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The purpose of this paper is to study the tribological properties of Cu nanoparticles (NPs) as lubricant additives in three kinds of commercially available lubricants.

A four-ball machine is used to estimate the tribological properties of Cu NPs as lubricant additives in three kinds of commercially available lubricants. Three-dimensional optical profiler and electrical contact resistance are evaluated to investigate the morphology of the worn surfaces and the influence of Cu NPs on tribofilms.

Wear tests show that the addition of Cu NPs as lubricant additives could reduce wear and increase load-carrying capacity of commercially available lubricants remarkably, indicating that Cu NPs have a good compatibility with the existing lubricant additives in commercially available lubricants.

The tribological properties of Cu NPs as lubricant additives in three kinds of commercially available lubricants were investigated in this paper. These results are reliable and can be very helpful for application of Cu NPs as lubricant additives in industry.

The paper aims to address the formulation of zirconium and oxalicum additive-based lubricants for use in slide ways to meet the demands of high positioning exactness based on reduction in stick–slip and coefficient of friction over a wide speed range and compares the same with commercially available lubricant.

An investigation into the frictional properties and stick-slip behavior of lubricating oil is carried out using linear reciprocating tribometer and correlated with ultraviolet spectroscopic analysis.

It is observed that these transition metal additive compounds support in increasing the flexibility of the molecular chains leading to improved lubricity.

The lubricant additives considered for the current study are based on transition metals zirconium and oxalicum. It is observed that these additive compounds support in increasing the flexibility of the molecular chains, leading to improved lubricity.

Depleting reserves of crude oils and their adverse environmental effects have shifted focus toward environment friendly and biobased lubricant base oils. Natural oils and fats act as good lubricants but they have low oxidation and thermal stability which makes them unsuitable for modern day uses. This paper aims to produce trimethylolpropane ester biolubricant from cottonseed oil and study the effects of its use in spark ignition (SI) engines.

In this work, cottonseed oil is converted to TMP lubricant by a two-step based catalyzed esterification. The lubricants thermophysical properties are then analyzed and a 20% blend with synthetic poly-alpha olefin is used in an spark ignition engine.

The produced lubricant has viscosity @100^oC of 4.91 cSt, a viscosity index of 230 and a flash point of 202^oC. When used as a 20% blend in a petrol engine, the rate of oil deterioration was reduced by 18%, however, the overall wear increased by 6.7%. However, this increase is offset by its improved environmental impacts.

In its current state, such a biolubricant can be used as an additive to most commercially available lubricants to improve oil deterioration characteristics and environmental impact. However, further work on improving biolubricant’s wear characteristics is needed for the complete replacement of mineral oil-based lubricants.

THE TERM “synthetic lubricant” has been adopted to designate a variety of fluids, derived from sources other than mineral oils, which have been developed by the technologist in order to satisfy the extreme conditions under which present‐day machinery has to operate : for example, high or low temperatures, or both, often with high bearing loads, and sometimes under conditions which demand resistance to ignition. Although, in fact, modern petroleum oils are prepared to such stringent specifications, and by such carefully controlled processes, that they are almost equally as “tailor‐made”, it is their comparatively limited temperature range that largely brought about the development of the so‐called synthetic product.

In the present study, an attempt has been made to examine friction and wear behaviour of Ti-6Al-4V alloy sliding against EN-31 steel under lubricative media of common commercial grade oil (hydrol-68). The paper aims to discuss these issues.

Tribological properties of Ti-6Al-4V under hydrol-68 as lubricative media are measured using multi-tribo tester. Lubricating oil samples at different normal loads have also been analysed with the help of laser net fines (LNF) as per ISO 4406:1999. Experiments have been designed by two level full factorial method.

Experimental results indicate that the wear rate of Ti-6Al-4V alloy decreases as sliding speed increases. But it shows typical transition characteristics as the normal load increases; till 30 N wear rate decreases then it increases from 30 to 50 N. Also for all loads and at every speed, the average wear increases as the sliding distance increases. The average coefficient of friction of the Ti-6Al-4V alloy decreases with the increase in sliding velocity and normal load. Lubricating oil analysis indicates that the maximum wear particle size (5-15 μm) was obtained at a normal load of 50 N.

This paper shows that considerable reduction in friction and wear is achieved by using common grade oil hydrol-68 as lubricative media. Further, the analysis of lubricating oil using LNF at different normal loads indicates the co-existence of various wear phenomena such as cutting, fatigue, and sliding wear simultaneously.

WO₃ particles were prepared by the sol-gel method. Tetraethyl silicate (TEOS) was used to obtain a SiO₂-coated WO₃ nanoparticle. Quantum chemical parameters of oleic acid, triethanolamine, glycerol and methyl pentane as dispersants were theoretically calculated. Tribological properties of SiO₂/WO₃ nanocomposite lubricant were carried out on an MRS-10A four-ball friction and wear tester.

The purpose of this study is to investigate the preparation and tribological properties of SiO₂/WO₃ nanocomposite lubricant.

The obtained SiO₂-coated WO₃ nanoparticle (nano-SiO₂/WO₃) with a particle size of about 70 nm. The calculated adsorption energy of triethanolamine on the surface of the steel ball is 554.6 eV, and triethanolamine is selected as the dispersant. The dispersion effect of SiO₂/WO₃ nanocomposite lubricant is good, which shows that triethanolamine oleate plays a good dispersion role in the preparation of lubricant, which is consistent with the calculation results of the adsorption capacity of dispersant. As a good auxiliary lubricant, SiO₂ can improve the tribological properties and wear resistance of WO₃.

Nanocomposite lubricants have been the focus of research in recent years, which could greatly reduce energy consumption. And the SiO₂/WO₃ exhibited excellent lubrication performance as a lubricant additive. The lubrication mechanism of SiO₂/WO₃ nanocomposite lubricant is the synergistic lubrication mechanism of friction film lubrication and antifriction bearing. This study could provide a certain reference for the practical application of nanocomposite lubricants.

THE above two‐day symposium sponsored by the Tribology Group of the Institution of Mechanical Engineers and held at their h.q. in London from the 19th‐20th February, clearly demonstrated that grease is an engineering component and needs as much attention in selection and application as might be given to the design of the component that it lubricates.

Refrigerant fraction and mixture viscosity values were determined for various operating conditions of compressors. The paper aims to discuss these issues.

In this study, an experimental setup that can be used to obtain refrigerant mass fraction and mixture viscosity data is designed and constructed. With the experimental setup, R600a mineral and R134a polyolester compressor lubricant mixtures were examined.

This study presents an experimental procedure for obtaining practical results related to refrigerants used in the refrigeration system. Some properties of refrigerant-lubricant mixtures are very important for the design of compressors and performance of the refrigeration cycle.

The paper is of value in presenting an experimental procedure for obtaining practical results pertaining to the tribological and other properties performance of the refrigerants.

The purpose of this paper was to examine the film-forming behaviour of simple compositions of polyalphaolefin (PAO) containing an oil-soluble polyalkylene glycol (OSP) alone, a zinc dialkyl dithiophosphate (ZDDP) alone and then combinations of an OSP and ZDDP.

A Mini-Traction Machine with Spacer Layer Imaging technology was used to evaluate friction and film formation under a specific contact pressure, temperature and slide-to-roll ratio. Electrical contact resistance measurements were used to follow surface film formation.

The inclusion of an OSP to a PAO showed evidence of friction-reducing behaviour with low friction values over the rubbing cycle but no significant tribo-film build up. When a ZDDP (1 per cent) is added to the PAO, a thick tribo-film forms of about 100 nm. Addition of an OSP (10 per cent) shows this film still forms despite the OSP being a polar and surface-active additive.

The study was conducted under a narrow range of test conditions (e.g. temperature and contact pressure), and future work will focus on friction and film formation across a broader set of conditions.

Despite OSPs being polar and surface-active, they do not interfere with the ZDDP in forming an anti-wear film in a PAO and, therefore, their inherent properties of good deposit control could enhance the performance of modern lubricants.

OSPs offer promising benefits as friction reducers in PAOs. The research also suggests that OSPs do not negate the formation of ZDDP anti-wear tribo-films when in combination in a PAO.

This paper aims to numerically investigate the influence of magnetic field and recess configurations on performance of hydrostatic thrust bearing. Electrically conducting fluid is supplied to bearing, operating in external magnetic field. Influences of recess geometric shapes (circular, rectangular, elliptical and triangular) and restrictor (capillary and orifice) are numerically examined on stead-state and dynamic performance characteristics of bearing.

Numerical simulation of hydrostatic thrust bearing has been performed using finite element (FE) method based on Galerkin’s technique. An iterative source code based on FE approach, Gauss–Siedel and Newton–Raphson method is used to compute steady-state and dynamic performance indices of bearings.

The presence of magnetic field is observed to be enhancing load-carrying capacity and damping coefficient of bearings. The effect is observed to be more pronounced at low value of Hartmann number, because of the saturation effect observed at higher values of Hartmann number. The enhancement in abovementioned performance indices is observed to be highly dependent on geometry of recess and restrictor.

This study presents a FE-based approach to numerically simulate a hydrostatic thrust bearing. It will help bearing designers and academician in selecting an appropriate recess shape, restrictor and strength of magnetic field, for obtaining optimum performance from hydrostatic thrust bearing.

The present investigation provides a coupled solution of modified Reynolds equation and restrictor equation, which is essential for accurately predicting the performance of hydrostatic thrust bearings.