Nanofluids, the fluid suspensions of nanomaterials, have shown many interesting properties, and the distinctive features offer unprecedented potential for many applications. This paper summarizes the recent progress on the study of nanofluids, such as the preparation methods, the evaluation methods for the stability of nanofluids, and the ways to enhance the stability for nanofluids, the stability mechanisms of nanofluids, and presents the broad range of current and future applications in various fields including energy and mechanical and biomedical fields. At last, the paper identifies the opportunities for future research.

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A review on nanofluids: preparation, stability mechanisms, and applications

The special mechanical properties of nanoparticles allow for novel applications in many fields, e.g., surface engineering, tribology and nanomanufacturing/nanofabrication. In this review, the basic physics of the relevant interfacial forces to nanoparticles and the main measuring techniques are briefly introduced first. Then, the theories and important results of the mechanical properties between nanoparticles or the nanoparticles acting on a surface, e.g., hardness, elastic modulus, adhesion and friction, as well as movement laws are surveyed. Afterwards, several of the main applications of nanoparticles as a result of their special mechanical properties, including lubricant additives, nanoparticles in nanomanufacturing and nanoparticle reinforced composite coating, are introduced. A brief summary and the future outlook are also given in the final part. (Some figures may appear in colour only in the online journal)

https://iopscience.iop.org/article/10.1088/0022-3727/47/1/013001/pdf

Mechanical properties of nanoparticles: basics and applications

Liquid phase exfoliated graphene sheets were modified by oleic acid and dispersed in lubricant oils as additives. The tribological behaviours of graphene-contained oils were investigated using a four-ball tribometer. The lubricant with optimized graphene concentrations of 0.02–0.06 wt% showed enhanced friction and anti-wear performance, with friction coefficient and wear scar diameter reduced by 17% and 14%, respectively.

https://iopscience.iop.org/article/10.1088/0022-3727/44/20/205303/pdf

Tribological properties of oleic acid-modified graphene as lubricant oil additives

The prospect of modern tribology has been expanded with the advent of nanomaterial-based lubrication systems, whose development was facilitated by the nanotechnology in recent years. In literature, a variety of nanoparticles have been used as lubricant additives with potentially interesting friction and wear properties. To date, although there has been a great deal of experimental research on nanoparticles as lubricating oil additives, many aspects of their tribological behavior are yet to be fully understood. With growing number of possibilities, the key question is: what types of nanoparticles act as a better lubricating oil additive and why? To answer this question, this paper reviews main types of nanoparticles that have been used as lubricants additives and outlines the mechanisms by which they are currently believed to function. Significant aspects of their tribological behavior such as dispersion stability and morphology are also highlighted.

Tribological performance of nanoparticles as lubricating oil additives

Lubrication performance of MoS2 and SiO2 nanoparticles as lubricant additives in magnesium alloy-steel contacts

Purpose – The purpose of this paper is to investigate the tribological properties of liquid paraffin with SiO2 nanoparticles additive made by a sol‐gel method.Design/methodology/approach – The tribological properties of the SiO2 nanoparticles as an additive in liquid paraffin are measured using a ball‐on‐ring wear tester to determine the optimal additive concentration. The mechanism that wear and friction are reduced is studied using scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), and atomic force microscope (AFM).Findings – Experimental results indicate that the sizes of the synthesized SiO2 nanoparticles are distributed uniformly and that the optimal concentrations of SiO2 nanoparticles in liquid paraffin is associated with better tribological properties than pure paraffin oil, and an anti‐wear (AW) ability that depends on the particle size.Originality/value – It is shown in the paper that by reducing friction and AW, the lubricant prepared by the methods described can prolong ...

Size effects of SiO2 nanoparticles as oil additives on tribology of lubricant

Purpose – The purpose of this paper is to study the dispersion and tribological properties of liquid paraffin with aluminum nanoparticles as additive, which are prepared by the surface‐modification method using oleic acid (OA).Design/methodology/approach – The dispersion stability of aluminum nanoparticles in liquid paraffin is measured by spectrophotometry, which can be optimization by Taguchi method. The tribological properties are evaluated by using a ball‐on‐ring wear tester.Findings – The results show that few concentrations of aluminum nanoparticles as additives in liquid paraffin have better antiwear and antifriction properties than the pure paraffin oil. Scanning electron microscopy and energy dispersive spectrometer analyses can show that the thin films on the rubbing surfaces can be formed by these aluminum nanoparticles, which not only bear the load but also separate the both interfaces, thus the wear and friction can be reduced.Originality/value – Machine components and mechanism pairs rely on...

Dispersion and tribological properties of liquid paraffin with added aluminum nanoparticles

Purpose – The paper aims to determine whether the type selection and parameters determination of the compensation are most important for yielding the acceptable or optimized characteristics in design of hydrostatic bearings.Design/methodology/approach – This paper utilizes the equations of flow equilibrium to determine the film thickness or displacement of worktable with respect to the recess pressure.Findings – The stiffness due to compensation of constant‐flow pump increases monotonically as recess pressure increases. Also, the paper considers which is larger than that due to orifice compensation and capillary compensation at the same recess pressure ratio.Originality/value – The findings show that the usage range of recess pressure and compensation parameters can be selected to correspond to the smallest gradient in variations of worktable displacement or film thickness.

Design for static stiffness of hydrostatic plain bearings: constant compensations

Purpose – Chemical mechanical polishing (CMP) has attracted much attention recently because of its importance as a nano-scale finishing process for high value-added large components that are used in the aerospace industry. The paper aims to discuss these issues. Design/methodology/approach – The characteristics of aluminum nanoparticles slurry including oxidizer, oxidizer contents, abrasive contents, slurry flow rate, and polishing time on aluminum nanoparticles CMP performance, including material removal amount and surface morphology were studied. Findings – Experimental results indicate that the CMP performance depends strongly on the oxidizer, oxidizer contents, and abrasive contents. Surface polished by slurries that contain nano-Al abrasives had a lower surface average roughness (Ra), lower topographical variations and less scratching. The material removal amount and the Ra were 124 and 7.61 nm with appropriate values of the process parameters of the oxidizer, oxidizer content, abrasive content, slur...

Chemical mechanical polishing of steel substrate using aluminum nanoparticles abrasive slurry

Purpose – The purpose of this paper is to test whether TiC clad layer deposited on carbon steel by gas tungsten arc welding (GTAW) improves carbon steel substrate wear resistance.Design/methodology/approach – Cladding microstructure and cladded surface hardness were tested in samples prepared under varying welding parameters. The chemical composition, microstructure and surface morphology of the cladded layer were analyzed by optical microscope, scanning electron microscopy and energy dispersive X‐ray spectroscopy. The wear behavior of the cladded layer was studied with a block‐on‐ring tribometer. Wear mechanisms in the specimens are discussed based on microscopic study of wear surface characteristics.Findings – The experimental results revealed an excellent metallurgical bond between the composite coating and substrate. Hardness was increased from HRb 6.6 in the substrate to HRb 65 in the modified layer due to the presence of the hard TiC phase. Experimental comparison of varying welding parameters revea...

De-Xing Peng

Papers

Size effects of SiO2 nanoparticles as oil additives on tribology of lubricant

Dispersion and tribological properties of liquid paraffin with added aluminum nanoparticles

Design for static stiffness of hydrostatic plain bearings: constant compensations

Chemical mechanical polishing of steel substrate using aluminum nanoparticles abrasive slurry

The effects of welding parameters on wear performance of clad layer with TiC ceramic