bluuebunny/crossref_metadata_2025 huggingface dataset:
Reduction of the roll force during lubricated cold rolling of aluminium strips
Authors: Zhang S. , Lenard J. G.
Published: July 2006

Lubricants, especially blended for cold rolling of aluminium, have been studied in terms of their effects on the roll‐separating forces during the process. Synthetic and mineral oils, with and without additives, were investigated. Two general observations are made. The first concerns the roll force in the pass, averaged over the length of the workpiece. The second deals with the variation of the force as the process continues. In both cases, the roll‐separating forces change in noticeable ways, depending on the lubricant. Tests, designed to identify some of the causes of these changes, were conducted. It was found that the effect of the lubricants on the roll‐separating forces can be divided into three groups. The forces measured while using the synthetic ester based oil, with or without additives, decreased as the rolling process continued. The forces with the other base oils without additives increased slightly or remained essentially unchanged with additives. The changing lubrication conditions in the roll gap are expected to cause the variations of the roll forces.
A new engine oil optimised for ecologically sensitive operational areas
Authors: Baumann W. , Böhme W. , Hubmann A. , Zeiner W.
Published: July 2006

In recent years, environmental awareness and legislation have focused public attention on vehicle emissions. Consequently, more research has been devoted to emissions and pollution by lubricants. A number of studies has been carried out to understand lubricant‐related emissions and leak rates as well as the effects on fuel economy of using low viscosity grades of lubricant. The purpose of the present investigation was to develop for use in gasoline and diesel engines a crankcase lubricant which contained improved performance in engine cleanliness with fuel economy and a low rate of particle emissions. Emphasis was placed on low toxicology and rapid biodegradability because of the risk of unintentional emissions. Such a sophisticated lubricant is desirable not only for normal road vehicles but also and especially for use in ecologically sensitive areas.

During the development of this lubricant, numerous laboratory tests were performed. In order to assess the quality and the fuel economy of the new lubricant, tests were carried out on an engine test rig and on a vehicle test bench. Field tests were run with various vehicles and stationary engines, using different fuel types. Unleaded gasoline, diesel fuels with a varying sulphur content, and rape seed oil methyl ester (RME) were used. This paper summarises the results of this investigation.
Effects of surrounding atmosphere on the formation of carbon films at 450°C
Authors: Zhou Chunhong , Jin Yuansheng , Wen Shizhu
Published: July 2006

The object of the present work is to present the results of research into the effects of surrounding atmosphere on the formation of carbon films by lubricating oil cracking at 450°C. The following six kinds of surrounding atmospheres were used: O2(5%), O2(95%), O2(70%), O2(50%), O2(20%) (with the remainders N) and air. Cr2O3 and Mo alloy coatings were selected as friction pair materials and a synthetic ester oil as lubricant. The experimental results on a SRV test machine showed that solid carbon films could be generated only in the atmosphere with a certain O2 content. No valid carbon films were generated in surrounding atmospheres rich in nitrogen and oxygen. Surface analyses with SEM, WDS, XPS and X‐ray diffraction indicated that graphite films with excellent solid lubricating effect resulted from the catalytic cracking of the hydrocarbon components in the lubricating oil at high temperature in the air atmosphere after the failure of fluid lubrication.
Improved maintenance and life extension of phosphate esters using ion‐exchange treatment
Authors: Phillips W. D. , Sutton D. I.
Published: July 2006

The present paper investigates the mechanism of degradation of triaryl phosphate esters and the methods that have been used to control this. A new chemical process, based on ion‐exchange resin treatment, is examined, including an evaluation of the behaviour of different resins in laboratory tests. Trial runs, notably in conjunction with a system of vacuum dehydration, have given extremely promising results.
Ester base stocks for synthetic lubricants
Authors: Vilics T. , Ciorbagiu F. , Ciucu B.
Published: July 2006

This paper reports on work on the synthesis and characterisation of mixtures of aliphatic adipates with complex esters based on polyols, adipic acid, and monohydroxy alcohols, in order to formulate new synthetic base stocks. The viscosity and pour point values of these mixtures are higher than those of adipates. Both of these physical properties become greater with the increasing molecular weight of the complex ester or of the ester's concentration in the mixture.
R‐134a compatible lubricants based on C4‐C6 esters of pentaerythritol and polyalkyleneglycol
Authors: Gryglewicz S. , Beran E. , Janik R. , Steininger M.
Published: July 2006

The results of work intended to produce inexpensive, synthetic lubricants compatible with R‐134a using waste carboxylic acids C4‐C6 as the base are presented in this paper.

The suitability of the products synthesised was first evaluated considering their physical and chemical properties, and their thermostability determined by the standard Philipp test (sealed glass tube method). Two ester bases were then selected for further testing — a pentaerythritol esterified with C4‐C6 monocarboxylic acids and a polyalkyleneglycol similarly esterified with monocarboxylic acids C4‐C6.

The base oils chosen were tested for their corrosive action on metals in the presence of water in different concentrations. The pentaerythritol ester proved to have the most advantageous properties at that stage. The results of the laboratory tests have been corroborated by trials conducted on real refrigerating compressor systems. Only the lubricant that was obtained using pentaerythritol esterified with monocarboxylic acids C4‐C6 as the base withstood the severe test.
Some experience with biodegradable lubricants
Authors: Legisa I. , Picek M. , Nahal K.
Published: July 2006

A significant amount of lubricating oils and greases can enter the environment, producing contamination of both soil and water. Over the last few years, pressure on lubricant producers and consumers has caused them to seek a solution involving less environmentally harmful lubricants. In Croatia, a significant quantity of lubricants is disposed of without control, polluting soil and water; as a result, lubricant producers have looked seriously at biodegradable lubricating oils and greases.

This paper presents information on development of some biodegradable hydraulic oils and lubricating greases based on lithium and calcium soaps, using synthetic esters and rapeseed oil, and presents their physical and chemical properties, and their applications.
Tribological behaviour of polymeric coatings lubricated with salt water
Authors: Mousa Mohamed O.
Published: July 2006

In many applications, such as marine industries, pumping of underground water, and in some chemical industries, sliding elements are lubricated with the process fluid (e.g. salt water). Therefore, the effect of salt water on the tribological behaviour of metallic friction couples has been a subject of study. In the present work, the influence of salt water solution (3 wt. % sodium chloride) on the tribological behaviour of some polymeric coatings is investigated, using a pin‐on‐disc testing machine, at different sliding speeds and normal loads. The coating consists of a base‐matrix of high‐density polyethylene (HDPE) and polyamide (PA6) with different concentrations of copper‐ and tin‐powder fillers. The effect of the formation of the oxide films, sodium hydroxide microlayers (NaOH) and the polymeric transformed films on the friction mechanism, is discussed. The results show that squeeze of the lubricant takes place in the presence of the NaCl‐solution; and, despite the relatively low viscosity of the lubricant, hydrodynamic pressure affected the friction mechanism at the sliding speed of 0.50 m/s, resulting in a significant reduction in the coefficient of friction. The value of the coefficient of friction seems also to be affected by the generation of sodium hydroxide, as well as the oxide films and material transfer layers. At a low speed (0.20 m/s), the PA6‐based composites with copper‐filler showed an optimal wear resistance at normal loads up to 15N.
Miscibility and stability of synthetic lubricants with HFC refrigerants
Authors: Wu Wei‐Te , Thomas Raymond H. P.
Published: July 2006

The phase‐out of CFC production and further regulations on HCFC are required because of their association with the depletion of stratospheric ozone. HFCs and their mixtures have evolved as long‐term replacements for CFCs and HCFCs. For air conditioning and refrigeration systems, new synthetic lubricants having miscibility with HFC refrigerants, similar to that of mineral oils with CFCs, have been developed. Data on the miscibility ofR‐32/125 and R‐125/143a with polyol ester lubricants are presented in this paper. In the temperature range of interest (−40°C to 60°C), we observed the upper immiscible region, lower immiscible region, as well as the coalescence of the two regions, for polyol ester lubricants with these HFC refrigerant mixtures. HFC‐143a is least miscible among the three pure HFC refrigerants. The stability of R‐32/125 and R‐125/143a with dry polyol ester lubricants is very good at 204° C. With high moisture content, hydrolysis of the lubricant occurs at high temperatures. The onset of significant hydrolysis of lubricant (B) takes place between 175°C and 200°C. Care must be exercised to maintain the dryness of polyol ester lubricants and refrigeration systems to prevent this occurring.
An investigation of the effect of the lubricant on the soluble organic fraction of particulate emissions from a DI diesel engine
Authors: Schramm Jesper , Hori Shigeo , Abe Tsugio
Published: July 2006

This paper looks at the effect of the lubricant on emissions of paniculate matter. A short literature review is presented, together with experimental results for an engine operating with a synthetic lubricant and a defined fuel. The influence of engine operating parameters such as engine load and speed on particulate matter (PM) emissions is discussed, based on measurement of the composition of the aliphatic fraction of the soluble organic fraction (SOF) of the PM. Based on the results from the experiments, which include some comparative data for a mineral‐based lubricant, it is concluded that the method that is generally used to estimate fuel and lubricant contribution to the SOF of the PM has to be reconsidered.
Structure effect of refrigeration polyolester oils for use in HFC‐134a compressors
Authors: Remigy J.‐C. , Nakache E. , Brechot P. D.
Published: July 2006

A study of polyolester oils (POE) for compressors using an ozone‐friendly refrigerant is presented here. The effect of the chemical structure of POE was studied in relation to three lubricant properties: miscibility with HFC‐134a (CF3‐CH2F), lubricity (steel‐on‐steel and aluminium‐on‐steel contacts), and viscosity. The paper shows the strong structure effect of POE on miscibility and lubricity. Based on the data obtained, some model lubricants were blended, and the performance of these lubricants was assessed on refrigeration test rigs.
Synthesis and hydrolytic stability of aqueous antiwear agents of organic phosphate and organic thiophosphate
Authors: Feng Lin , De‐hua Tao , Zhi‐cai Wang , Cheng‐lei Li
Published: July 2006

In the present paper, the two aqueous antiwear agents, zinc salts of longchain polyoxyethylene glycol phosphate and of long‐chain polyoxyethylene glycol thiophosphate (ZOP and ZTP), have been synthesised. Using a fourball tester, their antiwear properties were investigated in high water‐based fluids. The four‐ball test results showed that the antiwear property of the ZOP additive was better than that of ZTP, while its load‐carrying capacity was slightly lower than that of ZTP. The effects of the addition of triethanolamine (TEA) and hydrolytic stability on their antiwear properties were also studied. The antiwear properties of ZOP and ZTP increased as a result of the addition of triethanolamine. The hydrolysis stability directly affected their antiwear properties. Lastly, the elemental composition of the wear‐scars were investigated using Auger Electron Spectroscopy (AES).
Test methods to judge the eco‐compatibility of lubricants
Authors: Szabó Julianna Bérci
Published: July 2006

Diverse physical and chemical test methods are employed to evaluate important environmental characteristics of lubricants and lubricant related waste materials. The most important chemical tests are closely related to lubricant composition. The amount of aromatic and polycyclic aromatic hydrocarbons in base oils, as well as the potential amount of heavy metals in additives must be known. Among the biological tests, the most important are those dealing with biodegradation characteristics, but neither human nor ecotoxicity tests can be ignored.
Preparation and characterisation of oil‐containing POM/PU blends
Authors: Hu X. , Jiang L.
Published: July 2006

Polyoxymethylene (POM), one of the major engineering thermoplastics, has high strength and stiffness, excellent chemical resistance and superior antifriction and wear resistance. It suffers, however, from poor impact resistance due to its higher crystallinity. In this study we have investigated how to improve the toughness of POM by blending polyurethane (PU) with POM using dual‐roller compaction. The influences of PU, silicone oil, a surfactant, and fillers such as ultra‐high molecular weight polyethylene (UHMWPE), polytetrafluoroethylene (PTFE), graphite and carbon black, on the mechanical properties of oil‐containing POM/PU blends and its self‐lubrication performance in dry sliding against AISI1045 steel are examined. The results show that blends of POM with 10 wt.% PU reached the maximum notched Izod‐impact strength. The best processing method for oil‐containing POM/PU blends, and the optimal compositions of modified POM/PU blends were also determined.
A tribological study of electrolytic nickel‐PTFE composite coatings
Authors: Assoul M. , Pena‐Munoz E. , Roizard X.
Published: July 2006

The potential for co‐depositing PTFE particles in a metal matrix by means of electrodeposition has led to a new generation of composites that show promising tribological properties. In the present work, a study has been made of the parameters of the coating process (type of current, current density, and concentration of PTFE in the electrolyte bath) in order to optimise the properties of coatings.
Polyalphaolefins — base fluids for modern heavy duty diesel oils
Authors: Benda R. , Plomer A. , Reboul P.
Published: July 2006

A combination of environmental legislation and a need for improved economics currently presents both OEMs and fleet owners with a conflicting set of performance and operational requirements. These include lower emission and paniculate levels, fuel economy, longer drain/service intervals, and enhanced engine durability. Improved engine lubricants will play a crucial role in achieving these goals. The impact of base‐fluid composition and viscosity grade on emission/paniculate levels and fuel economy of a Euro II engine has been investigated. Polyalphaolefin‐based lubricants appear as an encouraging solution, as shown by our results centred on an SAE 5W40 grade.
On the rheological behaviour of synthetic fluids thickened by solid additives
Authors: Vergne P. , Prat P.
Published: July 2006

A variety of fluid space lubricants, i.e., synthetic oils thickened by solid additives (particles of PTFE and MoS2), has been developed. These lubricants present a solid‐like behaviour under yield stress, and a strong non‐Newtonian effect during flow. Measurement of the yield stresses revealed an unexpectedly strong interaction between a synthetic hydrocarbon oil and one type of PTFE particle. Furthermore, the substitution of 1 vol.% PTFE particles by MoS2 particles introduced a significant change in the yield stress values. This effect is also apparent in viscosity measurements. These lubricants display, through their rheological behaviour, good ability to replenish contacts over a wide range of temperatures, as shown by measurements taken at −20°C and −60°C.
An evaluation of the gassing tendency under electrothermal stress of some dielectric liquids
Authors: Shrinet V. , Patel M. J.
Published: July 2006

It is known that, under electrical or thermal stress, dielectric liquid produces gas. The performance of oil cooled, insulated, or impregnated electrical equipment such as transformers, cables, or capacitors, is affected by the presence of these small gaseous bubbles, which can give rise to partial discharges and to eventual insulation breakdown. Therefore, the gassing properties of an insulating liquid, i.e. its tendency to absorb or evolve gases, have been recognised as a factor of major importance in characterising dielectric liquids. The transition from gas absorption to gas evolution can occur at different temperatures and electrical stresses for different liquids. The effects of temperature, electrical stress, and ageing on gassing tendency have been well studied. Efforts have also been made to correlate the aromatic content of oil with a gassing tendency. However, such studies are limited to mineral insulating transformer oil.

In the present work, an effort has been made to study the gassing characteristics of some common dielectric fluids, including linear alkyl benzene (LAB), silicone oil, and capacitor oil, along with some naphthenic and paraffinic transformer oils.
Properties of naphthalene oligomers polyalkylated with linear 1‐alkenes
Authors: Nemes Sándor , Borbély János , Kovacs Mönika
Published: July 2006

Star‐shaped alkylaromatic hydrocarbons consisting of oligomeric naphthalene cores and long straight‐chain alkyl arms have been synthesised using a one‐pot method:magnified imageWhere 1‐alkene is 1‐hexene, 1‐octene, 1‐decene, 1‐dodecene, 1‐tetradecene, 1‐hexadecene, and 1‐octadecene, respectively. Different linear 1‐alkenes with increasing chain length have been reacted with naphthalene oligomers in an identical way, and the properties of the total products compared and related to the chain length of the alkylating normal 1‐alkene. Consequent to this, increases in M̌n, (= 550–1900), viscosity indexes (90–161), pour points (—24 to + 17°C), flash points (210–330°C), and oxidation resistance, could be observed. These products exhibited properties good enough to be suitable for use as lubricant base stocks and/or additives.
Film‐forming tendencies of some base fluids and viscosity modifiers
Authors: Hong Hyun‐Soo , Bair Scott
Published: July 2006

The film‐forming tendencies of selected mineral base oils and synthetic base fluids were investigated with and without conventional GL‐5 additive packages. A pressurised falling‐body viscometer and a concentrated contact simulator were used to measure low‐shear viscosities, central film thicknesses, and traction coefficients. Analysis of the mineral—based oils showed that a paraffinic base oil and a naphthenic base oil had similar film thicknesses, even though the naphthenic base oil has higher pressure‐viscosity coefficients. A very high viscosity index oil gave thinner film thicknesses and lower pressure—viscosity coefficients than the paraffinic or naphthenic base oils. Analysis of the synthetic base fluids showed that a PAO‐4 base fluid gave thicker film thicknesses than an ester base fluid. The analysis of fully‐formulated oils showed that the PAO‐4 oil containing a proprietary polyolefin provided a similar filnz thickness to the PAO‐4 oil containing a more expensive PAO‐100.
Polyglycols as base fluids for environmentally‐friendly lubricants
Authors: van Voorst R. , Alam F.
Published: July 2006

Polyglycols are used in a wide range of applications, including lubrication. Many advantageous properties can be obtained for lubricant applications by manipulating the four variables in polyglycol preparation: the initiator, the alkylene oxides, the molecular build‐up, and the mole weight. However, it has long been believed that it would not be possible to combine these properties with a good environmental profile of high biodegradability and low aqueous toxicity. Development work at the authors' laboratory has resulted in polyglycol‐chemistry‐based products that fulfil the application requirements and are also environmentally friendly. Assessment by the Umwelt Bundes Amt has led to a statement of suitability for Blue Angel formulations for two water‐soluble polyglycol grades (ISO 22 and IS0 46). Environmentally‐friendly watersoluble polyglycol base stocks currently includes the range ISO 10 to ISO 100. The development of environmentally friendly water‐insoluble and oil‐soluble polyglycols is under way.
Non‐food industrial products from crops: The example of biomolecular development in France
Authors: Davidand Olivia , Goss Ghislain , Gaouyer Jean Paul
Published: July 2006

A brief review of the oils, fuels, additives, and other industrial products being derived from non‐food crops in France, and the potential market for them.
Influence of degradation on the film‐forming properties of polyolester oils
Authors: Yokoyama F. , Spikes H. A.
Published: July 2006

The film thicknesses of two polyolester degraded oils were measured over a wide range of temperatures to investigate the influence of degradation on film‐forming properties. The results have been interpreted in the light of the idea that degradation of an ester lubricant can produce two different types of product which have opposing influences on film‐forming properties. One is the formation of smaller, polar molecules, such as acids, which may result in a decrease in effective pressure—viscosity coefficient. The other is the formation of larger, bulky molecules such as sludge, which result in increased pressure—viscosity coefficient. The effective pressure—viscosity coefficient decrease with degradation of the oil thus is made up of an earlier stage involving a series of reactions, followed in a later stage by an increase.
Base oils of high aromatic, long branched aliphatic pyromellitic esters
Authors: Mirci Liviu E. , Herdan Jean M.
Published: July 2006

The present paper deals with the synthesis of some tetraesters with a mixed structure of pyromellitic dianhydride, and with their characterisation as potential base oils. These esters are made on the basis of a long branched aliphatic alcohol, such as isotridecanol, and an alcohol with aromatic content, such as 2‐phenoxy‐ethanol. The variation of the principal properties as a function of both the length of the aliphatic chain introduced by the aliphatic alcohol, and the aromatic content introduced by the aryl‐alkyl alcohol has been assessed and the potential for viable products with a wide range of viscosity values has been examined. The enhanced aryl content is shown to induce superior thermal behaviour. These products present good test results and, thereby, demonstrate their versatility.
Detailed characterisation of heavy alkylated benzene fluids by multipulse one‐ and two‐dimensional NMR spectroscopy
Authors: Kapur G. S. , Sarpal A. S. , Jain S. K. , Srivastava S. P. , Bhatnagar A. K.
Published: July 2006

In this paper, the results of a characterisation of heavy alkylated benzenes (HAB) using multipulse NMR spectroscopy are presented. Four commercial samples of heavy alkylated benzene have been characterised in detail in terms of various structural parameters, such as percentage aromatic carbon (Ca), degree of aromatic substitution, average alkyl chain length, type of alkyl chain and their proportions. Three of the HAB samples were very similar in structure, whereas, in the fourth, the structures present were entirely different. The latter had an abundance of 2‐phenyl alkane‐type structures, and did not contain methyl substituted tetralin or naphthalene type molecules. The influence of the structures on lubricating oil properties, including viscosity index, pour point, and viscosity, as well as FreonTM floc point, are also discussed.
Research on liquid lubricants for space mechanisms
Authors: Jones William R. , Shogrin Bradley A. , Jansen Mark J.
Published: July 2006

Four research areas at the NASA Glenn Research Center in the United States, involving the tribology of space mechanisms, are highlighted. These areas include: soluble boundary lubrication additives for perfluoropolyether liquid lubricants, a Pennzane® dewetting phenomenon, the effect of non‐ozone depleting chemical bearing cleaning processes on bearing lifetimes, and the development of a new class of liquid lubricants based on silahydrocarbons.
Synthesis of dicarboxylic and complex esters by transesterification
Authors: Gryglewicz Stanislaw
Published: July 2006

A new method of manufacturing simple dicarboxylic esters and complex esters has been developed. This method is based on a transesterification reaction in the presence of powdered calcium oxide which acts as a catalyst. Commonly accessible raw materials, namely, dimethyl adipate, 2‐ethylhexanol, neopenthyl glycol, and trimethylolpropane were used for the synthesis of the esters. The methanol formed in the transesterification reaction was continuously removed by azeotropic distillation with isooctane. The possibility of producing complex esters with different viscosities and polarities by modification of their chemical structure was studied.
Lubricating properties of rapeseed oils compared to mineral oils under a high load oscillating movement
Authors: Vižintin J. , Arnšek A. , Ploj T.
Published: July 2006

The use of rapeseed‐based lubricating oils has become more widespread in recent years. When these oils have been tested for their tribological properties, some imperfections have been found, especially in conditions of highfrequency and low‐amplitude oscillating movements. In the present work, we compare the tribological properties of commercially available rapeseed‐ and mineral‐based oils, rapeseed and mineral base oils, and these base oils mixed with two additives for improving lubricity. The results are compared for a wide range of contact pressures.
Vegetable and synthetic hydraulic fluids to improve the overall efficiency of a hydrostatic transmission
Authors: Dahlén L. , Isaksson O.
Published: July 2006

The purpose of the investigation reported here was to determine whether or not a hydrostatic transmission can act as an alternative to a conventional one, and, if so, to ascertain to what extent the fluid type contributes to an improvement in the efficiency of the hydrostatic transmission. The results presented in this paper are derived from an experimental field test of the hydrostatic transmission of a belt conveyor. This belt conveyor is one part in an ore‐transport line at LKAB mining company in Kiruna. The hydrostatic transmission replaced a conventional transmission consisting of an electric motor, a belt drive and a gearbox. The hydrostatic transmission was operated using three different hydraulic fluids: Shell Tellus TX 68, a conventional mineral oil; Mobil SHC 526, a synthetic fluid; and Binol Hydrap II, a vegetable fluid. All fluids have the same ISO viscosity grade, VG 68.

The measurements on the transmission show a 3% overall efficiency improvement when using vegetable and synthetic hydraulic fluids compared with the mineral oil. The current at the start of the transmission was reduced by a factor of 6, compared to that of the conventional transmission. The installed 110 kW electric motor was replaced with one of 55 kW. The test also showed that a closer study of all operating conditions, and a selection of components suited to the size of the load, can improve the overall efficiency of the hydrostatic transmission.
Aspects of the use of polyoxyalkylene glycols in polymer quenchants
Authors: Thompson R. I. G. , Randles S. J. , Brown M. , Wood J. L.
Published: July 2006

Solutions of high molecular‐weight polymers, particularly polyoxyalkylene glycols (PAGs), are used widely in the heat treatment of metals known as ‘quenching’. This is mainly because of the non‐flammable nature of the polymer solution, compared with safety hazards associated with traditional mineral‐oil based quenchants. However, the use of PAG‐based quenchants for some heat treatment processes, particularly for slow cooling speeds, has been limited. This paper describes how, through an understanding of the quenching mechanism, the quench speed of PAG‐based quenchants can be slowed by the use of additives or controlling the conditions of operation. The paper also gives an overview of the experimental measurement of polymer quenching and the factors involved in quenching.
New synthetic ester type base oils with biodegradability potential
Authors: Mirci L. E. , Herdan J. M. , Boran S.
Published: July 2006

The present paper presents the results of some research into the production of synthetic ester oils of mixed structure on the basis of citric acid (2‐hydroxy‐1,2,3 propane tricarboxylic acid) with beneficial tribological properties and potential biodegradability. Two series of unsymmetrical triesters have been synthesised by varying the molar relationship between branched aliphatic alcohols from C4 to C13 along with a special alcohol of a complex aliphaticaromatic structure, namely 2‐(o‐sec‐butyl)phenoxy‐ethanol. Based on this, it has been possible to obtain products with various properties. The introduction of the aromatic function into the structure of these triesters induces interesting features, and the natural source of the citric acid holds potential for having good ecological characteristics, which are intended to be the subject of further research.
Total vegetable oil greases
Authors: Gangule N. G. , Dwivedi M. C.
Published: July 2006

A grease has two major constituents, namely, a lubricant, that performs the function of lubrication; and a gellant, that provides a solid continuous phase, occludes the lubricant, and gives apparent physical structure to the grease. Generally, the gellant is 5–30% and the lubricant 65–90%, additives and fillers making up the rest. In conventional greases, the gellant is a vegetable oil soap, and the lubricant is a liquid oil of petroleum origin or is a synthetic. Such greases have limited biodegradability, because the major constituent, i.e., the lubricant, is normally not biodegradable.

In total vegetable oil grease, both the gellant and the lubricant are derived from vegetable oils, giving a grease of potentially high eco‐compatibility. Esters, dibasic acid esters, and alkylated esters of vegetable oil are known to be high‐quality lubricants. These can be used with soap stocks prepared from vegetable oils to give a grease of total vegetable oil origin.

The vegetable‐oil based lubricants and soaps are prepared separately and combined in appropriate proportions to give a grease of the required specifications. Alternatively, esterification and saponification can be carried out simultaneously to give a grease of the desired specifications, where an alkali will be the catalyst for esterification, and reactant for saponification. In this paper, the process parameters, and kinetics of these simultaneous reactions are discussed. The results of experimental evaluation of some of these greases are also presented.
Phosphate esters with a complex structure of an alkyl‐aryl type considered as base oils
Authors: Mirci Liviu E. , Herdan Jean M. , Ilia Gheorghe
Published: July 2006

This paper presents results of work carried out to produce phosphate esters of the alkyl‐aryl type. Three new triesters of mixed structure have been synthesised using a special alcohol with an aryl content, e.g., 2‐phenoxy ethanol, and a very long branched alcohol, e.g., isotridecanol. The influence of the aryl content and the effect of the long aliphatic chain on the main tribological properties have been investigated.
Composition and oxidative stability of hydro‐cracked base oils and comparison with a PAO
Authors: Cerny Jaroslav , Pospisil Milan , Sebor Gustav
Published: July 2006

The oxidative stability of nine hydrocracked base oils from seven producers and a PAO was compared using the standard IP 48 test. After a comprehensive characterisation of the oils, an evaluation of oxidative stability was carried out by measuring some common oil parameters, such as viscosity characteristics, carbon residue, pentane insolubles, and acid number. Additionally, the compound‐class composition of the fresh and oxidised oils was determined, and an FTIR spectroscopic analysis was carried out.

The oxidative stability of the hydrocracked oils was largely affected by the sulphur and aromatic hydrocarbon concentration in the oils. Oils with an increased sulphur content (above 80 ppm) had better oxidative stability than oils with a low sulphur content (20 ppm and lower), and there was a relatively large variability in the stability of the oils depending on the sulphur concentration. The oxidative stability of most of the hydrocracked oils with a low sulphur content was similar, and matched somewhat the stability of the polyalphaolefin.
Structural characteristics and mechanism of action of antioxidant anticorrosive additives for perfluoropolyalkylether fluids
Authors: Wang Daxi , Ying Feng
Published: July 2006

The combination energies of perfluoropolyalkyletherphenylamide (PFPEA) with perfluoropolyalkylether oxygen radicals (RfO) and with Fe atoms have been calculated by quantum chemical methods. The values are ‐417.33 and ‐105.02 kJ/mol, respectively. The structural characteristics and the mechanism of action of an antioxidant anticorrosive additive have been explored. It was found that the highest occupied molecular orbital (HOMO) of the additive is a π molecular orbital and it has the properties of a typical electron donor. The HOMO of the PFPEA additive reacts with the lowest unoccupied molecular orbital (LUMO) of an Fe atom and forms a coordinate bond and chemically adsorbed film on the metal surface. The film inhibits catalytic degradation and protects the metal surface. The additive is also capable of accepting the electron of RfO. The RfO radical combines automatically with the C7 atom of the benzene ring to terminate the RfO decomposition reaction. The PFPEA additive has been synthesized and analysed by UV and IR. Measurement of antioxidant anticorrosive properties indicates that, in the presence of the synthesised additive, the weight loss of a perfluoropolyether lubricant is reduced by about 7 times and the degradation temperature is increased by about 19°C compared with the base oil without the additive. The experimental results are consistent with the conclusions from the theoretical study.
Tribological behaviour of three phosphate esters containing the benzotriazole group as additives in rapeseed oil
Authors: Li Jiusheng , Ren Tianhui , Zhang Yanyan , Wang Dapu , Liu Weimin
Published: July 2006

Since the 1970s more attention has been paid to biodegradable lubricants as a way of reducing the pollution caused by lubricants with a mineral oil base. This concern has promoted the use of vegetable oils as alternative base oils. This paper reports on a study of the effect of phosphate esters containing the benzotriazole group as additives in rapeseed oil (RSO), tests being carried out using a standard four‐ball tester. The results show that these additives produce good antiwear performance and load‐carrying capacity compared with RSO alone. Surface analysis of the worn halls was carried out using X‐ray photoelectron spectroscopy. The tribological mechanism is discussed on the basis of the experimental results.
The influence of some additives on the lubricating properties of semi‐synthetic ester oils
Authors: Szalajko Urszula , Fiszer Stefania , Lipa Barbara
Published: July 2006

This article presents research on the lubricating properties of semi‐synthetic oils, made as compositions of mineral oil and esters. The esters were synthesized from acid substrates from the oxidation of paraffins. The last non‐seizure load (Pn), the weld point (Pz), the load wear index (Ih), and the limiting wear load (Goz) were measured, and the effects of additives or mixtures of additives were investigated by their effects on these parameters. It was found that the efficiency of the additives depended on their chemical characteristics and concentration, and also on the chemical nature of the ester component of the semi‐synthetic oils.
The influence of chemical structure on the physical properties and antioxidant response of hydrocracked base stocks and polyalphaolefins
Authors: Gatto V. J. , Grina M. A. , Tat T. L. , Ryan H. T.
Published: July 2006

This study was conducted to determine the effect of hydrocracked base stock chemical composition on lubricant properties, oxidation performance, and antioxidant additive response. Fifteen hydrocracked base stocks and polyalphaolefins were analysed by mass spectrometry for paraffinics, and single‐, double‐, and multi‐ring naphthenics. Low levels of aromatics were confirmed in all the base oils. A linear relationship was found between certain naphthenic structures in the base stocks and properties, such as viscosity index, aniline point, and volatility. Additivated versions of the base stocks were also screened in the rotary bomb oxidation test (ASTM D 2272) and the thin‐film oxygen uptake test (ASTM D 4742). A relationship between the types of naphthenic structures in the additivated base stocks and oxidative stability was found. Base oils containing low levels of condensed multi‐ring naphthenic structures exhibited superior oxidation performance, lower volatility, and poorer solvency. Furthermore, antioxidant structure had a profound effect on oxidative stability as the level of multi‐ring naphthenic structures in the base oils decreased. These results suggest that deeper knowledge of chemical composition could help in selecting base stocks and additives to meet future product specifications.
Production kinetics of the esterification of a polyol
Authors: Patil T. A. , Sen T. K. , Chattopadhyay S.
Published: July 2006

Tailor‐made esters are becoming more widely used as either synthetic base stocks or performance additives for producing, for example, premium‐grade synthetic or semi‐synthetic speciality greases, aviation lubricants, or metal‐working fluids. The present work, using a laboratory batch autoclave to evaluate the kinetic parameters, considers the kinetics of a typical non‐catalytic esterification of a suitable polyol at elevated temperatures (190‐220°C) and corresponding vapour pressure. The proposed rate equation represents satisfactorily the progress of the reaction.
Influence of abrading particle size on the wear performance of various polyamides
Authors: Rajesh J. John , Bijwe J. , Tewari U. S.
Published: July 2006

Various polyamides (PAs) containing different CONH2/CH2 ratios were selected for abrasive wear studies. Eleven types of silicon carbide (SiC) papers varying in particle size (10–175 μm) were selected as abrading counterfaces. The wear performance under single‐pass conditions indicated that the selected PAs did not show a size effect, in contrast to the case of metals and some other polymers. Wear rates were of the order of 2–17 × 10−11 m3/Nm. Scanning electron micrographs of some of the worn papers indicated correlations between wear and the size and number of wear debris particles and the amount of material transferred to the papers.
Friction properties of perfluorinated polyethers for hot‐dipped tin low‐level separable electrical contacts
Authors: Noël S. , Lécaudé N. , Alamarguy D. , Boyer L.
Published: July 2006

Tin coatings are used as a final protection for cuprous substrates involved in low‐level electrical contacts. High friction forces and fretting phenomena remain a cause of electrical failure of connector terminals, and so should be minimised. A lubricant layer can improve the life and reliability of connector terminals but such a layer must ensure low and stable resistance values even under severe temperature conditions. Work has been undertaken to investigate the lubricant layer most suitable for the protection of tinned electrical contacts. Perfluorinated polyethers (PFPEs) were chosen for their inertness. The aim was to correlate various physico‐chemical properties of branched or linear PFPEs, with their frictional and electrical properties. The long‐term electrical properties of a contact are shown to be linked to the initial wear mode in the contact.
Theoretical characteristics of hydrodynamic journal bearings lubricated with soybean‐based oil
Authors: Mongkolwongrojn M. , Arunmetta P.
Published: July 2006

Vegetable‐based oils are not only biodegradable but also environmentally advantageous, and the range of lubrication applications offered by them continues to grow. Recently, vegetable‐based oils have been combined with synthetic esters to produce modified vegetable‐based oils.

This paper presents an investigation of the theoretical characteristics of hydrodynamic journal bearings lubricated with non‐Newtonian soybean‐based oil. The soybean‐based oil was mixed with synthetic esters and silicone oil. The relationship between the shear stress and shear strain rate of the oil was obtained experimentally. The time‐dependent modified Reynolds equation including non‐Newtonian effects was formulated for short circular journal bearings. The perturbation technique was applied to the Reynolds equation to obtain zero‐ and first‐order pressure equations. The finite difference method was used to calculate the pressure distribution numerically. The static and dynamic characteristics, such as pressure distribution, Sommerfeld number, attitude angle, and spring and damping coefficients, were obtained numerically. It was found that the nonlinear factors of the non‐Newtonian soybean‐based oil strongly affected the performance characteristics of the journal bearings.
Time of exposure to lubricating liquid for predicting wear of UHMWPE in joint prostheses
Authors: Nakanishi Y. , Miyagawa H. , Higaki H. , Miura H. , Iwamoto Y.
Published: July 2006

It is generally agreed that contact pressure and sliding speed are the predominant factors for the prediction of wear of ultrahigh‐molecular‐weight polyethylene (UHMWPE) in joint prostheses. A new parameter for predicting the wear of UHMWPE has been introduced with a wear test in vitro. The parameter is the time of exposure to a lubricating liquid on a bearing surface. A pin‐on‐disc machine was designed such that the exposure time of a CoCrMo alloy disc to a lubricating liquid could be varied. The specific wear of UHMWPE was increased by a decrease in the exposure time, even if the contact pressure and the sliding speed were held constant. The parameter is able to account for the contact pressure set in the experiment (2.0–20.0 mPa), and clarifies the conditions under which the specific wear of UHMWPE is found to be high.
The effects of acid passivation, tricresyl phosphate presoak, and UV/ozone treatment on the tribology of perfluoropolyether‐lubricated 440C stainless steel couples
Authors: Shogrin Bradley A. , Jones William R. , Herrera‐Fierro Pilar , Jansen Mark J.
Published: July 2006

Research on the boundary lubrication performance of two perfluoropolyether (PFPE) thin films in the presence of passirated 440C stainless steel is presented. The study used a standard ball‐on‐disc (BoD) tribometer operating in dry nitrogen and a vacuum spiral orbit tribometer (SOT). Stainless steel surfaces were passivated using one of four techniques: a high‐temperature and low‐temperature chromic acid bath, a tricresyl phosphate (TCP) soak, or UV/ozone treatment for 15 min. After passivation, each BoD disc had a 400 Å film of Krytox® 16256 (PFPE) applied to it. The lives of these films were quantified by measuring the number of sliding cycles before an increase in friction occurred. The lubricated life of the 440C couple was not altered as a result of the various passivation techniques. The resulting surface chemistry of each passivation technique was examined using X‐ray photoelectron spectroscopy. The SOT was used to examine the effects of the TCP treatment on the lubricated life of another PFPE, Brayco® 815Z, under rolling conditions. None of the passivation techniques were found to increase dramatically the oxide film thickness or lubricated life.
The influence of lubricating fluid type on the properties of biodegradable greases
Authors: Florea Ortansa , Luca Marcel , Constantinescu Anca , Florescu Danilian
Published: July 2006

The lubricating ability of a grease depends on both the base oil and the thickener. As a result of their intrinsic properties and/or because of their com‐patibility with thickeners and specific additives, base fluids have different influences upon the properties of grease formulations. It is well known that mineral oils are the most widely used lubricant bases due to their inherent lubricity and lower cost, but recent environmental concern has led to consideration of the use of vegetable oils and readily biodegradable synthetic fluids as raw materials in lubricating grease formulations. As well as the base materials, the additives for biodegradable greases should also be biodegradable. This requirement limits the kind of products that may be used in environmentally friendly greases.

This paper presents comparative data concerning the tribological and physico‐chemical properties of biodegradable greases formulated with certain vegetable oils, such as rape seed oil, castor oil, and soybean oil or their mixtures, and synthetic esters. The improvement of the load‐carrying properties of biodegradable greases and the antioxidative effect of some suitable additives have also been studied, and the results are presented here.
Effect of solid lubricant and fibrous reinforcement on the abrasive wear of polyamides
Authors: Rajesh J. John , Bijwe Jayashree , Tewari U. S.
Published: July 2006

Short glass fibre‐reinforced polyamide 6 and polyamide 11 (PA 6 and PA 11) with and without a solid lubricant of polytetrafluoroethylene and metal powders (e.g., bronze) and copper as fillers were formulated and characterised for their compositional and mechanical properties. A tribological evaluation of these composites' abrasive wear was carried out by abrading a polymer pin against 80 grade (175 um) silicon carbide (SiC) paper under single‐pass conditions at various loads. It was observed that the fibre reinforcement reduced the abrasive wear resistance of virgin polymers. A combination of fibre and particulate fillers was further detrimental in this respect. Efforts were made to correlate the wear performance with the ductility factor, fracture toughness, and fracture energy in the case of PA 6 and its composites.
New citric esters with aromatic content and a complex structure considered for use as tribological fluids
Authors: Mirci L. , Boran S. , Luca P. , Boiangiu V.
Published: July 2006

This paper presents the results of research carried out to produce synthetic ester oils with a mixed structure, based on citric acid, with beneficial tribological properties and potential biodegradability. Two series of unsymmetrical triesters have been synthesised by varying the molar relationship between aliphatic alcohols from C1, to C13 along with an alcohol of a complex alkyl‐aryl structure, namely 2‐[(p‐nonyl)phenoxy]ethanol. The variation of the principal properties as a function of the length of the aliphatic chain introduced by the aliphatic alcohol and the aromatic content introduced by the alkyl‐aryl alcohol has been assessed. The wide range of viscosities of these triesters demonstrates their versatility, and the natural citric acid origin holds potential for their having good ecological characteristics.