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This article investigates the effect of geometrical alternatives for fiber directions on the structural and tribological properties of glass and carbon fibers when molded with epoxy as polymeric composite fabrics for the safety and quality of bushing applications. To confirm the best composite fabric direction, scanning electron microscope and tribological analyses were carried out for the glass and carbon fabrics at horizontal and vertical geometrical alternative orientations. The tribological test was applied using a pin-on-disk tribometer at constant bark velocity of 0.520 m/s against different loads, beginning with 5, 10, 15, and 20 N for the investigated composite samples. The structural measurements demonstrated that the carbon fiber had a high ability to merge with the resin epoxy when compared with the glass fiber. The tribological analysis elucidated that the lower wear volume loss and friction coefficient were obtained when molding the resin epoxy horizontally to the fiber-stacking direction compared with the other vertical direction. Accordingly, the study deduced that the carbon fiber composite material achieves superior wear resistance when molded by resin epoxy horizontally to the direction of tribological wear, which is suitable for several advanced bushing applications. [ABSTRACT FROM AUTHOR]

Damage mechanism evaluation of polymer matrix composites reinforced with glass fibers via Arcan test has become a very vital research area for determining the weak part of composite structures in aircraft segments. So, the objective of the present article is to study the effect of changing different load angles as: α = 0°, 15°, 30°, 45°, 60°, 75°, and 90° of unidirectional glass-fiber-reinforced polymer matrix composite specimens by Arcan test. In this study, modified Arcan test specimens (butterfly shaped) are used to study the mechanical properties and the resulting fracture mode of unidirectional glass-fiber-reinforced polymer matrix composite under combined tension and shear stresses. Two cases of applied Arcan test specimens of unidirectional glass-fiber-reinforced polymer matrix composite specimens were evaluated: (1) notch-to-notch perpendicularly oriented fiber specimens are referred to as group A1, and (2) notch-to-notch longitudinally oriented fiber specimens are group A2. The results revealed that the shear modulus of A1 specimens is found to be G12 = 5.5 GPa ± 18%, which is close to the value calculated using the elastic properties of the composite components. On the other hand, the shear modulus of A2 specimens is found to be G21 = 4.2 GPa ± 8%, which is relatively close to calculated G23 value. It is observed that the fracture mode of A2 specimens is almost not affected by the loading direction. However, the number of cracks and its direction relative to the notch-to-notch line decreases as the test angle increases. Moreover, the strength of A1 specimens is much higher than that of A2 specimens at all applied loading angles, except for pure shear loading. [ABSTRACT FROM AUTHOR]

Hybrid nanocomposites can be synthesized by high energy ball milling to form different compositions of Copper (Cu) strengthened with 10% alumina (Al 2 O 3) and x graphene nanoplatelets (GNP) Cu–10%Al 2 O 3 /x GNPs (x = 0, 0.25, 0.5, 0.75, 1 wt%). Each mixture has been uniaxially compacted at pressures from 300 to 1200 MPa and sintered at three temperatures: 900, 950 and 1000 °C for 2hr. The effect of changing both compaction pressure and sintering temperature values for each mass fraction of the GNPs is investigated on the microstructural, mechanical characteristics, and electrical resistivity of the Cu–10%Al 2 O 3 /x GNPs hybrid nanocomposites. The results elucidate that the optimum mechanical and physical properties for producing the Cu–10%Al 2 O 3 /x GNPs nanocomposites are at compaction pressure of 700 MPa and sintering for 2 h at temperature of 1000 °C. Moreover, the addition of 0.5% of GNPs (Cu–10%Al 2 O 3 /0.5% GNPs) enhances the mechanical properties of the nanocomposites by 68% due to high mechanical properties and the reduction in the particle size of the graphene nanoplatelets. Whereas, increasing GNPs content more than 0.5%, leads to the reduction of the mechanical and physical properties of these composites due to the agglomerations of GNPs on the limits of the grain of Cu and Al 2 O 3. [ABSTRACT FROM AUTHOR]

The heat treatment of friction stir tailor-welded aluminum joints is one important key process to improve the efficiency of joint strength and ductility as well as fracture locations, since almost all of the welded parts are subjected to a forming process. Therefore, the effect of heat treatment on microstructural characterization and mechanical properties of welded joints is a very important research area to improve the nugget zone in welded structures of aircraft segments. The objective of this study is to investigate the effect of changing pre-weld heat treatment conditions (first case: solution heat treated with artificial aging (T6) and second case: annealed heat treatment (O)) by microstructural characterization with an optical microscope, scanning electron microscope and x-ray diffraction and mechanical properties using micro-hardness, tensile and bending tests. After that, ANOVA was used in order to determine the interaction effect between the conditions of heat treatment (T6 and O) and interlayer strip widths. The results revealed that the softened zone of FSW joints in the annealed condition (O) was relatively more homogeneous than FSW joints from solution heat treated and artificially aged (T6). On the other hand, the strength efficiency of FSW joints from annealed (O) samples was the higher value than the joints efficiency at solution heat treated and artificially aged (T6). Furthermore, the annealed (O) FSW joints fractured in the base metal, while FSW joints from solution heat treated and artificially aged (T6) samples fractured in the HAZ. The microstructure and mechanical properties of weld nugget zones were influenced by the pre-weld heat treatment conditions. Finally, the results of ANOVA agreed with the results of mechanical properties. [ABSTRACT FROM AUTHOR]

Improving microstructural and mechanical properties of AA2024 base metal reinforced with AA7075 via vertical compensation friction stir welding (VCFSW) have become a very vital research area to reinforce the weak part of nugget zone in welded joints. So this paper presents a novel and simple method to improve microstructural and mechanical properties especially ductility and fracture locations of welded aluminum joints by VCFSW technique. Anyhow, most of the welded parts are subjected to the forming processes so improvement in the property of ductility and fracture behavior of welded joints is required. One solution to increase ductility and improve fracture behavior of welded joints is the use of interlayer compensation strip width as a reinforcement which has superior mechanical properties between two blanks of base metal during friction stir welding process. The effect of changing interlayer compensation width was investigated on the microstructural characterization (by an optical microscope, scanning electron microscope and transmission electron microscope) and mechanical properties (using microhardness, tensile and bending tests). Microstructure observations revealed that the tailor-welded joint without compensation interlayer contains micro-voids in the stir zone, while in tailor-welded joints with compensation interlayer, the voids completely disappear on the microscale. X-ray diffraction detected that the use of compensation interlayer of AA7075 between two AA2024 blanks led to the appearance of two precipitates of intermetallic phases, Al2Cu and Mg2Zn, on grain boundaries of aluminum which improved ductility and fracture behavior of welded joints. Ductility enhanced till 54.4% at compensation interlayer width 2 mm when compared to the joint without compensation interlayer. Lower hardness values were detected at nugget zone in joint without compensation interlayer. By contrast, highest hardness values in the softened regions were obtained in compensation interlayer joints. Finally, the highest bending angle occurred without any cracks in case of compensation interlayer of 2 mm at ultimate bending load. [ABSTRACT FROM AUTHOR]

Process parameters of friction stir welding (FSW) with different values of interlayer strip widths have become a very vital research area to reinforce the weak part of the nugget zone in welded joints. So, the objective of this work is to study the effect of different process parameters of FSW such as the tool rotational speed (R), travel velocity (υ) and inclination angle (Θ) with different values of interlayer strip widths (W) of compensation material on microstructural characterization and mechanical properties. Optical microscope, scanning electron microscope, energy-dispersive x-ray spectroscopy and x-ray diffraction techniques were used to characterize the microstructural changes after FSW process. Microhardness and tensile tests were also used to characterize the mechanical properties of the produced joints. The results of mechanical properties of FSW process parameters with different values of interlayer strip width showed that when the tool rotational speed is increased till 2000 rpm, the tensile strength has been increased till 321 MPa, while the reduction in tool traverse speed till 20 mm/min led to an increase in the tensile strength till 239 MPa. Moreover, the best inclination angle was 2.5°. The microstructure observations revealed that the use of process parameters of FSW at 2000 rpm rotational speed, 20 mm/min traverse velocity and 2.5° inclination angle with different values of interlayer strip width showed excellent connections of reinforcement clusters of AA7075 compensation material between the matrices of AA2024 base metals. [ABSTRACT FROM AUTHOR]

Failure mode and failure load of composite joint design has become a very vital research area for being a weak part of composite structures in aircraft segments. So the objective of this study is to investigate the effect of different parameters on the shear strength and failure mode of adhesively bonded single-lap and scarf joints. The parameters included the overlap length, adherend thickness, and adhesive thickness of single-lap joints, and also the effect of single and double scarf angles of scarf joints. The results showed that in single-lap joints, the increasing overlap length led to increase shear strength until the length-to-width ratio becomes same value. The final failure mode of most tested thin adherends bonded joints with similar specimens was the delamination, while the interfacial failure mode occurred in thick adherends bonded joints. The shear strength increased when the adhesive thickness was reduced. On the other hand, in scarf joints, the ultimate shear strength was obtained when the scarf angle was around θ = 18°, while when scarf angle reached θ = 75°, the shear strength was decreased. The failure mode of scarf joints occurred at the interfaces between the scarf angles. [ABSTRACT FROM AUTHOR]

This study presents a novel nanocomposite of LLDPE/15 wt.% PTFE/1 wt.% GNPs by using a hot compression molding technique to increase its compatibility with harsh operations in bearing surface applications. From an industrial perspective, various problems occur in bearing surface applications during running, particularly an overheating problem. Therefore, the major objective of this study is to synthesize LLDPE by mixing a dual matrix of LLDPE/x wt.% PTFE with different weight fractions of PTFE (from 0 wt.% up to 20 wt.%) and then incorporating the optimum case of a dual matrix with different weight fractions of GNPs (from 0 wt.% up to 1.5 wt.%) to improve mechanical and tribological properties. SEM was used to describe microstructural observations of the prepared nanocomposites. Compression and microhardness tests were performed to investigate the mechanical properties. Dry sliding wear and COF tests were implemented by pin-on-disc with a load cell to examine the tribological characteristics. Microstructural observations of LLDPE/15 wt.% PTFE elucidate good mixing compared to pure LLDPE samples. In addition, observations of morphological properties show ideal mixing and adhesion between LLDPE/15 wt.% PTFE and 1 wt.% GNPs, which eliminate defects and cause a strengthening mechanism between matrix and reinforcement. Elastic modulus and microhardness of LLDPE/15 wt.% PTFE were improved by 73.77 % and 41.39 %, respectively, compared to pure LLDPE samples. Moreover, the wear rate and COF of LLDPE/15 wt.% PTFE composites were enhanced by 72.41 and 7.04 %, respectively, compared to pure LLDPE. Moreover, after adding 1 wt.% of GNPs to LLDPE/15 wt.% PTFE, elastic modulus, microhardness, wear rate, and COF were improved by 16.15 %, 27.47 %, 29.73 %, and 45.24 %, respectively, compared to the unfilled dual matrix of LLDPE/15 wt.% PTFE. [ABSTRACT FROM AUTHOR]

The utilization of renewable energy has become increasingly significant recently, yet it encounters great challenges. The present study focuses on enhancing the performance of copper-based nanocomposites for wind energy applications by achieving a desirable combination of wear resistance and electrical properties. The investigation explores the effects of graphite exfoliation and silver reinforcement coating on the properties of the composite. Cu–Ag-(C/Al2O3) nanocomposites are fabricated, varying the percentage of Al2O3 from 0 to 12.5% in increments of 2.5%. The study involves physical, electrical, mechanical, and tribological analyses, along with extensive metallography using techniques such as scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), and mapping. The results demonstrate significant enhancements in the composite properties with higher percentages of Al2O3, up to a limit of 10%. The inclusion of a hybrid reinforcement consisting of 10% Al2O3 and 5% exfoliated graphene, along with a 20% silver coating, results in a lighter-weight Cu-composite with 98% of the electrical conductivity of copper (IACS). Moreover, this composite exhibits the highest hardness (365 HV), which is six times greater than the hardness of the composite without the reinforcement (60 HV). The composite containing 10% Al2O3 exhibits the lowest wear rate (3.5 × 10 − 6 ( m m 3 /m)), while the composite without Al2O3 demonstrates the highest wear rate (6.7 × 10 − 6 ( m m 3 /m)). Metallographic analysis confirms the formation of graphene through exfoliation. The presence of graphene not only improves the coefficient of thermal expansion (CTE) stability due to its lubricating effect but also enhances the electrical conductivity of the composites when combined with the silver reinforcement coating. [ABSTRACT FROM AUTHOR]

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). The article has been retracted at the request of the Editor-in-Chief. Although the text has been rephrased, the whole content is largely identical with the article accepted in the CIRP Journal of Manufacturing Science and Technology, "Improvement of mechanical properties of AA5083 in shipbuilding applications by adding nano ceramic powders of silicon dioxide Si2O3 via friction stir processing technique", Majed H. Moosa, Yasmin A. Abdelraouf, W.M. Farouk, Eyd M. ELSayed, W.M. Shewakh, Ahmed Abu-Oqail, Hanan A. Abd El-Fattah, Mohamed Abu-Okail, Available online 7 June 2020, https://nam03.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdoi.org%2F10.1016%2Fj.cirpj.2020.05.007&data=02%7C01%7Cl.birla%40elsevier.com%7C0bc09cc711684473f04708d82e258c21%7C9274ee3f94254109a27f9fb15c10675d%7C0%7C0%7C637310086091620581&sdata=WloQpr SCnVn8OkpWP67l57DzKZomgjmZAEYhosxp3AU%3D&reserved=0. The manuscript was submitted to the CIRP Journal on April 20, 2020 and to the Journal of Alloys and Compounds on April 28, 2020, falling into the category of double submission. A detailed comparative analysis of the figures in these two articles revealed the following conclusion: - Fig. 1, lower right: identical to CIRPJ-Fig. 1, right. Strangely enough, it is claimed that this is a magnification of Fig. 1, lower left, which is obviously not the case. Fig. 1 upper right is claimed again to be a magnification of Fig. 1 lower right, which is also not the case. Figure captions are identical. - Fig. 2, right: more or less identical with JIRPJ-Fig. 2, right. Identical text below the figure, identical figure caption. - Fig. 4 (b): identical with JIRPJ-Fig. 4, lower part. Almost identical figure caption. - Fig. 7 (a), upper part: identical with CIRPJ-Fig. 17 (a). - Fig. 7 (b), upper part: identical with CIRPJ-Fig. 17 (b). Captions almost identical. - Figs. 8 and 9 and 13 and 20–23 with similar meaning as CIRPJ-Figures 15, 18 and 19 (lower part), 20 (lower part), 21, 22, 23. - Fig. 10 identical with figures in CIRPJ-Table 6, lower two pictures in the middle row. - Fig. 12 (lower part): very similar to CIRPJ-Fig. 25 lower part, with some conditions varying a bit. - Fig. 14: identical with figures in CIRPJ-Table 3, lower two pictures in the middle row, plus CIRPJ-Table 2, third picture in the middle row. - Fig. 16 (a): identical with JIRPJ-Fig. 7, upper right, including partial figure caption. - Fig. 17: identical to JIRPJ-Fig. 10, including figure caption. - Fig. 19: identical to JIRPJ-Fig. 14, including figure caption. The corresponding author and the co-authors were informed about this decision. One of the conditions of submission of a paper for publication is that authors declare explicitly that their work is original and has not appeared in a publication elsewhere. As such this article represents a severe abuse of the scientific publishing system. The scientific community takes a very strong view on this matter and apologies are offered to readers of the journal that this was not detected during the submission process. [ABSTRACT FROM AUTHOR]

Studies contributing to advanced composite materials for naval structures are essential for marine applications. However, there is a limitation in fully covered the different reinforcements' type and the manufacturing process' parameters. This paper presents the effect of adding nano-ceramic powders of silicon dioxide (Si 2 O 3) with a specific value of 22% by volume to the base metal (BM) of AA5083, which processing by Friction Stir Processing (FSP) on the mechanical, microstructural and electrical properties. The process has been analyzed at various values of travel feed and rotational speed. A comparable study has been conducted between the unreinforced and reinforced BM at values of 25, 50, 100, and 150 mm/min in travel feed and 400, 600, and 1000 rpm in rotational speed. The optimum operation values have been elucidated to be at 50 mm/min and 600 rpm. It is elaborated that the Si 2 O 3 nano-particles plays a vital role in improving the mechanical, microstructural and electrical properties such as ultimate tensile strength, elongation, micro-hardness, ductility, electrical resistivity, morphology and electrical conductivity. The microhardness, tensile strength and electrical conductivity attained higher quality in a percentage of 14.3%, 31.7% and 66.6%. To full examination of the optimal operation conditions, the microstructural characteristics of the produced FSP specimens affords an excellent distribution and dispersion of the nano-silica powders through the BM. •Several parameters were examined as following: • Effect of Silicon dioxide (SiO2) on surface performance. •Changing the number of passes during the processing of FS (one, two, three, and four passes). •Characterization achieved included: •Surface Characterization. •XRD, FESEM-EDS. •tensile strength and ductility. •Impact energy and micro-hardness. [ABSTRACT FROM AUTHOR]

Devices of solar water desalination confront many problems including the low thermal properties of phase change materials (PCMs) such as heat transfer, storage of heat capacity, charging and discharging capability. Thus, these properties need to be improved by using a simple and novel procedure. So, incorporation and dispersion of hybrid nano-powders inside PCMs is considered a simple and novel procedure to improve the thermal properties of solar water desalination devices. The present article is focused on incorporating different nano-powders of MWCNTs and Al2O3 inside PCMs to improve the thermal characteristics of solar water desalination applications. Different nano-powders of MWCNTs and Al2O3 have been incorporated as: (i) 1.0 mass% Al2O3, (ii) 1.0 mass% MWCNTs, and (iii) hybrid 1.0 mass% of Al2O3 + 1.0 mass% MWCNTs, inside a constant amount of 250 gm RT-65HC paraffin wax. An innovative prototype was designed and produced to measure the thermal characteristics of solar water desalination devices. Various analyses have been carried out to study the influence of nano-powders scattering on the morphological, microstructural observations, chemical and thermal characteristics, including SEM, XRD, FT-IR, TGA, DSC, thermal conductivity, and infrared thermography. Microstructural observations showed that the excellent dispersion of nano-powders was at hybrid nano-additives of 1.0 mass% MWCNTs + 1.0 mass% Al2O3 inside PCMs. The uniform scattering of hybrid 1.0 mass% MWCNTs + 1.0 mass% Al2O3 inside PCMs assists to eliminate any defects. Finally, thermal characteristics of hybrid nano-additives phase change materials (NAPCMs) were improved specially in thermal stability, latent heat temperature, and thermal conductivity at 89%, 80%, and 32.8%, respectively. [ABSTRACT FROM AUTHOR]

In this study, high-energy ball milling accompanied by compaction and sintering were employed for manufacturing Cu-based hybrid nanocomposite reinforced by Al 2 O 3 and GNPs. This hybrid nanocomposite is proposed to meet the specification of heat sink applications, where excellent mechanical and thermal performance is demanding. Different processing parameters were experimentally considered such as sintering temperature and weight percentage of GNPs, 0, 0.25, 0.50, 0.75, and 1 wt %. The weight percentage of Al 2 O 3 was fixed at 10%. The results demonstrated that the mechanical and thermal performance of the fabricated nanocomposites were superior for nanocomposite containing 0.5% GNPs and sintered at 1000 °C. The hardness, the thermal conductivity and the coefficient of thermal expansion (CTE) were improved by 21%, 16.7%, and 55.2%, respectively, compared to composite without GNPs addition. The improved mechanical and thermal properties were attributed to the low stacking fault energy, small crystallite size, high dislocation density, and low lattice strain of the composite prepared at this composition. Moreover, the better dispersion of the nano-particles of GNPs and Al 2 O 3 inside the matrix helped for the strength and thermal conductivity improvement while maintaining low CTE. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • An innovative technique of CO 2 -LTP produces precised micro grooves for Armox steel. • The study explores Laser Power (P), Gas Pressure (GP), Feed Rate (F), Motor Speed (S) on grooving. • Groove dimensions, cutting depth, upper/bottom width, root roundness, metal removal rate, were examined. • RSM is used to model LTP results, reducing additional cost experiments. • Optimal CO 2 laser settings: 3000 W power, 17.2370 bar N 2 pressure, 400 mm/min feed, 10 RPM motor speed. The production of micro grooves on extremely hard workpieces like Armox 500 T, commonly used in military sectors like armored protective vehicles, poses challenges in conventional machining processes. Accordingly, an innovative technique called CO 2 laser turning process (LTP) assisted by N2 gas was used for manufacturing micro grooves on Armox 500 T to confront the restrictions of traditional machining processes. This study was concerned with investigating the impact of various operating parameters related to the thermal grooving machining process such as: (i) laser power (P), (ii) gas pressure (GP), (iii) feed rate (F), and (iv) motor speed (S). These parameters were examined under various operating conditions like: (i) cutting depth (DC), (ii) upper width cut (UC), (iii) bottom width cut (BC), (iv) roundness error (RE), and (v) metal removal rate (MRR). Thus, response-surface-methodology (RSM) was used to examine the experimental results, enabling the mathematical modeling of the results, and reducing the need for additional experiments. The findings revealed that the optimal combination of condition settings for the CO 2 -LTP of Armox 500 T (assisted by N 2 gas) included a CO 2 laser power of 3000 Watts, N 2 gas pressure of 17.2370 bar, a feed rate of 400 mm/min, and a motor speed of 10 RPM. Furthermore, the optimized combinations of thermal machining conditions resulted in increasing MRR, DC, BC, UC, DC, and reducing RE, with values of 0.0163 µm, 0.2333 mm, 0.2511 mm, 0.5241 mm, and 19.403 µm, respectively. Additionally, the correctness of the optimization procedure was demonstrated by the difference between the optimal experimental findings and the forecasted magnitudes for MRR, DC, BC, UC, and RE, which were up to 7.9 %, 6.71 %, 6.1 %, 3.6 %, and 2.98 %, respectively. [ABSTRACT FROM AUTHOR]

The multiscale hybridization of ceramic nanoparticles incorporated into polymer matrices reinforced with hybrid fibers offers a new opportunity to develop high-performance, multifunctional composites, especially for applications in aeronautical structures. In this study, two different kinds of hybrid fibers were selected, woven carbon and glass fiber, while two different ceramic nanoparticles, alumina (Al2O3) and graphene nanoplatelets (GNPs), were chosen to incorporate into a polymer matrix (epoxy resin). To obtain good dispersion of additive nanoparticles within the resin matrix, the ultrasonication technique was implemented. The microstructure, XRD patterns, hardness, and tensile properties of the fabricated composites were investigated here. Microstructural characterization demonstrated a good dispersion of ceramic nanoparticles of Al2O3 and GNPs in the fabricated composites. The addition of GNPs/Al2O3 nanoparticles as additive reinforcements to the fiber-reinforced polymers (FRPs) induced a significant increase in the hardness and tensile strength. Generally, the FRPs with 3 wt.% nano-Al2O3 enhanced composites exhibit higher tensile strength as compared with all other sets of composites. Particularly, the tensile strength was improved from 133 MPa in the unreinforced specimen to 230 MPa in the reinforced specimen with 3 wt.% Al2O3. This can be attributed to the better distribution of nanoparticles in the resin polymer, which, in turn, induces proper stress transfer from the matrix to the fiber phase. The hybrid mode mechanism depends on the interaction among the mechanical properties of fiber, the physical and chemical evolution of resin, the bonding properties of the fiber/resin interface, and the service environment. Therefore, the hybrid mode of woven carbon and glass fibers at a volume fraction of 64% with additive nanoparticles of GNPs/Al2O3 within the resin was appropriate to produce aeronautical structures with extraordinary properties. [ABSTRACT FROM AUTHOR]