Search results

The purpose of this study is to evaluate the potentials of nano-additives in enhancement of oxidation and thermal stability of biolubricants thereby, improving the resistance of dispersed nanolubricants to thermal degradation under elevated temperature.

This study evaluates the oxidation stability and tribological performance of nano-enhanced biolubricants. Graphene and maghemite nanoparticles at 0.1% volume concentration were dispersed into coconut oil. Oxidation stability was analysed using a thermal analyser to understand the effect of nano-additives on thermal degradation of lubricants under increasing temperature. In addition, tribological performance and viscosity of the tested lubricants were evaluated using a four-ball friction tester and viscometer according to American Society for Testing and Materials standards.

The results reveal that the oxidation stability of biolubricants dispersed with nano-additives improves due to delayed thermal degradation. The nano-enhanced biolubricants’ oxidation onset temperature was delayed by 18.75 °C and 37.5 °C, respectively, for maghemite (MGCO) and graphene (XGCO) nanolubricants. This improvement imparts the performance viscosity and tribological performance positively. For graphene-enhanced nanolubricant, 10.4% and 5.6% were reduced, respectively, in coefficient of friction (COF)and wear scar diameter (WSD), whereas 3.43% and 4.3% reduction in COF and WSD, respectively, for maghemite-enhanced nanolubricant compared with coconut oil. The viscosity index of nanolubricants was augmented by 7.36% and 13.85%, respectively, for maghemite and graphene nanolubricants.

The excellent performance of nanolubricants makes them suitable candidate as sustainable lubricants for machining with regard to environmental benefits and energy saving.

The effect of graphene and maghemite nanoparticles on the oxidation stability and tribological performance of biolubricants has been investigated. It is an original work and yet to be published elsewhere.

This paper aims to report the tribological behavior of Ag nanoparticles/reduced graphene oxide nanocomposites (Ag/RGO NCs) and Ag nanoparticles (Ag NPs) as a green additive in oil with different concentration and under different friction conditions.

The Ag/RGO NCs and Ag NPs were both synthesized in a chemical reduction method. The diameter of silver nanoparticles implanted between RGO sheets was about 25 nm and that of silver sol was 70 nm. The morphology and structure of Ag/RGO NC were characterized by TEM, XRD and FTIR. The tribological properties of Ag/RGO NCs and Ag NPs as lubricant oil additive were evaluated by measuring the friction coefficients and wear of the surface in different condition which were tested on UMT-II.

The results indicated that both the additives improved the friction-reduced and anti-wear properties of paraffin oil, and Ag/RGO NCs has better tribological performance than Ag NPs. The excellent tribological properties were attributed to the special structure of Ag/RGO NC and the formation of tribofilm reducing the friction and wear on the shearing surfaces.

It is relatively difficult to observe the morphology of the lubricant film formed on the friction surface and to analyze the chemical composition at different depths of the lubricant film.

It is the first time for Ag/RGO NCs to be applied to improve the friction-reduced and anti-wear properties of lubricant oil as additive.

The purpose of this article is to study the steady laminar magnetohydrodynamics mixed convection stagnation-point flow of an alumina-graphene/water hybrid nanofluid with spherical nanoparticles over a vertical permeable plate with focus on dual similarity solutions.

The single-phase hybrid nanofluid modeling is based on nanoparticles and base fluid masses instead of volume fraction of first and second nanoparticles as inputs. After substituting pertinent similarity variables into the basic partial differential equations governing on the problem, the authors obtain a complicated system of nondimensional ordinary differential equations, which has non-unique solution in a certain range of the buoyancy parameter. It is worth mentioning that, the stability analysis of the solutions is also presented and it is shown that always the first solutions are stable and physically realizable.

It is proved that the magnetic parameter and the wall permeability parameter widen the range of the buoyancy parameter for which the solution exists; however, the opposite trend is valid for second nanoparticle mass. Besides, mass suction at the surface of the plate as well as magnetic parameter leads to reduce both hydrodynamic and thermal boundary layer thicknesses. Moreover, the assisting flow regime always has higher values of similarity skin friction and Nusselt number relative to opposing flow regime.

A novel mass-based model of the hybridity in nanofluids has been used to study the foregoing problem with focus on dual similarity solutions. The results of this paper are completely original and, to the best of the authors’ knowledge, the numerical results of the present paper were never published by any researcher.

This paper aims to provide details of recently reported work on the use of nanomaterials in sensors for physical variables.

Following a short introduction, this paper first discusses research involving the use of a range of nanomaterials for strain sensing. It then considers the applications of these materials to sensors for pressure, force, touch and allied variables. It concludes with a brief discussion and 33 references.

This paper shows that nanomaterials such as carbon nanotubes, graphene, metallic nanoparticles and nanowires are being studied extensively in the physical-sensing context. All manner of sensors have been developed, based on a diversity of principles and technologies, and many offer excellent performance and unique capabilities, making them particularly well-suited to emerging applications such as wearable sensing devices.

This paper provides a detailed and timely review of the rapidly growing body of research into the use of nanomaterials for sensing physical quantities.

Ti6Al4V is a commonly used titanium alloy with several applications in aerospace industry due to its excellent strength to weight ratio. But due to low thermal conductivity, it is categorized as “difficult to machine.” Though machinability can be improved with cutting fluids, it is not preferred due to associated problems. This study aims at eliminating the use of cutting fluid and finding an alternate solution to dry machining of Ti6Al4V. AlTiN coated tools provide good heat and oxidation resistance but have low lubricity. In the present work, graphene, which is known for lubricating properties, is added to the tools using five different methods (tool condition) to form graphene self-lubricated cutting tools.

Graphene-based self-lubricating tools are prepared by using five methods: dip coating (10 dips and 30 dips); drop casting; and filling of micro/macroholes. Performance of these tools is evaluated in terms of cutting forces, surface roughness and tool wear by machining Ti6Al4V and comparing with conventional coated cutting tool.

Self-lubricating tool with micro holes filled with graphene outperformed other tools and showed maximum decrease of 33.42% in resultant cutting forces, 35% in surface roughness (Ra) and 30% in flank wear compared to conventional cutting tool.

Analysis of variance for all forces show that tool condition and machining time have significant influence on all components of cutting forces and resultant cutting forces.

This study aims to the preparation and tribological characteristics of graphene/triangular copper nanoplate composites (abbreviated as GN/Cu nanoplates) as grease additive and clarifies the growth mechanism and tribological mechanism of GN/Cu nanoplates by different analysis methods. In this paper, it is expected to alleviate the problems of easy aggregation and poor dispersion stability of graphene in lubricants and provide theoretical support for the application of graphene and its composites in the tribology field.

In this study, the GN/Cu nanoplates have been successfully prepared by the electrostatic self-assembly method. The structural characteristics of GN/Cu nanoplates were analyzed via transmission electron microscopy and X-ray diffraction. Then the tribological properties of GN/Cu nanoplates were investigated under different loads with SRV-IV [Schwingung, Reibung, Verschleiß (German); oscillating, friction, wear (English translation)] tribotester. White-light interferometry was applied to quantify the wear loss of the disk. The element chemical state on worn surfaces was analyzed by an X-ray photoelectron spectroscope to clarify the tribological mechanism of graphene composites.

The electrostatic force between the negative charge of graphene and the positive charge of triangular copper nanoplates promotes the self-assembly of GN/Cu nanoplates. With the addition of GN/Cu nanoplates, the wear loss and average friction coefficient under the load of 200 N have been decreased by 72.6% and 18.3%, respectively. It is concluded that the combined action of graphene deposition film and the copper melting film formed on the worn surface could effectively improve the antiwear ability and friction reduction performance of the grease.

This manuscript fulfills a new approach for the preparation of GN/Cu nanoplates. At the same time, its tribological properties and mechanism as a lubricating additive were studied which provide theoretical support for the application of graphene and its composites in the tribology field.

The purpose of this paper is to contribute an analytical and numerical study of a new type of nanoshell particles operating in the visible regime.

The structure consists of a core/shell particle, arranged in a planar array configuration, with a polymethyl methacrylate (PMMA)-graphene core and gold thin shell.

By exploiting the proposed analytical model the design of a metamaterial-based sensor, operating in the optical frequency range, for the detection of tissue diseases is shown.

Full-wave simulations confirm the capability of the proposed sensor to identify different compounds by refractive index measurement.

This study aims to present the experimental and computational performance analysis in compact plate heat exchanger (PHE) using graphene oxide nanofluids at different concentrations and flow rate.

Field emission scanning electron microscope and X-ray diffraction were used to characterize graphene oxide nanoparticles. The nanofluid samples were prepared by varying volume concentration. Zeta potential test was done to check stability of samples. The thermophysical properties of samples have been experimentally measured. The experimental setup of PHE with 60° chevron angle has also been developed. The numerical analysis is done using computational fluid dynamics (CFD) model having similar geometry as of the actual plate. Distilled water at fixed temperature and flow rate is used in hot side tank. Nanofluid at fixed temperature with varying concentration and flow rate is used in cold side tank as coolant.

The numerical and experimental results were compared and found that both results were in good agreement. The results showed ∼13% improvement in thermal conductivity, ∼14% heat transfer rate (HTR), ∼9% in effectiveness and ∼10% in overall heat transfer coefficient at cost of pressure drop and pumping power using nanofluid. Exergy loss also decreased using nanofluid at optimum concentration of 1 Vol.%.

The CFD model can be significant to analyze temperature, pressure and flow distribution in heat exchanger which is impossible otherwise. This study gives ease to predict PHE performance with high accuracy without performing the experiment.

In this study, an attempt has been made to collect the research that has been done on the construction and design of the H₂O₂ sensor. So far, many efforts have been made to quickly and sensitively determine H₂O₂ concentration based on different analytical principles. In this study, the importance of H₂O₂, its applications in various industries, especially the food industry, and the importance of measuring it with different techniques, especially portable sensors and on-site analysis, have been investigated and studied.

Hydrogen peroxide (H₂O₂) is a very simple molecule in nature, but due to its strong oxidizing and reducing properties, it has been widely used in the pharmaceutical, medical, environmental, mining, textile, paper, food production and chemical industries. Sensitive, rapid and continuous detection of H₂O₂ is of great importance in many systems for product quality control, health care, medical diagnostics, food safety and environmental protection.

Various methods have been developed and applied for the analysis of H₂O₂, such as fluorescence, colorimetry and electrochemistry, among them, the electrochemical technique due to its advantages in simple instrumentation, easy miniaturization, sensitivity and selectivity.

Monitoring the H₂O₂ concentration level is of practical importance for academic and industrial purposes. Edible oils are prone to oxidation during processing and storage, which may adversely affect oil quality and human health. Determination of peroxide value (PV) of edible oils is essential because PV is one of the most common quality parameters for monitoring lipid oxidation and oil quality control. The development of cheap, simple, fast, sensitive and selective H₂O₂ sensors is essential.

This study aims to understand the current production scenario emphasizing the significance of green manufacturing in achieving economic and environmental sustainability goals to fulfil future needs; to determine the viability of particular strategies and actions performed to increase the process efficiency of electrical discharge machining; and to uphold the values of sustainability in the nonconventional manufacturing sector and to identify future works in this regard.

A thorough analysis of numerous experimental studies and findings is conducted. This prominent nontraditional machining process’s potential machinability and sustainability challenges are discussed, along with the current research to alleviate them. The focus is placed on modifications to the dielectric fluid, choosing affordable substitutes and treating consumable tool electrodes.

Trans-esterified vegetable oils, which are biodegradable and can be used as a substitute for conventional dielectric fluids, provide pollution-free machining with enhanced surface finish and material removal rates. Modifying the dielectric fluid with specific nanomaterials could increase the machining rate and demonstrate a decrease in machining flaws such as micropores, globules and microcracks. Tool electrodes subjected to cryogenic treatment have shown reduced tool metal consumption and downtime for the setup.

The findings suggested eco-friendly machining techniques and optimized control settings that reduce energy consumption, lowering operating expenses and carbon footprints. Using eco-friendly dielectrics, including vegetable oils or biodegradable dielectric fluids, might lessen the adverse effects of the electrical discharge machine operations on the environment. Adopting sustainable practices might enhance a business’s reputation with the public, shareholders and clients because sustainability is becoming increasingly significant across various industries.

A detailed general review of green nontraditional electrical discharge machining process is provided, from high-quality indexed journals. The findings and results contemplated in this review paper can lead the research community to collectively apply it in sustainable techniques to enhance machinability and reduce environmental effects.