Oil-based Lubricants Research Articles

Modified lanthanide-doped carbon dots as a novel nanochemosensor for efficient detection of water in toluene and its potential application in lubricant base oils

A fast and efficient method was developed for obtaining europium(III)-doped surface-modified carbon dots with a hydrophobic coating. This surface functionalization improved the dispersibility of the nanoparticles in non-polar media, as well as modified the accessibility of water molecules to the europium ions. These two features allowed studying the application of doped carbon dots as moisture nanochemosensor, demonstrating high stability over time of both the photoluminescent signal intensity and the stability of the dispersions. The developed nanochemosensor was used to determine water in toluene with a detection limit of 8.5 × 10−4 M and a quantification limit of 2.4 × 10−3 M. The proposed system matches and even improves other methodologies for water determination in organic solvents; it has a low detection limit and a fast response time (almost instantaneous) and requires neither expensive material nor trained personnel. The results suggest a promising future for the development of a new sensing phase for moisture determination in lubricant base oil.Graphical

Sustainable Vegetable Oil-Based Minimum Quantity Lubrication Assisted Machining of AZ91 Magnesium Alloy: A Grey Relational Analysis-Based Study

The implementation of magnesium alloys in a multitude of industries has been proven to be a mere effect of their attractive light weight, corrosion resistant, and biodegradable properties. These traits allow these materials to portray an excellent sustainable machinability. However, with increasing demand, it is essential to explore sustainable means of increasing production while mitigating reductions in sustainability. The current work aims to assess and optimize the high-speed machinability of AZ91 with the use of a vegetable oil-based minimum quantity lubrication (MQL) system using the grey relational analysis (GRA) on the basis of chip morphology and tool wear. The investigation entailed a full factorial design with MQL flow rate, cutting speed, and feed rate as the control parameters and flank wear, land width, chip contact length, saw-tooth pitch, chip segmentation ratio, chip compression ratio, and shear angle as the output responses. The optimal control parameters predicted and experimentally confirmed were an MQL flow rate of 40 mL/h, cutting speed of 300 m/min, and feed rate of 0.3 mm/rev. The usage of said optimal parameters results in a grey relational grade improvement of 0.2675 in comparison to the referenced first experimental run. Moreover, the MQL flow rate was regarded as the critical variable with a contribution percentage of 20% for the grey relational grade.

Evaluation of the techno-economic and environmental performance of all-component recycling process for waste lubricating oil

Conventional recycling processes cannot recycle the residual lubricating base oil contained in waste lubricating oil. Thus, an all-component recycling process was proposed to recover both the distillate and residual lubricating base oil. Here, we evaluate the techno-economic and environmental performance of this process. Several economic factors were considered and a sensitivity analysis of net incomes was conducted, and 13 environmental impact categories were included in a life cycle assessment (LCA) of the environmental performance. The effects of varying the transportation distance and fuel on the environmental impacts were discussed. The all-component process had a considerable economic benefit and strength anti-risk capability of the project. The total capital and production costs of the all-component process for 0.1 million ton/yr waste lubricating oil was around 50.8 MUSD and 651.9 USD per ton, respectively. The market price of base oil was the most important factor in the net income. The LCA results indicated that the all-component recycling process could be an advanced environmentally friendly recovery process. The global warming potential and primary energy demand were the most important environmental impacts with values of 425.6 kg-eq. CO2/ton waste lubricating oil and 2911.8 MJ, respectively. The variation of transportation distance resulted in slight changes in all environmental impact categories except water use.

Performance of multi-bionic hierarchical texture in green intermittent cutting

Creatures such as Phrynosoma cornutum, Odontodactylus scyllarus, Galeocerdo cuvier had structure with unique functions, providing great inspiration for proposing multi-bionic hierarchical texture. This work theoretically and experimentally studied the performance of the proposed texture in palm oil-based minimum quantity lubrication (MQL) assisted intermittent turning. Bionic rhombus microtexture, bionic ellipsoidal microtexture, bionic longitudinal microgroove and surface tension gradient were integrated when designing the texture. Nanosecond laser and spray coating were employed to fabricate the texture on ceramic tool surface. The proposed texture had high durability and it well maintained the function of oil-transport after impact. Nondestructive assessment of mechanical properties such as fracture toughness KICA and material damage Dc can be achieved based on the data of the fractal dimension Fdca of laser-induced crack. The texture resulted in more sufficient lubrication, thereby leading to reduction of cutting load. A texture performance index Pim was established fusing both the mechanical properties and the cutting load. The theoretical index was found to be an effective tool for the pre-evaluation of texture performance. The proposed texture efficiently decreased tool wear. The optimum texture was obtained when the side length of rhombus microtexture was 210 µm and the laser angle φl was 120°

Chemical modification of waste cooking oil for the biolubricant production through transesterification process

Concerns and restrictions around contamination and environmental pollution are developing. The production of waste cooking oil and the pollution brought on by mineral oils are two important issues. The FSSAI's new standards state that cooking oil that contains more than 25% polar compounds is inappropriate for use and should be discarded. Therefore, both issues can be resolved with the aid of chemical modifications to waste cooking oil. Waste cooking oils are an attractive alternative to mineral oils because they are biodegradable and renewable sources of lubricants. The goal of the current research work is to create an environmentally friendly lubricant through transesterification reaction. Fatty acid methyl esters (FAMEs) of WCO with various alcohols (1-Heptanol, 2-Ethyl-1-Hexanol & Neopentyl Glycol) with diverse branching were used to create bio lubricant. As a heterogeneous catalyst, zinc acetate was used to carry out the reaction. Complex esters, which have been produced, have the potential to be used as biodegradable lubricants in industrial lubricant applications. Using the GC-MS technique, the structure of the generated bio lubricant was examined. The structural modification of waste cooking oil resulted in improvement in both physicochemical and tribological properties. The created bio lubricant had improved flash and fire points as well as a superior viscosity index (>120). The generated bio lubricant possesses friction characteristics that are comparable to those of commercial mineral oil-based lubricants. According to the results of this study, waste cooking oil lubricant has a lot of potential for use as a base stock due to its favorable biodegradability and tribological performance.

Fabrication of carbon dots intercalated MXene hybrids via laser treatment as oil-based additives for synergistic lubrication

As an emerging two-dimensional material, MXene exhibits excellent anti-friction and anti-wear properties in lubrication systems. However, as an oil-based lubricant additive, their stable dispersion in base oil still faces great challenges. Optimizing the microstructure has been proved to be an effective strategy to improve the stable dispersion of MXene in base oil. In this work, catechol groups functionalized carbon dots are synthesized successfully by pulsed laser irradiation of tannic acid in acetone, and then they are grafted onto MXene surface to obtain MXene@CDs hybrids via chemical bond between catechol groups of carbon dots and Ti–OH of MXene surface. Carbon dots not only increase the layer spacing of MXene nanosheets, reduce self-weight stacking, but also make it easier to slide between layers. When used as oil based lubricating additives, MXene@CDs can reduce the coefficient of friction of PAO 10 from 0.58 to 0.1, and the wear volume is reduced by 91.3%. Due to the shear-induced and self-healing mechanism, the special intercalation structure of MXene@CDs is easily formed a protective film during the run-in period, which not only reduces the contact area of friction couples but also eliminates the polishing effect on the substrate surface, thus enabling synergistic lubrication.

Alkyl-tetralin base oils synthesized from coal-based chemicals and evaluation of their lubricating properties

Naphthenic base oil is an important lubricating base oil and very scarce in the global petroleum resources. Herein, a series of alkylated tetralin fluids similar to naphthenic base oils were produced by the alkylation of tetralin and α-olefins (n-hexene, n-octene, n-decene) with ionic liquid Et3NHCl/AlCl3 as the catalyst, where the applied raw materials are totally derived from the coal chemical industry. The product composition could be controlled by adjusting the feeding ratio of tetralin and olefin. The synthetic fluids were evaluated as lubricating base oils to reveal the structure–property correlations. Their principal physicochemical and tribological properties depend on the chain-length of α-olefins and the number of alkyl groups onto the aromatic rings. Bis-(octyl- or decyl-) alkyl tetralin exhibited good properties in terms of viscosity, thermo-oxidation stability and pour point, as well as friction-reducing and anti-wear performance, showing great potential for producing naphthenic base synthetic oils from coal-based chemicals.

Tribofilm formation mechanism and friction behavior of polycrystalline diamond compact after cobalt leaching added molybdenum disulfide nanoparticles in different base oils

To investigate the friction and wear properties of polycrystalline diamond compact after cobalt leaching(PDCACL)and the formation mechanism of lubricating oil film under different base oil lubrication conditions, AFM, SEM, EDS and XPS were used to analysis and discuss the friction behavior, microstructure and friction film formation process of PDCACL after adding nano molybdenum disulfide in different base oils. The results showed that there are differences in the speed and thickness of the friction protective film formed by PDCACL under different kinds of base oil lubrication environment. The physical and chemical properties of base oil are the key factors affecting the wear mechanism of PDCACL and the formation of friction film.

Moving towards green lubrication: tribological behavior and chemical characterization of spent coffee grounds oil

ABSTRACT With the EU aiming for net-zero greenhouse gas emissions by 2050, conventional production cycles must be transformed into cradle-to-cradle approaches. Spent coffee grounds are often dumped in landfills, with their potential as high-quality feedstock for biofuel or bio-lubricant production. Spent coffee grounds oil (SCGO) was investigated for its physicochemical properties while having more free acid groups compared to the reference polyalphaolefin 8 (PAO 8), which may cause faster oxidation. TGA results displayed comparable thermal stability of SCGO and PAO 8 for inert/oxidative atmosphere. The oil composition was characterized by ATR-FTIR, elemental analysis, and GC-EI-MS, where a higher oxygen content was found for SCGO, referring to functional ester/acid groups. The tribological behavior of SCGO was studied as lubricant base oil and as a 5% additive in PAO 8. The condition of fresh and tribologically used oils was investigated with High-Resolution-ESI-MS, and the worn surfaces were evaluated by light microscopy and topographic analysis. The results showed a superior friction coefficient of pure SCGO (µ = 0.092) to PAO 8 (µ = 0.129). The 5% SCGO additive in PAO 8 (µ = 0.095) could significantly reduce friction compared to pure PAO 8 on an unpolished 100Cr6 surface.

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.

Insight into Hydrolytic Stability and Tribological Properties of B-N Coordination Tung Oil-Based Lubricant Additive in Water

A tung oil-based boron-nitrogen coordination polymer (TWE-BN) was specially designed and synthesized as a highly efficient water-based lubricant additive, which has been beneficial to both energy conservation and conducive to environmental protection. Its hydrolysis stability and tribological properties in water were investigated. To better research the lubricating properties, and thus to understand the interaction between the surface and the lubricating additives. Herein, both experimental and theoretical computations based on density functional theory (DFT) were performed. The addition of TWE-BN reduces the water friction coefficient and wear scar diameter, and the maximum non-seizure load increased from 93 to 726 N. Moreover, the anti-corrosion ability on copper was classified as 1b level. The stainless-steel surface was analyzed using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). In hydrolytic stability testing, TWE-BN was better than nitrogen-free tung oil-based lubricant additive (TWE-B) and remained non-hydrolyzed for at least 15 days, implying the feasibility of tung oil-based boron-nitrogen coordination as highly effective and hydrolytic stability lubricant additives.

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.

Design of linear polymer-based liquid lubricants by a strategy of complementary advantages

Synthetic lubricating oils have attracted more and more interests due to their unique advantages. There are main two synthetic lubricating oils, poly-α-olefins (PAOs) and synthetic esters, while they each have strengths and weaknesses due to their specific molecular structures. Here, linear polymer-based liquid lubricants were designed via a strategy of complementary advantages, by esterifying the hydrogenated hydroxyl-terminated polybutadiene (HO-HPB-OH), with different saturated fatty acids (acetic acid, butanoic acid, octanoic acid and lauric acid). As lubricant base oil via overcoming one's weaknesses by acquiring others' strong points, ultralow friction and excellent wear-reduction performance were obtained with the proposed linear polymer-based liquid lubricants in comparison with the commercial PAO base oils, especially the dilaurate with the longer hydrocarbon chain length.

Functionalized polyethylene on property enhancement of lubricating oil and their performance evaluation study

AbstractMethyl methacrylate (MMA) functionalized polyethylene additives for improving the properties of lubricating oil has been investigated in which poly(MMA‐co‐ethylene) were synthesized by using three different polymerization techniques such as miniemulsion, post polymerization and reverse atom transfer radical polymerization with 1.0 molL −1 of MMA and 20 bar of ethylene pressure. The copolymers are block in nature with the composition of 1:3 molar ratios of ethylene:MMA which is independent of polymerization techniques used. 1H NMR analysis confirmed the successful incorporation of the copolymers in the lubricating oil. Thermogravimetric analysis reveals that the addition of poly(MMA‐co‐ethylene) increases thermal stability of the additive doped lubricating oil by approximately 40°C with a single stage decomposition pattern. Flash point measurements show an increasing flash point values for copolymer doped lubricating oil. From rheological study, the viscosity index of base lubricating oil has found significant increases from 102 to 129 with the addition of poly(MMA‐co‐ethylene) and the higher molecular weight (MW) of this copolymer provides better thickening efficiency. However, copolymer with higher MW seems to be more susceptible to mechanical degradation resulting in lower shear stability whereas copolymer with lower MW acts as a better pour point depressant.

Effect of lubricating base oil on the oxidation behavior of diesel exhaust soot

In this study, the oxidation behaviors of soot particles from diesel engine when using neat diesel fuel (DF) and lubricating base oil-blended fuel (BBF) were investigated. The changes in the average particle size and nanostructure parameters during soot oxidation process were analyzed. Exhaust particulate matter (PM) samples were collected from a four-stroke, four-cylinder and turbo0charged diesel engine operated under 1200 rpm and 200 Nm. DF and BBF Soot samples with different oxidation weight losses of 20 %, 40 %, and 60 % were obtained by thermogravimetric isothermal oxidation experiments at 600 °C, and the particle size and nanostructure parameters (fringe length, La; fringe tortuosity, Tf) were characterized using high-resolution transmission electron microscopy (HRTEM). Results show that the DF soot particles exhibited an oxidation mode that was initially dominated by surface oxidation and gradually deviated to internal oxidation. Combustion of the base oil increased the soot internal oxidation tendency. HRTEM results showed that as the soot oxidation progressed, the primary particles showed a shell-core, onion-like and hollow structure gradually. The La of the primary particles gradually increased, and the Tf gradually decreased, indicating that the soot layer crystallites were rearranged during the oxidation process, which resulted in a disordered nanostructure that transitioned to a more graphitized nanostructure.

Macroscale superdurable superlubricity achieved in lubricant oil via operando tribochemical formation of fullerene-like carbon

Friction and wear are ubiquitous in moving mechanical assemblies, causing energy and equipment loss and producing harmful emissions. Mitigation efforts have long relied on oil-based lubricants, but challenges remain in achieving concurrent ultralow friction and wear without oil additives. Here, we demonstrate that a dual-phase TiB2-MoS2 film lubricated by oil without additives exhibits superdurable superlubricity characterized by a vanishingly small friction coefficient (0.007) and ultralow wear rate (10−9 mm3N−1m−1) maintained in lubricants over an unprecedentedly long sliding distance without performance deterioration. We identify a tribochemical route for the decomposition of oil molecules catalytically activated by the TiB2-MoS2 film, leading to operando formation of fullerene-like carbon that leads to diminished friction. First-principles calculations unveil strong stress responses of a TiB2 structural framework under wear strains, offering insights into the ultralow wear rate. These findings showcase a promising strategy to develop high-performance superlubricating materials that meet stringent conditions for demanding applications.

Chemical transformation of Jojoba oil and Soybean oil and study of their uses as bio-lubricants

Bio-based lubricants have traditionally piqued interest as a supplement to mineral oil-based lubricants in response to rising environmental pollution concerns and declining petroleum assets. This paper discussed the synthesis of bio-lubricants from vegetable oils such as soybean (SOY), and jojoba (JOJ) oil using chemical transformation methods such as epoxidation of the carbon-carbon double bonds in the structure of their already high resistance to air oxidation using a combined catalyst of Amberlite IR 120 and peroxide catalyst with high yield (80 %), followed by transesterification, ring-opening of vegetable oils, and finally acetylation of the hydroxylated obtained products. The rheological and tribological characteristics of the compounds produced were examined to validate their suitability as bio-lubricants using FT-IR, 1H NMR, and TGA techniques. These results demonstrate the possibility of an environmentally sustainable method for producing bio-lubricants.

Alkylation of Tetralin with Butene/Propylene Catalyzed by Ionic Liquid and Its Lubricating Properties

Alkyltetralins similar to naphthenic base oil were successfully synthesized by Friedel–Crafts alkylation of tetralin with short-chain α-olefins (C3/C4), where the applied chemical feedstock could be obtained from coal chemical industry with ease. The Et3NHCl-AlCl3 ionic liquid (IL) as catalyst exhibited excellent catalytic performance for alkylation of tetralin with n-butene or propylene. The reaction conditions were investigated in detail to achieve the high selectivity toward multi-alkyltetralins, and the selectivity for multi-alkyltetralins could reach as high as 90% with the complete conversion of tetralin. For comparison, three alkyltetralins with various side-chain alkyl groups and number of side-chains on tetralin were isolated, which behaved as lubricating base oils for investigation. The synthetic oils exhibited an excellent low temperature fluidity, and good potential for compatibility with additives. Di-propyltetralins (DPT) and di-butyltetralins (DBT) displayed the lower friction and wear values than mono-butyltetralins (MBT), which had comparable tribological properties to the commercial naphthenic base oil 4006 (N4006).

Understanding the influence of graphene-based lubricant/coating during fretting wear of zircaloy

In order to study the relative effectiveness of oil-based and graphene-based lubrications towards suppressing the friction and wear damage of zircaloy-4 during low amplitude linear reciprocatory wear, fretting wear tests were performed with varying normal loads (5–20 N) under unlubricated, oil-lubricated (using Castrol TDN-81) and graphene-lubricated/coated (using ∼7 layers graphene film) conditions against stainless steel ball. While the oil-based lubricant has been found to be more effective towards lowering the co-efficient of friction at lower loads, the effectiveness of the graphene-based lubricant/coating increase significantly with an increase in load. In the contexts of suppressing the extent/severity of wear damage, the graphene-based lubricant/coating has been found to be significantly more effective than the oil-based lubricant. In fact, increase in effectiveness of the graphene-based lubricant/coating with load results in the wear volume remaining nearly invariant upon increase in load; thus, causing reduction in wear rate. This is in contrast to the increase in wear volume/rate with increase in load for the unlubricated and oil lubricated conditions; such that the wear volume and rate are lower for the graphene-lubricated/coated condition by more than a factor of 2 with respect to the oil-lubricated condition at 20 N. In the unlubricated condition severe sub-surface cracking induced material removal/delamination, presumably aided by incorporation of Fe and O due to tribochemical reaction, form the major mechanisms of wear damage of zircaloy-4. By contrast, all these get suppressed in the presence of the graphene-based lubricant/coating, even at 20 N; thus, leading to significant reduction in the overall wear damage.

Evaluation of the effect of silver nanoparticles on the tribological and thermophysical properties of bio-lubricants

In this article, the effect of infusion of silver nanoparticles into the base oil lubricants was investigated. In this study, Jatropha and Pongamia oils were used as base oils and silver nanoparticles infused at 0.25%, 0.5%, and 0.75% weight-percentage of the base oils to create nano-based bio-lubricants. The influence of silver nanoparticles on the Tribological and Thermophysical properties of the base oils was analyzed through various test procedures. The Pin-on-disc tribometer test was done to measure friction and wear at various loads. Pin made of Aluminum metal matrix composite fabricated by stir casting method was used and the results revealed that the inclusion of silver nanoparticles significantly improved the friction and wear properties of the base oils. Pin-worn surface morphology was analyzed using a field emission scanning electron microscope and X-ray diffraction. Thermal conductivity and kinematic viscosity of nano-based bio-lubricants were evaluated as per ASTM standards and the results showed that both the thermal conductivity and kinematic viscosity increased with the infusion of silver nanoparticles.