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This investigation involved the development and characterization (microstructure, mechanical properties, and dry sliding wear characteristics) of Al-Mg2Si composites for automobile applications. Consequently, the performance analysis of the Al-Mg2Si composites was conducted considering motorcycle disk brake rotor application. The digital logic method (DLM), a material selection process, was employed to compare the performance of Al-Mg2Si composites with traditional rotor materials, cast iron, and stainless steel. The motorcycle disk brake operation was simulated with steel and Al-20wt.% Mg2Si composite rotor to establish the findings of performance analysis. The DLM analysis revealed that the Al-20wt.% Mg2Si composite had a technical performance index of 73.65, while steel had a technical performance index of 78.10. Additionally, the energy efficiency index (EEI) for the composite and steel stood at 31.79 and 100, respectively. Furthermore, the composite exhibited much lower CO2 and CO emissions compared to steel, with values of 0.087 and 0.0026 g/km versus 0.276 and 0.0082 g/km, respectively. The simulation results indicated that both the stainless steel and the Al-20Mg2Si composite rotor exhibited structural suitability. In the Al-20Mg2Si composite rotor, the induced temperature ranged from 35.4 to 60.3 °C, while the heat flux ranged from 1.462 × 103 to 3.64 × 105 W/m2. On the other hand, the stainless steel rotor experienced induced temperature ranging from 41.55 to 87.4 °C, and heat flux ranging from 4.0 × 102 to 1.64 × 105 W/m2. The composite rotor demonstrated a lower induced temperature and higher heat flux, which in turn reduced the probability of both direct and indirect thermal damage and improved structural integrity. [ABSTRACT FROM AUTHOR]

The aim of this study is to investigate the impact of different metal deposition modes—spray (S), pulse (P), and pulse-switchback (PS)—on the metallurgical and mechanical properties of SS308L structures in wire arc additive manufacturing (WAAM). Three thin-walled structures were deposited using optimal process variables and inter-layer time delay. Through metallographic examination, it was found that the P-mode had the highest homogeneity (88.94%) in terms of grain size and phase fraction, followed by the S-mode (86.03%) and the PS-mode (74.68%). Based on micro-hardness data, the P-mode had the highest average hardness value (272.51 HV along BD and 276.99 HV along TD). However, the PS-mode (83.46%) had a more homogeneous hardness distribution compared to the S-mode (83.11%) and P-mode (78.59%). In tensile tests, the P-mode showed higher tensile strength (823 MPa) and more homogeneous (98.68%) properties than the PS-mode and S-mode. However, the P-mode exhibited the highest variability (21.14%) in terms of elongation, followed by PS-mode (20.82%) and S-mode (16.30%). It was also found that the P-mode induced the maximum stress-induced phase transformation from γ-phase to α'-phase, followed by PS-mode and S-mode. This study provides valuable insights for determining the optimal deposition mode for SS308L structural components in the WAAM process. [ABSTRACT FROM AUTHOR]

Graphene oxide/silicon nanowire heterojunction was fabricated through electrochemical deposition methods. The field emission scanning electron microscopy characterization showed the graphene oxide was deposited on the silicon nanowires. The energy-dispersive X-ray spectroscopy revealed that carbon and oxygen were also present in graphene oxide/silicon nanowire heterojunction in addition to silicon. The UV–Vis IR spectra showed that at 600 nm wavelength, silicon nanowires have a reflectance value of 11% and graphene oxide/silicon nanowire has 7% ATR-FTIR and XRD characterizations further suggested the successful deposition of GO on SiNWs. The Raman spectra showed the presence of characteristic peaks of GO in addition to the peaks of SiNWs. A red shift was observed in the peaks, which may be attributed to van der Waals interactions between GO and SiNWs. The Raman analysis further confirmed the formation of GO/SiNWs heterojunction. The valance band offset and the conduction band offset of the heterojunction formed using the electrochemical method were obtained as 1.37 and 0.41 eV, respectively. The power conversion efficiency was increased from 0.18 × 10–3 to 2.7 × 10–3% when silicon nanowires were coated with graphene oxide. The device was stored and after 75 days, a power conversion efficiency of 88% was retained. This shows that the device is relatively stable. The present work provides a hassle-free and simple method for fabricating heterojunction at room temperature. [ABSTRACT FROM AUTHOR]

A cost-efficient, eco-friendly and simple method was adopted to synthesize cobalt oxide/reduced graphene oxide (rGO) nanocomposite (NC). To simultaneously synthesize rGO and grow cobalt oxide on it, an extract of Eupatorium glandulosum Kunth has been used. Morphological analysis of the synthesized materials was conducted using field emission scanning electron microscopy and transmission electron microscopy. For the functional group analysis, attenuated total reflectance-Fourier transform infrared spectroscopy has been used. The structural characteristics of the materials were analysed with Raman spectroscopy and X-ray diffraction. X-ray photoelectron spectroscopy determined the oxidation state of cobalt oxide in the NC. Finally, the electrochemical property of the NC was studied using Tafel and electrochemical impedance spectroscopy. [ABSTRACT FROM AUTHOR]

A zinc oxide (ZnO) thin film-based carbon dioxide ( CO 2 ) gas sensor is proposed and designed in the present research from the perspective of sensing CO 2 emissions from vehicle tailpipes. Different ZnO thin films (ZnO-TF) have been synthesized on a silicon substrate using the radio frequency sputtering technique. The characteristics of the fabricated ZnO-TFs have been analyzed by x-ray diffraction and field emission scanning electron microscopy by observing the crystalline structure and the microstructure images, respectively, of the deposited thin films. One ZnO-TF sample has been selected for electrode deposition and further electrical characterization. ZnO-TF with an interdigital electrode has shown very good characteristics while performing electrical characterization. The same device has been used for gas-sensing experiments. A portable and compact gas testing experimental setup has been designed and developed. We have used that indigenous setup to evaluate the performance of the fabricated ZnO-TF gas sensor device upon exposure to CO 2 gas with varying concentrations from 1445 ppm to 4631 ppm. We mounted a reference meter (Temtop M2000 second-generation air quality monitor) on the experimental setup to measure the CO 2 concentration, temperature, and humidity. Excellent sensitivity of 17.5%, 23.3%, 30.9%, 40.7%, and 47.3% was found in the fabricated sensor when exposed to CO 2 concentrations of 2775 ppm, 2929 ppm, 3770 ppm, 4452 ppm, and 4631 ppm, respectively. [ABSTRACT FROM AUTHOR]

Blast furnace flue dust and thermal plant generated fly ash are major solid wastes coming from the two important industrial sectors. Flue dust mainly contains iron oxide and carbon. The fly ash contains mostly silica, alumina and iron oxide with small amount of lime. These materials are commonly used in making of bricks and tiles. Little amount of flue dust is used in charge material preparation for iron extraction. In this present study, fixed quantities of blast furnace flue dust (30 wt %) and pure iron oxide fines (65 wt %) are mixed with different binders such as bentonite, lime, sodium silicate, fly ash, starch, molasses, pitch and dextrin. The strength of composite briquettes was determined at green, dry and cured conditions. Moreover, the effect of the variation of fly ash quantity, fly ash particle size, briquetting pressure and curing temperature on the compressive strength of composite briquettes were also investigated. The optimized fly ash quantity of 5 wt%, fly ash particle size of 75 µm (200 mesh), briquetting pressure of 95 MPa and curing temperature of 300 °C provide maximum strength to the briquettes. The phase analysis through XRD and morphology analysis through FESEM-EDS of fly ash added cured composite briquettes were performed. [ABSTRACT FROM AUTHOR]

The present work has reported a microwave-assisted green reduction approach for reducing graphene oxide (GO) to reduced graphene oxide (rGO) using Artemisia vulgaris plant leaf extract. GO has been synthesised following the modified Hummers method. The reduction of graphene oxide (GO) has been conducted in three sets resulting in six reduced graphene oxide (rGO) samples (R1–R6) with a maximum reduction time of 1 h. Three sets of parameters with changes in microwave input power, reduction reaction time and volume of plant extract have been investigated to acquire an optimised set of reduction conditions. The reported optimised set exhibited the highest specific capacitance (CS) value out of the parameters investigated. The study is based on the comparative analysis of structural, morphological, vibrational, optical, bonding and networks and electrochemical properties of GO and its reduced products (rGO) for supercapacitor application. The potential of this plant extract to reduce GO into rGO has been reported. Furthermore, it was discovered that only a particular volume of Artemisia vulgaris extract might be employed for effective reduction. The rGO samples have been studied for supercapacitor electrode application. Total charge resistance (RCT) analysis through electrochemical impedance spectroscopy (EIS) reveals the decrease in RCT value from 295.51 Ω for GO to as low as 42.09 Ω for R5. The CS of the synthesised GO and all rGO samples have been calculated using CD and CV plots. The highest value recorded for R5 was 111.62 Fg−1 at a scan rate of 0.005 Vs−1 and 94.80 Fg−1 at a current density of Ag−1. The cyclic stability after 5000 cycles at a current density of 3 Ag−1 was recorded as 74.2%. [ABSTRACT FROM AUTHOR]

Products developed through the powder metallurgy route have significantly contributed to structural application, automotive, and aircraft industry in the last decades. Several research works are available on the use of pure metal powder for the development of useful products through the powder metallurgy process. The study on the physical and mechanical properties of compacted reduced composite fines produced after crushing of reduced composite briquette containing Blast furnace flue dust, iron oxide, graphite powder, and fly ash is limited. The physical property such as density of green briquettes made with reduced composite fines, and 0.5% sodium silicate has been measured as a function of compaction pressures (75, 90, and 100 MPa). The maximum density of 5341.6 kg/m3 was achieved at 100 MPa pressure. The samples possessing maximum density has been sintered at different temperatures of 1100 °C, 1150 °C, and 1200 °C for 60 min, 90 min, and 120 min respectively. The density, compressive strength, and hardness were measured after sintering of the samples. The samples were sintered at 1150 °C for 120 min achieve maximum density of 6111.4 kg/m3, compressive strength of 238.72 MPa, and hardness of 109.34 VHN. [ABSTRACT FROM AUTHOR]

Two-dimensional graphene oxide (GO) was coated on one-dimensional silicon nanowires (SiNWs) to form a GO/SiNWs heterojunction. SiNWs can be replaced with Si because SiNWs have better optical and electronic properties than bulk Si. The coating of crumpled and wrinkled sheets of GO on SiNWs was observed from FESEM images. The coating of GO also led to a decrease in the reflectance of light by SiNWs. The GO/SiNWs heterojunction improved the current–voltage characteristics compared to bare SiNWs. GO/SiNWs heterojunction showed an ideality factor of 1.42 and barrier height of 0.38 eV. A low value of leakage current (5.16 × 10−4 mA) was obtained for GO/SiNWs compared to bare SiNWs (1.63 × 10−3 mA). [ABSTRACT FROM AUTHOR]

The unresolved decisive aspect of joining T23 steel to T91 steel in a supercritical boiler is hereby taken up with reasonable success by adopting a cost-effective GTAW process with an iron-based filler wire (ER90S-B9). Quite a reasonable joint strength (UTS = 319 MPa) coupled with a considerable ductility (%elongation = 8) is ascertained by carrying out tensile test at boiler operation temperature (571 °C), known as one of the most critical tasks; and subsequently performing advanced characterization keeping all the significant regions of the weldment intact. Being pushed along with grain boundary sliding, Cr23C6 particles are clustered around the cavity evolved therein under tensile load applied at the boiler service temperature. The dimples originated through microvoid coalescence in the soft α-ferrite matrix eventually negate the cleavage mode of failure initiated at the segregated Cr23C6 particles around cavity so as to maintain a considerable level of ductility. Furthermore, the defect accumulation in the form of dislocation wall around Cr23C6 particle appears to be responsible for providing significant high-temperature strength so as to justify the success of the adopted joining route. [ABSTRACT FROM AUTHOR]

A near eutectic Al-12.6Si alloy was developed with 0.0wt%, 2.0wt%, 4.0wt%, and 6.0wt% Al-5Ti-1B master alloy. The microstructural morphology, hardness, tensile strength, elongation, and fracture behaviour of the alloys were studied. The unmodified Al-12.6Si alloy has an irregular needle and plate-like eutectic silicon (ESi) and coarse polygonal primary silicon (PSi) particles in the matrix-like α-Al phase. The PSi, ESi, and α-Al morphology and volume fraction were changed due to the addition of the Al-5Ti-1B master alloy. The hardness, UTS, and elongation improved due to the microstructural modification. Nano-sized in-situ Al3Ti particles and ex-situ TiB2 particles caused the microstructural modification. The fracture images of the developed alloys exhibit a ductile and brittle mode of fracture at the same time. The Alα5Tiα1B modified alloys have a more ductile mode of fracture and more dimples compared to the unmodified alloy. [ABSTRACT FROM AUTHOR]

Effect of manganese (Mn) addition (0.0, 1.0, 2.0 and 3 wt%) on the microstructural morphology, hardness, tensile properties and fracture behaviour of the gravity cast eutectic Al–12.6Si alloy has been studied through XRD analysis, chemical analysis, optical metallography, FESEM analysis, energy dispersive spectroscopy analysis, hardness test, tensile test and quantitative phase analysis. As-cast Al–12.6Si–0.0Mn alloy has a non-uniformly distributed coarser and irregular shape primary and eutectic silicon particles inside the α-Al phase, and both the Si phase have very sharp corners. Whereas, the 1 wt% Mn added alloy has uniformly distributed fine eutectic and primary Si particles with blunt corners. Further, the addition of 1.0 wt% Mn forms very few (0.26 vol %) irregular shape Al15(MnFe)3Si2 intermetallic phase within the α-Al phase and eutectic Si phase. But, 2.0 wt% and 3 wt% Mn added alloy has an irregular shape coarse plate-like Al15(MnFe)3Si2 intermetallic phase besides the primary and eutectic Si phase. The bulk hardness of the Al–12.6Si alloy is increased with an increase in Mn concentration as the harder Al15(MnFe)3Si2 intermetallic phase forms and both the Si phase morphology modify. The microhardness of the constituent phases also varies with the change in Mn concentration in the alloy. The Mn addition improved the ultimate tensile strength, yield strength, and elongation (%) of the alloy. However, fractographs reveal that the brittle mode of fracture has been increased due to the presence of a higher volume of brittle Al15(MnFe)3Si2 intermetallic in 2.0 and 3.0% Mn alloy. On the other hand, the amount of brittle and cleavage fracture of Si particles decreased, and ductile fracture with dimples formation increased in 1.0 wt%Mn added alloy. [ABSTRACT FROM AUTHOR]

This study investigates the dry sliding wear behaviour of Al–7.6Si–xZr (x = 0.0, 0.1, 0.2, and 0.3) alloys under different applied loads of 19.6 N, 39.2 N, and 58.8 N, aiming to understand the underlying wear mechanism of the alloys. The inclusion of Zr in the Al–7.6Si alloy led to the formation of in situ ZrSi and ZrSi2 compounds, serving as nucleation sites that result in finer and granular α-Al and acicular and fibrous eutectic Si formation. This Zr modification also contributed to improving the alloy’s bulk hardness. Wear test results indicated that the proportion of Zr and wear test loads was important factors influencing the cumulative wear loss (CWL) and coefficient of friction (COF). The wear resistance of the Al–7.6Si–xZr alloys decreased with an increase in the wear test load but increased with an increase in the sliding distance. The primary wear mechanisms were abrasive, adhesive, and oxidative wear, and they exhibited significant variations depending on the concentration of Zr in the alloy. The addition of Zr significantly improved the wear resistance of the Al–7.6Si alloy, and the wear resistance increased as the Zr concentration increased. The wear maps depicted the transitional stages between different wear mechanisms under varying loads and sliding distances.Graphical Abstract: This study investigates the dry sliding wear behaviour of Al–7.6Si–xZr (x = 0.0, 0.1, 0.2, and 0.3) alloys under different applied loads of 19.6 N, 39.2 N, and 58.8 N, aiming to understand the underlying wear mechanism of the alloys. The inclusion of Zr in the Al–7.6Si alloy led to the formation of in situ ZrSi and ZrSi2 compounds, serving as nucleation sites that result in finer and granular α-Al and acicular and fibrous eutectic Si formation. This Zr modification also contributed to improving the alloy’s bulk hardness. Wear test results indicated that the proportion of Zr and wear test loads was important factors influencing the cumulative wear loss (CWL) and coefficient of friction (COF). The wear resistance of the Al–7.6Si–xZr alloys decreased with an increase in the wear test load but increased with an increase in the sliding distance. The primary wear mechanisms were abrasive, adhesive, and oxidative wear, and they exhibited significant variations depending on the concentration of Zr in the alloy. The addition of Zr significantly improved the wear resistance of the Al–7.6Si alloy, and the wear resistance increased as the Zr concentration increased. The wear maps depicted the transitional stages between different wear mechanisms under varying loads and sliding distances. [ABSTRACT FROM AUTHOR]

In this research work 6351 Al-Al 4SiC 4 composite has been developed through stir casting route with incorporation of fine TiC powder in 6351 Al melt. During stir casting, round shaped Al 4SiC 4 particles were generated as TiC reacted with molten aluminum. These Al 4SiC 4 particles were found to be acting as nucleation sites for primary α (causing grain refinement) along with engulfment effects promoting particle distribution without clustering. Furthermore, as the volume fraction of Al 4SiC 4 particles increased, the proportion of dendritic region decreased (more equiaxed grains appeared) and the overall grain size of the matrix decreased. This resulted in an improved strength and ductility of the composite. Equations were developed with a reasonable accuracy correlating the strength with microstructural parameters. An excellent combination of strength (UTS = 215 MPa) and ductility (%Elongation = 10) was obtained for 6351 Al-7 vol.% Al 4SiC 4 composite as compared to base cast 6351 Al alloy (UTS = 121 MPa, %Elongation = 3). [ABSTRACT FROM AUTHOR]

This study investigates the tribological behaviour of Al-20Mg2Si composite having potential applications in automobiles. A pin-on-disc apparatus was employed to assess its performance under diverse operating conditions relevant to automotive components. These conditions encompassed variations in sliding conditions (dry and lubricated), temperatures (ranging from 30°C to 200°C), and loads (20N, 40N, and 60N), with a focus on understanding their influence on wear characteristics, mechanisms, wear maps, and surface topography. The findings emphasize the pronounced impact of test conditions on wear properties. Dry sliding conditions showed a substantial increase in both cumulative wear and friction coefficient, rising by 13.17 and 1.47 times, respectively, from the 30°C test to the 200°C test with a 60N load. Conversely, lubrication yielded significantly lower cumulative wear and friction coefficients, measuring only 0.07 and 0.15 times those observed during room temperature dry sliding conditions. Surface roughness analysis confirmed that higher loads and temperatures resulted in increased roughness, while lubrication effectively reduced surface roughness. FESEM analysis of worn surfaces and debris revealed that under dry sliding at room temperature, the primary wear mechanism was abrasive, with secondary mechanisms being oxidative and adhesive wear. In contrast, at high temperatures during dry sliding, the primary mechanism shifted to adhesive wear, accompanied by secondary mechanisms including delamination, oxidative wear, and plastic deformation. Wear map analysis showed that at room temperature, wear changed from severe to moderate to mild as sliding distance increased. However, with increased temperature and load, wear shifted from mild to moderate to severe. [ABSTRACT FROM AUTHOR]