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The most significant threat to the ecosystem is emerging pollutants, which are becoming worse each year and harming the planet severely and permanently. Many organic and inorganic contaminants are present and persistent due to various world events and population growth. As a result, there is a greater need for new technology and its application to address the problems caused by developing pollutants. Carbon composite nanomaterials have significant potential in the fight against numerous environmental contaminants due to their distinctive attributes. This review discusses the reports of customized carbon composite nanomaterials to meet the need for specific elimination of emerging contaminants. Physical and chemical features such as high surface area, conductivity (thermal and electrical), and vibroelectronic properties, size, shape, porosity, and composite nature are making these tailored materials of carbon-based nanomaterials an emerging and sustainable tool to remove persistent compounds like emerging contaminants in aqueous solution. Different composite materials are well discussed in this review, along with their adsorption efficiency of diverse emerging contaminants, including Bisphenol A, estradiol, metformin, etc. This review provides insight into the recent trends limited to 2017–2023. The limitations of carbon-based nanomaterials, such as regeneration and cost-effectiveness, have also been overcome in recent years by diverse modifications in the production process, which can be further improved to make these materials well suited for an extended group of emerging contaminants.

This work describes the fabrication of a self-lubricating and surface wear-resistant hybrid composite. It has an AZ91D base composite reinforced with a combination of WS2and MoS2particles. The friction stir processing (FSP) technique was utilised to produce all composite specimens by varying the volume fraction to 5%, 10%, and 15%. The samples were prepared, as per the ASTM standards, for conducting various tests to obtain the mechanical properties. The specimens with 15% volume fractions demonstrated the lowest wear rate and the lowest friction coefficient in the wear tests. The sliding speed of 3 m/s and load 30 N results in a lower roughness value of 0.285 μm. The wear mechanisms of the composite were identified from the SEM observations of the worn surfaces of the sample. The load and sliding speed determine what type of wear mechanisms predominate. At lower sliding speeds and loads, abrasion, oxidation, and delamination wear mechanisms were more prominent than adhesion and thermal softening/melting.

In this experimentation, an endeavour has been taken to develop the short carbon fibre (SCF) reinforced epoxy composites mixed with multi-walled carbon nano-tubes (MWCNT) and silicon carbide particles (SiCp) using a compression moulding machine. The quantity of MWCNT was modified by 0.5%, 1%, and 1.5%, and SiCp quantity has been taken as 15% by weight of the composite. The influence of the ceramic particles on the wear characteristics of SCF stiffened epoxy was explored. The wear testing variables, namely normal load, sliding speed, and sliding distance, were considered for the dry sliding wear test. As per the ASTM standards, the wear test was executed utilising the pin-on-disc apparatus, and the composite's rate of wear and friction coefficient were studied. The worn-out area on the wear test specimen was examined utilising a scanning electron microscope (SEM) to recognise the wear mechanism of the composites.

In this investigation, an effort has been made to develop the short carbon fibre stiffened epoxy composites (CFSEC) mixed with multi-walled carbon nano-tubes (MWCNT) and silicon carbide particles (SiCp) using a compression moulding process. The content of MWCNT varied as 0.5%, 1%, and 1.5%, and SiCp content was maintained at 10% by weight of the composite. The impact of the ceramic particles on mechanical characteristics such as hardness, tensile, flexural, and wear behaviour of CFSEC was investigated. For all the mechanical characteristics, the rise in the proportion of MWCNT in the composite has shown a significant improvement. The specific wear rate (SWR) and coefficient of friction (COF) of the composite were studied using the pin-on-disc tester. The wear parameters yielding the lowest SWR and COF were identified from the wear testing process parameters. The fractography analysis of tensile specimens was carried out using a scanning electron microscope (SEM).

In the present study, the Taguchi grey relational analysis was applied to optimize the wear behavior of graphene nanoplatelets-filled flax fiber-strengthened epoxy composites, which was fabricated in vacuum resin infusion bag. The impact of wear parameters, viz. applied load and sliding distance and speed on the wear performance, viz. wear rate and coefficient of friction coefficient were investigated. The experiments were planned and performed in agreement with the Taguchi L9orthogonal array. For each experiment, the coefficient of friction and wear rate was recorded. The applied load of 30 N, sliding speed of 240 rpm, and sliding distance of 5100 m are found to be optimal from the Taguchi grey relational analysis. An analysis of variance was performed to determine the dominant parameter, and the applied load with sliding speed was found to be significant. The sliding speed was proved to have the greatest impact on the composite wear with 76.58%. The confirmation experiments conducted by the optimum parameters revealed a 31.31% improvement in grey relational grade.

In this work, the effect of processing route on physical and tribological properties of cast AA8011 alloy, squeeze cast AA8011 alloy and stir cum squeeze cast AA8011 with 5wt% ZrO2& 5wt% Al2O3composite were investigated. Squeeze cast AA8011 alloy shows pore free fine structure when compared to as cast AA8011 alloy. In hybrid composite, ZrO2and Al2O3particles are homogeneously distributed with the matrix due to squeezing effect. Hardness of the hybrid composite is 45% higher than squeezed and base alloy. Pin-on-disc Tribometer is used to study the wear properties of castings produced. Wear rate of the hybrid composite is 60% lower than the as cast AA8011 alloy. Coefficient of friction is also low in hybrid composite compared to other alloys. This is owing to the AA8011 matrix's uniform distribution of reinforcement particles closely bonded with matrix due to applied load acting on the liquid melt. Abrasion and adhesive mode of wear mechanisms were observed in the casted specimens.

The plant-based green synthesis method is creating more interest in safety, low-cost, biocompatibility, and eco-friendly approaches to producing nanoparticles biologically than chemical and physical methods of synthesis. The copper oxide nanoparticles (CuONPs) attract researchers due to the wide range of industrial, pharmacological, and biomedical applications that depend on the size, charge, and shape of the nanoparticles. This research work aimed to synthesize CuO nanoparticles using aqueous extract of Salvinia cucullata, characterization, and assessment of in vitroantibacterial, antioxidant, and anticancer activity. The characterization of CuONPs was performed by different techniques which include UV spectroscopy, FTIR, XRD, TEM, SEM, EDXS, and Zeta size and potential analysis. UV spectroscopy confirms the synthesis of CuONPs with an absorbance peak of 266 nm. The monoclinic crystalline nature of CuONPs was revealed by XRD analysis, and this pattern exhibited similar diffraction peaks with no significant shift in peak position. The functional groups of phytocomponents present in the aqueous extract of S. cucullatawhich act as reducing and stabilizing agents responsible for CuONPs synthesis were analyzed by the FTIR technique. The spherical shape of the synthesized CuONPs was ascertained by SEM and TEM image techniques, and the selected area for electron diffraction shows the crystal orientation of the CuONPs. EDXS shows that only copper and oxygen were present and the synthesized CuONPs are in pure form. The average size and charge of the synthesized CuONPs were analyzed by PSA as 67.5 nm and − 2.2 mV. The antibacterial potential of synthesized CuONPs was tested against both gram- positive and gram-negative bacterial strains. Among all eight strains, the maximum and minimum zone of inhibition was observed against Enterococcusspp. and Aeromonas hydrophila(maximum inhibition against gram-positive strains than gram-negative strains). The antioxidant and anticancer activity of CuONPs were tested against DPPH and MCF-7 breast cancer cell line and are observed with increased activity in a dose-depending manner with the IC50 value of 81.21 μg/ml and 68.16 μg/ml concentration. The green synthesized CuONPs were characterized and exhibited antibacterial, antioxidant, and anticancer activity. Thus, CuONPs can be utilized for broad-spectrum biomedical applications.

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Various blends containing glycerol, castor oil (NCO) and cashew nut shell liquid (CNSL) were made following soft computational techniques and the blend consisting 60% glycerol and 40% NCO was proposed, which exhibited 37% less coefficient of friction (CoF) than NCO and CNSL and 50% less CoF and comparable extreme pressure properties to non-biodegradable commercial mineral oil (CMO). Accelerated wear was indicated by particle quantifier index for CMO, NCO and CNSL samples while normal wear was observed in glycerol and the proposed blend. SEM and 3-D profilometer images exhibited more damaged surfaces in NCO and CNSL than other lubricants. Raman spectra indicated the presence of FeOOH, OH, HOH and fatty acids on the wear tracks of the proposed blend.

A number of creep tests were performed on a Ni-base superalloy DS CM 247 specimens at three temperatures viz. 850, 950 and 1050 °C and over a range of stresses. Three-dimensional (3D) maps of creep curves (creep strain–time-stress) were generated by using the ‘in-house developed code’based on θ-projection methodology. These 3D maps with overlaid experimental creep curves show a very good agreement with the predicted creep behaviour at different stresses and at a given temperature. Also, the ability of the method in deducing the stress relaxation curves at different strains derived from 3D maps of creep curves has been demonstrated. Further, the relative performance of the LMP approach and the θ-projection approach in prediction of time to rupture has been reported.

The aim of this investigation is to enhance the thermal and viscoelastic performance of flax strengthened epoxy with graphene nanoplatelets (GNP). GNP was incorporated at various weight percentages with epoxy resin. Scanning Electron Microscopy (SEM) studies revealed a uniform and well-dispersed GNP with a few agglomerations and voids. Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), and Dynamic Mechanical Analysis (DMA) were used to evaluate the thermal degradation and viscoelastic properties. The flax strengthened epoxy with 0.1 wt-% GNP witnessed a 17% increase in initial degradation temperature and a 48% increase in char residue. Observations from the DSC revealed that GNP functioned as a thermal barrier due to its strong influence on the glass transition and crystallisation temperature of composites. The DMA findings indicated that the storage and loss modulus of GNP/flax strengthened epoxy increased by 18% and 25%, respectively.

ABSTRACTThe aim of this investigation is to enhance the thermal and viscoelastic performance of flax strengthened epoxy with graphene nanoplatelets (GNP). GNP was incorporated at various weight percentages with epoxy resin. Scanning Electron Microscopy (SEM) studies revealed a uniform and well-dispersed GNP with a few agglomerations and voids. Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), and Dynamic Mechanical Analysis (DMA) were used to evaluate the thermal degradation and viscoelastic properties. The flax strengthened epoxy with 0.1 wt-% GNP witnessed a 17% increase in initial degradation temperature and a 48% increase in char residue. Observations from the DSC revealed that GNP functioned as a thermal barrier due to its strong influence on the glass transition and crystallisation temperature of composites. The DMA findings indicated that the storage and loss modulus of GNP/flax strengthened epoxy increased by 18% and 25%, respectively.

The current work aims to develop a biodegradable lubricant by adding different volume percentages of cashew nut shell liquid (CNSL) in neat castor oil (NCO) and investigating its possibility as replacement to non-biodegradable mineral oil (commercial mineral oil) in industrial applications. The blend exhibiting better tribological properties was additived with different weight percentages of reduced graphene oxide (r-GO) nano-platelets and further tribological tests were performed. The performance of 40%CNSL+NCO was 45.8% better than commercial mineral oil, and with the addition of the 0.5% r-GO in the blend, the performance was improved by 61.7% than the commercial mineral oil. Finally, the novel biodegradable mixture blended with nanoparticles was employed as a lubricant in a gearbox, proving the superiority of the biodegradable lubricant over the commercial mineral oil.

Modified 9 Cr–1 Mo is an ideal candidate preferred for high temperature applications in power plants. In this study, three P91 welds of 12 mm thickness are produced using Gas Tungsten Arc Welding (GTAW), Cold Metal Transfer (CMT) and Pulsed-CMT (P-CMT) processes. The impact toughness is evaluated in the as-welded as well as in the PWHT (760 °C-2 h) condition. It is found that P-CMT process resulted in the highest toughness in both the conditions. The heat input was maximum in the case of GTAW (800 J/mm) welds and minimum in CMT (330 J/mm). Even though P-CMT (380 J/mm) has heat input slightly above CMT, the former is compensated by higher welding speeds. Electron microscopy analysis revealed the presence of fine M23C6and MX precipitates. Among the welds, P-CMT had minimal amount of the precipitates whereas GTAW welds had the maximum. The dimple morphology observed in the ruptured surface significantly varied and P-CMT process had finer dimples indicating finer weld microstructures and enhanced mechanical properties.

Attempts have been made to introduce a new class of algebras Kn, which we define as generalized knot symmetric algebras. The reason for this name is that these new algebras have a basis consisting of knot diagrams. The multiplication of two of these graphs turns Kninto an associative. The semi-simplicity of these algebras over Knhas been proved by making use of conditional exception and proving the non-degeneracy of the trace.

Synthetic plastics pose a major environmental threat and it is necessary to produce an alternative biopolymer. In the current study, the production of polyhydroxybutyrate (PHB) by Mesobacillus aurentiuswas enhanced using Response surface methodology (Box–Behnken design). This study explores the potential of aquabiofloc systems as a source of polyhydroxyalkanoates (PHB)-producing bacteria. The optimized medium conditions, as determined by Response Surface Methodology (RSM), included 18.68 g of sucrose, 4.0 g of yeast, an incubation period of 69.57 hours, and a pH of 7.1. The ANOVA results revealed that the model developed for predicting PHA yield was highly significant (p < 0.05). The predicted PHA yield was 63.12%, while the experimental yield was 65.35%. The maximum production of PHA was obtained with sucrose and yeast as carbon and nitrogen sources. The extracted polymer was characterized using UV, FTIR, 1H NMR, and SEM-EDAX analysis confirming the polymer to be PHB. The thermal stability of the produced PHA showed degradation temperatures ranging from 310°C. The mechanical properties of the extracted PHA were also assessed, demonstrating tensile strength and viscosity of 22.4 MPa and 1.23 MPa. respectively. The antimicrobial activity of the produced PHA was evaluated, demonstrating significant inhibitory effects against both Gram-positive and Gram-negative bacterial strains as well as fungal strains. The Cytotoxicity assessment in HepG2 cells indicated that PHB is less toxic in nature. The findings highlight the promising role of marine bacteria, Mesobacillus aurentius, in the development of environmentally friendly biopolymers. This bacterium represents a novel candidate for PHB production, offering a potential alternative to petroleum-based plastics.

Modified 9Cr-1Mo is a ferritic-martensitic steel widely used in steam generators of fast breeder reactors in the nuclear industry due to their enhanced creep resistance. In the present investigation, P91 steel was welded without preheat using three different heat inputs by pulsed short-circuit metal inert gas welding process using a ER90S-B9 wire electrode for the first time. The microstructural developments were characterized by using optical and electron microscopy, while the residual stresses were measured by X-ray diffraction using the sin2ψ method. The grain size variation in the fusion zone/heat-affected zone was effectively studied using electron backscattered diffraction to bring out the changes quantitatively. The weld zone had a consistent texture, while the heat-affected zone was random. The grain size tends to increase with the increase in heat input which leads to reduced joint strength. It is evident that at highest heat input, the weld microstructure shows substantial precipitation of M23C6-type carbides. The residual stresses were near compressive in the weld-HAZ, while maximum tensile stresses were found for the highest heat input.

The current work elucidates the tribological behavior of thermally sprayed AlCoCrFeNiTi high entropy alloy coatings under various temperatures of 200 °C, 400 °C, and 600 °C. Typically, most metallic alloys demonstrate softening and an increased wear-rate when exposed to extreme temperatures under loaded weight. The atmospheric plasma sprayed high entropy alloy coating exhibited minimal wear mass loss at high temperatures. The data analysis reveals the development of a tribolayer that facilitates a reduced mass loss of 15.34% in the alloy at 600 °C. The examination of the wear scars under field emission scanning electron microscopy analysis reveals the presence of an adhesive layer, wear debris, craters, and scratches. The existence of different types of oxides on the abraded surfaces was confirmed by the results of X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The results support the effectiveness of AlCoCrFeNiTi alloy coatings in enhancing wear resistance under extreme conditions.

The mechanical properties of hardened AISI 52100 bearing steel such as flexural strength, microhardness and Young’s modulus are considerably influenced by the austenite content retained in the microstructure. A microstructure-sensitive finite element simulation approach is presented which considers the effect of retained austenite to estimate the mechanical properties. The austenite grain size is derived as a function of austenitising temperature and holding time using a modified Arrhenius type equation. The simulation strategy involves division of the two-dimensional domain using triangular elements such that a group of six neighbouring triangular elements represented a hexagonal grain of calculated size. Material inhomogeneity is introduced by enforcing austenite properties to a fraction of the elements equal to the volume percent of retained austenite in the steel. The predictions from the simulation approach for 8% and 20% retained austenite volume fractions matched well with earlier experimental results.

Nickel based single crystal super alloys are widely used as aircraft engine blades and are still in the process of development to improve the high temperature capabilities. The typical microstructure of these alloys consists of gamma phase as the matrix strengthened by the gamma prime precipitates. In recent times, addition of refractory metals like Re are tried to improve the creep strength. The first generation of these alloys does not contain any such additions. The second generation of the alloys contains around 3–6% Re. These additions and modifications have been found to improve the temperature capability of the CMSX, though there are limitations in their addition. In this article the microstructural developments, the metallurgical and high temperature behavior of the first and second generation NiSX family subjected to stress annealing, are discussed from engineering point of view. Based on experimental findings reported in literature, deformation maps illustrating the different mechanisms over a wide range of temperature and stress levels for the first and second generation alloys are presented.

Lap joints of aluminum alloy A6061-T6 and AZ31B magnesium alloy were produced by cold metal transfer welding with Al-5 %Si filler metal. Four heat inputs designated as A (175 J/mm), B (185 J/mm), C (195 J/mm) and D (205 J/mm) were used during the process and the joints made were subjected to analysis of microstructure, mechanical properties and corrosion behaviour. The thickness of the fusion line (diffusion layer) varied from 3 to 12 µm depending on the heat input. It was also found that the joints made using the heat input of 205 J/mm exhibited highest tensile strength of 360 N/mm, least tensile stress in the weld and better pitting corrosion resistance. Electron microscopy study of the weld revealed the presence of β′-Mg2Si, Al6Mn and β-Al3Mg2particles. X-ray diffraction study in the weld revealed the formation of γ-Al12Mg17and β-Al3Mg2phase with Mg2Si strengthening precipitates. Tensile failure occurred at the fusion line near magnesium.

Lap joints of aluminium alloy A6061-T6 and galvanised steel DP800 were produced by an advanced gas metal arc welding process with AlSi3Mn filler. Four heat inputs designated as A (110 J mm−1), B (120 J mm−1), C (130 J mm−1) and D (140 J mm−1) were used during the process and the joints made were subjected to analysis of the microstructures, mechanical properties, residual stresses and corrosion behaviour. Microstructural analysis shows the formation and variation of Fe–Al intermetallic (IM) layer. It is also found that the joints made using the heat input of 120 J mm−1exhibited highest tensile strength and better corrosion resistance. Electron microscopy and X-ray diffraction analysis revealed the presence of different IM phases with other strengthening precipitates.

Lap joints of aluminium alloy A6061-T6 and galvanised steel DP800 were produced by an advanced gas metal arc welding process with AlSi3Mn filler. Four heat inputs designated as A (110 J mm-1), B (120 J mm-1), C (130 J mm-1) and D (140 J mm-1) were used during the process and the joints made were subjected to analysis of the microstructures, mechanical properties, residual stresses and corrosion behaviour. Microstructural analysis shows the formation and variation of Fe–Al intermetallic (IM) layer. It is also found that the joints made using the heat input of 120 J mm-1exhibited highest tensile strength and better corrosion resistance. Electron microscopy and X-ray diffraction analysis revealed the presence of different IM phases with other strengthening precipitates.

The microsegregation in alloy 718 fusion zone during gas tungsten arc welding affected the aging response and the mechanical properties. The average weld cooling rate was enhanced in gas tungsten arc (GTA) welding process by employing liquid nitrogen during the process. The combination of in-process and external cooling methods reduced the microsegregation of Nb in alloy 718 fusion zone. Detailed characterization of the weld microstructures in the as-welded and the direct aged conditions was conducted. The dendritic structure have been refined to a level of 10-20 μm dendrite arm spacing and Laves particle sizes ranging from 0.04 to 1.43 μm due to the enhanced weld cooling rate. Similarly, the average Laves volume fraction was reduced from 45 to 0.1 % when compared to the conventionally cooled GTA welding process. The microsegregation was quantified through the computed solidification time through the DSC analysis and the volume fraction of the eutectic phases. It was found that the solidification time was reduced significantly from 2.499 s to as low as 0.36 s with the liquid nitrogen-cooled GTA welding process. The microhardness survey revealed an improved aging response of the fusion zone. Graphical abstractCryogenically cooled alloy 718 weldments

This paper reports the procedure to join aluminium A6061-T6 to AZ31B magnesium alloy using Al-5%Si filler by cold metal transfer and pulsed-cold metal transfer processes. The effect of process parameters on the microstructure of weld, nugget/magnesium interface and tensile strength of the joints are analysed. Microstructural analysis shows that the diffusion layer thickness increases with increase in the welding current. The diffusion layer thickness was found to vary depending on the process. Pulsed process resulted in high joint strength compared to conventional method. X-ray diffraction study revealed the formation of different phases in the weld. The welding current, welding speed and the wire-feed rate had significant effect on the joint strength. Failure at the weld/Mg interface was observed.

AbstractThe micro-segregation of niobium and Laves phase formation during Gas Tungsten Arc (GTA) welding of alloy 718 were studied by employing different cooling techniques which resulted in weld cooling rates ranging from 43.2 °C/s to 508.7 °C/s. The weld cooling rates were achieved by the combinations of modified pulse wave form, argon and helium shielding gases, copper heat sink and liquid nitrogen cooling. A combination of compound current pulse (CCP) waveform with helium shielding and liquid nitrogen cooling resulted in lesser niobium segregation and discontinuous, finer Laves particles in the interdendritic regions compared to that of the conventional constant current GTA weld metal. This process yielded better ageing response and improved high temperature mechanical properties of the weldments.

This paper reports the procedure to join aluminium A6061-T6 to AZ31B magnesium alloy using Al-5%Si filler by cold metal transfer and pulsed-cold metal transfer processes. The effect of process parameters on the microstructure of weld, nugget/magnesium interface and tensile strength of the joints are analysed. Microstructural analysis shows that the diffusion layer thickness increases with increase in the welding current. The diffusion layer thickness was found to vary depending on the process. Pulsed process resulted in high joint strength compared to conventional method. X-ray diffraction study revealed the formation of different phases in the weld. The welding current, welding speed and the wire-feed rate had significant effect on the joint strength. Failure at the weld/Mg interface was observed.

In this work, an attempt was made to join A6061-T6 aluminium alloy to Dual Phase 800 steel using AlSiMn filler by cold metal transfer (CMT) processes. The effect of process parameters on the microstructures and tensile strength of the joints are analysed. Microstructural analysis revealed the formation of the Fe–Al intermetallic (IM) layer. The IM layer thickness was found to be very small. Electron microscopy analysis revealed the presence of long plate shape (Al5FeSi) and fragmented particles in the IM layer. At the interface, ⊖-FeAl3and η-Fe2Al5phases were formed. Pulsed process resulted in better joint strength when compared to conventional CMT method. X-ray diffraction study revealed the formation of the Fe3Al and η-Fe2Al5phases in the weld. The welding currents and arc length correction factor had significant effects on the joint strength. Tensile failure occurred at the heat affected zone.

In this work, an attempt was made to join A6061-T6 aluminium alloy to Dual Phase 800 steel using AlSiMn filler by cold metal transfer (CMT) processes. The effect of process parameters on the microstructures and tensile strength of the joints are analysed. Microstructural analysis revealed the formation of the Fe–Al intermetallic (IM) layer. The IM layer thickness was found to be very small. Electron microscopy analysis revealed the presence of long plate shape (Al5FeSi) and fragmented particles in the IM layer. At the interface, ⊖-FeAl3and η-Fe2Al5phases were formed. Pulsed process resulted in better joint strength when compared to conventional CMT method. X-ray diffraction study revealed the formation of the Fe3Al and η-Fe2Al5phases in the weld. The welding currents and arc length correction factor had significant effects on the joint strength. Tensile failure occurred at the heat affected zone.

The evolution of creep damage in a directionally solidified DS CM247 alloy during creep at 950 °C/250 MPa has been evaluated using alternate current potential drop (ACPD) technique in which a constant alternating current was passed through the specimen and corresponding potential drop was measured. Creep tests were interrupted at different strain levels in order to examine the microstructural degradation of the alloy during creep. The creep curve of the alloy exhibited limited primary and secondary creep regimes, but extended tertiary creep regime. Microstructural examination revealed the progressive directional coarsening of γ′ precipitates i.e., rafting and widening of γ matrix channel with accumulation of creep strain. The specimen exhibited a considerable amount of creep strain prior to fracture. Further, creep cavitation was observed only close to the fractured end of the specimens. Various factors responsible for the extended tertiary creep regime of the alloy are discussed. The potential of ACPD technique to be used as a NDE tool to monitor in service/online creep damage evaluation, has been established/demonstrated.

In this study, an attempt has been made to investigate the mechanistic pathway for the aerobic oxidation of alcohols over nitrogen-doped graphene using density functional theory methods employing a suitable model for graphene. The formation of activated oxygen species (AOS), upon oxidation, by dioxygen has been investigated with the aid of various possible nitrogen-doped models. The detailed reaction mechanism for the oxidation of benzyl alcohol and ethanol by the three AOS obtained in the present study has been unraveled. Results indicate that the ketonic oxygen species oxidizes aromatic alcohol with minimum activation energy of ∼26.5 kcal/mol. On the contrary, the activation energy for the oxidation of alkyl alcohol by AOS present at the center is the lowest, which is also similar to that of ketonic oxygen species. On the basis of the results, a generalized reaction mechanism has been arrived for alcohol oxidation by nitrogen-doped graphene. Findings reveal the valuable lead information for the optimal control over selective oxidation of alcohol by N-doped graphene based on dopant concentration and temperature

This work is carried out to study the copper metal foam as porous wick structure in a flat heat pipe. The method of fabricating copper foam has been described. The characterization of copper foam has been carried out by scanning electron microscope (SEM) and X-Ray Diffractogram (XRD) analysis. Effect of liquid velocity on pressure drop and maximum capillary heat transport of fabricated copper foam has been presented.

Hydropower generation from the Himalayan rivers in India face challenge in the form of sand-laden water. These sediments contain abrasive particles which can erode the turbine blades and reduce turbine life. This calls for the development of newer materials for turbine blade. To address this issue in the present investigation, 16Cr–5Ni martensitic stainless steel has been selected. Silt erosive wear tests were done at various test conditions determined by Taguchi design of experiments of impact velocity, impingement angle, erodent size and silt concentration. Analysis of variance studies of erosion rate and roughness indicated that impact velocity is the single most important parameter and interaction of impact velocity and impingement angle are proved to be significant. The optimized artificial neural networks are finally used to estimate the erosion rate for different combinations of the test conditions in conjunction with optimization techniques like Genetic algorithm were employed to arrive at the worst possible scenario (impact velocity 20 m/s, impingement angle 30°, erodent size 245 µm and silt concentration 60 kg/m3).

Abstract

An efficient protocol for in vitro organogenesis was achieved from callus-derived immature and mature petiole explants of West Indian gherkin (Cucumis anguriaL.). Calluses were induced from immature petiole explants excised on 7-day-old in vitro seedlings and mature petiole explants of 40-day-old in vivo plants. The maximum frequency of immature petiole explants (98.0 %) and mature petiole (91.5 %) produced green, compact organogenic callus in Murashige and Skoog (MS) medium with Gamborg (B5) vitamins containing 30 g l−1sucrose, 8.0 g l−1agar and 4.0 μM naphthalene acetic acid (NAA) with 2.0 μM benzyl amino purine (BAP) after two successive subculture at 11 days interval. Adventitious shoots were produced from the organogenic callus when it was transferred to MSB5medium supplemented with 3.0 μM TDZ, 1.0 μM NAA and 0.05 mM L-glutamine with shoot induction frequency of immature petiole 45 shoots and mature petiole 40 shoots per explant. The shoots were excised from callus and elongated in MSB5medium fortified with 3.0 μM gibberellic acid (GA3). Then elongated shoots were rooted in half strength MSB5medium supplemented with 3.0 μM indole 3-butyric acid (IBA). Histological analyses of the regeneration process confirmed the indirect organogenesis pattern. Plantlets with well-developed shoot and root systems were successfully acclimatized (95 %) in winter season and exhibited normal morphology and growth characteristics. The survival percentage differed with seasonal variations.

•Introduction and development of metal-cored arc welding process is of recent origin.•Influence of process variables, shielding gas composition, microinclusion content on toughness of welds was studied.•Possible use of pure argon as shielding gas in metal-cored arc welding process.

The microstructure, hardness and wear properties of atmospheric plasma spray coating of TiO2and Al2O3–13TiO2with incremental hydrogen fractions (11·1–23·8%) in primary gas have been investigated in this work. TiO2coating shows a fine bead-like surface structure, while Al2O3–13TiO2predominantly exhibits a splat-like morphology. The microstructure shows a slight refinement in the structure for the highest hydrogen content possibly due to the higher specific enthalpy of the plasma plume. Both coatings show the highest hardness for samples coated with the highest hydrogen content possibly due to the refined structure. The roughness shows a mild decreasing trend for TiO2coating, while the reverse trend is observed for Al2O3–13TiO2coating. The wear loss and friction coefficient show a flat trend (0·4–0·6) for all the hydrogen contents. The worn tracks show a compacted mixture of ceramic, graphite and metallic particles.

Abstract: The influence of incremental sliding speeds and normal loads on friction, wear and interface temperature have been investigated on a series of hypereutectic alloyed gray cast irons. Mass loss and friction coefficient values show inverse trend with sliding speeds. The interfacial temperature increases with incremental speeds and loads while the friction coefficient decrease with the same. The alloys with higher volume of graphite show slightly lower interfacial temperature due to higher thermal transport capacity. The conjoint interaction of asperities and debris possibly predominates at lower speeds and higher mass loss predominates at higher sliding speeds.

The detrimental laves formation in fusion zone during welding of Inconel 718 is controlled with compound current pulsing technique along with helium shielding gas. Also solid solution filler wire is used to minimize the niobium segregation. Welds were produced in 2mm thick sheets by GTA welding process and subjected to the characterization techniques. The results show, refined fusion zone microstructure, reduced amount of laves phase, minimum niobium segregation and softer fusion zone in the as welded condition.

Abstract: In the present study, Ni-based Colmonoy 5 was deposited on Type 316L (N) stainless steel. The deposit was aged at 580 and 650°C for 5,000 h to study the influence of aging on sliding wear resistance. The aged deposits show more wear loss due to reduced hardness. However, the reduced hardness after aging was not reflected on wear test at 550°C irrespective of sliding distance. This is due to stability of microstructure as well as the generation of oxide layer during high temperature tests. Subsequently, an empirical relation was developed based on outcome experimental data using full factorial design of experiments in terms of hardness (H), test temperature (T) and sliding distance (D). Based on the empirical relation, it was found that the test temperatures (T) play a predominant role on wear loss than hardness (H) and sliding distance (D). Further, the developed relationships were validated using analysis of variance (ANOVA).

The nickel based Colmonoy 5 alloy powder was deposited on 316 L (N) austenitic stainless steel substrate. In order to examine the effects of aging treatment on the wear behavior of a nickel based hardfacing alloy, the as-deposited coating was aged at 580°C for 5000h in ambient atmosphere. Coating microstructures were characterised by scanning and transmission electron microscopy. Sliding tests were conducted under self mated condition at room temperature and 550°C using a pin-on disc type apparatus. The wear loss of the aged coating was found to be higher than that of the as deposited coating. The coarse grained structure with carbide (Cr23C6) precipitation in the aged coating would account for the higher sliding wear loss. However, the aged coating, with reduced hardness exhibits similar wear behavior of as deposited coating during sliding at 550°C.

Oil jet peening makes use of high-pressure oil jet to impart compressive residual stresses on the surface of metallic materials in order to improve the surface properties. This article reports the dry sliding wear characteristics of oil jet peened aluminium alloy, AA6063-T6. The presence of compressive residual stress and high hardness improves the wear resistance of oil jet peened surfaces. Changes in the hardness, surface morphology, and residual stress distribution due to peening affect the tribological behaviour. The initial and steady-state coefficient of friction are less in the treated samples compared to untreated samples. The scanning electron microscope images of the worn surfaces reveal the dominant adhesive and mild abrasive form of wear.

Abstract: Austempering of a ferrite-pearlitic grade of ductile iron was carried out to assess the potential use of the material for crank shaft application reported. A commercial material was austempered at 340°C to realize the properties. The austempered ductile iron gave good strength although the ductility values were lower. The material developed had complete ausferritric structure free of pearlite. The various phase constitution and phase transformation associated with the treatment and during mechanical deformation was examined. Using XRD analysis the volume fraction of the austenite in the matrix was estimated. The various aspects of processing a commercial cast iron during ausetmpering, the phase transformation, microstructural evolution have been examined along with the property of the material. The mechanical behaviour of the material and the scope for further improvement is discussed.

Abstract: This study reports the synthesis of Ferro boron coatings deposited over AISI 304L austenitic stainless steel substrate using D-Gun (Detonation gun) technique. The microstructure, adhesion and wear properties of the coating were investigated using X-ray diffraction, optical microscopy, scanning electron microscopy, micro-hardness measurements and pin-on-disc wear tests. Hardness of the coated surface was found to increase from 350 HV to about 1600 HV on laser modification. The effect of laser treatment on the microstructural modification of coating is also described.

Abstract: Fretting is a form of adhesive wear normally occurring at the contact points gradually leading to premature failure of load bearing medical implants made of titanium alloys. The aim of this work is to characterize the fretting fatigue damage features of PVD TiN coated, plasma nitrided, ion implanted, laser nitrided and thermally oxidized Ti-6Al-4V and Ti-6Al-7Nb contact pairs. The surface layers were characterized. The damage progression during fretting process is apparently explained with tangential force coefficient curves. Plasma nitrided pairs showed highest fretting fatigue life compared to others. PVD TiN coated pairs have experienced early failures due to third body mode of contact interaction with irregular tangential force coefficient pattern. Ion implanted layers showed similar damage as unmodified alloys. Laser nitrided and thermally oxidized pairs experienced early failures due to brittle and irregular modified layers.

Abstract: 1Cr1Mo¼V low alloy forging and casing steels exhibited considerable secondary and tertiary stages in the creep tests conducted in the temperature range between 773 and 873 K. The primary stage, though present, was rather negligible at higher temperature ranges. Casting steel showed wedge type cavities which grew as cracks along the grain boundaries. In the case of forging steel, the voids were elliptical and flat which developed during the tertiary stage of creep deformation. Tertiary creep deformation and creep ductility of the two steels investigated have been analysed based on the type of voids developed during the tertiary stage.

Cobalt based alloy with the addition of 5 and 10 wt% boron carbide have been deposited by PTA process on stainless substrates effectively. The dry sliding wear performances of the coated alloys have been studied at room as well as at elevated temperatures. Addition of boron carbide to satellite 6 resulted in refinement of grains and formation of complex carbides and borides, which has lead to increase in hardness and wear resistance of the hardfaced layers. Superior wear resistance has been found to be at the composition of Stellite 6 with 5 wt% addition of boron carbide.

The performance of lithium-ion batteries depends on the morphology and distribution of components in the electrode. LiNi1−x−yMnxCoyO2(NMC) with nano-micro hierarchical structure is a commercially important cathode material for electric vehicle application. The commonly used slurry preparation method is to dry-mix the active material with a conductive additive and then disperse it in the binder solution. The energy imparted during premixing, while helping in controlling the distribution of CB to establish conducting network, can deteriorate NMC by mechanically dismantling the aggregate structure. Herein, a comprehensive effort is put forward to understand dry-mixing by high-energy ball-milling. It is found that mixing-intensity influences the establishment of both long-range and short-range electronic conductive pathways.The sample mixed with very low intensity and high intensity exhibited a capacity of 68 mAh.g−1and 20 mAh.g−1respectively, while the sample with optimum mixing exhibited 100 mAh.g−1at 5C. This study highlights the guidelines for preparing electrodes for high-energy and high-power applications. At low C-rates, the capacity depends on the integrity of the microstructure of NMC, while at high C-rate optimum short and long-range electronic conductivity is the deciding factor.

In this study, a pure magnesium material reinforced with 0.5, 1, 1.5, and 2 w% of CaO was prepared through disintegrated melt deposition technique (DMD process). Nanocomposites were investigated for their sliding wear behavior in dry condition at room temperature. The amount of CaO, load, sliding distance, and sliding velocity were selected as input design parameters at their five level in central composite design using minitab 18.1 statistical software. The influence of design parameters on wear loss is reported through the response surface methodology (RSM). Analysis of variance (ANOVA) was used to confirm the soundness of the developed regression equation. The results indicate the contribution of linear, quadratic, and interaction terms of design parameters on response. Three-dimensional response surface and two-dimensional contour plots indicate the interaction effect. The result shows that an increase in the sliding velocity contributes to a decrease in the wear loss of the composites because of the emergence of protective oxidative layer at the surfaces of the pins, which is confirmed through field emission scanning electron microscope and energy dispersive X-ray analysis analyses of the pin surfaces. Wear loss of the material decreased as the amount of CaO increased. The ANOVA analysis concluded that the sliding distance and load contribute significantly to wear loss of the composites, and their percentage of contribution is 64.02% and 3.69%.

Abstract: The present work describes an investigation of the effect of 3 different parameters of laser surface alloying—i.e., laser scanning speed (LSS), nozzle stand-off distance (NSOD) and laser beam scan-off distance (LBSOD) on coating height, depth and width. Nickel-based Colmonoy 88 alloy powder has been deposited on 13Cr-4Ni steel by single-step process of laser surface alloying. Laser power and powder feed rate were maintained at 3kW and 25 g/min, respectively. L8 orthogonal array has been designed to study these 3 parameters at 2 levels each. The results of single pass with extent of dilution, surface hardness and microstructures produced by different conditions are presented and discussed. For a specified NSOD and LBSOD, there was a decrease in coating height and depth with increase in LSS. Coating height and depth were not affected much by increase in NSOD. From the present investigation, optimized parameters were identified for enhanced hardness, minimum dilution and desired coating height and coating depth.