Base Oil Type Research Articles

Influence of water on the tribological properties of zinc dialkyl-dithiophosphate and over-based calcium sulphonate additives in wet clutch contacts

Usually the wet clutch lubricant properties vary with different formulations of base oil types and additives. The aim of this paper was to evaluate the effect of water on the performance of additives in ATF. Simplified lubricants, ZDDP and over-based Ca-sulfonates detergent additives in an API Group I mineral base oil, were employed to compare with the commercial fully-formulated automatic transmission fluid (DEXRON®VI) during water-contamination. A full-scale wet clutch test rig was used to evaluate the frictional response due to water contamination of the lubricants. Fourier Transform Infrared Spectroscopy was utilized to evaluate the variation in the solubility of these polar organic additives in the water phase and Karl-Fischer titration was utilized to evaluate the post-test water content for different formulations.

Stable deformation of droplets surface subjected to a high-voltage electric field in oil

Abstract Electro-demulsification is widely applied to the dehydration of emulsified oil. A droplet exposed to an electric field is polarised in oil and then stretched to a prolate sphere. The internal electric field distributions of prolate-sphere and spherical droplets are analysed in this work. The expressions of force acting on the droplets surface are obtained by establishing a model of stable droplet stretching deformation. An experiment is conducted to determine the draw ratio of water droplets subjected to a high electric field and exposed in four types of base oil. Comparison of the results of the experiment and model shows that the stable deformation of droplets is well predicted by the model. System parameters, such as electric field strength, droplet initial radius, interfacial tension of droplet – oil, permittivity and effect on the deformation of droplets, are also discussed.

Influence of Additive Chemistry on the Physical, Chemical, and Cooling Properties of Quenching Oils

Abstract Quenching, the most common method of hardening metals, involves continuous cooling from a given austenitization temperature to achieve full transformation into martensite. Thus, optimal mechanical properties are obtained. The quenching media contains a base oil and different types of additives depending on application requirements. The cooling rate mainly depends on the thermal characteristics of metals, section thickness of workpieces, and heat-removal properties of the quenching medium. For the base oil, it is possible to use petroleum oils, synthetic oils, and natural oils separately or in combination. Petroleum base oils are widely used because of their thermal-oxidative stability advantages in comparison to natural oils, or lower prices in comparison to synthetic oils. There are numerous compounds available for potential use based on their functional properties. Environmental and safety requirements also exhibit a strong influence on additive selection. For this reason, the current use ofbarium-containing additives must be replaced with less harmful compounds. Petroleum basestocks should be replaced by renewable basestocks that are biodegradable, as is the current general trend in lubricant development. By changing the composition of quenching oils, base oils, and/or additives, the heat transfer characteristics are also changed. In this study, quenching oils with different types of additives are tested and the results regarding their physical and chemical properties as well as cooling characteristics are presented. Cooling curves of the tested oils have been evaluated according to ISO 9950:1995.

The Slow-Speed Wear Behavior of Case-Carburized Gears Lubricated with NLGI 00 Grease under Boundary Lubrication Conditions

NLGI 00 greases are often used to lubricate gears running at low pitch line velocities, such as, for example, in large open gear drives. At low pitch line velocities, sliding wear, which under these operating conditions is referred to as slow speed wear, is often the limiting factor to gear lifetime. A thorough knowledge of the effect of different grease components on the wear behavior is therefore important when selecting a grease to effectively reduce gear wear in a given gear drive. In order to systematically investigate and analyze the influence of different grease components on the slow-speed wear behavior of case-carburized gears, systematic gear tests using the Gear Research Center's (FZG) back-to-back gear test rig were conducted. Primarily, the focus of the experimental investigations is on the influence of the base oil viscosity and type, the additive type, and also the type of soap thickener on the gear wear behavior at low pitch line velocities. To experimentally determine the influence of these different grease components on the wear behavior of case-carburized gears, a modified, more stringent wear test, based on the standard DGMK slow-speed wear test for gear oils, was developed. Different NLGI 00 greases with base oil viscosities between ν40 = 70 and 1,200 mm2/s were investigated.Base oil type and base oil viscosity were shown to have only a minor effect on the wear behavior under boundary lubrication conditions. On the other hand, the thickener type and especially the additive type play an important role in determining the wear behavior.

Influence of Lubricant Properties on ARKL Temperature Rise and Transmission Efficiency

It has been suggested in the literature that the ability of a lubricant to produce low “end of test temperature” (EOTT) in the achsialrillenkugellager (ARKL)—that is, axial groove ball bearing—thrust bearing test is an indicator of its likely efficiency in vehicle transmissions. Based on this, the current study has used regression analysis to correlate the ARKL EOTT with a range of physical and friction properties of a set of 26 lubricants. The latter have been selected to span a wide variety of base oil and additives types. It has been found that the most important lubricant property in determining ARKL EOTT is the elastohydrodynamic (EHD) friction or traction coefficient at low slide–roll ratio. Lubricants with low EHD friction were found to give low EOTT. Two lubricant properties of secondary importance have been identified. One is the lubricant viscosity index (VI), where a high VI contributes to high EOTT. The second is the heat transfer capability of the fluid, where a high capability was found to correlate with lower EOTT. The findings help clarify how low EOTT in the ARKL test can be achieved via lubricant composition. If the correlation between ARKL and transmissions that has been suggested in the literature is valid, then these findings are transferable to the design of high efficiency transmission lubricants.

A STUDY OF THE PERFORMANCE AND CHARACTERIZATIONS OF CLEANUP FLUIDS FOR RESERVOIRS DRILLED BY USING OIL-BASED MUD

The correct selection of the reservoir drilling fluid is critical to achieve the ultimate aim of minimizing formation damage for the completed such wellbores. This study evaluates the performance of a standard Oil Based Mud (OBM) to drill horizontal wellbores, concentrating on its formation damage characteristics and the Flow Initiation Pressures (FIP) required for production to flow through the filter-cake. For heterogeneous reservoirs, the study shows that in low permeability rocks the damage is relatively low but the FIP is high. Conversely, for high permeability rocks the FIP is low but formation damage is relatively high. If the drawdown pressure available from the reservoir is low, then we have the scenario where inflow will occur predominantly from the higher permeability formations which could be badly damaged but little inflow will occur from the relatively undamaged lower permeability rocks. In terms of maximizing production, this is obviously a less than optimal scenario. With this in mind, evaluations were conducted of cleanup fluids to gauge their effect on lowering the FIP of the OBM filter-cake. Various fluids were screened for their mud removal performance which would potentially indicate good OBM ‘chemical breakers’. Mud parameters such as oil: water ratio, base oil type and emulsifier content all affected the efficiency of the cleanup fluids. The best cleanup fluids were then utilized in a series of core tests to evaluate their effectiveness in reducing the filter-cake FIP.

Toward the Development of Raman Spectroscopy as a Nonperturbative Online Monitoring Tool for Gasoline Adulteration

There is a critical need for a real-time, nonperturbative probe for monitoring the adulteration of automotive gasoline. Running on adulterated fuel leads to a substantive increase in air pollution, because of increased tailpipe emissions of harmful pollutants, as well as a reduction in engine performance. Consequently, both classification of the gasoline type and quantification of the adulteration content are of great significance for quality control. Gasoline adulteration detection is currently carried out in the laboratory with gas chromatography, which is time-consuming and costly. Here, we propose the application of Raman spectroscopic measurements for on-site rapid detection of gasoline adulteration. In this proof-of-principle report, we demonstrate the effectiveness of Raman spectra, in conjunction with multivariate analysis methods, in classifying the base oil types and simultaneously detecting the adulteration content in a wide range of commercial gasoline mixtures, both in their native states and spiked with different adulterants. In particular, we show that Raman spectra acquired with an inexpensive noncooled detector provides adequate specificity to clearly discriminate between the gasoline samples and simultaneously characterize the specific adulterant content with a limit of detection below 5%. Our promising results in this study illustrate, for the first time, the capability and the potential of Raman spectroscopy, together with multivariate analysis, as a low-cost, powerful tool for on-site rapid detection of gasoline adulteration and opens substantive avenues for applications in related fields of quality control in the oil industry.

The influence of quenchant composition on the cooling rate

Abstract Adequate selection of quenching media decreases the risk of tensile stresses, and also of cracking and workpiece distortion. High-performance quenching oils must have very high oxidation and thermal resistance and low sludge formation, must be non-staining and have a high flash point and acceptable heat-transfer characteristics. The quenching media contain a base oil and different types of additives according to application requirements. Mineral oils, synthetic and natural oils, used separately or in combination, may be used as base oils. Mineral base oils are widely used because of their advantages with respect to stability in comparison to natural oils, or lower prices in comparison to synthetic oils. There are numerous compounds available for use but, besides their functional properties, the environmental and safety requirements have to be considered in the selection of components. Based on that, barium additives must be replaced with less harmful compounds. Petroleum derivatives should be replaced with renewable base stocks that are biodegradable, which is a general trend in lubricant development. By changing the composition of quenching oils, base oils and additives, heat transfer characteristics are also changed. In this study, the results of investigation into physical and chemical properties and also cooling characteristics of new quenching oils with different compositions are presented. Cooling curves for different compositions have been evaluated according to the ISO 9950 Standard.

Bearing torque characteristics of lithium soap greases with some synthetic base oils

This article describes the influence of rheological properties on the bearing torque characteristics of the lithium soap greases with five types of base oils. The greases used had different yield stress depending on the base oils even with the same thickener concentration. Measurement of bearing torque was conducted for a deep-groove radial ball bearing by using a bearing test apparatus. The bearings filled with greases initially exhibited high torque but showed gradual decrease in the torque with prolonged rotation, where the greases with higher yield stress showed larger normalized torque decrease. Observation of bearing after the rotation revealed a tendency that the greases with larger normalized torque decrease had been pushed aside in the raceway by channeling. This implied that the greases with higher yield stress tended to show channeling. On the other hand, the greases with lower yield stress circulated within the bearing by churning and showed smaller normalized torque decrease. These behaviors were explained in terms of the yield stress of the greases and the shear stress to entrain the greases into the contacts. Observation of grease structure was made with atomic force microscopy showed that the greases whose thickener network structure was distributed more densely had higher yield stress.

Effect of composition on oil quenchant performance

AbstractQuenching is the most common method of hardening metals and involves continuous cooling from a given austenitising temperature to achieve full transformation into a martensitic structure. The cooling rate depends mainly on the thermal characteristics of the metal, the section thickness of the workpieces and the heat removal properties of the quenching medium. Oils, when used as quenching media contain a base oil and different types of additives according to the application requirements. As the base oil, it is possible to use mineral, synthetic and natural oils, either separately or in combination. Mineral base oils are widely used because of their advantages in stability in comparison with natural oils, or lower price in comparison with synthetic oils. There are numerous additives available for use but, besides functional properties, the environmental and safety requirements have to be considered in their selection, e.g. barium additives must be replaced with less harmful compounds. Additionally, ...

2308 金属新生面によるグリースの分解と水素発生挙動におよぼす添加剤の影響(トライボロジー(2),一般講演)

In application of bearings under the severe frictional conditions, nascent clean surfaces of bearing steel are created, so that the hydrocarbon components of greases can adsorb on and thus decompose by such reactive surfaces. As a result, generated hydrogen penetrates into the bearing steel and related hydrogen embrittlement occurs with anomalous structural change. Using controlled atmosphere cutting apparatus, therefore, this study investigated the decomposition behavior of greases with nascent clean surfaces of a carbon steel. Quadrupole mass spectrometer monitored the ion strength of fragment ions inside the test chamber and this spectrometry demonstrated that the behaviors of grease decomposition and the resultant hydrogen generation were greatly influenced by the types of base oils and the chemical structures of additives.

Elastohydrodynamic lubrication friction mapping – the influence of lubricant, roughness, speed, and slide-to-roll ratio

A friction test is conducted in a Wedeven Associates Machine ball-on-disc test rig. The output from the test, friction coefficient versus entrainment speed and slide-to-roll ratio (SRR), is presented as a three-dimensional friction map. A number of parameters are varied while studying the friction coefficient; surface roughness, base oil viscosity, base oil type, and extreme pressure (EP) additive package. Entrainment speed, SRR, and oil temperature are also varied. The results show that the mapping is efficient in showing the different types of friction that may occur in an elasto-hydrodynamic lubrication contact. The results also show that the friction behaviour can be strongly influenced by changing surface roughness as well as base oil viscosity, base oil type, EP additive content, and operating temperature.

Tribological behaviour of an elastomer aged in different oils

This paper presents the influence of aging the nitrile rubber, the most popular seal material, in various base fluids on sliding friction and abrasive wear. The lubricants used are synthetic esters, natural esters, different types of mineral base oils, poly-α-olefins and very high viscosity index oils. Friction has been studied for two directions of motion with respect to lay on the elastomer sample by using the SRV Optimol test machine. These findings show that as compared to all other lubricant formulations, ageing the elastomer in polyol ester leads to the maximum reduction of friction coefficient especially in perpendicular sliding to the initial lay on the surface. The abrasive wear studies were carried out by using a two-body abrasive wear tester against dry and lubricated elastomer. It was interesting to note that two-body abrasive wear of elastomeric material was higher during rubbing in presence of the fluids as compared to that in dry condition. Further, aging the elastomer in these base fluids especially in ester base fluids, results in more abrasive wear.

Exposure to Oil Mist and Oil Vapour During Offshore Drilling in Norway, 1979–2004

To describe personal exposure to airborne hydrocarbon contaminants (oil mist and oil vapour) from 1979 to 2004 in the mud-handling areas of offshore drilling facilities operating on the Norwegian continental shelf when drilling with oil-based muds. Qualitative and quantitative information was gathered during visits to companies involved in offshore oil and gas production in Norway. Monitoring reports on oil mist and oil vapour exposure covered 37 drilling facilities. Exposure data were analysed using descriptive statistics and by constructing linear mixed-effects models. Samples had been taken during the use of three generations of hydrocarbon base oils, namely diesel oils (1979-1984), low-aromatic mineral oils (1985-1997) and non-aromatic mineral oils (1998-2004). Sampling done before 1984 showed high exposure to diesel vapour (arithmetic mean, AM = 1217 mg m(-3)). When low-aromatic mineral oils were used, the exposure to oil mist and oil vapour was 4.3 and 36 mg m(-3), and the respective AMs for non-aromatic mineral oils were reduced to 0.54 and 16 mg m(-3). Downward time trends were indicated for both oil mist (6% per year) and oil vapour (8% per year) when the year of monitoring was introduced as a fixed effect in a linear mixed-effects model analysis. Rig type, technical control measures and mud temperature significantly determined exposure to oil mist. Rig type, type of base oil, viscosity of the base oil, work area, mud temperature and season significantly determined exposure to oil vapour. Major decreases in variability were found for the between-rig components. Exposure to oil mist and oil vapour declined over time in the mud-handling areas of offshore drilling facilities. Exposure levels were associated with rig type, mud temperature, technical control measures, base oil, viscosity of the base oil, work area and season.

Seal Material and Base Fluid Compatibility: An Overview

This study compares the seal material compatibility of environmentally adapted base fluids with that of mineral and synthetic base fluids. The seal materials studied were nitrite rubber (NBR), hydrogenated nitrile rubber ( HNBR), and fluorine rubber (FKM) elastomers, which are common in lubricated applications. The base fluids studied were synthetic esters (monoester, polyol ester, complex ester, and diester), a natural ester (i.e., vegetable oil), different types of mineral base oils, polyalphaolefin, and a fluid of very high viscosity index. The base fluids have been studied without additives. The elastomeric properties measured include volume, hardness, tensile strength, and elongation. A small elastomer volume increase was observed for mineral base oils whereas a significant increase was noted for all synthetic esters when tested on NBR and HNBR. The mechanical properties of the elastomers deteriorated in all cases. The amount of deterioration (i.e., in the tensile strength and the elongation) was in general less than 30%.

High temperature tribological behaviour of lubricating emulsions

This study investigates the oil release mechanism of oil in water emulsions at temperatures well over the boiling point of emulsions. Emulsions E1 and E2 were prepared by shearing two different types of base oils in water. The tests were performed using a modified wear and friction tester with ball-on-ring configuration operated at temperatures up to 300 °C. The ring samples were made of AA 5182 aluminium alloy and were rubbing against SAE (AISI) 52100 type bearing steel ball in lubricated condition. The tests were performed in a range of loading conditions (e.g. load from 4 to 24 N and sliding speed from 0.1 to 0.25 m/s). The sliding distance for each test was dependent on the breakdown point of the emulsion, which was attained by increasing the sample temperature, and could reach to a maximum of 50 m. It was shown that for each type of emulsion there was a critical temperature above which the emulsion could not release oil to the contact surfaces. At and above this temperature, friction coefficient increased dramatically and severe material transfer to the steel ball was occurred. The critical temperature was found to be independent of load, sliding speed and type of sliding materials, but it was strongly related to the oil concentration in emulsions. It was shown that at the critical temperature, film boiling was inhibiting oil release to the contact surface, resulting in dry sliding condition. The critical temperature of an emulsion was defined as the temperature at which the vapour layer between the emulsion and the hot surfaces was so thick that it was able to separate all the components of the emulsion from the hot metal surfaces.

Molecular spectroscopic studies of the effect of base oils on additive—additive interactions

AbstractThe effect of different types of base oil of API Groups I to V, such as mineral based (solvent refined, hydrofinished, hydro‐cracked/ wax isomerised) and synthetic based (polyalphaolefin and ester), on the interaction of zinc dialkyldithiophosphate (ZDDP) with polyisobutylene succinimide (PIBS) has been studied by variable‐temperature (VT) IR and 31P NMR spectro‐scopic techniques. Since ZDDPs are known to exist in monomeric and polymeric forms and as neutral and basic salts, and their functioning is temperature dependent, the structural changes observed in the NMR and IR spectra of the ZDDP—PIBS system in different base oils have been addressed with this in mind. The strength and composition of ZDDP—PIBS complexes has been explained in terms of the degree of solvation provided by the medium (base oil) in which they are present, and thermodynamic parameters ΔH and ΔS estimated from the VT IR spectra. The results indicate that the complexes are stronger and stable in polar base oils, such as from Groups I and V. The equilibrium shifts towards the neutral form of ZDDP in polar base oils. The results have been substantiated by correlating the variation in the shift and width of IR and 31P NMR signals to the stability of the complexes and low values of ΔH and ΔS. Polar solvents, such as methanol and tetrahydro‐furan, also favour the formation of the neutral form of ZDDP and stronger complexes between PIBS and ZDDP, in a manner similar to that observed for polar base oils.

The behaviour of friction modifiers under boundary and mixed EHD conditions

AbstractThe behaviour of a range of model and commercial friction modifiers (FMs) has been evaluated under elastohydrodynamic (EHD) and boundary lubrication conditions. Using a series of long‐chain carboxylic acids, it has been shown that measured boundary friction coefficients (BFCs) decrease with increasing chain length, unsaturation level, temperature, and concentration. Base oil polarity was found to have no effect under these conditions. Commercial oleate esters in synthetic base fluids gave lower BFCs than nitrogen‐containing compounds under the same conditions. This difference was observed over a range of concentrations and temperatures. The friction performance of formulated oils under mixed and full‐film EHD conditions was found to be dependent on FM, base oil, and detergent type. Under boundary conditions, friction was found to vary with FM type, but the effect of changing the base oil and the detergent system was negligible.

An in-line ampoule-breaking furnace for mass spectrometric study of the thermal stabilities of volatile oils

This paper describes the design, development, and construction of an in-line pyrolysis unit for the mass spectrometric study of the thermal stabilities of light oils or volatile liquids. A sealed glass ampoule, containing about 100 μg of sample, is dropped into the furnace which is preheated and controlled at the desired temperature. After the chosen pyrolysis time has elapsed, a piston is screwed down to break the ampoule, and the pyrolysis products are thereby released and impelled by helium carrier gas via a heated capillary into the mass spectrometric source. For gas chromatography–mass spectrometry (GC–MS) analysis, the products pass directly through the GC column before entering the MS source. The glass fragments are contained within a perforated tube, which is removed, cleaned, and replaced before inserting a new ampoule. This new pyrolysis unit has small dead volume, is precisely temperature-controlled, and contains no cold regions where products would condense. Results obtained with this equipment show that the pyrograms have good resolution, and because there are no product losses, the available sensitivity is high. The use of this unit is demonstrated by measuring the thermal degradation of two types of base oil at 400 °C for various durations of heating, and analysing the products by GC–MS. The unit can also be used to study the thermal behaviour of oils in different atmospheres or with specific additives.

A comparative life cycle assessment of the manufacture of base fluids for lubricants

AbstractA comparative life cycle assessment (LCA) study of three types of base oils used in the manufacture of hydraulic fluids has been carried out, and is reported here. The fluid types investigated are a mineral oil, a synthetic ester, and a rape seed triglyceride oil. The applications chosen for the finished lubricants are in mobile hydraulic systems in forestry operations, some of which are almost 100% total loss applications. The scope and limitations of the LCA model are discussed, and conclusions drawn concerning the application of LCA models as evaluation tools for the development of environmentally adapted lubricants. The methodology used is compatible with the ISO 14000‐type industrial standard.