Vegetable Oil-based Lubricants Research Articles

Tribological performance and mechanism of graphite, hBN and MoS2 as nano-additives in palm kernel oil-based lubricants: A comparative study

Layered nanoparticles have received considerable interest in tribological applications owing to their outstanding tribological performances, including in vegetable oil-based lubricants. Despite the advantages of vegetable oil-based lubricants over petroleum-based lubricants, the limited manufacturing scale of vegetable oil-based lubricants restricts their more comprehensive implementation in various industries. In order to gain further insights into the exquisite nano-additive properties of layered nanoparticles, this research was conducted to explore the tribological performance of palm kernel oil-based lubricants combined with three different layered nanoparticles, namely graphite, hexagonal boron nitride (hBN), and molybdenum disulfide (MoS2), using a four-ball tribotester. The four-ball tribotester analysis indicated that the wear scars lubricated with graphite, hBN, and MoS2 nanolubricants exhibited a lower coefficient of friction (COF) and wear scar diameter (WSD) than the base lubricant. The findings also showed that the MoS2 nanolubricant had the best friction reduction and anti-wear performance, with a 24.9% drop in COF and a 12.3% drop in WSD. It was followed by the hBN and graphite nanolubricants. To fully understand the lubricating mechanisms involved, the worn surfaces of the tested balls were characterised using various microscopic and spectroscopic methods. Accordingly, the structural changes that occurred during sliding were shown to affect the formation of protective tribofilm. In summary, the findings in this study suggest that the formulated layered nanolubricants possessed exceptional tribological performance, which was contributed by the inherent properties of the individual nanoparticles and the formation of effective tribofilms.

Influence of green synthesized aluminum oxide nanoparticle concentration on wear and coefficient of friction of vegetable oil-based lubricants

Influence of green synthesized aluminum oxide nanoparticle concentration on wear and coefficient of friction of vegetable oil-based lubricants

Synthesis, characterization and tribological investigation of vegetable oil methyl esters based bio-lubricants

The lubricating ability of vegetable oil-based lubricant additives with commercially used engine lubricant is investigated in this article. The methyl esters of Neem, Pongamia and Tamanu oils were formulated by transesterification process and blended with SAE20W40 oil in 10%, 20% and 30% of its volume. These biolubricant blends were tested for physiochemical properties and tribological behavior using LM13 Aluminium alloy as the pin material in accordance with ASTM standards. Experimental outcomes established that the biolubricant blends like N10, P10, P20, N20 are capable of reducing wear about 77%, 52%, 92%, 81% respectively and the frictional coefficients of N10, P20 and T30 were found to be appreciable. In the long run, they can be used as primary alternatives to conventional lubricants.

A Review on the Effect of Minimum Quantity Lubrication on Different Machining Parameters Emphasizing Vegetable Oil-Based Lubricants for Sustainable Manufacturing

The cutting fluid plays a significant role in minimizing heat generation and chip removal process during the machining of materials, hence improving tool life and surface finish of the workpiece. Many researchers have focused on minimum quantity lubrication (MQL) among the existing methods on the application of the coolant as it reduces the usage of coolant by spurting a mixture of compressed air and cutting fluid in an improved way instead of flood cooling. The MQL method has demonstrated to be appropriate as it fulfills the necessities of ‘green’ machining. Additionally, considering current environmental issues and provisions for safe healthy working conditions at the workplace, it is important to divert machining processes towards an eco-friendly path. Hence, the focus of research has been shifted to MQL using eco-friendly lubricants for green and sustainable manufacturing processes. In this review paper, the effect of different vegetable oil-based biodegradable coolants like castor oil, coconut oil, palm oil, etc. for different machining process parameters like cutting force, cutting temperature, surface finish, tool wear, etc. has been reviewed. It is observed that proper selection of cutting parameters along with lubricant through MQL can provide enhanced machinability to get desired outputs.

Multifunctional Lubricant Additive Improves Lubrication and Antioxidation Properties of Tung Oil

It is of considerable significance to develop efficient and environmentally friendly machinery lubricant additives because of the increasing depletion of petrochemical resources and severe environmental problems. Herein, we proposed a facile strategy to synthesize a multifunctional vegetable oil-based lubricant via the lignin derivative vanillin coupled to amine and diethyl phosphite to produce a lubricating additive with both extreme pressure and antioxidant properties. Compared with pure tung oil, the lubricating and antioxidant performance of tung oil is significantly improved after adding additives. Adding the 1.0 wt% additive to the tung oil reduced the friction wear coefficient and the volume, and the oxidation induction time was much longer than pure tung oil.

Tribological study of sunflower TMP ester and silica nanoparticles additives for hydrodynamic journal bearing application under boundary lubrication condition

PurposeThis study aims to study the tribological performance of sunflower TMP ester and silica nanoparticles additives as a biolubricant alternative to the conventional lubricants for hydrodynamic journal bearing applications.Design/methodology/approachNanolubricants were synthesized using an ultrasonicator and a homogenizer. A pin-on-disk tribometer was used to simulate the boundary lubrication condition for hydrodynamic journal bearing application in the presence of the studied lubricants. Surface analysis of the pin (bearing material) was done using scanning electron microscopy and energy dispersive X-ray spectroscopy.FindingsThe sunflower TMP ester performed well in terms of the coefficient of friction compared to commercial lubricants, but its wear performance was poor. The silica nanoparticles improved the wear and friction performance of the sunflower TMP ester. With the addition of 1% silica nanoparticles to sunflower TMP ester, the reduction in the coefficient of friction was 27.92% and the reduction in specific wear rate was 54.79%, making it the best lubricant out of all studied lubricants.Originality/valueAlthough there are various available studies on vegetable oil-based lubricants for hydrodynamic journal bearing applications, the studies on the use of vegetable oil-based TMP esters for hydrodynamic journal bearing applications are limited. Also, the effect of silica nanoparticles on the tribological performance of TMP esters under boundary lubrication condition has not been studied extensively in the available literature.

Tribological Study of Functional Fluids Based on Castor Oil

Vegetable oil-based lubricants are environment-friendly options as against conventional lubricants. This paper discusses the synthesis as well as characterisation of esters from ricinoleic acid and sebacic acid whose main source is castor oil. Physicochemical properties, tribological study as well as oxidation study have been carried out for the esters. With the increase in ester chain length, extreme pressure properties, viscosity index and pour point has improved, whereas oxidation stability had a detrimental effect. The coefficient of friction for commercial base stocks was better than any of the studied esters.

Experimental investigation on the effects of clove oil as an anti-oxidant additive on the lubricant properties of transesterified rice bran oil

Lubrication is a basic requirement in any equipment with relative motion. Most of the commercially available lubricants are based on petroleum oil, which are not at all biologically degradable and necessitated an alternative for commercial lubricants. The vegetable oil-based lubricants could be treated as a promising replacement for petroleum oil-based lubricants, since they possess superior properties of lubrication and are biodegradable. However, it possesses some major limitations like insufficient oxidation stability and it can be treated via chemically modifying methods and by adding preferable additives which are eco-friendly in nature. In the current study, rice bran oil (RBO) is chemically modified via transesterification using hexanol as alcohol and clove oil is added as an eco-friendly additive. The lubricant properties are evaluated for transesterified RBO, and modified RBO with additive. It was identified from the results that the addition of clove oil has improved the oxidation stability of transesterified RBO significantly. Thus, the characteristics of the vegetable oil could be improved by chemically modifying methods as well as with the addition of desirable additives and thereby it can become a possible feed stock for lubricants.

Microalgae Biomass as a New Potential Source of Sustainable Green Lubricants.

Lubricants are materials able to reduce friction and/or wear of any type of moving surfaces facilitating smooth operations, maintaining reliable machine functions, and reducing risks of failures while contributing to energy savings. At present, most worldwide used lubricants are derived from crude oil. However, production, usage and disposal of these lubricants have significant impact on environment and health. Hence, there is a growing pressure to reduce demand of this sort of lubricants, which has fostered development and use of green lubricants, as vegetable oil-based lubricants (biolubricants). Despite the ecological benefits of producing/using biolubricants, availability of the required raw materials and agricultural land to create a reliable chain supply is still far from being established. Recently, biomass from some microalgae species has attracted attention due to their capacity to produce high-value lipids/oils for potential lubricants production. Thus, this multidisciplinary work reviews the main chemical-physical characteristics of lubricants and the main attempts and progress on microalgae biomass production for developing oils with pertinent lubricating properties. In addition, potential microalgae strains and chemical modifications to their oils to produce lubricants for different industrial applications are identified. Finally, a guide for microalgae oil selection based on its chemical composition for specific lubricant applications is provided.

Performance characteristics of lubricant based on rapeseed oil containing different amounts of metal-containing additive

PurposeThe purpose of this study was to investigate the biobased (rapeseed) oil with the addition of different amounts of metal-containing additive in a steel–bronze tribological system. The additional purpose was to find the optimal value of the additive.Design/methodology/approachThis paper exposes experimental results of the performance characteristics (coefficient of friction (COF), working temperature and wear) of the biolubricant based on rapeseed oil. The amount of commercial metal-containing additive in formulated lubricant was 1, 1.5, 3 and 5 wt.%. All results were compared with the results obtained for the base rapeseed oil. Two different tribometers were used, with the same tribosystem elements materials (bronze and steel). COF experiments were performed under four different normal loads and fixed sliding speed and time. Temperature and wear were continuously monitored.FindingsResults showed that the metal-containing additive in rapeseed oil reduced all monitored characteristics. It was also found that the dependence of all characteristics on the amount of additive is nonlinear and that there is an optimal value of it.Originality/valueOwing to growing environmental concerns, vegetable oil-based lubricants and other biodegradable lubricants are expanding their area of application. Currently, one of the most widely used vegetable oil is rapeseed oil. The metal-containing additive used in this study is previously investigated as an addition to mineral- and synthetic-based oils. There are very few studies that investigate its influence on the vegetable oil-based lubricants. In addition, there is no comparative investigation of its influence on several performance characteristics (COF, temperature and wear).

Tribological Analysis of novel Apricot oil based Biolubricant against 15W40 oil tested on High Temperature Tribometer

Nowadays, petroleum products have become an integral part of day-to-day life. Lubricants made from petroleum products were widely used as automobile lubricants. But the use of petroleum-based lubricants has significantly damaged the environment. The concern of environmental damage caused by petroleum-based lubricants has increased the search for environmentally friendly lubricants. The vegetable oil-based lubricants proved to be environmentally friendly. In the present work, a bio lubricant is produced from the apricot oil, scientifically known as Prunus Armeniaca, using the trans-esterification method. The tribological behavior is analyzed for pure bio-lubricant, 15W40 oil, and also for the blend of apricot oil and 15w40 at different volume percentages. A high-temperature Pin on disc tribometer is used to perform friction and wear tests at 40oC and 100oC. It was found that the blend of apricot oil-based biolubricants and 15W40 lubricant showed better tribological behavior as compared to the pure bio-lubricant and 15W40 oil alone.

A sustainable methanol-based solvent exchange method to produce nanocellulose-based ecofriendly lubricants

A prospective methodology aimed to develop totally sustainable oleogels with potential application in lubrication is reported. Oleogels were prepared with cellulose nanofibrils from elm pulps in castor oil. Even at a concentration as low as 1.4 wt%, the oleogels showed rheological behaviors similar to a traditional lithium grease used as reference. In that sense, the high thickening power of cellulose nanofibers was remarked. Never-dried bleached and unbleached elm pulps were mechanically treated with PFI mill refiner and microfluidizer. Moreover, as an alternative way of producing cellulose nanofibrils, the never-dried bleached elm pulp was chemically oxidized using 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO). The three types of nanofibers were characterized and used in the production of oleogels. The great challenge was to remove the high amount of water retained by the nanofibrils during the nanofibrillation treatment before it was incorporated into the vegetable oil-based lubricant. Alternative strategies such as liophilization or drying failed because the nanofibers, with very high specific surface and strong capacity to interact among them by hydrogen bonding, underwent severe aggregation. Instead, the proposed methanol-based solvent exchange method enabled the transfer of the cellulose nanofibrils from the origin hydrogel to the vegetable oil with no detriment of both their aspect ratio and thickening capacity. Chemical considerations are provided with regard to such a solvent-mediated method, which yielded homogeneous and storage-stable oleogels. This work may attract the interest of lubricant manufacturers to produce nanocellulose-based eco-lubricating greases for industrial applications.

Study of Friction and Wear Effects in Aluminum Parts Manufactured via Single Point Incremental Forming Process Using Petroleum and Vegetable Oil-Based Lubricants.

This paper focuses on studying how mineral oil, sunflower, soybean, and corn lubricants influence friction and wear effects during the manufacturing of aluminum parts via the single point incremental forming (SPIF) process. To identify how friction, surface roughness, and wear change during the SPIF of aluminum parts, Stribeck curves were plotted as a function of the SPIF process parameters such as vertical step size, wall angle, and tool tip semi-spherical diameter. Furthermore, lubricant effects on the surface of the formed parts are examined by energy dispersive spectroscopy (EDS) and scanning electron microscope (SEM) images, the Alicona optical 3D measurement system, and Fourier-transform infrared spectroscopy (FTIR). Results show that during the SPIF process of the metallic specimens, soybean and corn oils attained the highest friction, along forces, roughness, and wear values. Based on the surface roughness measurements, it can be observed that soybean oil produces the worst surface roughness finish in the direction perpendicular to the tool passes (Ra =1.45 μm) considering a vertical step size of 0.25 mm with a 5 mm tool tip diameter. These findings are confirmed through plotting SPIFed Stribeck curves for the soybean and corn oils that show small hydrodynamic span regime changes for an increasing sample step-size forming process. This article elucidates the effects caused by mineral and vegetable oils on the surface of aluminum parts produced as a function of Single Point Incremental Sheet Forming process parameters.

Natural emulsifier assisted lubricity of the colloidal system: Effect of natural emulsifier concentration

Environmental needs, human health issues, government regulations have motivated this work to explore an alternative to mineral oil-based systems to vegetable oil-based environmental friendly lubricants. The present study is an attempt to use natural products (soybean oil and Gum Arabic) to develop environmental friendly oil-in-water emulsion to be used as metalworking fluid. The role and effect of Gum Arabic (GA) concentration on emulsion stability, wettability, and lubricity is explored. Three concentrations of GA corresponding to critical micelle concentration (CMC), below CMC and above CMC are selected to formulate the emulsions (Formulated fluids (FFs)). The emulsion characteristics (droplet size and zeta potential), pH, wetting dynamics, and lubricity are evaluated using dynamic light scattering (DLS), pH glass electrode, Goniometer, and four-ball tester (FBT), respectively. Worn surfaces are analysed using Fourier transform infrared (FTIR) spectroscopy and field emission scanning electron microscope (FESEM). The physical characteristics and tribological responses suggest that the FF @ CMC of GA exhibited better stability, lubricity, and antiwear properties than other formulations. Different responses of FFs are benchmarked with that of mineral oil-based commercial fluid (CF). FF @ CMC of GA showed a better anti-friction and similar anti-wear response as compared to CF. The excellent lubricity of the FF @ CMC of GA is attributed to the formation of the low shear strength stable lubricious film due to the active participation of GA molecules at the tribo-pair interface.

Tribological evaluation of vegetable oil-based lubricant blends

Increasing environmental pollution concerns and diminishing petroleum reserves has brought in attention towards the use of edible and non-edible vegetable oils as an alternative to petroleum oil based lubricants. Most of the vegetable oil plant contains high amount of oil in its seeds which can be converted into bio lubricant. Bio lubricant is a renewable lubricant that is environmental friendly, easily degradable and nontoxic in nature. There is a need to explore the possibility of using non edible varieties and their blends as bio-lubricant in order to achieve the twin objectives of reducing environmental and energy security of the country. Bio-lubricant have come a long way in recent years, and they are now capable of providing extremely low friction and wear coefficients under certain or highly controlled test conditions. Bio-lubricant from non-edible vegetable oils have received considerable research attention in the last decades owing to their remarkable improved tribological characteristics. Yet full potential has not been explored for the bio-lubricant production. This paper is an investigation of vegetable oils viz. Castor, Mahua and Sunflower oils using pin on disc tribotester which can prove to be premium source of biolubricants emphasizing the benefits on the rural and urban economy.

Thermophysical and wear properties of eco-friendly nano lubricants

Nano lubricants are widely used from heavy machinery to compact equipment to enhance their reliability. The research towards developing eco-friendly and biodegradable lubricants using natural oils has attracted the lubrication industries worldwide in recognizing the sustainable agrarian initiatives towards developing innovative green technologies. An attempt was made to investigate the use of vegetable oil-based nano lubricants prepared by dispersing molybdenum disulfide (MoS2) nanoparticles with the raw castor and olive oils, without adding surfactants or property modifiers. The prepared nano lubricants were tested for lubrication performance using a pin-on-disc tribometer, with EN31 as disc material and aluminum Al2024 as pin material. The wear study results are compared with the commercially available mineral oil, SAE20W40 multigrade engine oil. The castor and olive oil-based nano lubricants exhibited good thermal conductivity, higher flash point, and fire point, with better heat-carrying capacity comparatively with SAE20W40 engine oil. The study reported a 43% and 37% reduction in wear for a continuous sliding of 5 min, with castor and olive oil-based nano lubricants respectively compared with dry lubrication. Also, 56% and 51% improvement in thermal conductivity was observed for castor and olive oil reinforced with 0.7 wt% of MoS2 nanoparticles respectively, compared with SAE20W40 engine oil. The study revealed the possibility of using vegetable oil-based nanofluids as functional lubricants, which has better replacement potential with synthetic or petroleum-based mineral oils for tribological applications.

Effect of Poly(ε-Caprolactone) as a bio-lubricant additive in AISI 4140 Steel/Al2O3 tribosystem

ABSTRACTSince ancient times, lubricants have been used to reduce friction and wear problems of mechanical systems. However, nowadays, there is a constant effort to improve their performance through additives so that they can accomplish properly in this modern world. In that sense, in this study, it was proposed the use of Poly(ε-Caprolactone) (PCL) as a biodegradable additive in Castor oil. The effect that this additive has on the tribological properties of AISI 4140 steel/Al2O3 tribosystem was analyzed. For this purpose, PCL was dissolved in Castor oil at 65 °C for 15 minutes. Later, once the lubricant formulations got into room temperature, friction tests were conducted with a ball-on-disk configuration. Several experiments were systematically carried out in order to study the factors that could influence the performance of the tribological system, for instance: additive concentration, velocity, temperature, and wear track radius. The kinetic friction coefficient was used to analyze the results as an output variable. The parameters in which the best friction behavior was observed were employed again to compare the efficiency of the polymeric additive by profoundly analyzing and comparing the wear response of the system. The PCL additive showed great results by decreasing friction up to 30% compared to the neat Castor oil. Nevertheless, as the opposite effect, this additive increased the steel wear to almost half an order of magnitude. Given the above, this investigation showed that, with further studies, Poly(ε-Caprolactone) could be used as an additive in vegetable oil-based lubricants for the improvement of friction performance.

Synthesis and physicochemical properties of novel lauric acid capped estolide esters and amides made from oleic acid and their evaluations for biolubricant basestock

Vegetable oils have been used as environmentally friendly biolubricants because of their inherent biodegradability, good lubricity, higher viscosity index and low evaporative loss. However, their use is limited due to significantly poor cold flow properties and inferior oxidative stability. This paper presents an approach to modify vegetable oil derivatives namely oleic acid to yield biolubricant with good cold flow properties and oxidation stability. Oleic acid was converted to polyhydroxy estolide through reaction with only hydrogen peroxide, which is considered a ‘green’ oxidant. The synthesized polyhydroxy estolide was further reacted with appropriate amount of lauric acid to end-cap its hydroxy groups, which yielded lauric acid capped estolide as the product. Subsequently, the prepared lauric acid capped estolide was reacted with branched and straight chain alcohols as well as secondary amines to afford estolide esters and amides. In general, most of the prepared samples showed improved cold flow properties as compared to vegetable oil-based lubricants, where the best pour point (−41 °C) was achieved by 4-methyl-2-pentyl estolide ester. Meanwhile, estolide amides exhibited the best oxidative stability among samples evaluated with an oxidation onset temperature of 205 °C, which is significantly higher than vegetable oil-based lubricants. Generally, the oxidative stability, viscosity index and anti-wear properties of prepared estolide esters and amides were found to be comparable to the properties of commercial samples used as benchmark.

Tribological and Thermal Transport Performance of SiO2-Based Natural Lubricants

Fluids and lubricants are critical for the mechanical manufacturing processing of metals, due to a high amount of friction generated, also reflected as heat, could wear and damage tooling and machine components. The proper application of lubricants increases machinery lifetime, decreases long-term costs, and energy and time consumption due to the maintenance or components exchange/repairs. Besides being non-renewable, mineral oils bring consequences to the environment due to their low biodegradability and could affect the user with respiratory and skin diseases. Recently, due to an increase in environmental awareness, the search of biocompatible and efficient lubricants has become a technology goal. The vegetable oil-based lubricants are slowly emerging as ecofriendly and high-performance alternatives to petroleum-based lubricants. This study evaluates soybean, sunflower, corn and paraffinic oils reinforced with SiO2 nanoparticles. The thermal and tribological evaluations were performed varying the temperature and nanofiller concentrations. The thermal conductivity improvements were observed for all nanolubricants as the temperature and filler fraction increased. The highest thermal conductivities were observed at 323 K with 0.25 wt % SiO2. The soybean and corn oils unveiled a maximum enhancement of ~11%. The tribological evaluations showed that SiO2 addition, even in small concentration, resulted into a significant improvement on a load-carrying capacity. For instance, at 0.25 wt % enhancements of 45% and 60% were observed for soybean and sunflower oils, respectively. The coefficient of friction performance also showed enhancements between 10% and 26%.

Pentaerythritol rosin ester as an environmentally friendly multifunctional additive in vegetable oil-based lubricant

Abstract Abietic acid is an abundant renewable natural resource. Pentaerythritol rosin ester (PRE), which is synthesized by esterification of abietic acid and pentaerythritol, is notably environmentally friendly. In our study, we first report PRE as an environmentally friendly multifunctional additive in vegetable oil-based lubricant. The dynamic viscosity, kinematic viscosity, thermal stability and oxidation stability were investigated. The dynamic viscosity of rapeseed oil (RO) and soybean oil (SO) increased by 136.11% and 179.3% at 25 °C when 20 wt% of PRE was added. The viscosity results indicated that PRE can significantly increase the viscosity of RO and SO base oils to expand their range of applications. Moreover, lubricant samples with PRE had higher thermal stability and oxidation stability compared with pure RO and SO. The onset temperature (OT) of oxidation of RO and SO increased by 7.7 °C and 12.6 °C, respectively, when the concentration of PRE was 20 wt%. The oxidation induction time (OIT) of RO and SO increased by 305% and 124%, respectively, when the concentration of PRE was 20 wt%. Therefore, environmentally friendly multifunctional additive of PRE may be a potential alternative to the traditional additives in the preparation of eco-friendly bio-based lubricant.