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Recently, the demand for lightweight multilayered parts in electronics and biomedical fields has been accelerated and shown great interest in understanding the combined effect of multilayered materials. However, these industries are still facing the challenge of developing dissimilar multilayered materials that can be suitable for biomedical applications. In this context, magnesium emerges as a promising biocompatible material used for several biomedical applications. However, the issues related to joining magnesium alloys with other similar materials still need to be solved. Moreover, friction stir additive manufacturing (FSAM) occupies a niche domain for developing or joining biocompatible materials such as magnesium alloys with low weight and high strength. Therefore, the present work highlights the development of a multipurpose three-layered multifunctional laminated composite plate of magnesium-based AZ31B–Zn–Al 1100 through the FSAM route. Microstructural and morphological examinations were carried out by light microscopy and FESEM equipped with EDS analysis and line mapping. Moreover, the grain refinement at the interfaces during the FSAM was also addressed using the electron backscattered diffraction (EBSD) study. Further, investigation on mechanical properties such as tensile test with fractography analysis and microhardness variation at the cross-section of the built-up section has been investigated. Furthermore, the corrosion and tribological analysis was also performed, and a 3D profilometer was used to visualize the corroded and worn-out surfaces. The microstructural results revealed that the average grain size of 6.29 μm at interface AZ31B–Zn and 1.21 μm at interface Zn–Al 1100 occurred, improving the bonding strength and overall properties. The tensile strength has occurred as 171.5 MPa at 15.5% elongation, whereas maximum microhardness is reported as 105 HV at the interface of AZ31B–Zn and 84.6 HV at the interface of Zn–Al 1100. The corrosion rate was calculated as 0.00244 mm/day, and the average coefficients of friction (COF) for both the interfaces, such as AZ31B–Zn and Zn–Al 1100, are 0.309 and 0.212, respectively. [ABSTRACT FROM AUTHOR]

Growing age and different conditions often require the replacement of orthoses, and FDM-based 3D printing can produce them quickly with less investment. In today's market for orthotics, these characteristics are highly desired. Therefore, this study is fully focused on the optimization and strength analysis of FDM 3D-printed ankle–foot orthoses (AFO) fabricated using PLA and PLA reinforced with carbon fiber (PLA-C). An increase in ankle plantar-flexor force can be achieved by reinforcing thermoplastic AFOs with CFs. Specially designed mechanical strength tests were conducted at the UTM to generate force–displacement curves for stored elastic energy and fracture studies. The mechanical behavior of both AFOs was predicted with the help of an FEA. The model predictions were validated by comparing them with mechanical strength testing conducted under the same loading and boundary conditions as the FEA. In both the prediction and experimental analysis, the PLA-C-based AFOs were stiffer and could withstand greater loads than the PLA-based AFOs. An area of high stress in the simulation and a fracture point in experimentation were both found at the same location. Furthermore, these highly accurate models will allow the fabrication of AFOs to be improved without investing time and resources on trials. [ABSTRACT FROM AUTHOR]

• Examined rheological effects and revealing shear-thinning after 3 wt% CNTs. • Substantial increase in elastic modulus with CNTs in tensile test. • The Payne effect and non-linearity in fabricated nanocomposites were observed. • Storage modulus and strain rate sensitivity increases during DMA. • Fractography demonstrated CNTs effect for enhanced fracture resistance. Direct Ink Writing (DIW) revolutionizes 3D printing with carbon-based inks, offering design, complexity, and sustainability advantages. This study centers on formulating Polydimethylsiloxane (PDMS) and Multiwalled-Carbon Nanotube (CNT) nanocomposite-inks, assessing their rheological properties for DIW suitability and minimum reinforcement demands. Mechanical tests on DIW-fabricated samples are conducted under static and dynamic conditions substantiated by fractographic analysis. Rheological investigation confirms a 3 wt % reinforcement threshold for printability. Comparatively, 3.5 wt % CNT nanocomposites exhibit a substantial 143% increase in elastic modulus over neat PDMS. Dynamic mechanical analysis reveals heightened storage modulus with increasing CNT content, while fractography underscores localized areas resisting fracture, demanding elevated stress for breakage. [ABSTRACT FROM AUTHOR]

Purpose: The industrial application of continuous glass fabric-reinforced polymer composites (GFRPCs) is growing; however, the manufacturing boundedness of complex structures and the high cost of molds restrict their use. This research proposes a three-dimensional (3 D) printing process for GFRPCs that allows low-cost and rapid fabrication of complex composite parts. Design/methodology/approach: The composite is manufactured using a digital light processing (DLP) based Vat-photopolymerization (VPP) process. For the composites, suitable resin material and glass fabrics are chosen based on their strength, stiffness, and printability. Jacob's working curve characterizes the curing parameters for adequate adhesion between the matrix and fabrics. The tensile and flexural properties were examined using UTM. The fabric distribution and compactness of the cured resin were analyzed in scanning electron microscopy. Findings: The result showed that the object could print at a glass fabric content of 40 volume%. In DLP-based VPP printing technology, the adequate exposure time was found to be 30 seconds for making a GFRPC. The tensile strength and Young's modulus values were increased by 5.54 and 8.81 times, respectively than non-reinforced cured specimens. The flexural strength and modulus were also effectively increased to 2.8 and 3 times more than the neat specimens. In addition, the process is found to help fabricate the functional component. Originality/value: The experimental procedure to fabricate GFRPC specimens through DLP-based AM is a spectacular experimental approach. [ABSTRACT FROM AUTHOR]

In order to investigate the effects of different functional groups on graphene on the mechanical behavior of carbon fiber reinforced epoxy composites were fabricated by hand layup technique. In this study, three different variety of functionalized graphene (–NH2, –COOH, and –OH) with varying weight percent (i.e. 0.1, 0.3, and 0.5 wt%) was considered. Tensile, interlaminar, and three-point flexural tests were conducted to evaluate the effects of graphene concentration and fiber stacking sequence (i.e. 0/90° and 0/90/ ± 45°) on composites. The microstructures of the composites were characterized by a scanning electron microscope. Experimental results showed that pristine and functionalized graphene significantly improved the mechanical properties of carbon fiber epoxy composites. Compared to neat carbon fiber epoxy composites, the maximum tensile strength of 33.34% and 26.35% were noticed for 0/90°–COOH–0.5 and 0/90/ ± 45°–NH2–0.3 stacked functionalized graphene modified carbon fiber epoxy composites, respectively. Moreover, 48.44% and 59.1% flexural strength were recorded for 0/90°–COOH–0.3 and 0/90/ ± 45°–OH–0.5 stacked functionalized graphene modified carbon fiber epoxy composites, respectively. Furthermore, maximum interlaminar shear strength (ILSS) of 120.25% was observed for 0/90/ ± 45° stacked carbon fiber epoxy composites. Finally, the results obtained with graphene as reinforcement filler can cause a significant improvement in the mechanical performance of fiber composites. Henceforth, they can also be considered as a promising candidate for designing composites for structural applications. [ABSTRACT FROM AUTHOR]

In this article, we investigated the effects of different functional groups in graphene on the mechanical performance of epoxy nanocomposites fabricated using the in-situ polymerization method. This study considered pristine graphene and three different varieties of functionalized graphene (–NH2, –COOH, and –OH) with varying weight percent (i.e., 0.25, 0.5, and 1.0 wt%). The functional groups grafted of graphene have been confirmed through Fourier transforms infrared (FTIR) spectra. Microstructural features and fracture surfaces were also examined by field-emission scanning electron microscopy with energy-dispersive X-ray spectroscopy. In comparison to pure epoxy, –OH functionalized graphene/epoxy nanocomposites showed a maximum improvement of 37.24% in tensile strength and 38.05% in flexural strength. The improved mechanical properties of epoxy nanocomposites were attributed to homogeneous dispersion, graphene bridging, and better interfacial contact between epoxy and graphene. The effect of pristine and functionalized graphene on the mechanical properties of epoxy nanocomposites was studied. Nanocomposites were fabricated for three different wt% (0.25, 0.5, and 1.0) of graphene nanofillers. Field emission scanning electron microscopy (FE-SEM) with EDX was used to examine the microstructural features of fractured surfaces. Graphene enhanced the mechanical properties of epoxy nanocomposites. [ABSTRACT FROM AUTHOR]

This study investigated the effect of abrasive water jet kinematic parameters, such as jet traverse speed and water pressure, on the surface of magnesium-based metal matrix nanocomposites (Mg-MMNCs) reinforced with 50 nm (average particle size) Al2O3 particles at concentrations of 0.66 and 1.11 wt.%. The extent of grooving caused by abrasive particles and irregularities in the abrasive waterjet machined surface with respect to traverse speed (20, 40, 250 and 500 mm/min), abrasive flow rate (200 and 300 g/min) and water pressure (100 and 400 MPa) was investigated using surface topography measurements. The results helped to identify the mode of material disintegration during the process. The nanoindentation results show that material softening was decreased in nanocomposites with higher reinforcement content due to the presence of a sufficient amount of nanoparticles (1.11 wt.%), which protected the surface from damage. The values of selected surface roughness profile parameters—average roughness (Ra), maximum height of peak (Rp) and maximum depth of valleys (Rv)—reveal a comparatively smooth surface finish in composites reinforced with 1.11 wt.% at a traverse speed of 500 mm/min. Moreover, abrasive waterjet machining at high water pressure (400 MPa) produced better surface quality due to sufficient material removal and effective cleaning of debris from the machining zone as compared to a low water pressure (100 MPa), low traverse speed (5 mm/min) and low abrasive mass flow rate (200 g/min). [ABSTRACT FROM AUTHOR]

The demand for tailored properties of the materials and lightweight characteristic accelerates the development of metal matrix composites (MMCs). The conventional methods of MMCs development require several post-processing techniques like a microstructural modification or grain refinement, to fulfil the desired requirement of specific applications. In this regard, friction stir processing (FSP) can be proved as an alternative, not only for microstructural modification but also utilized for the development of surface composites. This solid-state approach is an environment-friendly process. It also refines the grain structure of the alloys and composites, which in turn, enhances the mechanical properties such as tensile strength, hardness and fatigue strength. The present work aims to focus on the state of the art research in the field of friction stir processing and to highlight its key points and merits over traditional methods. The present work also emphasizes the developments in friction stir processing, especially on aluminium and magnesium-based alloys and composite and futuristic approaches adopted in various industrial application. • The present work focusses on friction stir processing and highlights the key points and merits of FSP. • It also emphasis the developments in FSP work especially on aluminium and magnesium alloys and composite. • The effect of process parameters related to heat generation, material flow and tool pin profile is explored. • Microstructural, mechanical characterization, and grain refinement are some keen point of the present work. [ABSTRACT FROM AUTHOR]

[Display omitted] • Machine Learning models were developed to predict the output of the supercapacitor. • Artificial neural network model had achieved the highest performance. • Machine Learning provides optimum material composition for better output. Herein, machine learning (ML) models using multiple linear regression (MLR), support vector regression (SVR), random forest (RF) and artificial neural network (ANN) are developed and compared to predict the output features viz. specific capacitance (C sp), electrical conductivity (σ) and sheet resistance (R s) for MXene/Graphene Nanoplatelets (GNPs) based energy storage devices. These output features are modeled as a function of wt.% in different weight ratios of GNPs in MXene, optimum potential window and scan rates. The datasets are obtained by the real time output measurements through the experimental runs of these composites in different weight ratios. Among these models, ANN had achieved the highest performance followed by MLR, SVR and RF. From both the experimental and ANN results, the electrode with 20 wt% of GNPs in MXene (MG-80) exhibited the highest C sp of 226.6F/g at 5 mV/s with a long cycle life having 84.2 % retention even after 5000 cycles of charging-discharging. ANN model is further utilized to predict the cyclic stability of MG-80 electrode upto 10,000 cycles and the results show the accuracy of the ML model to fabricate storage devices. Furthermore, the structure of MXene/GNPs composites are investigated by different characterization techniques. XRD spectra confirmed the successful synthesis of MXene and the successful intercalation of GNPs into MXene sheets. The morphology of the embedded GNPs in layered MXenes are determined through FE-SEM/EDX and HR-TEM analysis. The increase in the surface area and pore volume in the MXene/GNPs composite are revealed by BET measurements. XPS is utilized to find out the chemical element states of the bare MXene as well as its composite with GNPs. [ABSTRACT FROM AUTHOR]

Direct ink writing (DIW) is a rapidly expanding additive manufacturing (AM) technique valued for its cost-efficiency and material adaptability. While DIW offers substantial process flexibility, achieving precise manufacturing demands a thorough understanding of its printability parameters. Key process variables such as printing speed, nozzle-bed gap, pulses for extrusion, and extrusion multiplier wield significant influence over the shape and dimensions of printed components. In this study, a machine learning model based on k-nearest neighbors is employed to predict dimensional accuracy. The model is trained using measured width and thickness data from printed rings, with flow and printing-speed tests defining parameter boundaries for printing. The final model demonstrates an accuracy of 81% and 74% for two PDMS-CNT composite ink compositions. The principal components analysis underscores the pivotal roles of the extrusion factor and printing speed in achieving superior geometric fidelity. Additionally, retraction-residual tests were conducted, revealing that the initial 10 seconds of extrusion hold critical importance as they can lead to distortions when traversing printed regions or perimeters, necessitating consideration in part design. To evaluate layer adhesion strength, a crucial aspect of AM, T-peel tests were performed. Furthermore, rheological tests provided insights into extrudability, printable reinforcing percentages, shape retention, and yield stress. Highlights • Rheological tests yield insights into minimum reinforcing% and shape retention. • Developed k-NN model predicts accuracy using measured printed rings' data. • PC analysis shows key roles of extrusion factor and print speed. • Retraction-residual tests reveal initial 10 seconds are critical. • Model validation results show 83.45% and 77.95% accuracy, close to prediction. [ABSTRACT FROM AUTHOR]

Short or nanofillers‐reinforced composites increase the thermo‐mechanical characteristics of additive manufacturing (AM) base materials. Effective outputs were regulated via parametric optimisation and custom production. One of the most used AM method, Vat photopolymerization (VPP), creates complex and geometrically precise photopolymer parts. This study prepares photopolymer composite (PPC) samples with 2.0, 4.0, 6.0, and 8.0 volume percentages of short glass fiber (SGF) using an inter‐stage stirring method in DLP‐based VPP process. An adequate curing time and formable layer thickness were evaluated for the printability performance of SGF‐photopolymer composite. The 4.0% PPC‐sample showed a 20% higher compressive yield strength than pure photopolymer and other volume fractions. The consequences of increased strength values were assessed by the effect of stirring method and the fractography analysis of PPC specimen. The investigation additionally encompassed numerical simulations that employed an innovative technique for constructing and simulating three‐dimensional representative volume elements (RVEs). The RVEs were designed to replicate the experimental outcomes by randomly situating and orienting fillers within the matrix. The study employs the calibrated Three Network (TN) viscoplastic constitutive material model as the matrix property, and the simulation results demonstrate a margin of error of 5%–10% when compared to the experimental findings. Highlights: Layer‐wise availability of SGFs through inter‐stage stirring methodThe exposure time and layer thickness were determined by Jacob's working curveConcept of RVE is used to combine individual SGF layers into a single layerSEM showed that increasing SGF layer resists cracking better than neat matrixExperimental data and numerical simulations are in good agreement [ABSTRACT FROM AUTHOR]

Ultrasonic pulsating water jet for non-thermal and selective removal of acrylic bone cement is studied. Variation of acoustic chamber length is used for tuning of the ultrasonic system into the resonance regime to gain maximum power transmission. The study investigates the minimal technological conditions such as nozzle traverse speed and supply water pressure required to generate disintegration grooves in bone cement mantle. It also proposes the safe standoff distance range, which is essential for its potential application during the extraction of bone cement without compromising host bone. Palacos R+G bone cement was used for the experiments. Generated groove depths were measured using MicroProf FRT and analyzed using SPIP software. Depth values showed an increasing trend with an increase in acoustic chamber length, decrease in traverse speed, and increase in supply pressure values. From the entire experimental domain, a maximum depth of 615 μm was obtained at 22-mm chamber length, 0.5-mm/s traverse speed, 10-MPa pressure, and a standoff distance of 4 mm. Brittle fractured surface features like material chipping, micro-pits, cracks, and sheared material layers were observed in the SEM images. Disintegrated debris, diameter 21–37 μm, conceived from pit diameters can be used to design a suction unit. Real-time control of the disintegration process using accelerometer sensors was shown. The results support the idea of using pulsating water jet for bone cement removal in a single blind hole. Minimal technological parameters reduce reaction force of the hand tool, allowing bone cement removal without bone fracture or perforation. [ABSTRACT FROM AUTHOR]

Powder mixed EDM is getting popularity due to its improved machining efficiency. The properties of powder particles play an important role in influencing the process. Therefore, the present work is focused on the phenomenon of electrical discharge machining (EDM) process for different dielectric conditions. Experiments on EDM have been performed using plain deionized (DI) water, nonconductive Al2O3 powder mixed DI water, and conductive Al powder mixed DI water as the dielectric. The experimental result shows that the conductive powder mixed EDM process is more stable and is able to generate better surface topography compared to other processes. To explicate the observation, sparking behavior, bubble formation, and interelectrode gap (IEG) for the different dielectric conditions have been investigated using high-speed camera. The average interelectrode gap was measured as 0.05 mm, 0.1015 mm, and 0.1392 mm in conventional EDM, nonconductive alumina powder mixed EDM, and conductive aluminum powder mixed EDM process, respectively. Similarly, mean sizes of bubble diameter in conventional EDM, alumina powder mixed EDM, and aluminum powder mixed EDM are observed as 0.1583 mm, 0.17789 mm, and 0.20621 mm, respectively. [ABSTRACT FROM AUTHOR]

In this review, recent progress in the mechanical, thermal and interfacial properties of graphene/CNT multiphase polymer composites is examined. Progress in the mechanical and thermal properties of CNT (1D) and graphene (2D) nanostructure materials is also reviewed and compared. Furthermore, this review highlights the improvements in the mechanical, thermal and interfacial properties of two- and three-phase composites, owing to the addition of graphene/CNT. In particular, analysis of several notable papers on hybrid composites (graphene/CNT) provides an intensive review of synergetic effects on the overall properties of the corresponding composites. This holistic review describes an improved interface between fibers and a nanofiller-reinforced matrix. Although the presence of nanofillers even at low loadings confers an overall improvement in composite properties, the exact ratios of individual fillers and combined forms remain to be discussed in depth. Finally, potential applications, current challenges and future perspectives for use of these multiphase composites are discussed with regard to their extraordinary capabilities and promising developments in graphene/CNT family-based composite materials. [ABSTRACT FROM AUTHOR]

Simulation of molecular dynamics (MD) allows mimicking the systematic variation of mechanical properties beyond the capacity of experimental methods. In this review, the status of the molecular modelling, simulation and mechanical and thermal characterisation of graphene and the properties of bulk nanocomposites using MD are extensively examined. The molecular models of graphene (pristine and functionalised), and the most common epoxy matrix with preeminent MD energy minimisation tools are thoroughly examined. The presence of MD's simulation setup and the computational procedure for different styles of mixing the polymer matrix with graphene as nanofiller are exhaustively reviewed. In particular, in the analysis of several papers on graphene and their composites, it has been noticed that mechanical, thermal and interfacial properties are ubiquitous to most of the engineering applications. In this review, advances in the molecular modelling and simulation of graphene and their composites has been discussed in detail keeping graphene structures, aspect ratio, weight fraction and density effect as major factors. Finally, the research gaps and future scope are discussed, which indeed helps the researchers in scaling up their researches in graphene and their composites, which may further lead to their experimental findings. [ABSTRACT FROM AUTHOR]

In the present review, the recent progress in describing the intricacies of mechanical and thermal properties of all types of graphene- and modified graphene-based polymer nanocomposites has been comprehensively examined. The effectiveness of microscopy bouquet for the intrinsic characterization of graphene family and their composites was clearly demonstrated in this research. Furthermore, the utility of the dynamic mechanical analysis and thermo-gravimetric analysis employed for thermal characterization that has been reported by various researchers was exhaustively analyzed in this paper. This research primarily focused on the analyses of several good articles concerned with hybrid graphene composites and the synergetic effect of graphene with other nanofiller to assess its effect on the mechanical properties of its corresponding composites. Such systematic analysis of previous literatures imparted a direction to the researchers about the solution of improved interfacial properties as well as the enhanced dispersion into the vicinity of the matrix. This current research has suggested that the presence of the graphene filler even at very low loadings has shown considerable improvement in the overall mechanical properties of graphene. Further studies to optimize the value of the filler need to be addressed in order to gain complete understanding of the properties of graphene. The potential applications, current challenges, and future perspectives pertaining to these nanocomposites were elaborately discussed in the current study with regard to the multi-scale capabilities and promising developments of the graphene-family-based nanocomposites materials. [ABSTRACT FROM AUTHOR]

In this paper, an attempt is made to explore the possibilities of modifying the dielectric by adding alumina (Al2O3) nanopowder for improving the machining performances. The performance of newly developed nano powder-mixed electrical discharge machining (NPMEDM) process is compared with conventional EDM. Peak current, gap voltage and pulse-on time are taken as considerable process parameters to investigate material removal rate (MRR), surface roughness (SR), recast layer thickness, surface morphology, surface topography and induced residual stress. It is observed that the nanopowder-mixed dielectric medium gives better surface finish and higher metal removal rate as compared to conventional dielectric. The value of MRR increases from 32.75 to 47 mg/min and surface roughness improves from 2.245 to 1.487 μm. Thereafter, atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM) investigation of the machined surface reveals that presence of micro-crack, micro-hole and uneven deposition decrease substantially during NPMEDM process. Also, induced tensile residual stress on the machined surface significantly reduces in this modified process. Further, the basic mechanism of these processes are investigated by analysing pulse train discharge waveforms and reveals the better sparking stability of NPMEDM process, which results in the higher MRR and better surface quality. [ABSTRACT FROM AUTHOR]

Abstract The paper deals with microhardness measurement up to a depth of 3 μm on hybrid metal matrix composite A359/Al 2 O 3 /B 4 C from the surface created by wire electric discharge turning and abrasive waterjet turning at the same of a range of rotational speed. The study also includes the topographical and morphological aspects of measurements to compare the surface quality. The microhardness was measured by Vickers indentation test at a load of 100 g for 10 s. Surface roughness profile parameters (Ra, Rq and Rz), and 3D surface visualisation were measured by an optical profilometry. Laser confocal microscope was used to characterize the topographical details. FE-SEM analysis was used to discuss the morphological observations and to explore the quality and defects of the machined surfaces. The sub-surface element like residual stresses is also investigated through the depth profile for both types of turning process by means of XRD machine. The results showed that a lower value of microhardness (165 HV) as compared to cast sample (200 HV) has been observed in the recast layer of wire electrical discharge turning along with induction of tensile residual stress (340 MPa). During abrasive water jet turning a nominal change in microhardness (204 HV) along with compressive residual stress (−285 MPa) was observed. [ABSTRACT FROM AUTHOR]

Lightweight composite materials for potential thermal applications are the contemporary demand for manufacturing and aircraft industries where the possibility to improve and tailor the desired properties is based on the application. Carbonized eggshell powder is a solid lubricant with absorbent capability and has proven as a reinforcement for metallic base composites. In the present work, an attempt is made to investigate the effect of carbonized chicken eggshell powder (3 to 9% by weight) on the microstructural and thermal properties of Al7075 alloy processed by solid-state friction stir processing. An infrared thermography and three K-type thermocouples equipped with the base plate at three equal distances are used to measure the temperature with respect to time. The comparative study of microstructure and grain structure analysis has been done by light microscopy, scanning electron microscopy, and electron backscattered diffraction methods. The findings explored the dynamic recrystallization and grain recovery with a reduced grain size of 6.2 to 10.3 µm at a varying percentage of eggshell powder (3 to 9%) in the stir zone. The thermal conductivity and coefficient of thermal expansion (CTE) were measured for the temperature range of 50 to 400 °C. In addition to it, differential thermal analysis (DTA), thermo-gravimetric analysis (TGA), and derivative thermo-gravimetric analysis (DTG) are conducted for the temperature range of 25 to 900 °C to discuss the endothermic, exothermic nature, and degradation characteristics. The result revealed the decreasing trend of thermal conductivity, and CTE values were found in the range of 97 to 53 W/mK and 26.6 to 24 × 10−6 K−1 (heating cycle), 27.2 to 23.8 × 10−6 K−1(cooling cycle), respectively. Furthermore, the higher and lower thermal conductivity of 108 W/mK and 62 W/mK is observed at higher and lower terminal voltages, 250 V and 100 V, respectively. The DTA, TGA, and DTG curves explored the maximum weight loss, which varies up to 5.25% with exothermic peaks and decomposition steps for each surface composite. [ABSTRACT FROM AUTHOR]

The accurate measurement of tool tip temperature in turning has been a challenging task for researchers. The present study covers the computational fluid dynamics (CFD) analysis of a single point carbide cutting tool dissipating heat and subjected to streams of nanofluid mist. This study is an attempt to numerically analyze the thermal behavior of the cutting tool having constant temperature heat source at its tip. To determine the optimized experimental value of nodal temperature, machining of AISI 304 steel has been carried out using alumina and alumina-MWCNT hybrid nanofluid mist with minimum quantity lubrication (MQL) system. Furthermore, the conjugate heat transfer (CHT) analysis has been performed to investigate the temperature distribution over the rake and flank face of carbide cutting insert. An overview of the mathematical model, complete geometry, and mesh generation of the carbide cutting tool is presented. Additionally, the CHT simulation results for the mist of alumina and alumina-MWCNT hybrid nanofluids were compared and validated successfully with the experimental data. The maximum variation of 5.79% has been observed between experimental and simulation data, which in turn proves the proposed conjugate heat transfer-based CFD model as an alternative approach to investigate the influence of cooling media on cutting tool under MQL technique. [ABSTRACT FROM AUTHOR]

Present work investigates the effect of alumina/graphene (GnP) hybrid nanoparticle additives on tribological properties of lubricant as cutting fluid in turning of AISI 304 steel. The hybrid nano-lubricant has been developed in different volumetric concentrations (0.25, 0.75 and 1.25 vol%). The tribology and wettability testing of lubricants confirm that wear and friction coefficient reduces with an increase of nanoparticle concentration. The hybrid nanofluid has shown the lowest pin wear and friction coefficient. The performance of hybrid nano-lubricant have been compared with the alumina nanofluid. The results establish that mixing of GnP with alumina enhanced its tribological properties. The developed hybrid nano-lubricant significantly reduced the tool flank wear and nodal temperature by 12.29% and 5.79%, respectively compare to alumina based lubricant. [ABSTRACT FROM AUTHOR]

A hybrid nanofluid (NF) with better thermal and tribological properties has been developed in this investigation by mixing alumina-based nanofluid with graphene nanoplatelets (GnP) in the volumetric concentrations of 0.25, 0.75 and 1.25 vol %. It was noted that an increase of nanoparticle concentration enhances both, the thermal conductivity and viscosity, though the hybrid nanofluid has lower thermal conductivity compare to its constituents and the viscosity lies in between its constituents. The tribological test confirms that the wear decreases with the increase of nanoparticle concentration and the hybrid nanofluid generated least amount of wear. Hybrid nanofluid shows better wettability results as compared to alumina-based nanofluid as well as base fluid. The turning of AISI 304 steel under minimum quantity lubrication (MQL) technique clearly establishes that application of hybrid nanofluid performs better as compared to alumina nanoparticle mixed cutting fluid. The study reveals that blending of GnP with alumina enhances the performance of hybrid nanofluids. The application of hybrid nanofluid with MQL significantly reduces the surface roughness by 20.28% and cutting force, thrust force and feed force by 9.94%, 17.38% and 7.25%, respectively. [ABSTRACT FROM AUTHOR]

In any metal cutting operation, the cutting fluid plays a vital role by cooling the surface of the work piece and the cutting tool, removing chips from the cutting zone and by lubricating the tool–work piece interface. However, misuse of the cutting fluid and wrong methods of its disposal can affect human health and the environment badly. Also, it accounts for 16–20% of the total cost of manufacturing in the production industry. Among various techniques available on application of the coolant, researchers, of late, have been focussing on Near Dry Machining (NDM)/Minimum Quantity Lubrication (MQL) as it minimizes the use of coolant by spraying the mixture of compressed air and cutting fluid in an optimized manner instead of flood cooling. The MQL technique has proved to be suitable because it complies with the requirements of ‘green’ machining. This paper presents a review of the important research papers published regarding the MQL-based application of mineral oils, vegetable oils and nanofluid-based cutting fluids for different machining processes, such as, drilling, turning, milling and grinding, etc. The paper explains the mechanism of the MQL technique. In a systematic manner, the present work also discusses its effect on the performance parameters of different machining processes. Most of the experimental studies have shown that application of MQL produces surface better than dry machining and similar to that as produced under wet machining. Its application also reduces cutting forces, cutting zone temperature, tool wear, friction coefficient in comparison to dry and wet machining. Therefore, MQL technique has proved to be a viable alternative to the flood lubrication under similar performance parameters. [ABSTRACT FROM AUTHOR]

A colloidal mixture of nanometre-sized (<100 nm) metallic and non-metallic particles in conventional fluid is called nanofluid. Nanofluids are considered to be potential heat transfer fluids because of their superior thermal and tribological properties. In recent period, nanofluids have been the focus of attention of the researchers. This paper presents a summary of a number of important research works that have been published on rheological behaviour of nanofluids. This review article not only discusses the influence of particle shape and shear rate range on rheological behaviour of nanofluids but also studies other factors affecting the rheological behaviour. These other factors include nanoparticle type, volumetric concentration in different base fluids, addition of surfactant and externally applied magnetic field. From the literature review, it has been found that particle shape, its concentration, shear rate range, surfactant and magnetic field significantly affect the rheological behaviour of any nanofluid. It has been observed that nanofluids containing spherical nanoparticles are more likely to exhibit Newtonian behaviour and those containing nanotubes show non-Newtonian flow behaviour. Furthermore, nanofluids show Newtonian behaviour at low shear rate values while behave as non-Newtonian fluid at high shear rate values. Authors have also identified the inadequacies in the research works so far which require further investigations. [ABSTRACT FROM AUTHOR]

The work presents the surface integrity of TiN/TiAlN coated surfaces produced using hexagonal boron nitride suspension in the dielectric fluid through the micro-electrical discharge coating (μ-EDC) process. The performance of the coated surfaces is evaluated on the grounds of surface topography, wettability, indentation depth, layer height, crack density, roughness profiles, residual stress, and composition analysis. The recast layer height varies between 1.53 μm and 13.38 μm, while the water contact angle lies in the range of 91.28° to 118.23° (hydrophobicity is induced). The residual stress generated due to the presence of micro-cracks on the coated surfaces prepared at a maximum voltage (60 V) and powder concentration (12 g/L) varies between 225.87 MPa and 300.93 MPa. The occurrence of Ti, Al, Cu, Zn, V, B, N, and O in EDX plots affirmed the transfer of tool and dielectric material to the work surface. The indentation depths obtained in the study lies within the range of coating thickness. The surface roughness parameters, i.e., R a , R q , R z , R sk , and R ku are also evaluated in this work. Such micro-deposited surfaces find application in lab-on-chip devices where selective surface modification is needed. • Modified layer of TiAlN/TiN formed on Ti-alloy using hBN powder mixed dielectric micro-electrical discharge coating. • Surface integrity and residual stress analysis conducted on the coated samples. • Increase in residual stress observed with increasing duty factor. • Water contact angle varies from 91.28° to 118.23° for the coated samples. • Metallurgical transformations account for hard and lubricating coatings. [ABSTRACT FROM AUTHOR]

Among the different metal nanoparticles for formulating inkjet-based conductive inks, gold remains the best choice for fabricating different patterns on economical and bio-degradable substrates such as commercial photo papers for developing low-cost sensing devices. Formulating customized gold nanoparticle (AuNPs) inks remains challenging as the ink must meet specific physical, chemical and rheological properties to achieve appropriate jettable behaviour and printable characteristics. It should exhibit well-controlled viscoelastic response for the smooth and optimized flow through the nozzles and then cure immediately to facilitate the shape retention of deposited feature. In this work, the jettability window definition framework using dimensionless numbers such as Re, We, Ca, and Z are defined for the aqueous-based AuNPs inks synthesized via ultrasonic spray pyrolysis technique and formulated into three concentration levels of 300, 600, and 1200 ppm. A theoretical CFD based simulation study is conducted to observe the ink droplet formation behaviour at different droplet velocities through inkjet nozzle. Among these formulated inks, 1200 ppm shows the most favourable behaviour as obtained through the simulation and jettability window results. It is tested further to see how different printing settings, like pulse voltage and number of repetitions, affected the continuity and density of the ink, affecting the quality of the printed AuNPs. This work demonstrates the process capabilities of inkjet printing technology by testing the formulated AuNPs ink. [Display omitted] [ABSTRACT FROM AUTHOR]

The present study focuses on the hydrodynamic erosion of tantalum in the form of the disintegration depth when exposed to periodic impingements of water clusters. Discrete water clusters were generated using a pulsating water jet at excitation frequencies of 20 and 40 kHz to modulate the continuous jet into a pulsating jet. The influence of the technological parameters, such as the excitation frequency (20 and 40 kHz), supply pressure (20, 30, and 40 MPa), nozzle diameter (0.3 and 0.5 mm), and time exposure (0.25–128 s), on the erosion depth of tantalum was observed. The disintegration depth trend showed a proportional nature with the number of impingements directed to the tantalum surface keeping all other technological parameters constant. An increase in the water flow rate from 0.76 l/min (p = 20 MPa, d = 0.3 mm) to 3 l/min (p = 40 MPa, d = 0.5 mm), reduces the time exposure required for the initiation of disintegration from 4 s (80,800 impingements with f = 20 kHz) to 1 s (40,600 impingements with f = 40 kHz), respectively. The effect of change in the excitation frequency from 20 to 40 kHz was observed in form of an increase in the erosion depth from 1587 to 1762 μm at p = 40 MPa, d = 0.5 mm, and t = 128 s. The surface morphology observed using scanning electron microscopy revealed erosion features, such as craters, micro-holes, surface upheaving, and tearing, on the tantalum surface. No significant change in the mean micro-hardness values were observed near the periphery of the eroded cavity as compared to original material due to high-density of tantalum which obstruct the propagation of shock waves into the material. The outcome of the study enhances the knowledge regarding the hydrodynamic erosion of high-density materials (ρ > 15 kg/mm3) in response to the water flow rate, frequency, and time exposure. • The hydrodynamic erosion mechanism of tantalum using a pulsating waterjet was studied. • Three erosion regions were approximated within an exponential increase in impingements. • A proportional relation between the number of impingements with the erosion depth was observed. [ABSTRACT FROM AUTHOR]

Lightweight and high strength materials are the primary requirements in the field of defense like in aircraft structures and aerospace applications. In this context, aluminum-based composites are one of the suitable choices because of its improved characteristics. In the present work, an attempt is made to develop aluminum (A359) based surface composites by incorporating the Si 3 N 4 particles through friction stir processing (FSP). The numbers of FSP tool passes (single, two and three) are considered as variable parameters to evaluate its effect on various characteristics. The microstructural examination has been carried out by optical microscope and surface morphological analysis was done by scanning electron microscopy images. EDS with mapping images are used to observe the phase distribution and to identify the elements of the alloying and reinforcement materials. The elemental presences are also validated by X-ray diffraction and Raman spectroscopy. Further, mechanical properties like tensile test supported by fracture analysis and Rockwell hardness profile of the FSP zone are also discussed. In addition to it, the present work also an emphasis on the effect of the number of FSP tool passes on its wear resistance and thermal expansion. The results revealed that the value of maximum tensile strength and hardness were found to be 576 MPa and 125 HRB respectively in single pass FSPed composite. However, if the number of passes is increased then the maximum wear loss (11.7 × 10−3 g), maximum expansion due to heat (9 mm3) is observed at three-pass of FSP tool. Image 1 • Development of novel A359/Si 3 N 4 surface composite produced by friction stir processing. • Microstructural, morphological and structural analysis of A359/Si 3 N 4 surface composite. • The effect of multiple tool passes on tensile strength and Rockwell hardness profile of FSP stir zone. • The effect of multiple tool passes on Wear loss with respect to sliding distance. • Thermal expansion test to discuss the behavior of developed composite at high temperature. [ABSTRACT FROM AUTHOR]

The study acclaims the generation of hard, wear-resistant, and lubricating layer on Ti alloy using molybdenum disulfide (MoS2) powders mixed in dielectric (deionized water) using a brass tool electrode (diameter 800 μm) through the micro-electrical discharge process. The deposition rate, micro-hardness, recast layer, and surface roughness were studied for the surface generated through the process and correlated with the XRD, AFM, electron probe micro-analyzer, EDS analysis, and FESEM images. Results indicate that a higher voltage (60 V) and powder concentration (12 g/L) increase the material deposition rate in the form of intermetallic compounds deposited on the recast layer. The coated layer formed shows an increase in micro-hardness ranging from 426.42 to 714.25 HV, which is more when compared to the base material hardness of 417.61 HV. In addition to this, lower micro-cracks were seen at high powder concentration, voltage, and duty factor with improved surface quality. The pin-on-disc wear test of the coated samples was performed, and results indicated that the specific wear rate decreased with the increase in duty factor due to the formation of hard and wear-resistant intermetallic compounds as confirmed from the EDS and XRD plots. [ABSTRACT FROM AUTHOR]

The residual stress and subsurface hardness of welded joints treated by peening using an ultrasonic pulsed water jet at pressures of 20–60 MPa with various traverse speeds and standoff distances were measured. The effect of the treatment was quantified by measuring the residual stress using X-ray diffraction in three regions (the welded zone, heat-affected zone, and base metal). To analyse the depth of the plastic deformation induced by the pulsating water jet, microstructural analyses and micro-hardness measurements were conducted. The surface topography of the treated samples was examined by measuring the surface roughness using a contact surface roughness profilometer. After pulsating water jet treatment, the samples showed both increased residual stress and surface roughness at pressures of 20–60 MPa. Increased subsurface hardness of the treated region was observed up to a depth of 200–250 µm at pressures of 40 and 60 MPa, deeper than that of the sample prepared at 20 MPa. The microstructural analysis identified the involved plastic deformation phenomenon occurred during the treatment process. This method of surface treatment, where the efficiency of the jet is enhanced by the generation of pulses using an acoustic generator, showed promising results for its practical application as a post-weld treatment method. [ABSTRACT FROM AUTHOR]

This study focused on the development of an AZ31B/Si 3 N 4 /Eggshell surface composite via solid-state multi-pass friction stir processing. The study aimed to characterize the developed surface composite based on its structural, microstructural, mechanical, and tribological performance at one, two and three successive tool-passes. The structural and compound analysis was conducted using an XRD pattern. Microstructural characterization and grain refinement studies were conducted using FESEM images and EBSD analysis. Furthermore, the mechanical properties were investigated through tensile tests equipped with digital image correlation (DIC) images and fractography analysis via FESEM images. In addition, tribological characteristics, such as COF, friction forces, and volumetric wear losses, were examined using a universal tribometer, and the 3D profile of the wear track was analyzed through surface profilometry. The results revealed the formation of structural compounds such as Mg 2 Al 4 , Mg 2 SiO 4 , Mg 2 Ca, and Ca 2 Mg 4 Zn 13 in the stir zone. The morphological study revealed plenty of white-grey (ESP) and dark grey (Si 3 N 4) sub-micron precipitates uniformly dispersed into the AZ31B matrix alloy. The EBSD map exhibited an average grain size of 2.95 ± 1.83 μm. The ultimate tensile stress at one, two and three successive tool-passes were found to be 357 MPa, 366.5 MPa and 375.4 MPa, respectively, which was comparatively 20–25% higher than the base alloy. The FESEM images of the fractured surface exhibited ductile striations and tear ridges with flat shear bands mixed with brittle fracture. The lowest COF obtained in this study was 0.29 for three too-passes at an average frictional force (Fx) of 2.17 N with a volumetric wear loss of 0.0769 mm3. • Multi-pass FSP of AZ31B alloy to overcome the challenges associated with the less hexagonal structure. • Utilization of waste chicken eggshell in a useful reinforcement to enhance the mechanical and tribological properties. • Microstructural changes and grain refinement analysis has been done through FESEM and EBSD analysis. • Tensile behavior with (DIC) images and fractographic analysis. • Tribological characteristics supported with 2D and 3D wear track analysis through surface profilometry. [ABSTRACT FROM AUTHOR]

Short carbon fibre (C f ) reinforced silicon carbide (SiC) composites with 7.5 wt% alumina (Al 2 O 3 ) as sintering additive were fabricated using spark plasma sintering (SPS). Three different C f concentrations i.e. 10, 20 and 30 wt% were used to fabricate the composites. With increasing C f content from 0 to 20 wt%, micro-hardness of the composites decreased ~28% and fracture toughness (K IC ) increased significantly. The short C f in the matrix facilitated enhanced fracture energy dissipation by the processes of crack deflection and bridging at C f /SiC interface, fibre debonding and pullout. Thus, 20 wt% C f /SiC composite showed >40% higher K IC over monolithic SiC (K IC ≈4.51 MPa m 0.5 ). Tribological tests in dry condition against Al 2 O 3 ball showed slight improvement in wear resistance but significantly reduced friction coefficient (COF, μ) with increasing C f content in the composites. The composite containing 30 wt% C f showed the lowest COF. [ABSTRACT FROM AUTHOR]

Wire Arc Additive Manufacturing (WAAM) is a revolutionary process under the category of Direct Energy Deposition (DED) method in the field of Additive Manufacturing (AM). The research is being done exponentially since 2011 which is integrating into the advancement of production specifically for fourth Industrial Revolution (Industry 4.0). The deposition of filler metals in layers over the substrate is done mainly through Gas Metal Arc Welding (GMAW), Gas Tungsten Arc Welding (GTAW), and Plasma Arc Welding (PAW) which are leading heat input sources to fabricate the product with improved strength of material than from other DED's. Although defects are similar as of welding defects. In this paper, concepts and processes for WAAM have been studied thoroughly and a critical review is done on important and defining parameters of good quality WAAM manufactured products. It also focuses on the recent advancements in tuning the mechanical and microstructural properties of WAAM fabricated parts and the financial aspects of WAAM for the production of cost-effective fabricated materials. [Display omitted] • The present work focusses on wire-arc additive manufacturing (WAAM) and highlights the key points and merits of it. • It also emphasis the developments in WAAM, especially on alloys and composite. • The effect of process parameters related to heat generation, material flow is explored. • Microstructural, mechanical characterization and defects associated with WAAM are the key highlights of the present work. [ABSTRACT FROM AUTHOR]