Oil-based Lubricants Research Articles

The effect of electrical current on premature failures and microstructural degradation in bearing steel

Premature failures associated with microstructural degradation, i.e. white etching cracks (WECS), are becoming commonplace as applications are requiring tribological components to operate under extreme conditions. Although the specific drivers of WECs are still debated, the failures are often found in applications where cyclic loading is combined with added energy from stressors such as slip, impacts, or stray current. The aim of the current work is to elucidate effect that variable current has on premature failure. Numerous commercially available lubricants were tested, and both lubricant base oil type and additive package were found to have an effect on WEC failure time.

Smart carbon dots as chemosensor for control of water contamination in organic media

A novel nanoprobe was synthesized by functionalizing gluthatione/citric acid–carbon dots (CDs) with a benzo-isoquinolin-based molecule, methyl 3-(4-(2-(5-((methylsulfonyl)oxy)pentyl)-1,3-dioxo-2,3-dihydro-1H-benzo[de]isoquinolin-6-yl)piperazin-1-yl)propanoate (water chemosensor, WCS), to detect trace amounts of water in non-aqueous media via on-off fluorescence. The design and synthesis of the free molecule WCS and the functionalized nanoprobe (CD-WCS) are described in detail and as well as their full characterization by different spectroscopic methods. WCS was found to be an excellent indicator of pH in aqueous media and exhibited, in solvents of different polarity, solvatochromic behaviour. On the other hand, the modified fluorescence intensity of CD-WCS was found to be an excellent indicator for water in non-aqueous media (organic solvents and oil-based lubricants). In these media, CD-WCS showed weak fluorescence intensity due to a photoinduced electron transfer (PET) process. Sequential addition of trace amount of water led to revival of CD-WCS fluorescence intensity. The fluorescence on-off mechanisms are proposed for WCS in aqueous media as well as for CD-WCS in non-aqueous media. The analytical performance characteristics of CD-WCS showed a limit of detection for water of 0.00021 % (v/v) in toluene and 0.00014 % v/v in base-oil lubricant. The potential application of CD-WCS as chemosensor of water contamination in oil-based lubricants as well as green anti-wear/anti-friction lubricant additive are outlined.

Comparison and Analysis of Custard Apple Seed Oil with Engine Lubricant (Bio Lubricant)

Now a day’s the prices are increase and the decline of fossil fuels is generating a great deal of need to find an alternative lubricant from non-edible oil seeds. To order to solve the issue of energy shortages, an alternative energy source must be required. Vegetable oils are perceived to be alternatives to mineral oils for lubricant base oils because of certain inherent technical properties and their biodegradability. Vegetable oils with high oleic contents are considered to be the best alternative to substitute conventional mineral oil-based lubricating oils and synthetic esters. This paper mainly reveals about extraction of oil from custard apple seeds and the study of its composition and physic-chemical properties. Custard apple seeds were tested for their physicochemical properties in the production of biological lubricants. Research indicated that 27.5 percent of oil content in the seeds. The bio lubricant was analyzed for a quality test such as density, viscosity, flashpoint, fire point, calorific value.

Evaluation of lubricant properties of polyolester oil blended with sesame oil-An experimental investigation

The yearly emissions of synthetic oil to the watercourses alarmingly affect the living organisms in the water bodies, lands and affects the entire earth as a harmful pollutant. Oils from the vegetables/seeds are nowadays preferred as base lubricating oil over synthetic oils because of their less toxicity, biodegradability and renewability. Among the agricultural seed oils, sesame oil is one of the major oil produced around the globe and in this work, it is selected because of its variety of advantages reported in various literature and its similar physical properties as that of base polyolester oil. Seven blends were made using sesame oil and polyolester oil and their thermal, rheological, physiochemical, oxidative, corrosive, tribological, foaming, contact angle and ecological properties are studied and compared with that of base oil. The fatty acid profile of oils is found out using GCMS technique. The thermal properties, viscosity and viscosity index, are found to be increasing with the increase in the proportion of sesame oil in the blend. The foaming tendency of all blended lubricants is found to be less than the polyolester oil. The CoF and WSR of the 15POE+25SESO blend are the least when compared to other blends and the base polyolester oil, whereas the contact angle/wettability is found higher for 20POE+20SESO blend. Up to 100 μg per ml of water of 15POE+25SESO blend is found to be least toxic to the microorganisms and all the blends were biodegradable as the proportion of sesame oil in the blend increased. Hence as a lubricant, 15POE+25SESO blend is the best alternative for conventional POE oil in terms of thermal, rheological, oxidative, nature-friendly, foaming, wettability and tribological properties in a refrigerant compressor.

Effect of temperature and mating pair on tribological properties of DLC and GLC coatings under high pressure lubricated by MoDTC and ZDDP

Diamond-like carbon (DLC) and graphite-like carbon (GLC) coatings have good prospects for improving the surface properties of engine parts. However, further understanding is needed on the effect of working conditions on tribological behaviors. In this study, GLC and two types of DLC coatings were deposited on GCr15 substrate for investigation. The friction and wear properties of self-mated and steel-mated pairs were evaluated. Two temperatures (25 and 90 °C), three lubrication conditions (base oil, molybdenum dithiocarbamate (MoDTC)-containing oil, MoDTC+zinc dialkyldithiophosphate (ZDDP)-containing oil), and high Hertz contact stress (2.41 GPa) were applied in the experiments. The results showed that high temperature promoted the effect of ZDDP on steel-mated pairs, but increased wear under base oil lubrication. The increased wear for steel-mated pairs lubricated by MoDTC-containing oil was due to abrasive wear probably caused by MoO3 and β-FeMoO4. It was also found that in most cases, the tribological properties of self-mated pairs were better than those of steel-mated pairs.

Chemical Characterization Using Different Analytical Techniques to Understand Processes: The Case of the Paraffinic Base Oil Production Line

Mineral base oils are used to produce commercial lubricants and are obtained from refining vacuum residue. Lubricants are used to reduce friction in industry devices, so their viscosity is a key characteristic that needs to be optimized throughout the process. The purpose of this study is to show how global chemical characterization of samples from the base oil production chain can facilitate a better understanding of the molecular impacts of processing and their effect on macroscopic properties like viscosity. Eight different samples were characterized by different analytical techniques, including liquid chromatography and mass spectrometry techniques, to understand their chemical evolution through the different process units at the molecular level. Furthermore, a statistical treatment allowed for the identification of parameters that influence viscosity, mainly sulfur and polyaromatics content. This study demonstrates the importance and effectiveness of cross-checking results from different complementary analytical techniques to acquire valuable data on lubricating oil base samples.

Research progress of molecular level exploration of lubricant base oil and liquid-liquid extraction process

Research progress of molecular level exploration of lubricant base oil and liquid-liquid extraction process

Madhuca Indica (Mahua): A novel feedstock for bio based lubricant application treated with trimethylolpropane and tribological analysis

ABSTRACT The degradation of the lubricant is not possible as they are non-biodegradable and are toxic to nature. Around the globe, various studies are going on while concentrating on bio-based lubricant which could be environment friendly. In this analysis, friction and wear of the Mahua oil-based lubricant have been carried out at different loads. The mahua oil was treated with trimethylolpropane for improving lubrication characteristics and then blended with synthetic oil in the ratio 4%, 8%, and 12% by volume. The proper mixing of the blends was done with help of ultrasonicator. The loads assigned were 20, 80, and 140 N. The tribological analysis at various loads was assessed using a pin on disc tribometer. The sliding velocity of the disc on every load applied has been 0.4 m/s. The lubricating framework that existed during the experiment constituted boundary lubrication. Improvement in frictional behaviour and anti-wear characteristics was shown by 4% and 8% blends of Mahua oil at all the applied loads. The 12% blend shows maximum friction and wear. The worn surface images were better obtained with 4% and 8% blends.

Performance assessment of vegetable oil-based minimum quantity lubrication (MQL) in drilling

Metalworking fluids are widely used to increase productivity and quality of metal cutting. However, these metalworking fluids possesses the problems in terms of the effect on environment and health of the worker. Hence, various approaches to provide cooling and lubrication are explored such as mist cooling, high-pressure cooling, minimum quantity lubrication (MQL), nano fluids, solid lubricants, etc. In this regards, the present work exhibits the performance evaluation of vegetable-based minimum quantity lubrication (MQL) in drilling of aluminium alloy. This drilling tests have been performed in different cutting environments such as Dry, flood cooling, MQL with castor oil, MQL with sunflower oil with uncoated HSS twist drill. The effect of various drilling parameters have been analysed by measuring surface roughness, axial thrust, and torque produced. The comparison of results indicates effectiveness of the vegetable-based MQL in terms improved surface finish and reduction in axial thrust and torque during drilling.

Performance evaluation of bio-lubricants in strip drawing and deep drawing of an aluminium alloy

ABSTRACT With the increasing awareness and concerns towards the detrimental impact of mineral-oil-based lubricants, a step forward is crucial to replace them with benign environment-friendly lubricants. Bio-lubricants, due to their intrinsic lubricant properties attributed to the presence of long chain fatty acids, have an immense potential to be utilised as green lubricants and could be promising substitutes for the mineral oil-based lubricants. In this work, the performance evaluation of three bio-lubricants (Cottonseed, Karanja, and Jatropha oils) is carried out by applying in strip drawing and deep drawing experiments. The strip draw tests are conducted to determine the coefficient of friction, whereas the effectiveness of the bio-lubricants in the deep drawing are examined evaluating the drawability, thinning, drawing load and surface finish. The obtained results are compared with a mineral-oil-based lubricant and a water soluble paste. All the three bio-lubricants are found to perform well in comparison to mineral-oil-based lubricant in terms of resulting friction coefficient, drawability, and thinning at low normal pressure. Cottonseed oil is found to be better than the other two bio-lubricants. However, with an increase in normal pressure, the lubricating performance of bio-lubricants decreased significantly which can be addressed by adding extreme pressure additives.

Green synthesis of ester base oil with high viscosity — Part II: Reaction kinetics study

As an eco-friendly lubricant base oil, ester base oil is receiving increasing attention. However, studies on synthetic reaction kinetics of high viscosity complex ester have been rarely reported. In this work, based on the principle of equal reactivity of all functional groups and simplified kinetics models, synthetic reaction kinetics for high viscosity complex ester was investigated in two steps. As for the esterification of trimethylolpropane with glutaric acid, the activation energies of the first and second stage were 55.3 and 73.5 kJ/mol, respectively. As for the esterification of the first step products with 2-ethylhexanoic acid, the activation energies of the first and second stage were 60.6 and 98.2 kJ/mol, respectively. As for the esterification of the first step products with n-heptanoic acid, its activation energy was 68.9 kJ/mol. A mutation phenomenon on reaction order from zero to second order was discovered, which could be explained by the strong adsorption of organic acid on catalyst surface. The conversion rate of carboxyl of synthetic reaction for mixed acid ester was estimated by simulation, and average relative error was less than 3.0%. The synthetic process of high viscosity complex ester was considered to consist of a series of parallel–consecutive reactions with addition–elimination mechanism.

Tribological Analyses of Modified Jatropha Oil with hBN and Graphene Nanoparticles as An Alternative Lubricant for Machining Process

The increase of health and environmental consciousness has motivated the effort of technology improvement on lubrication by finding and exploring another potential alternative to replace mineral-based metalworking fluids. Due to this concern, vegetable-based oils have been recognised as an ideal lubricating base oil in machining due to low toxicity, biodegradable, and renewable energy sources. Moreover, nanofluids have attracted enormous attention in the field of lubrication due to excellent physical and chemical properties that can enhance tribological characterisation. The objective of the current work is to develop a new formulation of nanofluids in modified jatropha oil (MJO) by adding hexagonal boron nitride (hBN) and graphene nanoparticle additives at the lowest concentration (0.01, 0.025. and 0.05 wt. %). The physicochemical tests in terms of kinematic viscosity and viscosity index were conducted and compared with synthetic ester (SE). Tribology testing was conducted through four-ball test to determine the coefficient of friction, mean wear scar diameter, and friction torque. The result shows a significant improvement of MJO samples by adding nanoparticle additives compared to the SE. MJOg2 (MJO + 0.025 wt. % of graphene) exhibited excellent tribological behaviour by providing the lowest coefficient of friction and friction torque. Meanwhile, MJOh1 (MJO + 0.01 wt. % of hBN) provided with a smaller mean wear scar diameter among other lubricant samples. Conclusively, the addition of nanoparticle additives significantly enhanced the tribological characteristics and is highly suitable as a substitute for SE.

Influence of Hydrogen Bonding and Ionicity of Protic Ionic Liquids on Lubricating Steel–Steel and Steel–Aluminum Contacts: Potential Ecofriendly Lubricants and Additives

Three ecofriendly protic ionic liquids (PILs), 2-hydroxyethylammonium 2-ethylhexanoate, 2-hydroxymethylammonium 2-ethylhexanoate, and 2-hydroxydimethylammonium 2-ethylhexanoate, with different extents of hydrogen bonding and ionicities, were synthesized and examined as neat lubricants and lubricant additives to a mineral oil (MO) under steel/steel and steel/aluminum contacts. The stability of each PIL–MO blend was observed and correlated to their individual structural features; their physicochemical and tribological properties were investigated and compared to a commercial mineral oil-based lubricant. The addition of any PIL to the mineral oil improved lubricity in steel/steel contact. In aluminum/steel contact, the PILs were studied as neat lubricants and additives showing different effects. The PIL with lower extent of hydrogen bonding but higher ionicity presented poor friction and led to higher wear as neat lubricant. However, as additive, this PIL prevented the intense tribo-corrosion reactions and generated a stable lubrication film that reduced friction; and was capable to form a protective layer on aluminum surface to avoid severe wear.

Miscibility, corrosion and environmental properties of six hexanoate- and sulfonate-based protic ionic liquids

In this work, six different types of protic ionic liquids (PILs) have been studied. For all these PILs, the bacteria toxicity and environmental biodegradability have been investigated, as well as their corrosive behavior and miscibility in different types of lubricating base oils. The PILs studied showed poor to moderate biodegradability (BOD5/COD from 0.072 ± 0.002 to 0.18 ± 0.01) and slight toxicity (TU values between from 1.18 ± 0.04 and 2.7 ± 0.1). However, these environmental properties are much better than those obtained for the reference lubricant additive used in industry (ZDDP). In addition, five of the PILs did not show corrosive activity on steel. Only one of the PILs showed some miscibility in an ester as a base oil and the rest of the mixtures were highly unstable.

Experimental investigation of effect of biodiesel fatty acid methyl ester on performance of engine oil dispersant additive

In the present work, blends of methyl oleate (MO), polyisobutylene-bis-succinimide (PIBSI) and a mineral lubricant base oil were oxidized and some of their physicochemical properties were evaluated to understand the effects of biodiesel fatty acid methyl esters on the performance of the engine oil dispersant additive PIBSI. The oxidation experimentations of blends were conducted under elevated temperatures. Thereafter, the viscosity and acidity of fresh and oxidized blends were determined. The dispersancy, thermal stability and chemical species of oxidized samples were tested and analyzed by the blotter spot method, a TGA, and a GC/MS, respectively. Results showed that the viscosity and acidity of blends containing MO increased significantly after oxidation. The dispersing ability of PIBSI was markedly impaired by only a small amount of MO in a blend. In addition, the thermal characteristics of blends were altered by MO. Many varieties of oxygenated chemicals in the oxidized blend containing MO were detected. The negative impact of MO on performances of PIBSI was attributed to the accelerated oxidation caused by MO, and to the chemical interactions between MO and PIBSI. The present results demonstrated that PIBSI was incompatible with MO.

Moringa Oleifera: Bio based lubricant development from a novel feedstock for tribological characterization

ABSTRACT The vegetable oils are the possible substitute to the conventional lubricants as they are biodegradable and non-toxic. In this study, friction and wear of the Moringa oleifera oil-based lubricant have been carried out at different loads. The Moringa oleiferaoil was chemically modified with treatment with trimethylolpropane. The synthetic oil was blended with Moringa oleifera Oleifera oil in the ratio of 5%, 10%, and 15% (% by volume). The applied loads were 50, 100, and 150 N. The sliding velocity of the disc was 1.3 m/s at each applied load. The physicochemical characteristics of the lubricants were identified through various instruments. The worn surface images was obtained using scanning electron microscope after performing test at 150 N load. The 5 and 10% blends of Moringa oleiferaoil shows minimum COF and specific wear rate among all the blends. Also, they show minimum wear scar diameter at all loads. Better worn surfaces were observed during the addition of 5% and 10% chemically modified Moringa oleiferaoil.

Studying the influence of single droplets on fuel/air ignition in a high-pressure shock tube.

The interaction of fuel and lubricant droplets with gaseous fuel/air mixtures close to autoignition is relevant in the context of unwanted early autoignition in spark-ignition internal combustion (IC) engines. To study the influence of droplets on the ignition of fuel/air mixtures independent from the in-cylinder pressure/temperature history, the shock-tube technique in combination with an injection system was established, which enables the generation and injection of single droplets or droplet clusters of n-dodecane and lubricant base oil behind reflected shock waves at pressures and temperatures representative for the compression phase of IC engines. Injected droplets were imaged by high-repetition-rate laser-induced fluorescence. The ignition process was observed by imaging in the visible and UV simultaneously through the shock-tube end wall with a combination of color- and UV-sensitive high-repetition-rate cameras. It was found that the amount and composition of the injected liquid are important factors determining the extent of the interference with the ongoing autoignition of the premixed fuel/air bath gas. For a stoichiometric mixture of primary reference fuels (PRF95) in air, the droplets significantly accelerate ignition especially in the negative temperature coefficient regime at around 760 K. The comparison of the timing of local ignition and the occurrence of volumetric ignition indicates that only in cases where the surrounding gas is close to autoignition, the droplets can trigger early autoignition. This required temporal and spatial coincidence might explain the high level of randomness of early autoignition in engines.

Micromanufacturing Technology and its Practice

In order to make micro composite drills (Fig. 1), cemented tungsten carbide (WC-10Co) and high strength (AISI 4340) steel were successfully bonded by hot compaction diffusion bonding at a low temperature. The effects of holding time, pressure and temperature on microstructure and mechanical properties of the sintered carbides and bonding strengths of the bimetallic composites were examined, and a transitional layer was found at the interface as a result of elemental inter-diffusion. The optimal bonding parameters were determined to achieve the maximum bonding strength of 226 MPa of the WC-10Co/AISI 4340 steel joints, which is helpful in producing micro composite drills. Microforming is introduced to produce lighter and more energy effective products. In this study, Magnesium-Lithium (Mg-Li) alloy, new material in microscale, was chosen to superior formed micro-cup due to its ultralight weight with outstanding ductility. The dry and oil lubrication conditions were chosen as benchmarks to investigate effects of a novel oil-based nanoparticle lubricant in micro deep drawing (MDD) process of Mg-Li alloy. Finite Element (FE) modelling was conducted and the simulation results of the drawing force were in a good agreement with the experimental results. The formed cup quality with consideration on the surface roughness has been extensively evaluated and the results illustrated the quality improvement was substantial.

PVD Coated Tools and Surface-Structured Workpieces in Dry Cold Forming of Steel

Cold forming, particularly forward impact extrusion, is used for mass production of steel components. To ensure robust forming processes, the workpieces are usually phosphated and then soaped as well as mineral oil-based lubricants are used. As these lubricants are often harmful to the environment and health, alternative approaches are to be investigated from an ecological, economic and legislative perspective. To achieve dry, lubricant-free cold forming of steel, two approaches are being pursued here. The tool-sided approach focuses on self-lubricating hard coatings, which are deposited on the forming tools by means of physical vapor deposition (PVD). The developed coating system CrAlN+Mo:S is synthesized in an industrial coating unit by a hybrid sputtering process, which combines direct current (DC) and high power pulsed magnetron sputtering (HPPMS) technology. The coating consists of a hard matrix CrAlN which is modified by Mo and S to provide friction reduction due to the in situ formation of MoS2 reaction layers under tribological load. The workpiece-sided approach focuses on the surface structuring by shot peening with various peening materials and particle shapes. In order to evaluate the influence of the self-lubricating tool coating CrAlN+Mo:S and the various workpiece topographies, dry full forward impact extrusion tests were carried out in an industrial scale with coated and uncoated tools. On the one hand, a one-shouldered die geometry and on the other hand a two-shouldered die geometry were tested. The field trials reveal that for both die geometries, the tool coating significantly reduces the punch force and the wear compared to the uncoated dies. Depending on the workpiece topography, it was shown that a smoother surface leads to reduced adhesive wear. Furthermore, it was proven that the dies with an opening diameter of D = 31.4 mm and an outlet diameter of d = 20.7 mm could be coated continuously over a length of l = 50 mm on the entire inner surface. After the dry field trials, the CrAlN+Mo:S coating remained completely intact. Hence, the developed coating system CrAlN+Mo:S exhibits great potential to conduct dry, lubricant-free cold forming of steel at industrial scale.

Synthesis and Tribological characteristics of a nano CuO particle-filled water-based lubricants

The oil-based lubricating system tends to produce high cutting temperatures owning to the low cooling capability of oil lubricants. The addition of lubricating additives in nanoscale could increase the tribological and lubrication performance of the water-based lubricants. In this work, nano CuO particle-filled water-based lubricants as cutting fluids were developed using ultrasonication process. The Thermophysical Properties of synthesized nano filled water-based lubricant was tested and analyzed. The tribological characteristics were fairly investigated using four-ball and pin on disc apparatus testing units. The results indicated that nano CuO filled water-based lubricant shows enhanced tribological performance in terms of coefficient of friction (COF) and wear scar diameter (WSD) compared with base coolant. The superior performance of CuO filled water-based lubricant was credited to the detail that CuO nanoparticle additives arrived the rubbing interface and made a tribo-thin layer of CuO. Water-based lubricant showed the highest surface deformation compared to nano-based lubricants which indicate that the damage was due to adhesive wear.