Extreme Pressure Tests Research Articles

High-performance and promising biolubricants from agro-waste cashew nut shell liquid

Purpose This study aims to replace petroleum-based lubricating oils with sustainable biomaterials, addressing issues associated with existing alternatives, such as poor performance, high cost and limited availability. Design/methodology/approach The transformation of agricultural waste cardanol, a nonedible vegetable oil that is abundantly available, into green cardanyl acetate (CA) biolubricating ester oil. The potential of CA as a base stock for lubricants is validated by assessing its lubrication performance. Findings CA exhibited a higher viscosity index, flash point and thermal stability than commercially available mineral-based (CTL3, coal-to-liquid) and synthetic (PAO2, poly-alpha-olefin) lubricant base stocks. Moreover, CA exhibits excellent anticorrosivity properties as well as PAO2 and CTL3. The tribological properties of CA were evaluated, and the results show that CA exhibits a smaller average wear scar diameter (WSD) of 0.54 mm than that of PAO2 (0.85 mm) and CTL3 (0.90 mm). In extreme pressure tests, acylated CA demonstrated the highest last nonseizure load capacity at 510 N, outperforming commercial CTL3 (491 N) and PAO2 (412 N). All results demonstrate that CA displays an excellent series of base stock properties. Originality/value The novelty of this work lies in the utilization of renewable agricultural waste, cashew nut shell liquid, to produce a high-value biolubricant as an alternative to commercial fossil-based lubricants. The renewable nature, low cost, and large-scale availability of raw materials pave a new path for the production and application of biolubricants, showcasing the immense potential of converting agricultural waste into high-value products. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-03-2024-0064/

Highly robust electronic skin for object recognition of robot hand based on carbon nanomaterials and SEBS

When robot hands work in a complex environment, they not only need to sense the objects in contact but also need to respond to remote events before physical contact. In this way, robot hands can make predictions, to better adapt to the complex environment. In this paper, we have designed a flexible sensor array, which integrates a piezoresistive sensor and a capacitive sensor for detecting pressure and proximity direction and distance signals simultaneously. Piezoresistive sensors can detect pressure signals in real-time, and capacitive sensors detect pressure and proximity signals. The sensors are arranged in a patterned array and installed on the robot hand to help the robot hand detect the distance and direction of approaching objects, as well as the shape and size of the grasped objects. To avoid mechanical mismatch, piezoresistive sensors and capacitive sensors are fabricated with the same flexible materials. In addition, after extreme pressure tests, the sensors can still work normally, to ensure that the robot hands can work normally after collision. We also combined the detected signal with machine learning, so that the robot can accurately identify objects of different shapes. In the fruit recognition test, the recognition accuracy reached 90 %.

Investigating the tribological properties of TiO2 nanoparticles added Thevetia peruviana and Cucurbita pepo L. blend oils

The paper studies the lubricant properties of blends of Thevetia peruviana oil (TPO) and Cucurbita pepo L. oil (CPO) prepared at different proportions. The physicochemical properties were determined as per ASTM standard and the anti-wear and extreme pressure tests were performed using four-ball tribotester as per ASTM D4172–94 and ASTM D2783, respectively. The blend of 40% TPO and 60% CPO was found the best blend as per the Entropy-TOPSIS method and further at optimal concentration of 1 wt% of titanium oxide nanoparticles it exhibited the coefficient of friction of 0.0329 ±0.002 and wear scar diameter of 0.291 ± 0.005 mm. The present study indicates that TPO-CPO blends with optimal additivation can be an alternative biodegradable solution to commercial mineral oils.

Enhanced extreme pressure and tribological performance of hybrid nano lubricant

ABSTRACT The present study reports the tribological performance of a novel hybrid nano-lubricant for bronze/AISI 4340 alloy-steel tribopair. The hybrid nano-additive used in the present study helps to improve the lubricity and can sustain under extreme conditions. Initially, friction and wear properties are recorded by varying concentrations of Al2O3 (0.5, 0.8, 1.0, and 1.5 wt. %) and GNP (0.05, 0.1, 0.2, and 0.5 wt. %). Based on the results, an optimum hybrid concentration (OHC) is prepared by adding 0.8 wt. % of Al2O3 and 0.2 wt. % of GNP which resulted in 83.84% and 79.75% reductions in coefficient of friction (COF) in comparison to optimum Al2O3-based and GNP-based lubricants, respectively. However, the wear volume (WV) for OHC lubricant indicated 98.28% and 75% reduction in comparison to the above-mentioned lubricants, correspondingly. Extreme pressure (EP) tests were carried out and OHC lubricant reported improved weld point for hybrid nano additive-based lubricant.

Extreme pressure properties of garlic oil: comparative investigations with PAO4 base oil and PAO/garlic oil blend

This study aims at exploring the improvement in extreme pressure (EP) properties with addition of natural Garlic oil as EP additive. Comparative investigations were conducted on PAO4 base oil, Natural Garlic oil (NGO) and PAO4 + 1 wt% NGO (Natural Garlic Oil) for evaluating the extreme pressure properties. The EP tests were conducted on a four ball tester according to ASTM D 2783. The results revealed that NGO possesses significantly good extreme pressure properties having a weld load of 3087N and load wear index of 513N. The results also revealed that NGO could significantly improve the weld load and load wear index of PAO4 base oil. After adding 1 wt% garlic oil to PAO4 the load wear index increased by 62.51% and weld load increased by 25%. This study proposes garlic oil as a replacement to the use of nano-particles as EP additives and aims to eliminate the disadvantages that are prominent with nano-particles without comprising the performance.

Tribological characteristics of synthesized hybrid nanofluid composed of CuO and TiO2 nanoparticle additives

Friction and wear are inherent in the interfacing elements of machine components having relative motion. As per estimates, up to 30% of the total energy consumed is lost in overcoming friction. It can be minimized by development of material for surface enhancement, and with the proper application of lubricant. The accessibility of nanoparticle manufacturing facility promoted its use in lubricant. In last decade investigations have been made to find the optimum content of a single type of nanoparticle additive to improve desired tribological property to a certain extent. The main objective of the present research is to further enhance the tribological characteristics by use of combination of two different nanoparticles as additives. Gear oil EP 140 is considered as a base oil. Copper oxide (CuO) and Titanium oxide (TiO2) nanoparticles have been blended in different concentrations to the base oil for formulation of the hybrid nanofluid. Anti-wear tests and extreme pressure tests were performed on the Four-ball tribo-tester to investigate the coefficient of friction, wear prevention property, and load-carrying capacity of the nanofluid. Measurement of wear scar diameters (WSD) and characterization of the balls scar were performed using optical microscopy, scanning electron microscopy (SEM), and energy dispersive spectrometry (EDS) tools. Anti-wear tests of the nanofluids showed promising results with a remarkable reduction of 19.33% in the coefficient of friction and a significant reduction of 23.03% in the wear. The load-carrying capacity (poz) has increased by 89.24% with the addition of CuO and TiO2 nanoparticles in comparison to the base oil. The promising results of the hybrid nanofluid can lead to improvement in performance and significant saving of energy consumption in machinery especially the gearbox.

Physico-chemical and tribological properties of commercial oil - bio-lubricant mixtures dispersed with graphene nanoplatelets.

This study focuses on the physicochemical and tribological properties of bio-lubricants and commercial lubricant blends dispersed with graphene nanoplatelets. In the processing of the bio lubricant, special care was taken to ensure that the physicochemical properties do not deteriorate too much when the bio lubricant is blended with commercial oil. Calophyllum inophyllum (Tamanu tree) seed oil was used to prepare a penta-erythritol (PE) ester. The PE ester was mixed with commercial SN motor oil at 10, 20, 30 & 40% v/v concentrations. The oil samples are tested on a four-ball wear tester to see how well they perform under wear, friction, and extreme pressure conditions. The optimum blend of PE ester - commercial SN motor oil for the best performance is found in the first phase. Later the optimum blend of commercial oil and bio-lubricant is dispersed with graphene nanoplatelets in 0.025%, 0.05%, 0.1%, 0.25%, 0.5% and 1% weight fractions. A blend ratio of 30% bio-lubricant in commercial oil dispersed with 0.05% graphene nanoplatelets dramatically reduces friction and wear. During the extreme pressure test, commercial oil, and bio-lubricant blends performed better in load-carrying capacity and welding force, indicating an improved load-wear index. These improved properties due to the dispersion of graphene nanoplatelets could facilitate the use of a higher blend percentage of bio lubricant. Analysis of the worn surfaces after the EP test showed that bio lubricant, additives, and graphene worked together in the blend of bio lubricant and commercial oil.

Unexplored potential of acacia and guar gum to develop bio-based greases with impressive tribological performance: A possible alternative to mineral oil-based greases

A potential, sustainable, and economical eco-friendly alternative to harmful petroleum-based lubricants is a big challenge for the 21st-century lubricant industry. The present study explores, for the very first time, polysaccharide gums like gum acacia (GA) and guar gum (GG) as additives (0.5–10 %w/w) to enhance the extreme-pressure (EP) performance of greases (based on vegetable oil and organoclay). The greases are evaluated on a four-ball tester for the standard EP test (ASTM D2596). Adding GA or GG to greases enhances EP performance significantly. The performance ameliorates with the gum's concentration showing impressive results at higher concentrations (up to ≈ 60% better than a commercial grease). The superior performance is attributed to an in-situ formed polymer-layered silicate nanocomposite tribofilm at the interface via chemisorption (for GA) or physisorption (for GG). The formulated greases are a possible replacement for existing mineral oil-based commercial greases.

High-efficient and environmental-friendly PTFE@SiO2 core-shell additive with excellent AW/EP properties in PAO6

Environmental-friendly polytetrafluoroethylene@silica (PTFE@SiO2) composite particles characterized by core-shell structure were synthesized. The tests demonstrated that the synthesized particles had good dispersibility and stability in poly-α-olefin 6 (PAO6) and its corrosion resistance was better than zinc dialkyl dithiophosphate (ZDDP). The extreme pressure (EP) and tribological tests evidenced that PTFE@SiO2 particles possessed superior EP and anti-wear (AW) properties, which could enhance the wear-resistance and load-bearing capacities of PAO6 in high efficiency, whereas the tribological performance was greatly affected by the load. Besides, EP tests for different kinds of base oils demonstrated that the addition of PTFE@SiO2 particles could significantly improve the bearing capacity of these base oils, and the corresponding performances were also better than ZDDP. Scanning electron microscope and X-ray photoelectron spectrum characterizations proved that there was an organic-inorganic co-extruded transfer film generated on the worn surface, and a possible lubrication mechanism on this basis was also put forward.

Experimental Evaluation of the Tribotechnical Properties of Engine Oils for Combine Harvesters

A four-ball extreme pressure test has been performed to study and evaluate the tribotechnical properties of motor oils. The studies have shown that the tribotechnical properties of the engine oil stored in the crankcase during the winter period exhibit a significant change. The average ball wear level has shown a 40% increase compared with that observed in the case of new oil. The average ball wear diameter for the oil samples taken from the combine engines in autumn amounted to 0.5 mm, whereas the average ball wear diameter for the oil samples taken from combine engines in spring amounted to 0.7 mm. When testing new semisynthetic engine oil, the average ball wear diameter varied within 0.48 ± 0.04 mm. It is assumed that the boundary layer formed by the oil is weaker, which causes an increase in the risk of its breaking and sealing the friction pores.

Avocado oil mixed with an antiwear additive as a potential lubricant – Measurement of antiwear and extreme pressure properties

The paper aims to study the antiwear (AW) and extreme pressure (EP) properties of avocado oil mixed with zinc dialkyl dithiophosphate (ZDDP) in concentrations of 1% to 3% by weight for lubrication purposes. The AW and EP tests are conducted as per ASTM-4172 and ASTM-2783 standards respectively. Further, the rheological behavior of avocado oil mixed with ZDDP is determined for varying shear rates of 50 – 2000 s−1. The maximum improvement in the wear properties for avocado oil is equal to 39.8% at 1 wt.%. The load wear index of pure avocado oil increases from 32.6 to 80.3 at 3 wt.% ZDDP whereas, the weld point increases to 252 kgf at 3 wt.% ZDDP. The improvement in the antiwear and extreme pressure properties are attributed to the protective film formation on the tribopairs as characterized by SEM and EDX analysis. Also, the addition of ZDDP increases the viscosity of the oil at all concentrations and maintains the Newtonian behavior of oil.

Tribological properties of polyol ester – commercial motorbike engine oil blends

This current study investigates the effect of blending bio-lubricant with commercial lubricant on physico-chemical and tribological properties. The synthesis of TMP and PE ester are optimized to obtain 100% long chain tetra-esters and extreme care was taken during preparation of bio-lubricant to lessen deterioration of physio-chemical properties by blending with commercial oil. SM grade commercial petrol engine oil was blended with Tri-methylolpropane (TMP) ester, Penta-erythritol (PE) ester derived from Calophyllum-inophyllum in 10, 15, 20 and 25% v/v. The tests for anti-wear, anti-friction and extreme pressure properties are conducted on the sample oils on a four-ball wear tester. The friction coefficient and wear of bio-lubricant – commercial oil blends have decreased significantly up to 20% blending percentage. In the extreme pressure test, there is a substantial improvement in the weld load and marked improvement in the load wear index signifying the better load-bearing capacity of commercial oil – bio-lubricant blends. A synergy between bio-lubricant and additives in the commercial oil was found from a metallographic examination of worn balls after the EP test. The optimum volume percent of blend was found to be 15% PE blend and 10% TMP blend for optimum overall performance.

Study on the Friction and Wear Characteristics of Bio-lubricant Synthesized from Second Generation Jatropha Methyl Ester

The demands for eco-friendly bio-lubricants are growing due to the environmental concern and the rapid depletion of petroleum oil. This paper outlines the tribological evaluation of jatropha methyl ester (JME) based bio-lubricant by analyzing its anti-wear (AW) and extreme pressure (EP) characteristics. The AW and EP tests were conducted using a four-ball tribotester with standard test methods of ASTM D 4172 and ASTM D 2783, respectively. After each test, the wear scar diameter, flash temperature parameter, viscosity and viscosity index (VI) were measured. The SEM analysis characterized the surface structure of the worn surface. The properties of formulated bio-lubricants were compared with the commercial lubricant SAE 15W-40. Experimental results showed that under boundary lubrication, the bio-lubricants showed excellent tribological properties up to the initial seizure load (ISL). Over the ISL, the friction and wear were increased slightly as compared to the commercial lubricant. The final seizure load (FSL) found for the bio-lubricant (BL 10), and commercial lubricant was 220 kg. The bio-lubricant with 10 % JME (BL 10) was found to be the most favorable, which met standard ISO requirements except for pour point. © 2020 Published by Faculty of Engineering.

Tribological Behaviour of Neem Oil with and without Graphene Nanoplatelets Using Four-Ball Tester

The present work was aimed to study the friction and wear behaviour of graphene nanoplatelets (GNPs) under extreme pressure conditions as an anti-weld additive for neem oil. The effect of neem oil, blended with various loading of GNPs on the friction and wear characteristics has been investigated. From the experimental results, it was found that 1 wt.% of GNPs in neem oil showed the least coefficient of friction and smoother wear scar diameter. The extreme pressure test was performed on neem oil with and without GNPs as per ASTM standards. The extreme pressure test results indicated the improvement in seizure load of neem oil by 27.8% at 0.5 wt.% of GNPs as compared to pure neem oil. Optical microscopy of worn steel ball surface revealed the pit formation and the formation of wedge cutting edge in GNPs modified neem oil.

Study of the tribological properties of paraffin and polyethylene wax as antiwear additives in refined sesame oil

Los aceites de origen vegetal fueron una de las principales fuentes de aceites lubricantes antes de la aparición del petróleo. Actualmente, debido a la baja estabilidad térmica y a la oxidación, no se emplean con la misma frecuencia en el sector industrial. Sin embargo, los diferentes ácidos grasos que componen los aceites vegetales pueden reducir significativamente el coeficiente de fricción. Para optimizar la lubricación, el aceite vegetal puede ser mezclado con aditivos. En esta investigación, se realizó un estudio comparativo del poder lubricante del aceite de Ajonjolí con Cera polietilénica y Parafina como aditivos. Esta propiedad, fue evaluada mediante ensayos de desgaste preventivo y presión extrema en un tribómetro cuatro bolas. Los resultados experimentales, mostraron que para la prueba de desgaste preventivo D.P la mezcla con cera polietilénica, presenta el menor diámetro promedio de huella, mientras para la prueba de extrema presión E.P la mezcla con parafina dio una mayor resistencia a la carga aplicada, obteniendo un punto de soldadura a 32 Kg-F (314N) siendo mayor que para el aceite y con cera polietilénica (24 Kg-F (235N)). En relación al coeficiente de fricción los resultados obtenidos muestran que no existe diferencia entre el aceite y las mezclas con los diferentes aditivos. A partir de estos resultados, se puede concluir que el rendimiento del aceite de ajonjolí como lubricante, se puede mejorar mediante su mezcla con parafina y cera polietilénica, sin embargo, los porcentajes añadidos deben determinarse correctamente.

A Friction–Wear Correlation for Four-Ball Extreme Pressure Lubrication

AbstractA first-ever friction–wear model for four-ball extreme pressure (EP) lubrication is developed in this work based on 12 oil samples comprising minerals, esters, and other formulated lubricants. The model considers the rate of entropy generation and dissipation within the lubricated tribosystem to describe the interaction between the friction and the wear behaviors at extreme pressure conditions. The model can be used to calculate the probability to pass or fail at a specific load to estimate the weld point of a lubricant. The calculated probability exhibited a similar trend as a load-wear index from the ASTM D2783 EP test method. Besides, the model is able to estimate the EP performance of an unknown lubricant based on the model parameter, namely the dissipative coefficient. This parameter describes the proportionality between the friction and the wear phenomena from the perspective of thermodynamic analysis. This work provides useful tools to better understand the fundamentals of EP lubrication and to characterize the lubricants without overly relying on tribotest machines.

The Effect of the Different Percentage of Pour Point Depressant (PPD) On the Tribological Properties of Palm Kernel Oil

A research has been done to investigate the tribological performance of palm kernel oil (PKO) with addition of different percentage of pour point depressant, PPD (5w%, 10wt%, 20wt% and 30wt%) according to ASTM D2783. The main analyses that have been done in this research are low temperature performance ability of blended PKO, coefficient of friction (COF), wear scar diameter (WSD) and surface profile. The result of the experiment has shown that for low temperature performance, PKO with 20wt%PPD (A2-20%) and 30wt%PPD (A2-30%) show great performance in withstanding lower temperature (15℃). Under extreme pressure test, it can be seen that PKO can only withstand lower load (110kg) compared to mineral oil (140 kg). The sample 10wt%PPD (A2-10%) shows good lubricity performance in terms of COF as compared to other sample. 5wt%PPD (A2-5%) and 10wt%PPD show good lubricity performance in terms of anti-wear behaviour (A2-10%) by producing the lowest WSD when compared to other samples. From overall view, PPD is considered as successful in improving low temperature performance of PKO, but in terms of lubricity performance, adding PPD will slightly reduce the lubricity performance under extreme pressure if compared to pure PKO.

Development and testing of nano particulate lubricant for worm gear application

Bio-degradable lubricants are an attractive alternative for the mineral based and synthetic based lubricants. Bio-degradable lubricants are environmental-friendly and non-toxic. The present study deals with the tribological investigation of bio-degradable nano lubricants for worm gear applications. Nano additives like CuO and TiO2 were used. Bio-degradable oils like palm oil and sunflower oil were used as base oils. The nano lubricants were prepared by adding two nano additives and two bio-degradable oils each of 0.1 % and 0.2 % weight composition. Friction and wear characteristics were tested on pin-on-disc tribometer under varying load conditions. Extreme pressure tests for nano lubricants were carried out using four ball tester. The wear surface obtained was analyzed using scanning electron microscopy (SEM) and energy dispersive spectroscopy. From the tests conducted, it was found that the addition of nano additives in biodegradable oils reduced the friction co-efficient and wear rate to a considerable extent.

Tribological study of castor oil with surface-modified CuO nanoparticles in boundary lubrication

PurposeThe present work aims to formulate nanolubricants and improve antiwear, antifriction and extreme pressure (EP) performances of castor oil (CO) with surface-modified CuO nanoparticles as an additive in the boundary lubrication regime.Design/methodology/approachIn this study, CuO nanoparticles are modified with a surfactant sodium dodecyl sulfate (SDS) by means of a chemical method. These modified nanoparticles with varying concentrations of 0.1, 0.25, 0.5 and 1.0%w/v were used to formulate the nanolubricants. The tribological properties of non-formulated and formulated CO were examined using a four-ball tester. The tribological test results were compared with paraffin oil (PO) for similar compositions.FindingsThe nanoparticle concentrations in base oils were optimized by wear scar diameter (WSD) and load carrying capacity during antiwear and EP tests, respectively. In the antiwear test, the maximum reductions in WSD were 28.3 and 22.2 per cent; however, the coefficient of friction was reduced by 34.6 and 17.3 per cent at optimum nanoparticle concentrations in CO and PO, respectively. A significant improvement in the weld load was observed for both nanolubricants.Originality/valueThis work indicates that nanoparticle-based CO in industrial applications provides on par or better results than mineral oil. Also, it has a negligible hazardous impact on our eco-system.

Tribological study on rapeseed oil with nano-additives in close contact sliding situation

The present work deals with the tribological evaluation of three types of nano-additives, i.e., copper oxide (CuO; ≈ 151.2 nm), cerium oxide (CeO2; ≈ 80 nm) and polytetrafluoroethylene (PTFE; ≈ 90.4 nm) with rapeseed oil under steel–steel sliding contacts. The nano-additives concentrations in the base oil were 0.1, 0.25 and 0.5% w/v for the lubricant formulation. Further, the rapeseed oil was also epoxidized by a chemical method and the tribological behavior was compared with the base oil (unmodified oil) at similar nano-additives concentrations. The ASTM standards were followed for the study of wear preventive and extreme-pressure analysis of nanolubricants, and it was carried out using four-ball tester. In the antiwear test, CeO2 and PTFE nano-additives have shown the significant reduction in the wear scar diameter at the concentration of 0.1% w/v. In the extreme-pressure test, 0.5% w/v concentration was optimum for oxide nanoparticles; however, PTFE nanoparticles did not show positive effect with both the base oils. Different characterization techniques were employed to confirm the oil modification and for the study of the worn surfaces.