Friction-reducing Additives Research Articles

Comparison of Eco-Friendly Ionic Liquids and Commercial Bio-Derived Lubricant Additives in Terms of Tribological Performance and Aquatic Toxicity.

Approximately half of the lubricants sold globally find their way into the environment. The need for Environmentally Acceptable Lubricants (EALs) is gaining increased recognition. A lubricant is composed of a base oil and multiple functional additives. The literature has been focused on EAL base oils, with much less attention given to eco-friendly additives. This study presents the tribological performance and aquatic toxicity of four short-chain phosphonium-phosphate and ammonium-phosphate ionic liquids (ILs) as candidate anti-wear and friction-reducing additives for EALs. The results are benchmarked against those of four commercial bio-derived additives. The four ILs, at a mere 0.5 wt% concentration in a synthetic ester, demonstrated a 30-40% friction reduction and >99% wear reduction, superior to the commercial baselines. More impressively, all four ILs showed significantly lower toxicity than the bio-derived products. In an EPA-standard chronic aquatic toxicity test, the sensitive model organism, Ceriodaphnia dubia, had 90-100% survival when exposed to the ILs but 0% survival in exposure to the bio-derived products at the same concentration. This study offers scientific insights for the future development of eco-friendly ILs as lubricant additives.

Effect of Friction Reducers with Unreinforced PEEK and Steel Counterparts in Oil Lubrication

The increasing adoption of PEEK (polyetheretherketone) in many industrial applications has promoted intense research to optimize its lubrication along with the development of friction reducers (FRs), additives that help in reducing fuel consumption and, consequently, CO2 emissions. In this study, the effect of FRs in improving the lubrication of PEEK–steel couplings was evaluated and their mechanism studied using the Mini Traction Machine (MTM) tribometer. Different types of FRs (such as Molybdenum dithiocarbamate, glycerol monooleate, amine and polymeric derivatives) and coupling combinations (steel/steel, steel/PEEK and PEEK/steel) were considered. The oil samples were evaluated as fresh and after a rubbing time considering different operative conditions (from high to low T, fixed load and type of contact motion), and a measurement of the tribofilm was acquired. The experimental campaign showed a ranking among FRs friction-reducing behavior and, in some cases, a synergistic effect was noted between the tribofilm containing the friction modifier and the PEEK surface. Comparing the top performing FRs with reference oil showed a reduction in friction of 22%, 21% and 37%, respectively, in steel–steel, PEEK–steel and steel–PEEK couplings, while in the standard steel–steel coupling, two out of four FRs did not reduce the friction. After conditioning in the presence of PEEK, all friction-modifier additives reduced the friction effectively. This demonstrates the promising performance of PEEK, its compatibility with friction-reducing additives, and its applicability to sliding machine parts in order to improve efficiency and thus reduce CO2 emissions.

Cargill to buy Croda unit

The US-based food processor Cargill plans to acquire the bioindustrial business of the British specialty chemical maker Croda for about $1 billion. The unit makes industrial chemicals including antistatic, antifog, and slip agents for polymers, and friction-reducing additives for engine oils. It also makes building blocks for polymers that improve flexibility and water repellency in coatings, adhesives, and sealants. About two-thirds of the raw materials for those products are biobased and renewable. In October, Cargill bought Arkema’s epoxidized vegetable oil business for $39 million. Last year, Cargill launched a joint venture to make biobased 1,4-butanediol , and its joint venture NatureWorks has been making biobased polylactic acid for decades. Croda says canola oil is the most common feedstock for its bioindustrial products. Cargill is a major vegetable oil producer, with two canola processing plants and a third slated to open in 2024. The deal includes five Croda plants in Europe

Mit explorativer Datenanalyse und Data Mining zu hoch effizienten polymeren Tribo-Schicht-Systemen

Since current developments in machine building and automotive industry are dealing with the amplification of energy efficiency and sustainability of components, the reduction of friction and wear losses plays the most important key role. A further aspect of energy saving by mass reduction can be taken into account by substituting steel by lightweight metals. To fulfill these requirements, this study focuses on the development of a tribo-coating system, based on PEEK (poly-ether-ether-ketone) as a base coating material for Al substrates. The coating is applied by using laser radiation to increase the energy efficiency of the coating process on the one hand and to reduce thermal stress on the component on the other hand. Furthermore, the laser process improves the mechanical prosperties of the polymeric coating. In the first step the correlation between the coating process parameters and the resulting coating morphology accompanied by its mechanical properties and the tribological behavior was elucidated by using explorative data analysis. Here, the influence of different wear and/or friction reducing additives and their variable concentrations was also taken into account, while the tribological response of the resulting coating systems was examined and valuated under dry sliding conditions. Using data mining, the most dominant correlations between the process parameters and the tribological answer of the coating system could be found. Utilizing these findings, the process parameters for different additives in the PEEK dispersions could be optimized, and a multilayer system was established, which combines high corrosion and wear protection accompanied by a tribo-film formation resulting in low friction and an increased lifetime of the coating system.

Polyacrylamide's function on increasing salinity in shale gas wastewater production

Large volumes of water containing friction-reducing additives are injected into target rock formations during hydraulic fracturing in shale gas production. The interactions between the fracking fluids and the reservoir rocks may increase the flowback and produced (FP) salinity, rendering the fluid ineffective for reuse and recycling. To explore the function of polyacrylamide (PAM; a widely applied friction-reducing additive) on the evolution of FP water salinity, three fluid-rock interaction experiments were conducted under relevant temperature conditions. Sr concentrations and 87Sr/86Sr were measured to identify mineral exchanges. Results showed that the dominant geochemical reactions were pyrite oxidation, carbonate, and silicate mineral dissolution, and halite dissolution; the hydrolysis of polyacrylamide facilitated mineral dissolution. Another one-tenth of carbonate was mobilized and the total oxidized pyrite mass was nearly 30 times greater on the function of PAM. These findings imply that the development of brine-tolerant polyacrylamide is necessary to effectively reuse and recycle FP water. This is beneficial for the environment as this minimizes the dependency on freshwater supplies. This study provides new information on the interactions between the fracturing fluid and the reservoir rocks and further elucidates the influence of polyacrylamide on wastewater salinity.

Preparation of a new ionic liquid from cococnut oil for friction-reducing additive for lubricant

A new ionic liquid triethylammonium carboxylate [(C2H5)3NH][RCOO] (where R is fatty acid groups of coconut oil) was synthesized from fatty acid of coconut oil and triethyl amine. Graphene oxide (GO) was synthesized from graphite via modified Hummers method then was reduced to form reduced graphene oxide. The products were characterized and confirmed by FT-IR, XRD and NMR analysis. Friction-reducing additives was prepared from by dispersed reduced graphene oxide in [(C2H5)3NH][RCOO] (0.1%). Friction-reducing properties of materials were measured by GOST P56946-2016 (equivalent to ISO 13500:2008). The results show that using graphene and liquid triethylammonium hydrogen carboxylate lead to increase in the friction-reducing property of based oil in drilling fluid and mixture of them showed highest capacity of increasing the friction-reducing property of drilling fluid.

Adsorption of Stearic Acid at the Iron Oxide/Oil Interface: Theory, Experiments, and Modeling.

Improved friction performance is an important objective of equipment manufacturers for meeting improved energy efficiency demands. The addition of friction-reducing additives, or friction modifiers (FMs), to lubricants is a key part of the strategy. The performance of these additives is related to their surface activity and their ability to form adsorbed layers on the metal surface. However, the extent of surface coverage (mass per unit area) required for effective friction reduction is currently unknown. In this article, we show that full coverage is not necessary for significant friction reduction. We first highlight various features of surface adsorption that can influence the surface coverage, packing, and free energy of adsorption of organic FMs on iron oxide surfaces. Using stearic acid in heptane and hexadecane as model lubricant formulations, we employ a combination of experiments and molecular dynamics (MD) simulations to show how the dimerization of acid molecules in the bulk solvent and the crystallographic orientation of the surface modifies surface adsorption. In addition, we show that the solvent can strongly influence the adsorption kinetics, and MD simulations reveal that hexadecane tends to align on the surface, increasing the energy barrier for the adsorption of stearic acid to the surface. Furthermore, we present a combined approach using MD and molecular thermodynamic theory to calculate adsorption isotherms for stearic acid on iron oxide surfaces, which agrees well with experimental data obtained with a quartz crystal microbalance (QCM). Our results suggest that while the friction of systems lubricated with organic FMs decreases with increasing coverage, complete coverage of the surface is neither practically achievable nor necessary for effective friction reduction for the systems and conditions studied here.

What is the effect of lipophilic polymeric ionic liquids on friction and wear?

In this work, methacrylate-type ionic liquid (IL) monomers containing a quaternary ammonium cation and two different counter-anions were synthesized and used as co-monomers to obtain functional poly(alkyl methacrylates) (PAMAs). They were then evaluated as friction and wear reducing additives for lubricants. The effect of molecular weight, polymer topology (random or diblock), and IL counter anion on friction and wear behavior of polymer PAO (poly-alpha olefin) solutions have been investigated. The results were compared to those of PAO solutions additized with a small molecule, non-polymeric ionic liquid, or non-ionic copolymers containing 2-(dimethylamino)ethyl methacrylate (DMAEMA) as the polar comonomer. No clear correlation between polymer molecular weight and friction or wear behavior was observed. Random ionic liquid copolymers led to lower wear volumes than their block counterparts. Polymers containing dicyanamide (DCA) counter anion showed lower wear volume compared to those containing bis((trifluoromethyl)sulfonyl)imide (TFSI) anion. Surprisingly, none of the IL copolymers studied outperformed the DMAEMA containing block copolymer in terms of wear volume reduction, suggesting the IL moiety had no beneficial effect on wear.

Friction- and Wear-Reducing Properties of Multifunctional Small Molecules

Nitrogen- and oxygen-containing compounds were designed empirically and subsequently synthesized, and their rheology, friction, and wear performance as multifunctional base oils (MFBOs) were evaluated. Two of the compounds displayed good viscosity/rheology profiles without the addition of polymeric viscosity modifiers, displaying high viscosity indexes (VIs) above 200. Furthermore, all three MFBOs had lower coefficients of friction compared to well-established and accepted benchmarks. The most significant advancement is their impressive wear improvement by a factor of 5.5 to 70 compared to either of the benchmarks, which is attributed to the polar nature of the base oil which promotes boundary lubrication with metal surfaces. Moreover, these compounds were easily synthesized in one step from commercial starting materials. This work demonstrates that a careful design could provide the features/performance/functions of base oil, rheology modifiers (or VI improvers), and antiwear and friction-reducing additives, all-in one molecule.

Quantitative structure tribo-ability relationship of ultra-high molecular weight polyethylene modified by inorganic compounds

PurposeUltra-high molecular weight polyethylene (UHMWPE) has an excellent performance and application value; however, as a tribological material, its main drawback is its poor performance under dry friction, impacting its ability to work in high-speed dry friction conditions. Modification of UHMWPE can be carried out to overcome these issues. A significant number of inorganic materials have been used to modify UHMWPE and provide it with good tribological performance. However, thus far, there has been no systematic investigation into the methodology of modifying UHMWPE. The authors take a quantitative approach to determine the structure tribo-ability relationship and basic principles of screening of inorganic compounds suited to modify UHMWPE.Design/methodology/approachThe tribological properties of modified UHMWPE using a series of inorganic additives have been qualitatively studied by the authors’ research group previously. In this study, basic quantitative structure tribo-ability relationships (QSTRs) of inorganic additives for modifying UHMWPE were studied to predict tribological properties. A set of 15 inorganic compounds and their tribological data were used to study the predictive capability of QSTR towards inorganic additives properties.FindingsThe results show that the anti-wear and friction-reducing properties of these inorganic compounds correlate with the calculated parameters of entropy and dipole moment. Increased entropy and smaller dipole moment can effectively improve the anti-wear and friction-reducing ability of inorganic compounds as UHMWPE additives. Additives with larger molecular weight, lower hardness and lower melting and boiling points provide good tribological properties for UHMWPE. For inorganic compounds to act as UHMWPE additives, the chemical bond should be less covalent and have more ionic character.Research limitations/implicationsOnly 15 inorganic compounds and their tribological data were used to study the predictive capability of QSTR towards inorganic additives properties. If the samples number is more than 30, the other QSTR methodology can be used to study the modified UHMWPE, and the models finding can be more precise.Practical implicationsA QSTR model for modified UHMWPE has been studied systematically. While the results are not more precise and detailed, the model provides a new way to explore the modified UHMWPE characteristics and to reveal new insight into the friction and wear process.Social implicationsBecause the method of studying tribological materials is entirely different from others, the authors want to present the works and discuss it with colleagues.Originality/valueThe paper presents a new method to study the modified UHMWPE. A QSTR is used to study the tribology capability of compounds from calculated structure descriptors. This study uses the Hartree–Fock ab initio method to establish a QSTR prediction model to estimate the ability of 15 inorganic compounds to act as anti-wear and friction-reducing additives for UHMWPE.

Microwave Dehydration Behaviour of Inderite and Comparison with Thermal Analyses Methods

Dehydration is called as the water removal from hydrated structure. Dehydration behavior is important for the usage areas and transportation of minerals. Magnesium borates can be used as additive materials in areas such as in the production of superconducting materials, in the composition of detergents, due to the content of boron in the friction-reducing additives in oils and insulating coating compositions due to their good mechanic and thermal properties. In this study, dehydration behavior of Inderite (Mg(B 3 O 3 (OH) 5 ).5H 2 O) was experimented by both using microwave energy different and thermal analyses techniques. In microwave dehydration, power level was selected as 600W. Mass loss and drying rates were determined. In thermal dehydration, hydrated mineral was applied to thermal analysis (TG-DTG). Structural changes of hydrated and dehydrated samples were characterized using the techniques of XRD and FT-IR. XRD results show that crystallinity of sample may decrease in microwave dehydration. According to FT-IR results, characteristic band values of water disappeared at the end of the dehydration.

Tribological Performance Evaluation of Task-Specific Ionic Liquids Derived from Amino Acids

Aspartic acid and glutamic acid derived ionic liquids were found to be efficient antiwear and friction-reducing additives for base oils. The tribological performance evaluation of lubricant blends, prepared as 0.15%, 0.3%, 1%, 1.5%, 2%, and 3% concentration by weight into the mineral base oil, was carried out on a four-ball tribotester. The concentration of ionic liquids along with the chain lengths of alkyl groups influenced the tribological performance of the formulated blends. The synthesized ionic liquids exhibited excellent antifriction and antiwear characteristics.

Impact of connection between specimen and load plate on viscoelastic material response of hot mix asphalt

In routine testing of hot mix asphalt (HMA) cyclic compression tests (CCT) are carried out to assess the permanent deformation behavior. However, CCTs can also be employed for determining the material response within the linear viscoelastic domain in terms of stiffness and phase lag, when a frequency and temperature sweep is considered. In the compressive domain two test setups are possible regarding the connection between load plate and specimen: The specimen is either firmly connected (glued) to the load plates, which prevents transverse strain at the end planes, or the specimen is placed between the load plates without firm connection. In this case friction-reducing additives (e.g. silicone grease) applied to the end planes of the specimen help to create a more homogeneous strain distribution over the height of the specimens, since limited transverse strain are also be activated at the end planes of the specimen. This paper investigates whether these two test setups produce comparable results in terms of viscoelastic material reaction of HMA. Therefore, CCTs were run on HMA-specimens with the two test setups. Data evaluation was carried out by means of regression analysis with a standard sine and an advanced function containing the first harmonic oscillation term. It is shown that the parameters of the first harmonic term are able to describe the magnitude and shape of a distorted sine. Data from force and axial deformation signals are analyzed as well as the derived viscoelastic material reaction. From the findings of the study it can be concluded that cyclic material tests in the compressive domain are capable of describing the viscoelastic material behavior of HMA regardless of the connection between specimen and load plates and that they are comparable to results of a well-established, standardized stiffness test, the 4-point-bending test. It is also shown that the regression analysis with the advanced function can be employed to analysis the quality of response of the test machine. Thus, technical limits of test machines and deformation sensors can be detected by using the regression analysis with the advanced approximation function.

The Tribological Properties of Ionic Liquids Composed of Trifluorotris(pentafluoroethyl) Phosphate as a Hydrophobic Anion

The tribological properties of trifluorotris(pentafluoroethyl) phosphate [(C2F5)3PF 3 − , FAP]-derived ionic liquids were evaluated under boundary conditions. The anion is hydrophobic in comparison with bis(trifluoromethylsulfonyl)imide [(CF3SO2)2N−, TFSI]. 1,3-Dialkylimidazolium salts of FAP provided much lower friction than 1,3-dialkylimidazolium salts of TFSI. In addition, the FAP salts exhibit better anti-wear properties than the TFSI salts. Another advantage of the FAP anion is availability of several cations to prepare ionic liquids. For example, tetraalkylphosphonium, N,N-dialkylpyrrolidium, and tetramethylisouronium salts of FAP provided friction coefficient of approximately 0.1. Straight-chain carboxylic acids as model friction-reducing additives improved the tribological properties of the FAP salts. Surface analyses were conducted to study the boundary film formed by rubbing. It was found that the boundary film is composed of adsorbed anion on uppermost surfaces and reacted anion on sub-surfaces. The model friction-reducing additives were found on the rubbed surfaces.

Improvement in the tribological properties of imidazolium‐derived ionic liquids by additive technology

AbstractMolecular design of wear‐preventing and friction‐reducing additives for ionic liquids is described. The tribological properties of carboxylic acid‐derived additives were evaluated by a ball‐on‐flat type tribotest under reciprocating motion. Tetraalkylammonium and tetraalkylphosphonium salts of N‐benzyl‐protected aspartic acid were dissolved in 1‐alkyl‐3‐methylimidazolium‐derived ionic liquids. They prevented wear remarkably and reduced friction fairly. Influences of alkyl group in imidazolium molecule on additive response were observed. In tetraalkylammonium‐derived ionic liquids, the additive reduced wear but did not reduce friction under these conditions. The salt of N‐acetyl‐protected glutamic acid prevented wear, but did not reduce friction. Copyright © 2008 John Wiley & Sons, Ltd.

Performance of Used Engine Oil as Gear-Cutting Oil

In Japan, the lubricating oil used for the internal combustion engine of passenger cars is usually exchanged for fresh oil after running a distance in the range from 3,000 to 10,000 km. Refining of the used engine oil is very costly because friction-reducing additives containing sulfur, phosphorus, etc., are included in the oil. Therefore, wasted engine oil (used engine oil) is burned in many cases. This investigation was conducted to effectively re-use wasted engine oil without chemical refining. Performance of used engine oil as a gear-cutting oil was examined by conducting five kinds of experiments: (a) chemical analyses of the oils, (b) measurements of friction coefficients on the four-ball tester, (c) tool wear tests using a lathe, (d) tool life tests using a gear-cutting machine, and (e) accuracy and surface finish of the cut gears. In contrast to general expectations, longer tool lives were obtained when the used engine oils were used instead of a high-grade gear-cutting oil. The reason for this was discussed and it was concluded that used engine oil may be used as a high-performance gear-cutting oil if health risks for workers are removed.

Chemical and Physical Analysis of Reaction Films Formed by Molybdenum Dialkyl-Dithiocarbamate Friction Modifier Additive Using Raman and Atomic Force Microscopy

In order to improve the fuel economy of engines it is now common to include in modern engine oils small quantities of soluble, molybdenum-based friction-reducing additives. These additives are generally believed to form MoS2 in rubbed contacts and thereby reduce friction in boundary lubrication conditions. This paper describes the application of Raman and atomic force microscopy to study the reaction films formed in rubbing contacts by simple solutions of molybdenum dialkyl-dithiocarbamate additive. Raman microanalysis shows that MoS2 is present in the wear scars produced whenever this molybdenum additive effectively reduces friction. In reciprocating friction tests, the MoS2 is unevenly distributed in the wear scar, with more in the centre of the stroke than at the reversal points. This explains the experimentally observed influence of stroke length on friction. Atomic and lateral force microscopy show that when the additive effectively reduces friction, tiny, discrete, flake-like low friction domains are present in the wear scar. These are typically 10–25 nm in diameter and 1–2 nm thick and are believed to represent MoS2 nanocrystals as have been previously reported in the literature using high-resolution TEM. Coupled topography and lateral force measurements shows that these nanocrystals are present only on the high spots of the rubbed surface.

Anti-wear and friction reducing additives composed of ortho-phenylene phosphate-amine salts for polyether type base stocks

Lubrication properties of amine salts of diaryl phosphates in polyether type base oils were evaluated by means of the four-ball wear test. The unique cyclic phosphate, ortho-phenylene phosphate, prevented wear and reduced friction when combined with tertiary amines. Adsorptivity, solubility, and corrosivity of the additives were taken into account.

The relationship of tangential stress to wear particle formation mechanisms

Experimental results and observations by scanning electron microscopy have demonstrated that the process of wear particle formation under lubricated sliding conditions is greatly affected by the tangential stress. In these experiments, the normal load was kept constant and the tangential stress was varied by changing the friction coefficient using different friction-reducing additives in the base oil. The predominant wear mechanism is related to the magnitude of friction coefficient attained by the friction modifier. The wear rate and the level of surface damage are greatly reduced if the friction coefficient is lower than a specific threshold value. Under these conditions wear particles are formed from deformation of surface asperities. At higher friction coefficients more wear was observed to occur by the process of plowing and delamination ( i.e. subsurface microvoid and crack formation). Under severe wear conditions and lubrication failure, extremely large amounts of wear and severe surface damage result from the adhesive wear mechanism ( i.e. material transfer across the contact surface).

Turbulent structure of flows with friction-reducing additives

The mean-velocity and turbulence intensity profiles are measured in water flows containing additives of polymers and surface-active agents.