bluuebunny/crossref_metadata_2025 huggingface dataset:
Some characteristics of silicones developed as lubricants
Authors: Lonsky P.
Published: July 2006

This paper outlines some of the properties of various silicone products, such as thermal and oxidative stability, corrosion protection, and vapour pressure. It looks at the suitability of developed fluids in various applications, and provides basic data on the performance of certain silicone fluids in tests.
Thermal oxidative ageing of neopentylpolyol ester oils: Evaluation of thermal‐oxidative stability by quantitative determination of volatile ageing products
Authors: Zeman A. , Koch K. , Bartl P.
Published: July 2006

During thermal‐oxidative ageing of pentaerythritol ester‐based oils a variety of volatile degradation products, eg acids, aldehydes, ketones, esters and O‐heterocyclic compounds are produced. It is shown that quantitative determination of individual acids and carbonyls using GC‐MS and/or HPLC can be used to assess the ageing behaviour of fully formulated aviation turbine oils. Of special importance is the Tenax‐GC method which allows a simultaneous determination of all volatile degradation products by GC‐MS. This is the third of a series of papers on thermal‐oxidative ageing of neopentylpolyol ester oils.1,3
The action of organo‐phosphate additives in polysiloxane fluids
Authors: Conte Alfeo A.
Published: July 2006

The four ball wear test apparatus was used to study the antiwear properties of four organo‐phosphate additives in dimethyl‐, phenyl methyl‐, and two chlorophenyl methyl siloxane fluids as a function of load, additive concentration and viscosity. In most cases an antagonistic ‘prowear’ effect is observed refuting the commonly held belief that the lack of antiwear activity is the result of the additive not getting to the surface or being displaced from the surface by polysiloxane fluids.
Performance testing of a multiservice synthetic grease for industrial and automotive use
Authors: Baudouin P. , Cholcha G. , Raich H.
Published: July 2006

This paper describes Grease A, a high drop point PAO type grease with multiservice capability, developed to fill the performance/cost gap which has existed in industrial and automotive applications between mineral‐based multiservice greases and synthetic greases, either specialised, or with multiservice capability orientated towards military applications, and usually expensive. It also briefly gives details on Grease B and Grease C, two other greases based on the same chemistry as Grease A, developed for very specialised and severe applications which cannot be covered by a multiservice grease, even synthetic, such as Grease A.
The influence of molecular structure on the frictional behaviour of lubricating fluids 2: Low coefficients of traction
Authors: Hentschel K.‐H.
Published: July 2006

In order to establish correlations between the chemical structure or constitution of fluid lubricants and their friction characteristics under elastohydrodynamic conditions, a number of model test fluids were tested in a twin‐disk machine. As test fluids, special saturated monobi‐, and tricyclic compounds, alkanes and polyethers were selected. The traction coefficients were shown to be strongly dependent on the chemical structure of the lubricants and on operational parameters. High coefficient values mostly arise from lubricant molecules that are shaped irregularly, with indentations and teeth as seen with Stuart‐Briegleb models, and allowing only heavily hampered rotational intramolecular motions along single bond axes. Low traction coefficients derive from lubricant molecules with a thread‐like shape and a minimum of structural subunits or functional groups involved in significant intermolecular interactions. In order to account for the results obtained, several paradigms and hypotheses are established and discussed in detail.
Analysis of the ester constituents of synthetic and semi‐synthetic oils
Authors: Forestière A. , Hipeaux J. C. , Denis J.
Published: July 2006

The analysis of lubricating oils commonly practised in petroleum laboratories is important in following the evolution of products available on the market. Several analysis methods have been proposed, particularly by Van Rysselberge, 1 Amos2 and Coates.3 All these extremely useful methods make use of conventional separation and identification techniques such as molecular distillation, dialysis, bydrolysis, chromatographic techniques, spectragraphic techniques and chemical methods for determining functional groups. Their main aim is to identify the different types of additives present in lubricants.

For several years now, however, base stocks have also been composed of synthetic products. Therefore, it seems important to add a simple method of ester identification to these analytical methods. Esters are normally analysed by saponification (to determine water‐insoluble acids and polyols) and by hydrolysis (for water‐soluble alcohols). Yet a complete reduction transforming constituent acids into alcohols simultaneously reveals all the elements making up an ester. Its reconstitution is then relatively easy. This reduction technique can be applied not only to esters but also to polymethacrylates used as viscosity index improvers and to antioxidant zinc dithiophosphates.
Aircraft engine oils and their behaviour at high temperatures
Authors: Maier K.
Published: July 2006

The characteristics of aero‐engine oils are changed considerably under high‐temperature conditions (≧ 200–250°C). The consequences of this are the formation of ageing products and deposits, deficiencies in tribological behaviour, and spontaneous ignition in extreme cases. The problems arising from these are illustrated using several selected examples, and their effects on engine functioning are described.
Future helicopter transmission oils
Authors: Spikes H. A.
Published: July 2006

For many years helicopter transmissions have shown low reliability relative to planned overhaul lives and to other comparable lubricated systems. Reasons for this include the extremely wide range of conditions encountered by the lubricant in helicopter transmissions and also the requirement that, in many cases, the oil be common to both transmission and gas turbine engines.

Recently acquired understanding of lubrication mechanisms shows that potential exists both for improved performance and for the ability to cater for higher temperatures by the development of new helicopter transmission oils based on synthetic lubricants.

This paper discusses the particular lubricating problems associated with helicopter transmission lubrication and describes test methods and formulation approaches to improving such lubricants.
PAH emissions of synthetic organic esters used as lubricants in a two‐stroke engine
Authors: Cosmacini E. , Cottica D. , Pozzoli L. , Leoni R.
Published: July 2006

In this paper are presented some results of research into gaseous emissions from a two‐stroke engine. These engines require a particular fuel consisting of a mixture of petrol and lubricating oil. In the research, a comparison was made between fuel mixtures containing mineral and synthetic base‐stock lubricants, in order to check the chemical differences between exhaust emissions from the same motor run under the same conditions. This comparison was made because synthetic lubricants based on organic carboxylic esters, when compared to mineral ones, have some peculiar properties: a smaller combustion residue, better lubricating ability and better thermal stability. There are therefore good reasons to suppose that the lubricant fraction of fuel mixtures, after combustion, may cause gaseous emissions whose composition may vary according to the lubricant used.
Military aircraft propulsion lubricants–current and future trends
Authors: Beane G. A. , Gschwender Lois J. , Snyder Carl E. , Shimski John T.
Published: July 2006

An assessment of the performance of MIL‐L‐7808J and MIL‐L‐23699C Military Specification lubricating oils in turbine engines and helicopter gear boxes is presented along with predicted performance of current and upgraded military specification oils in advanced and ‘growth’ engine designs. Data is presented on advanced ester base engine lubricants, corrosion inhibited engine oils, and separate helicopter gear box oils evolving from current developmental research efforts. Future high temperature candidate fluids representing the ultimate stability for turbine engine oils are also discussed. Their use, in most cases, entails engine design considerations to accommodate their unique properties. The advantages and disadvantages of the various classes of synthetic lubricants for turbine engine applications are discussed, and deficiencies are identified where additional research programmes are needed.
Biodegradability test for synthetic esters
Authors: Versino C. , Novaria M.
Published: July 2006

Various synthetic esters were tested for their biodegradability, using a test sequence that began with the creation of biomass using sucrose and municipal wastewater; biodegradation was measured using biochemical oxygen demand and chemical oxygen demand values. The test esters and resulting extractable matter were analysed by spectrophotomety. The esters were found to be biodegradable, to different degrees, subject to the presence of large amounts of water and the correct saline nutritive substratum.
Synthetic lubricants in India — an overview
Authors: Rao A. Madhusudhana , Srivastava S. P. , Mehta K. C.
Published: July 2006

Different synthetic products currently available and which find wide application as lubricants, are described, and their merits and demerits compared with the mineral based lubricants are outlined. Some of the major synthetic lubricants used in Indian industries are identified. The Indian chemical industry's potential to meet some of the requirements of synthetic lubricants is discussed and the need to create additional facilities in India for the manufacture of certain critical products, is described.
Improving the performance of synthetic base fluids with additives
Authors: van der Waal G.
Published: July 2006

Because of their improved performance characteristics over mineral oil based lubricants, partly and fully synthetic fluids are being used more open, the main types of synthetic base fluids being esters and polyalphaolefins (PAOs). The response of additives, such as anti‐oxidants, anti‐wear additives and viscosity index improvers, to mineral oil, eslers or PAOs will obviously differ. This paper reports an attempt to find the most effective types of such additives for esters and PAOs, in order to optimize lubricant performance. PAOs have deficiencies in terms of a number of peformance characteristics, particularly with respect to additive solubility, and they are thus blended with esters to improve these properties.
Thermal oxidation behaviour of synthetic oils: Basic studies in the polymerization of polyol ester oils
Authors: Koch B. , Jantzen E.
Published: July 2006

The oxidation behaviour of synthetic oils has been extensively studied during recent decades, and there is general agreement on both the mechanism and products of the oxidative degradation of oils. However, the other phenomenon of oil ageing, polymerization has been little studied. These polymers are responsible for the increase of viscosity, production of sludge and the formation of deposits. In the investigation reported here, oligomers have been isolated and studied at an early ageing stage. The dependence of viscosity on the degree of polymerization is demonstrated. A polymerization mechanism and a monomer for polyolester oils are proposed and discussed.
The hydrolytic stability of aircraft coolant/dielectric fluids
Authors: Conte Alfeo A. , Ruzansky Martin , Chen Richard
Published: July 2006

The change in flashpoint, volume resistivity and dielectric strength of 2‐ethylbutyl silicate ester (2‐EBSE) based and 1‐decene dimer polyalphaolefin (PAO) based fluids were measured as a function of initial water content and temperature. The PAO fluid was found to be stable while the 2‐EBSE fluid degraded to alcohol which significantly reduced its flashpoint. This was found to occur even with trace quantities of water present. Volume resistivity and dielectric strength were shown to be inadequate monitoring techniques for determining the extent of hydrolytic degradation.
Soft layer lubrication of artificial hip joints
Authors: Unsworth A. , Pearcy M. J. , White E. F. T. , White G.
Published: July 2006

An experimental study of the lubrication mechanisms existing in prototype artificial hip joints which have compliant surface linings, has shown that for a lining with a hardness of about 4N/mm2, fluid film lubrication can be achieved even with the low viscosity synovial fluid present in diseased joints after surgery. In tests, a synthetic lubricant was used in place of the synovial fluid. The best results seem to be produced with a 2 mm thick layer.
Evaluation of ferrofluids as lubricants
Authors: Deysarkar Asoke K. , Clampitt Bert H.
Published: July 2006

A ferrofluid is a colloidal suspension of up to 10% magnetic particles in a carrier fluid, which may be mineral or synthetic. The resultantfluids have many applications, for example where a magnetic field is present. A study was conducted of the effects of the nature of the carrier fluid and particle diameter on the viscosity build‐up characteristics of the ferrofluid in the presence of a magnetic field, and the results are presented. Tests were also carried out on a 4‐ball machine.
Influence of counterface roughness on the friction and wear of polytetrafluorethylene‐ and polyacetal‐based composites
Authors: Tanaka K. , Yamada Y.
Published: July 2006

The friction of various composites is generally little dependent upon the roughness. When the composites contain glass or carbon fibres, their wear rates are also little dependent upon the roughness. However, the wear rates of PTFE incorporating MoS2, graphite or bronze and polyacetal incorporating PTFE increase rapidly as the roughness increases beyond a certain critical value characteristic of each of these composites. The roughness‐dependency of the wear rate is markedly affected by the transfer during sliding.
Waste treatability of aqueous based synthetic metal‐working fluids
Authors: Napier S. , Cattell H. G. , Coffin P. S.
Published: July 2006

Synthetic coolants for the metalworking industry represent a wide array of chemical designs. The chemical types generally found in commercially available synthetic coolants are reviewed in terms of their treatability and their effect on the environment. Waste treatment schemes are discussed for two simple examples of anionic and nonionic aqueous based synthetic coolants respectively. The results obtained show that synthetic coolants may be successfully waste treated by conventional means. Total Organic Carbon (TOC) and Chemical Oxygen Demand (COD) are considered to be key parameters for measuring the waste‐treatability of aqueous synthetic coolants.
Development of high dilution, low pollution out‐board oils
Authors: Kenbeek D. , van der Waal G.
Published: July 2006

Two‐stroke outboard engines have long been considered noisy and polluting devices. However, attitudes towards these engines are changing thanks to the introduction of new engine designs and high dilution, low pollution outboard oils. In this paper the development of such oils is described. It is shown that using esters, with their excellent lubricity and inherent biodegradability, it is possible to formulate outboard oils with high performance in all respects.

When these oils are combined with automated oil supply systems, to avoid misblending and oil spillage, an optimal and environmentally friendly system is obtained. It is, however, desirable that appropriate legislation is established to speed up the introduction of these systems.
Lubrication of reciprocating compressors
Authors: Matthews P. H. D.
Published: July 2006

When gases with different chemical and physical properties are compressed, the type of lubricant to be used in compressing equipment must be given careful consideration. Basically, this equipment can be categorized as reciprocating or rotary. This paper describes the lubrication of reciprocating compressors. The development of lubricants for use in specific applications, such as the compression of air, natural gas, etc., is discussed in detail. This will include a section dealing with the development and use of screening tests to predict the performance of candidate lubricants, the role of current international specifications, compressor rig tests and field applications. The advantages and disadvantages of mineral oils and synthetic fluids in various applications will also be described in detail.
Perfluoropolyalkylether lubricants under boundary conditions: Iron catalysis of lubricant degradation
Authors: Carré D. J.
Published: July 2006

Perfluoropolyalkylether (PFPAE) oils and oil‐based greases exhibit signifcant degradation under boundary lubrication conditions. In the absence of significant concentrations of oxygen, as in the case of spacecraft orbital environments, the degradation mechanism consists of two steps: (1) the initial reaction of the PFPAE molecules with freshly exposed iron to form the Lewis acid, FeF3, followed by (2) the reaction of the FeF3 with unreacted PFPAE molecules, which results in the cleavage of the etherate linkages. The result is an autocatalytic degradation that takes place at temperatures below the onset of thermal decomposition. This mechanistic hypothesis is supported by the following experimental results: (1) The reaction of PFPAE with FeF3 has been shown to give rise to fluorinated‐ketone and acid fluoride ether‐cleavage products that are more reactive than the parent PFPAE molecules and have lower molecular weights and thus poorer lubricating ability. (2) FeFx compounds are formed in the wear tracks of wear‐test components under boundary lubrication conditions. On the basis of these experimental results, poor performance can be predicted for PFPAE oils under conditions in which high temperatures (approximately 350 °C) and freshly exposed metal surfaces are present (i.e., the conditions of boundary lubrication). This prediction is corroborated through wear tests in which the performance of PFPAE is compared to the performance of commercial petroleum‐based and synthetic‐ hydrocarbon lubricants to which lead naphthenate or antimony dialkyldithiocarbamate have been added. The test results confirm the well‐known fact that the antiwear additives are very important to prolonged wear life under boundary lubrication conditions. In addition, the results show that, compared to the other lubricants tested, the PFPAE lubricants do not demonstrate adequate lubrication pevormance. Both the PFPAE degradation mechanism and the fact that soluble antiwear additives are not currently available imply that PFPAE lubricants are not currently suitable for applications in which boundary lubrication conditions exist, especially when high loads are involved.
The mechanisms governing crack and pit formation in steel in rolling sliding contact in aqueous lubricants
Authors: Sullivan J. L. , Middleton M. R.
Published: July 2006

This paper presents the results of an investigation of the fatigue damage of steel surfaces operated in rolling/sliding contact conditions in the presence of water glycol‐based fire resistant fluids. It has been shown that pitting life depends on the relative magnitude of fluid film thickness and the lubrication regime in which the system is operated. A minimum in pitting life is shown to occur in the mixed‐elastohydrodynamic region.

Mechanisms for crack initiation, propagation and subsequent pit formation in aqueous lubricants are proposed.
Synthetic fluids for automotive gear oil applications: A survey of potential performance
Authors: O'Connor B. M. , Ross A. R.
Published: July 2006

This paper describes studies of transmission lubricants in an axle efficiency test rig. The test lubricants were evaluated over various temperature ranges, for each of five road load speed conditions. This was done for both truck and passenger car. Three synthetic gear oils were evaluated, based on various combinations of synthetic hydrocarbons, esters, and viscosity improvers, and were compared to conventional SAE 80W‐90 lubricants. All three oils demonstrated improvements in axle eficiency. Also reported are evaluations of seven test lubricants in a high‐temperature, high‐torque test, and results of seal compatibility tests.
Lubricant and additive effects on spur gear fatigue life
Authors: Townsend D. P. , Zaretsky E. V. , Scibbe H. W.
Published: July 2006

Spur gear endurance tests were conducted with six lubricants using a single batch of consumable‐electrode vacuum melted (CVM) AISI 9310 spur gears. The sixth lubricant was divided further into four batches, each of which had a different additive content. Lubricants tested with a phosphorus‐type load carrying additive showed a statistically significant improvement in life over lubricants without this type of additive. The presence of sulphur‐type antiwear additives in the lubricant did not appear to affect the surface fatigue life of the gears. No statistical difference in life was produced with those lubricants of different base stocks but with similar viscosity, pressure‐viscosity coefficients and antiwear additives. Gears tested with a 0.1 wt % sulphur and 0.1 wt % phosphorus EP additives in the lubricant had reactive films that were 200 to 400 Å (0.8 to 1.6 μin) thick.
The properties and applications of Perfluoropolyether lubricants
Authors: Caporiccio G. , Flabbi L. , Marchionni G. , Viola G. T.
Published: July 2006

This paper looks at the properties of perfluoroether fluids, in terms of their phyisical and chemical properties and antiwear characteristics. The molecular weight‐, kinematic viscosity‐ and specific gravity‐temperature relationships are given, and the fluids' chemical resistance and compatibilty with plastics and elastomers. Test results for for fluids on lubricity are given, as well as information on PTFE greases.
Synthetic two‐stroke engine oil as a tool of exhaust emission control
Authors: Kovács A. , Olagos D.
Published: July 2006

Polypropylene oligomers were used to formulate two‐stroke (2T) engine oil for once‐through lubrication systems, to enhance the exhaust emission characteristics of two‐stroke engines. The oligomers alone are suitable from a stability viewpoint, but must be reinforced with polyol‐ester components to have good load‐carrying capability. Both ash‐forming and ash‐free commercial additive packages can be used to formulate the end‐product. The exhaust stream includes the unburnt portion of the fuel:oil mixture. The lubricating oils formulated on polypropylene oligomer base do not contain polynuclear aromatics, the sulphur‐dioxide emission is due to the sulphur content of the fuel and additive (if any). On a bench test, the hydrocarbon emission was significantly lower using polypropylene oil, in comparison to using a commercial mineral‐oil‐based composition.
The lubrication mechanism in low speed plastic deformation with a synthetic lubricant — infiltration of lubricant into the boundary contact region
Authors: Kataoka S. , Kihara J. , Aizawa T.
Published: July 2006

To investigate and evaluate the micro‐pool mechanism in a mixed lubrication regime using polybutene lubricants, experiments were performed using 1 mm brass sheet, for various surface rough nesses of a work piece and die, lubricant viscosities and extrusion speeds. Systematic study showed that (1) the lower viscosity lubricant is easily squeezed out from the micro‐pools into the flat are a through the troughs between the tool and work piece caused by plastic deformation of work piece, and (2) with decrease in lubricant viscosity and speed, or the larger the tool surface roughness becomes, the more lubricant infiltrates into the tool‐work piece interface, which reduces the actual friction coefficient.
Rheology of synthetic lubricating oils
Authors: Wiślicki Bogdan
Published: July 2006

A lubricating fluid's flow characteristics are affected by fluid deformation resulting from the action of mechanical forces: flow resistance, dissipation of mechanical energy, transfer and dampening of mechanical disturbances. These in turn affect the lubricating ability of the fluid through energy absorption, power transfer and other properties. Synthetic fluids can display various thixotropic characteristics and non‐Newtonian effects. In this paper, experimental work on these phenomena are reported.
Properties of synthetic oils derived from waste polyolefins
Authors: Déak Gy. , Bartha L.
Published: July 2006

Synthetic oils are mainly used in lubricant compositions meeting strict or special technical requirements. Most synthetic oils presently manufactured belong to three types of oils, i.e. polyalphaolefins (PAO), esters and alkyl benzene derivatives. Elsewhere, the authors have described results obtained in synthesising polyolejin oils starting from olefin mixtures produced by mild thermal degradation of waste polyethylene.1,2 In the present paper, the dependence of the flow properties of polyolefin oils on the average molecular mass of the starting olefin mixture is discussed, and some preliminary results are given on synthesising alkenyl succinic esters and alkyl benzene derivatives starting from the same raw materials obtained from waste polyethylene.
Wear reduction of partially stabilised zirconia by lubrication
Authors: Maurin‐Perrier Ph. , Kapsa Ph.
Published: July 2006

Lubricants are often used to improve the behaviour of ceramics for tribological applications. In this paper, the case of Zirconia, lubricated with different additive‐containing lubricants, is described, to show the antiwear mechanisms during boundary lubrication of ceramics. It was found that the presence of a lubricant eliminates the surface degradation observed in dry friction (mainly transfers). The use of an ester‐based lubricant is associated with a decrease in wear of the ceramic, while silicone‐based lubricants lead to surface damage.

With additives, the formation of an interfacial layer adherent to the ceramic is dependent upon the tribological behaviour of the base alone. If that layer is created, zirconia does not form part of its composition.
Compositional changes in lubricated sliding metal surfaces related to seizure
Authors: Johansson Erik , Hogmark Sture , Nilsson Helen , Redelius Per
Published: July 2006

This paper presents an investigation into the mechanisms of failure in lubricated sliding metal contacts. Reciprocated sliding with cylinder‐on‐disc geometry was performed with three types of lubricants based on polyalphaolefin (PAO) oils and three sets of additives. The normal force and sliding speed were chosen to give partial scuffing or seizure within a few hours. The chemical surface films which form through reactions between additives in the lubricants and the metal surfaces were analysed by scanning electron microscopy and Auger electron spectroscopy, before and after the onset of seizure.

It is concluded that all three oils formed a rigid surface film as a result of a combination of chemical and mechanical actions in the contact surface. Seizure was initiated by mechanical fatigue and disruption of the film which exposed the metal surfaces to severe scuffing. It Was Also Noticed that different additives gave different friction and wear properties to the contact system.
Lubrication characteristics of oils and greases applied to ball bearings for use in vacuo
Authors: Seki Katsumi , Nishimura Makoto
Published: July 2006

Three experiments were conducted to evaluate the long‐term running performance in vacuo of ball bearings lubricated by a synthetic oil and grease. The first experiment was carried out using ball bearings of a shielded deep‐groove type (no. 6204) filled with a grease containing perfluoropolyalkylether (PFPAE) as a base oil and TFE as a thickener. Tests were done at room temperature in a vacuum of 10−4∼10−5 Pa mainly at a rotational speed of 2,000 r/min under an axial load of 50N. The bearings were successfully run for a period of 24,400 h, which corresponds to 3 × 109 revolutions. About 10% in weight of the grease was lost during the test. An inspection of the running accuracy of the bearings tested showed negligible change. The degradation of the grease inspected by FTIR was found to be negligible. A change in the molecular weight distribution of the grease was not observed during the test. The second experiment was conducted with angular‐contact‐type ball bearings (no. 7204), with retainers impregnated with PFPAE oils. Exploratory work was done using full‐component‐type ball bearings (no. 7204), lubricated by a heat‐cured PFPAE oils, both in vacuo and in an air environment. The bearings were run for 280 h (5.0 × 106 revolutions) in air at a speed of 300 r/min under an axial load of 50 N, but failed to operate afer 25 h (4.5 × 105 revolutions) in a vacuum.
EHL traction and related rheological parameters under high temperature conditions
Authors: Muraki M.
Published: July 2006

An approximate formula is presented for the maximum traction coefficient in EHD conditions, by making some reasonable simplifications of an Eyring fluid model. Experiments are conducted for some mineral and synthetic hydrocarbon oils over a wide range of temperatures. Among the rheological parameters related to maximum traction, the representative stress τ0, is determined from the experimental traction curve while the effective viscosity‐pressure coefficient α is obtained in a high pressure viscometer. When the temperature is raised, α falls and τ0 rises. The behaviour of τ0 for some paraffinic oils follows the Eyring theory while the effect of the dissociation of molecular clusters appears with the naphthenic oils. The increase in temperature causes a reduction in the maximum traction coefficient, which can be predicted with sufficient accuracy by the formula using the rheological parameters expressed as a function of temperature.
Chlorotrifluoroethylene oligomer based nonflammable hydraulic fluid. 1 Fluid, additive, and elastomer development
Authors: Gschweder L. J. , Mattie D. , Syder C. E. , Warer W. M. , van Brocklin C. H.
Published: July 2006

A chlorotrifluoroethylene (CTFE) based nonflammable hydraulic fluid for use in the −54 °C to 175 °C temperature range has been developed for use in future aircraft and armoured land vehicles to reduce fire losses and improve survivability. The desired flammability, chemical, and physical properties of a non‐ flammable hydraulic fluid were defined in the 1970s and extensive screening tests were performed to determine the best candidate nonflammable hydraulic fluid basestock. CTFE was selected because it had the best overall properties of all the candidates investigated. Structurelproperty correlation studies were conducted better to understand the behaviour capabilities and limitations of the CTFE basestock. Extensive research and development have been per‐ formed to develop soluble, effective antiwear and antirust additives to improve some of the critical properties of CTFE. A successful formulation utilising a stabilised zinc, containing corrosion inhibitor and a sulphonamide antiwear additive, has been developed which meets all temperature, lubricity, compatibility, and thermal stability requirements. Research was concurrently conducted to develop elastomers and seals compatible with the CTFE fluid. Several materials have been developed which are usable in somewhat limited applications and Viton GLT has been found to be successful for wide temperature range applications. This paper also discusses toxicity studies and results, environmental effects, future plans and applications, and the current military specification, MIL‐H‐53119.
A naphthenic oil of hydrogenated coal tar distil‐ late as a lubricant with low solidification pressure
Authors: Sakai T. , Murakami T. , Yamamoto Y. , Uchiyama H. , Komoto T. , Tezuka T.
Published: July 2006

A new type of lubricant, TN, composed mainly of condensed polycyclic naphthenic hydrocarbon rings, was developed from coal tar through a complete hydrogenation process. This oil is characterised by a high pressure‐viscosity coefficient and low solidification pressure.

The tribological characteristics of this new oil were investigated in an elastohydrodynamic lubrication regime under sliding, rolling/sliding, and rolling contact conditions. The results for the TN oil were compared with those of several oils of different molecular structures: polyalphaolefin of paraffinic hydrocarbon, and naphthenic and paraffinic petroleum oils. It was found that the TN oil was superior to the other oils tested in its ability to form thick oil films, to reduce wear, to increase the coefficient of traction, and to prolong fatigue life.
Chlorotrifluoroethylene oligomer based nonflammable hydraulic fluid. 2 Hydraulic components' development
Authors: van Brocklin C. H. , Campbell W. B. , Gschwender L. J. , Sharma S. K. , Snyder C. E.
Published: July 2006

A requirement for a nonflammable hydraulic fluid was defined in the 1970s to eliminate losses attributable to hydraulic system fires. In order to increase the possibility of success of the nonflammable hydraulic fluid development programme, requirements for compatibility with current hydraulic fluids, seals, and system designs were not established. All previous attempts to develop a compatible nonflammable hydraulic fluid had been unsuccessful. Extensive screening of many chemical classes of candidate base fluids led to the selection of a Chlorotrifluoroethylene (CTFE) oligomer. Considerable hardwarel system development was performed for hydraulic system applications, including development of high‐pressure actuators, pumps, and motors. The major thrust of the programme, a totally new system design, was demonstrated in the Lockheed High Technology Test Bed air craft and in the McDonnell Douglas Aircraft 55.2 MPa (8000 psi) technology ‘Iron Bird’ demonstrator. Possible retrofit applications for current systems include a C135E fireproof brake system and the M1/M1A1 Abrams tank gun mount. This paper also discusses material compatibility requirements, design considerations, and the results of pump testing of the nonflammable hydraulic fluid.
Polymer formation during thermal‐oxidative ageing of aviation turbine oils
Authors: Fuchs Hans‐Joachim , Zeman Alfred
Published: July 2006

Oligomers/polymers formed during the thermal‐oxidative ageing of ester‐based aviation turbine oils have been investigated, using pentaerythritol tetraheptanoate as a model ester. The principal polymer structures in the primary ageing state were revealed by means of chromatographic and spectroscopic methods. The most probable structures are dicarboxylic acid polyesters with variable amounts of α,ω‐dicarboxylic acids having chain lengths of C2 up to C7 The C7‐branches also contained ester‐bonded hydroxy as well as oxo substituents. Pentaerythritol triheptanoate discarboxylic acid mono esters were active precursors in polymer formation.
Oil soluble polyethers in automotive crankcase lubricants
Authors: Cracknell Robert
Published: July 2006

The evaluation of oil soluble polyethers (OSPs) in fully and semi‐synthetic automotive crankcase lubricants is described. Parameters including viscosity, additive compatibility, lubricity/wear performance, oxidative stability, and piston cleanliness are assessed. It is possible to formulate OSP‐containing lubricants with lower VI improver treatment level, superior viscometric properties, and Noack volatilities to comparable lubricants without OSPs. Data from engine tests and field trials show that semi‐ and fully synthetic lubricants containing OSP possess all the performance advantages of ester‐containing lubricants, with additional benefits in terms of engine and inlet system cleanliness. The results indicate that OSPs have excellent potential as synthetic lubricant base fluids.
Hydrolysis of phosphate‐based aviation hydraulic fluids
Authors: Aberathy S. M. , Laurent J. W.
Published: July 2006

High‐temperature in‐service failure of phosphate ester‐based aviation fluids is primarily due to acid‐catalysed hydrolysis. The reaction is controlled with epoxides, but careful attention to the other additives is needed to avoid including species which catalyse hydrolysis. From an airline's point of view, water concentration is the critical factor, since it is the only variable that it can control. From a system designer's point of view, minimising fluid temperature should be a goal. Plots relating fluid life to temperature and water level for typical commercial fluids are included.
The lubrication property of LB films of cadmium salt of long chain fatty acids
Authors: Du Zuliang , Zhu Ziqiang , Zhang Jun , Xue Qunji
Published: July 2006

In this paper, the authors have systematically studied the friction characteristics of various Langmuir‐Blodett (LB) films of cadmium salts of long alkyl chain fatty acids. The parameters chosen were the number of layers of LB film, the load, and the sliding velocity. The results showed that there exists a range of numbers of layers for which a kinetic friction coefficient value (uk)as low as 0.02 is obtained. On the other hand, the friction coefficient in‐creased gradually as the sliding velocity increased.
The design of fuel efficient automotive hypoid gear lubricants
Authors: Law D. A. , Rowe C. N.
Published: July 2006

Synthesised lubricant base stocks and the performance additives used in hypoid gear lubricants can both be chemically designed to give improved hypoid gear efficiency and, therefore, better vehicle fuel economy than provided by conventional lubricants

In this paper, the authors review, relative to a widely used SAE 90 grade mineral oil‐based lubricant, the changes in gear efficiency which have been documented using certain classes of synthesised lubricants. These advantages are described in terms of (a) EPA City and Highway Cycle efficiencies, (b) absolute data over a wide temperature range under four selected speed/torque combinations, and (c) absolute changes in inefficiency compared to the mineral oil product.

Newtonian and non‐Newtonian fluids have been studied. The bulk oil temperature at which a specific lubricant gives maximum efficiency is dependent on both gear operating conditions and on the chemical composition of the lubricant.
A reaming test for cutting fluid evaluation
Authors: De Chiffre L. , Lassen S. , Pedersen K. B. , Skade S.
Published: July 2006

As an alternative to tapping torque measurement and thread finish evaluation, a reaming test is suggested for the evaluation of the lubricating efficiency of cutting fluids. An investigation was carried out where results from tapping torque measurements were compared with those from measuring torque, feed force, and surface roughness in reaming. Two different tap geometries and two different reamer geometries were used. Technically‐pure aluminium was used as the workpiece material and four laboratory water‐based cutting fluids as well as a commercial cutting oil were investigated.

The results show that lubricants have a significant and similar effect with respect to both tapping torque and reaming torque, when tools with straight flutes are used. In reaming, a more comprehensive picture of lubrication can be obtained if torque measurement is accompanied by determination of the surface roughness. In a subsequent investigation, the reaming torque and roughness test was used to evaluate two different water‐based cutting fluids and a neat oil, using austenitic stainless steel as the workpiece material.
The tribology of plastics — an overview
Authors: Wang Chenghe
Published: July 2006

With the widening use of plastics, it has become an urgent task to study their behaviour in friction systems. The present paper reviews the applications of plastics during the past decades and their function in friction systems. The paper analyses the basic differences between metals and plastics in structure and properties, and points out the limitations, or inapplicability, of using metal tribology to solve problems in plastic friction systems when even different kinds of high‐molecular materials have different shapes and applications.

The paper also looks at the variety of plastic surfaces, and briefly presents the mechanism, theory, and calculation of the fiction, wear, and lubrication of plastics; theories of plastic wear are summarised. Also presented are the technical functions, simple application techniques, and economic benefits of plastic friction systems.
Determination of synthetic lubricant concentrations in soil during laboratory‐based biodegradation studies
Authors: Haigh Susan D.
Published: July 2006

The use of synthetic, biodegradable lubricants for two‐stroke engines has become widespread due to increased concern over the build‐up of hydrocarbons, derived from mineral oil‐based lubricants, in the aquatic environment. A method for assessing the biodegradation potential of new lubricants was developed by the Co‐ordinating European Council (CEC) for the Development of Performance Tests for Lubricants and Engine Fuels in 1982. However, this method deals only with the aquatic environment. The use of such lubricants in agricultural machinery led to a modification of the CEC method to assess the relative biodegradability of lubricants in soil. After incubation of oil‐treated soil in a simple and inexpensive incubation assembly, samples were extracted with solvent and the level of lubricant determined by infrared spectroscopy. The method was found to be both accurate and reproducible, giving excellent recoveries. It compared favourably with a gravimetric method and was so sensitive that it gave appreciable blank values from untreated soils owing to their content of long chain aliphatic natural products. The incubation and extraction methods were used successfully to assess the biodegradability of a range of synthetic lubricants in soil in comparison to a mineral oil‐based lubricant and a natural vegetable oil. The synthetic oils were found to degrade more rapidly and extensively than the mineral oil‐based lubricant but not as rapidly or extensively as the vegetable oil. Amendment with nitrate considerably enhanced the loss of all the oil tested, indicating the importance of nitrogen availability when assessing the inherent biodegradability of hydrocarbons in soil. As the data generated is from laboratory‐based studies the results do not necessarily translate directly to the field situation. However, the method is suitable for screening new materials and for comparative purposes.
Investigation of biomass formation during the biodegradation of ester base lubricants
Authors: Hund K. , Grolms U. , King J. M. H. , Bünemann T.
Published: July 2006

Comparative studies were performed to assess the biodegradation of the synthetic lubricant base stock, Priolube 3999, by P. putida using the CEC test method and manometric respirometry. Supplementary analyses demonstrated the production of a non‐readily biodegradable metabolite, trimethylol‐propane, the alcohol group of the candidate fluid. Evidence was obtained that indicated that a significant fraction of carbon added as test substance remained incorporated in the biomass. The implications of these results are discussed and modifications to the CEC test proposed.
Effects of solid lubricants in backward extrusion
Authors: Nakamura Tamotsu , Saiki Hiroyuki , Nkk Naoki Ikeuchi , Ishibashi Itaru
Published: July 2006

In the present paper, some solid lubricants were tested in backward extrusion friction tests with flat‐headed punches using aluminium at room temperature. The results showed that anti‐seizure ability was improved when wax was added to the solid lubricant samples. In addition, a water‐based graphite lubricant and an ultrahigh molecular weight polyethylene (UHMW‐PE) lubricant were tested using aluminium workpieces heated to 500°C. The lubricity of the UHMW‐PE lubricant was found to be superior to that of the graphite lubricant.
Tribological performance of PBT/PC/TPE ternary polymer alloy
Authors: Lin Heng Yao , Holmberg Kenneth , Säynätjoki Matti
Published: July 2006

Polybutylene terephthalate (PBT)/Polycarbonate (PC)/thermoplastic elastomer (TPE) ternary polymer alloy (TPA) is one of a new generation of PBT based polymer alloys with good thermal conductive, mechanical, and physical properties. TPA‐59 was chosen as representative material factorially‐de‐signed experiment and has been studied, in the present work, to evaluate its potential as a tribological material. Its sliding, friction, and wear behaviour under unlubricated conditions was investigated with a pin‐on‐disc machine using various loads, sliding velocities, sliding distances, and disc surface roughnesses. The specific wear rates were found to be comparable to those of commercial materials currently used in bearings.
Structure—activity correlations for sulphur EP additives
Authors: Herdan J. M. , Valeanu Gabriela , Popescu A.
Published: July 2006

A series of new sulphur compounds was synthesised. Mercaptoheterocycles and mercaptoethanol were reacted with C12‐C22 chloroacetates. Mercaptoethanol derivatives were subsequently reacted with trialkyl borates. The solubility of S‐methylcarbalcoxy derivatives in both mineral oil and synthetic esters strongly depended on the alkyl group length, the most soluble being the C12. C14 derivatives. Three tests were used to estimate the antiwear (AW) and extreme pressure (EP) performance of the sulphur compounds: a four ball machine, an LFW‐I machine, and a Falex tester. Despite some differences resulting from the test methods, the best EP characteristics were obtained with the 2‐mercaptobenzothiazole derivatives. This showed that even a strongly bonded sulphur atom, such as that of the thiazolic ring, participates in surface layer formation. Mercaptoethanol derivatives were less soluble in either mineral or ester‐based synthetic oils. Esterification of the hydroxyl groups with trialkyl borate improved their solubility and load carrying performance.
On sliding friction and wear of polyetheretherketone (PEEK) composites at elevated temperatures
Authors: Lu Z. , Friedrich K. , Küntzler B.
Published: July 2006

The friction and wear behaviour of polyetheretherketone (PEEK) composites, incorporating different amounts of short carbon fibres with different surface treatments, was studied under dry sliding conditions against smooth steel on a pin‐on‐disc apparatus at different temperatures. Wear of the composites was reduced considerably in all cases, but, whatever the surface treatment, wear increased with increasing temperature for all proportions off fibres. For minimum friction coefficient there was an optimum proportion of fibre volume fraction of about 10 vol.%. The effect of the fibre surface treatment was not significant for the tribological behaviour of the PEEK composites. To predict wear performance, a wear model proposed by Friedrich and Voss seemed to work properly, and, furthermore, a friction model was developed to predict the friction behaviour of PEEK composites with short carbon fibres.
An approach to characterisation of producibility and lubricity of reacted films under boundary lubrication
Authors: Jin Y. S. , Zhou C. H.
Published: July 2006

Boundary oil films can be transformed into reacted films during an extremely short period of time under certain conditions of reactive dynamics. A comprehensive index R is introduced to characterise the producibility and lubricity of the reacted films. Index R, which is calculated using maximum and minimum friction coefficients in the formation process of the reacted films as well as from the reacting and maintaining periods of the films, is correlated to conditions of reactive dynamics, such as temperature, pressure, and velocity.