[en] Highlights: • AlSi10Mg alloy with MWCNT composite brake pads are developed with varying wt.%. • Artificial Neural Network (ANN) is used for developing predictive models. • The near optimal process parameter has been observed by DOE. • ANOVA shows that load is most significant factor than speed and temperature. • The average of absolute percentage error is below 1%. The present research paper deals with AlSi10Mg alloy/MWCNT metal matrix composite brake pads with varying weight percentages. The Development of new brake pad materials has been done at compacting load (10 Tons) and sintering temperature (450 °C) using the powder metallurgy process. The input parameters of 40 N normal load, 500 rpm, 150 °C pin temperature as the near-optimal combination of parameters for minimum wear and maximum coefficient of friction compared to other test conditions have been observed by the design of experiment (DOE). The overall average percentage error in the output against experiment output is less than 1%. Analysis of variance (ANOVA) indicates that load is a most significant factor than speed and temperature for wear and CoF. Artificial Neural Network (ANN) is used to develop a prediction model to calculate wear and coefficient of friction for different loads, pin heating temperature and speed. The model developed shows a strong correlation with experimental output. The experimental and predictive model developed from artificial neural network are strongly correlated with a correlation factor of 0.99447 for the training algorithm of Levenberg-Marquardt technique. ANN prediction model and Taguchi L₁₆ array reveal that the experimental and predicted data for mass loss and CoF have less than 3% and 4% error, respectively. The closeness between the artificial neural network and experiment results enhances the scope of ANN for predicting the wear of materials. The model will help engineers to predict the failure of components with reference to running time and can be applied in automobile or manufacturing sectors to study wear, thus saving their time and cost in carrying out experiments.

[en] Ring closing metathesis of acyclic trienes that can provide oxacycles or carbocycles has been investigated. It was found that a substituent on one of the alkene units determines the reaction course to provide either oxacycles or carbocyles exclusively irrespective of the ring size of the resulting compounds.

Graphical Abstract

Ring closing metathesis of acyclic trienes with Grubbs’ first generation (G-I) catalyst was found to be greately influenced by the presence of an alkyl substituent on one of the alkene units to provide either oxacycles or carbocyles exclusively irrespective of the ring size of the resulting compounds. .

[en] Graphical abstract: - Highlights: • Substrate dependent growth of vertical graphene nanosheets (VGNs) is studied under ECR-CVD. • Substrate properties like surface energy and thermal conductivity plays the major role in differential growth of VGNs. • Formation of a-C and pentagon–heptagon structure at early stage nucleation dictates the morphology and structural quality. • A phenomenological model is demonstrated to understand substrate dependent growth. - Abstract: The present study reports the role of substrate on nucleation and growth of vertical graphene nanosheets (VGNs) under electron cyclotron resonance chemical vapor deposition (ECR-CVD). The VGNs are grown on Pt, Ni, Au, Cu, Si(100), Si(111), SiO_2 and quartz substrates simultaneously. The morphology of VGNs is found to vary significantly with substrate. VGNs on Pt have the highest aerial density of vertical sheets while quartz have the lowest. The structural defects in VGNs vary with substrate as evidenced from Raman spectroscopy. The observation of defect related Raman bands such as D″ and D* at 1150 and 1500 cm"−"1, respectively revealed the existence of pentagon–heptagon rings or carbon onions in VGNs. Formation of such defects at early stage of nucleation dictates the growth mechanism and hence the morphology. A phenomenological four-stage model is discussed, to substantiate the nucleation and growth mechanism of VGNs on different substrates, by evoking substrate–plasma interaction during growth

[en] Highlights: • The overall latest development in perovskite solar cells based on Ionic Liquids is reviewed. • The effects of surface and interface engineering/modifications of perovskite cells are emphasized. • The key role of Ionic liquids for efficiency and stability of solar cells and future directions are suggested. -- Abstract: Organic-inorganic metal halide perovskite solar cells (PSCs) are developing in a rapid pace as a potential energy harvesting material. Within a short time span it has achieved the power conversion efficiency comparable to the similar mature technologies (crystalline Silicon, CIGS, CdTe etc.) available in the market. Unfortunately, PSCs have stability issues in real time operating conditions and posed a hurdle towards its commercialization. Various modifications and engineering aspects have been applied so far to cope up with this issue and among these players, ionic liquids (ILs) have certainly grabbed the attention of the researchers recently. ILs have unique and versatile properties like high ionic conductivity, thermal and electrochemical stability; which are suitable for application in PSCs. This review describes the fundamental, present status and future prospects of role of ILs in perovskite solar cells focussing on the stability and efficiency. Strategies regarding surface/interface modifications, engineering of interfaces and interaction of ions (cations/anions) from ILs with various perovskite precursors are discussed.

[en] Hydraulic oils used in heavy machinery are designed to provide lubrication and anti-wear properties under extreme load conditions. In the present study, thermophysical and tribological properties of industrial-grade hydraulic oil (SAE68) with hybrid nanoparticle (MWCNT/SiO₂) additives have been experimentally evaluated. Field Emission Scanning Electron Microscopy (FESEM) revealed that MWCNT and SiO₂ nanoparticles are having tubular and spherical morphology, respectively. UV-Spectroscopy test reflects the stability of prepared hybrid nano lubricants with moderate agglomerations of nanoparticles dispersed into base oil. The viscosities of nano lubricants were determined varying both the nanoparticle volume fraction and temperature. Anti-friction and anti-wear properties of nano lubricants are inspected using a Four-ball tribotester apparatus according to ASTM D4172 standard. The hydraulic oil containing an optimum volume fraction of 1.8% MWCNT/SiO₂ nanomaterials at a ratio of 20:80 reveals a remarkable reduction in coefficient of friction and wear scar diameter by 92.99% and 14% respectively compared to pure oil. The morphology and chemical compositions of worn steel ball surfaces are examined by FESEM and Energy-Dispersive Spectroscopy (EDS) for both base oil and nano lubricant samples. It is also evident from the present tribological investigation that the combination of ball bearing effect and mending effect mechanism improves the friction and wear properties for hybrid nano lubricants which will certainly enhance the performance of machine components. (author)

[en] In this investigation, crack density and wear performance of SiC particulate (SiCp) reinforced Al-based metal matrix composite (Al-MMC) fabricated by direct metal laser sintering (DMLS) process have been studied. Mainly, size and volume fraction of SiCp have been varied to analyze the crack and wear behavior of the composite. The study has suggested that crack density increases significantly after 15 volume percentage (vol.%) of SiCp. The paper has also suggested that when size (mesh) of reinforcement increases, wear resistance of the composite drops. Three hundred mesh of SiCp offers better wear resistance; above 300 mesh the specific wear rate increases significantly. Similarly, there has been no improvement of wear resistance after 20 vol.% of reinforcement. The scanning electron micrographs of the worn surfaces have revealed that during the wear test SiCp fragments into small pieces which act as abrasives to result in abrasive wear in the specimen.

[en] Herein, 3D porous carbon-based nanocomposites are synthesized by single-step pulsed laser deposition at room temperature. In this work, a unique strategy of splitting the green laser beam is adopted to ablate the species from two different targets simultaneously. The strategy is employed for a variety of carbon-based nanocomposite fabrication, and its compositional and structural properties are thoroughly investigated. It has also shown that the elemental composition ratio and hence the structural properties can be tuned by controlling the process- specific parameters of the deposition. We anticipate the utilization of as-synthesized various composites in a single PLD production run as next-generation active materials for energy storage and optoelectronic applications. (author)

[en] Gear oil of heavy mining machineries are designed to provide anti-wear and anti-friction protection under extreme load condition. In present study thermophysical and tribological properties of industrial gear oil with nanoparticles additives (Al₂O₃ and SiO₂) has been experimentally evaluated. Morphology of dry nanoparticles under FE-SEM shows that both nanoparticles are spherical. DLS test shows the presence of mild-agglomeration of nanoparticles in the dispersion. Density and viscosity of nanolubricants is tested with varying temperature and particle volume fraction. Measured viscosity results for Al₂O₃/gear oil nanolubricants follow the existing empirical model and new model has been proposed for SiO₂/gear oil nanolubricants. Anti-friction and anti-wear properties of nanolubricants are tested on pin-on-disc test apparatus. FE-SEM and energy dispersive spectroscopy (EDS) analysis of wear scar (pin SS-304), evident the occurrence of ball bearing and surface polishing effects, which may be responsible for advanced tribological properties of the oil. Test results reveals that ball bearing have dominating effect in enhancement of tribological performance.

[en] In the present investigation, an in-situ multi-component reinforced aluminum based metal matrix composite was fabricated by the combination of self-propagating high-temperature synthesis and direct metal laser sintering process. The different mixtures of Al, TiO₂ and B₄C powders were used to initiate and maintain the self-propagating high-temperature synthesis by laser during the sintering process. It was found from the X-ray diffraction analysis and scanning electron microscopy that the reinforcements like Al₂O₃, TiC, and TiB₂ were formed in the composite. The scanning electron microscopy revealed the distribution of the reinforcement phases in the composite and phase identities. The variable parameters such as powder layer thickness, laser power, scanning speed, hatching distance and composition of the powder mixture were optimized for higher density, lower porosity and higher microhardness using Taguchi method. Experimental investigation shows that the density of the specimen mainly depends upon the hatching distance, composition and layer thickness. On the other hand, hatching distance, layer thickness and laser power are the significant parameters which influence the porosity. The composition, laser power and layer thickness are the key influencing parameters for microhardness. - Highlights: • The reinforcements such as Al₂O₃, TiC, and TiB₂ were produced in Al-MMC through SHS. • The density is mainly influenced by the material composition and hatching distance. • Hatching distance is the major influencing parameter on porosity. • The material composition is the significant parameter to enhance the microhardness. • The SEM micrographs reveal the distribution of TiC, TiB₂ and Al₂O₃ in the composite

[en] Electrode materials design is the most significant aspect in constructing a supercapacitor device. The evolution of metal nitrides/oxynitrides as supercapacitor electrode is strikingly noticeable today besides prevailing carbon or 2D materials, metal oxides/hydroxides and conducting polymers electrode materials. The theoretically estimated specific capacitance of a nitride-based supercapacitor is 1,560 F g^-1. These nanostructures exhibit an excellent capacitive behavior with a specific capacitance of 15–951.3 mF cm^-2 or 82–990 F g^-1, high energy density (16.5-162 Wh Kg^-1) and power density (7.3-54,000 W Kg^-1). On this account, supercapacitor performance of metal nitrides/oxynitrides is reviewed exclusively. The major focus of the present review is directed towards state-of-art progress in supercapacitor performance of nitrides/oxynitrides, underlying charge-storage mechanism, important outcomes and their limitations. Finally, we conclude with challenges and prospects of metal nitrides/oxynitrides for supercapacitor electrodes.