiro, Justin; Ech-chihbi, Elhachmia; Salim, Rajae; Chaanaoui, Meriem; Hammouti, Belkheir Abstract. This study examines the corrosion resistance of H13 tool steel exposed to ionic molten salt solution through electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) techniques. H13 steel samples were produced via selective laser melting (SLM) with three different build orientations (0 deg, 45 deg, and 90 deg) using the Build Processor v3.2 machine. Nyquist and Bode plots, along with polarization curves, were used to assess the impact of orientation on corrosion resistance. The findings were supported by microstructure analysis of the corroded samples using optical and scanning electron microscopies. The phase angle and the impedance modulus increased with building orientation, with the 0 deg orientation showing the highest values. Polarization resistance values were 1704 Ω cm2, 1540 Ω cm2, and 1430 Ω cm2 for 0 deg, 45 deg, and 90 deg, respectively, demonstrating superior corrosion resistance for the 0 deg orientation. Results highlight the critical impact of SLM build orientation on corrosion resistance, providing insights for future corrosion mitigation strategies for alloys. Thu, 01 Jan 2026 00:00:00 GMT http://yetl.yabesh.ir/yetl1/handle/yetl/4316784 2026-01-01T00:00:00Z http://yetl.yabesh.ir/yetl1/handle/yetl/4316684 Analysis of the Potential for Enhancing Resistance to Dynamic Loads of Welded Joints in Hardox 450 Steel Through Heat Treatment Zemlik, Martyna; Konat, Łukasz; Roszak, Maciej; Meda, Tomasz; Jamroziak, Krzysztof Abstract. Welding procedures in high-hardenability steels often lead to adverse microstructural changes, resulting in a sharp decline in mechanical properties within the weld metal zone and the heat-affected zone. Due to the limited tensile strength Rm of commercially available welding consumables, which in many cases do not exceed 1000 MPa, the reduction in mechanical properties can reach up to 60% in steels with hardness levels of 600 HBW. Martensitic boron steels are among the materials with the highest mechanical strength indices and are used both in components exposed to abrasive wear and in ballistic protection. Consequently, welding techniques often produce joint zones with functional properties (e.g., ballistic resistance or resistance to abrasive wear) that fail to meet the required performance of the base material. Only through advanced welding techniques, the use of high-quality fillers, and subsequent heat treatment can the highest mechanical strength indices be achieved in the weld zone. This article presents the results of tests on the resistance of 450 HBW grade steel welded joints to dynamic loads. The research demonstrated that, when subjected to firing using intermediate 7.62 × 39 mm ammunition (43 model, PS bullet) from a distance of 10 m, a minimum plate thickness of 5 mm ensures material continuity across all characteristic zones of the welded joint. Thu, 01 Jan 2026 00:00:00 GMT http://yetl.yabesh.ir/yetl1/handle/yetl/4316684 2026-01-01T00:00:00Z