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• 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]

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]

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]

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 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]